Seismic Applications by alicejenny


									                                    S E I S M I C              A P P L I C A T I O N S

Geostatistical reservoir characterizations     BACKGROUND                                         thickness were determined from a reservoir
from three-dimensional (3D) -seismic vol-      The study uses two volumes of “off-the-            interpretation of the 1988 data by use of a
umes provide most static descriptions for      shelf” data for time-lapse analysis. The           time/depth transfer table and inverted
reservoir models. These models can be          base 3D-seismic volume was acquired in             acoustic impedance.
improved by integrating the dynamic data       1988 before production of the reservoir,              Data from the initial reservoir-characteri-
in the reservoir-description process. Three-   and the monitor 3D-seismic volume was              zation study were combined with log, labo-
dimensional time-lapse-seismic surveys         acquired in 1994, after more than 5 years          ratory, and production information to build
have been proposed to relate time-depen-       of production. The difference in orienta-          an initial simulation model. Depth, thick-
dent changes in seismic attributes to the      tion of the two surveys was small. The base        ness, and porosity were scaled up. Absolute
flow processes in the reservoir. Once an oil   survey was reprocessed to improve imag-            permeability was determined with a poros-
reservoir has been found and is being pro-     ing to match the 1994 processing sequence          ity/permeability relation provided by the
duced, it is important to understand fluid     more closely. Both volumes were processed          producer. The relative permeability, pres-
movement as it relates to the flow mecha-      through deterministic and adaptive decon-          sure, and initial saturations were obtained
nism and reservoir heterogeneity. Recently,    volution, 3D dip moveout, and one-pass             from well-test, log, and core data. The
3D-seismic data have been used success-        3D migration. The monitor volume was               reservoir had an initial reservoir pressure of
fully to improve reservoir characterization    interpolated to smaller bins before migra-         approximately 9,000 psia at a depth of
with extraction of reservoir parameters by     tion. Because the focus of the study was to        11,000 ft. Once the initial model was built,
inversion, geostatistics, and petrophysics     demonstrate an improved seismic history-           forward modeling was performed to match
to understand the coupling between seis-       matching method, legacy data (rather than          the time-dependent or dynamic data.
mic and rock properties. More than 10          data reprocessed from field tapes) were
years ago, laboratory work demonstrated        used to minimize differences. Accuracy of          FORWARD MODELING
that different fluid substitutions can cause   results should improve with the use of             Time-lapse-seismic data are multiple mea-
acoustic changes, and time-lapse seismic       carefully reprocessed data sets. The sand is       surements on the same reservoir at different
was proposed to capture the changes in         Pliocene Age and pinches out onto a salt-          times. They can be considered dynamic
reservoir properties with time. These most-    related structural high that controlled            information related to reservoir production.
ly qualitative studies showed that time-       deposition. The average porosity is approx-        To optimize production-history and time-
lapse seismic, even on legacy data, resulted   imately 31%, and permeability is approxi-          lapse-seismic matching, it is essential to
in a better understanding of the production    mately 500 md. Analysis of log and                 understand forward modeling, especially
behavior of the reservoir. Time-lapse-seis-    water/oil-contact data indicates that the          modeling that bridges seismic responses
mic data are used mainly for monitoring        reservoir has good lateral continuity and          and fluid flow.
fluid movement in reservoirs. With the         shows high acoustic contrast between live
integration of other data, they can provide    oil and water. The production is controlled        Flow Simulation. Fluid flow in the reser-
an avenue for reservoir characterization,      by a strong waterdrive.                            voir can be simulated with a conventional
including fluid movement and other reser-                                                         simulator. An efficient simulator is critical
voir properties. The full-length paper         RESERVOIR DESCRIPTION                              to the entire process because the simulation
details a case study on a turbidite sheet-     The reservoir-description goal is to obtain
sand reservoir in the Gulf of Mexico off-      the spatial distribution of the reservoir’s sta-
shore Louisiana.                               tic properties. The 1988 seismic-survey
                                               data were calibrated with well data, and the
                                               top and bottom of the reservoir were
                                               mapped in depth. More than 20 attributes
This article is a synopsis of paper SPE        were extracted and analyzed. The instanta-
38695, “Reservoir Characterization by          neous amplitude (Fig. 1) measured in a 24-
Integration of Time-Lapse-Seismic and          millisecond window from the top of the
Production Data,” by Xuri Huang, SPE,          reservoir correlated best with the average
Laurent Meister, and Rick Workman,             porosity from the wells (0.82 correlation
SPE, Western Geophysical, originally           coefficient). The spatial distribution of the
presented at the 1997 SPE Annual               porosity inferred from the instantaneous-
Technical Conference and Exhibition,           amplitude map was then computed with                Fig. 1—Instantaneous-amplitude map.
San Antonio, Texas, 5–8 October.               geostatistical cosimulation. Depth and

30                                                                                                                           MAY 1998 •
                                      S E I S M I C              A P P L I C A T I O N S

must be repeated many times. The synthet-         TIME-L APSE-SEISMIC                                 If a production-history match is ob-
ic production history and fluid saturations       DIFFERENCING                                     tained without use of time-lapse-seismic
are obtained in the entire reservoir from the     To “difference” two 3D-seismic surveys,          information and no other constraints are
simulation results.                               one survey is subtracted from the other for      used, the model characterization will be
                                                  certain events. Seismic data or attribute vol-   nonunique. In addition, the characteriza-
Seismic Forward Modeling. Seismic                 umes may be differenced. The two volumes         tion probably will be unable to capture the
response is a function of the seismic source      of seismic data must be in the same grid         high degree of heterogeneity in the reser-
and the acoustic properties of the reservoir.     system and the nonreservoir part must be         voir. In turn, the residual-oil distribution
For post-stack seismic data, the major            repeatable for the two volumes. Repeat-          and future fluid movement can be erro-
property is acoustic impedance (compres-          ability is important in establishing confi-      neous or lack detail.
sional velocity multiplied by density) of the     dence in the physical meaning of the differ-        If the seismic history is matched without
reservoir rocks. Therefore, a simple convo-       ence in the reservoir zone. Regridding and       consideration of production data, the
lution model can be used. To produce              processing the data to improve repeatabili-      result is a quantitative time-lapse-seismic
unstacked data, wave-equation forward             ty is called normalization. To achieve these     analysis because the simulation provides a
modeling can be used. From the synthetic          goals, the two surveys were rebinned into        quantitative distribution of saturation and
data, attributes (such as average or instan-      the same grid system by use of linear inter-     pressure. Two important issues must be
taneous amplitude in the reservoir zone)          polation in the frequency domain. The data       addressed to obtain the best results. First,
can be computed. Time-lapse-seismic-data          of the two volumes may be different in           the time-lapse seismic must be repeatable.
matching compares the actual seismic              amplitude and phase. To normalize the vol-       A lower difference should exist for the
attribute from the second survey with the         umes further, several approaches can be          nonproducing zone compared with the
attribute from forward modeling on the            applied, including the following.                detectable signal. Otherwise, the noise or
basis of the reservoir-simulation result.                                                          artifacts from the data acquisition or pro-
                                                  Windowed Spectral Crossequalization.             cessing may lead to the wrong conclusion
Petrophysical Model. To integrate time-           In this approach, a zone outside the reser-      about the reservoir. Second, the petrophys-
lapse seismic with the fluid flow, it is criti-   voir is chosen. For the common frequency         ical model should reflect a reasonable
cal to synthesize the acoustic properties         band, the spectra are forced to be equal         change compared with reality. An incorrect
from the fluid-flow information. The full-        trace by trace and other frequencies are fil-    petrophysical model can lead to an incor-
length paper provides details on the use of       tered out. The filter determined from the        rect saturation interpretation. This weight-
Gassmann’s model to compute synthetic             equalization is then applied to the full         ing of the objective function is critical for
seismic attributes. These attributes were         window. This approach generally zeros out        the residual or bypassed oil/gas detection
analyzed for a time-lapse feasibility study.      the difference in the zone of crossequaliza-     and analysis. It may not be satisfactory for
The porosity anomaly alone cannot create          tion while increasing the difference in the      future production prediction; however, if
the amplitude anomaly shown in Fig. 1 for         other portion.                                   the data can be repeated and the petro-
the example field. Fluid content dominates                                                         physical model reflects the truth, the
the seismic change for this field.                Windowed Phase Crossequalization. In             model should predict a result consistent
   The model, which uses production-his-          this approach, the phases of corresponding       with that from the history match.
tory and borehole-pressure data con-              traces from different surveys are equalized         If the optimization integrates both types
straints, can be simulated to the time when       in the selected window. Once the phase is        of constraints to perform the reservoir char-
the second survey was acquired (1994).            equalized, the amplitude can be scaled lin-      acterization, the model can match both
Fig. 2 shows the water-saturation distribu-       early with regression or other such tech-        types of data. However, if the time-lapse
tion in 1994. The synthetic 3D-survey data        niques. For this approach, the residual dif-     seismic is not repeatable or the petrophysi-
were built from this simulation result and        ference can be relatively uniform over the       cal model is not accurate, the optimized
the petrophysical model. Pressure and tem-        whole data volume; higher differences in         result may be compromised. All data must
perature effects were not considered.             the reservoir can be attributed to the phys-     be high quality. The example in the full-
                                                  ical reservoir-property change.                  length paper shows that porosity and per-
                                                                                                   meability are similar to those obtained with
                                                  INTEGRATION AND                                  the time-lapse-seismic data only. It is diffi-
                                                  OPTIMIZATION                                     cult to judge which are the correct porosity
                                                  To match the production data, the static         and permeability for this case. However, the
                                                  data must be honored with an optimization        reservoir models generated with both con-
                                                  technique. The time-lapse-seismic data pro-      straints do achieve a better match to the
                                                  vide another constraint for history match-       pressure and production rate compared
                                                  ing because they are related to dynamic          with the case that uses time-lapse-seismic
                                                  properties. To match the production histo-       data only.
                                                  ry and time-lapse-seismic data, the simula-
                                                  tion model is perturbed and an objective
                                                  function is evaluated. The algorithm iter-
                                                  ates the process by choosing a parameter,        Please read the full-length paper for
                                                  such as porosity (while the statistical rela-    additional detail, illustrations, and ref-
 Fig. 2—Simulated water saturation for            tion between porosity and permeability is        erences. The paper from which the syn-
 the initial model as of 1994.                    unchanged), to be perturbed until the func-      opsis has been taken has not been peer
                                                  tion is less than a given threshold.             reviewed.

       • MAY 1998                                                                                                                             31
                                          S E I S M I C              A P P L I C A T I O N S

                                                      Nine additional appraisal wells were drilled     reservoir section is characterized by a strong
                                                      during 1988–91. Two wells, PY-3-3 and PY-3-      amplitude package (Fig. 2). However, the
                                                      4, tested hydrocarbons, and the rest were        event defining the top of the true effective
                                                      abandoned as dry holes. This appraisal cam-      reservoir appears to be composite in nature
                                                      paign, which used an assortment of two-          and is affected by the presence of thin sand
                                                      dimensional (2D) -seismic lines, led to the      stringers almost directly above.
                                                      acquisition of a three-dimensional (3D) -seis-      The reservoir is sealed by the overlying
                                                      mic survey in 1990–91 to delineate the reser-    Porto Novo shale that comprises a thick
                                                      voir distribution.                               sequence of calcareous mudstones and silts.
                                                                                                       The trap is formed by dip closure to the
                                                      GEOLOGIC AL SETTING                              north and south, by a combination of dip
                                                      The PY3 field lies in the Cauvery basin with-    and stratigraphic pinchout to the west, and
                                                      in the north-northeast trending Tranquebar       dip and truncation to the east.
                                                      sub-basin. Developed in late Jurassic/early
                                                      Cretaceous, the basin straddles the present-     SEISMIC INTERPRETATION
                                                      day east coast of India. The upper               Six main seismic markers were picked dur-
                                                      Cretaceous reservoir comprises turbiditic,       ing the interpretation.
                                                      debris-flow sand bodies that have been sub-         1. Intra-Eocene Event. This event forms a
                                                      divided vertically into five units [A (upper-    prominent feature toward the south and
 Fig. 1—Location map.                                 most) through E]. Sand quality and distrib-      east of the area where it appears as the junc-
                                                      ution are highly variable, with the best         tion between an underlying seismically
                                                      reservoir characteristics observed on the        opaque sequence and an overlying relative-
The PY3 field is in the Cauvery basin approxi-        western side (core area) of the field. In the    ly-high-amplitude, layered, on-lapping
mately 10 km off the coast of southeast India         core area, porosities of 20% and permeabili-     sequence. These sequences are interpreted
(Fig. 1). An accurate depth model has been            ties of 30 to 40 md are recorded in the upper    to represent a low-stand buildup feature
difficult to define in this field, which has led to   sand units. Gross reservoir thickness aver-      that was subsequently submerged beneath a
problems with well prognoses and reserve esti-        ages approximately 70 m. Seismically, the        transgressive (high-stand) sequence.
mations. Depth-conversion difficulties result
from rapidly varying overburden stratigraphy
because the field is beneath a series of stacked
shelf-edge sequences. This phenomenon caus-
es rapid, unpredictable lateral velocity changes
that lead to conversion of time “lows” to depth
“highs.” Discovery Well PY-3-2 was drilled by
Oil and Natural Gas Corp. (ONGC) in 1988
and produced approximately 3,000 B/D of
48°API oil plus 3.45 MMcf/D of associated gas.

This article is a synopsis of paper SPE
39499, “The Application of Prestack
Depth Migration Using Tomographic
Analysis To Aid in the Reduction of
Uncertainty in the Depth Model for the
PY3 Field, Cauvery Basin India,” by
N.K. Oates, Hardy E&P India Inc.;
P. Harinder, Tata Petrodyne; and
C. Willacy, GX Technology, originally
presented at the 1998 SPE India Oil
and Gas Conference and Exhibition,
                                                       Fig. 2—Representative seismic line (151) through the PY3 field.
New Delhi, India, 7–9 April.

32                                                                                                                                MAY 1998 •
                                     S E I S M I C               A P P L I C A T I O N S

   2. Top-Eocene Marker. This event is              6. Near-Top Basement. This event was              a range of values for structural elevation
defined as a strong trough at the top of a       mapped to increase regional understanding            and to test the drilling-location sensitivity
high-amplitude seismic package. It shows         of the basin development. The event was              to different depth-conversion treatments.
evidence of slump faulting related to deep-      based on seismic character changes
seated structuring. Several good-quality         between the predominantly crystalline                Interval-Velocity Method. The seismic
sands are in this package, but no prospects      Archean basement and the sedimentary                 sequence down to the reservoir top was
have been identified.                            infill. Although this event comprises fault-         divided into four layers (water; seabed to top-
   3. Near-Top-Cretaceous Unconformity.          scarp zones, it was picked as a continuous           Eocene marker; top-Eocene marker to near-
This event appears as a broad trough that        horizon to ease mapping and modeling.                top-Cretaceous unconformity; and near-top-
shows, in places (particularly the south and        Because of the nature of the mute applied to      Cretaceous unconformity to reservoir top).
east), marked truncations below and onlaps       the 3D data set, it was not possible to pick a          Interval velocities within each layer were
above. Toward the north and west of the          seabed reflector. Water-depth information was        mapped with a combination of acceleration
area, this event becomes parallel to subpar-     restricted to well measurements and soundings        factors and well-interpolation/-extrapola-
allel with adjacent events and, therefore, is    taken during seismic acquisition. The two-           tion techniques. A back-calculated average
more difficult to interpret.                     way-time structure map of the reservoir-top          velocity (mean sea level to reservoir top)
   4. Effective Reservoir Top. The true          level indicates that the field exhibits no closure   was created by use of the depth map and
reservoir top is difficult to define seismi-     in the time domain. Therefore, the existence of      the two-way times. This calculation
cally but, for mapping purposes, the             any structural closure can be demonstrated           enabled a direct comparison with the stack-
pick was made at a zero crossing (peak           only by time-to-depth conversion.                    ing-velocity approach.
to trough) beneath a pronounced peak.
The reservoir interval itself is characterized   DEPTH CONVERSION                                     Stacking-Velocity Method. The stacking
by a single, broad, generally-high-ampli-        Historically, depth conversion has been a            velocities used for the original processing of
tude trough.                                     major problem in the Cauvery basin and a             the 3D data set were loaded as a velocity
   5. Reservoir Base. This event is generally    significant factor in well failure. The chal-        cube. From this cube, an average velocity
defined as a moderate-to-strong peak, but        lenge was to devise a depth-conversion               from mean sea level to reservoir top was
occasionally becomes indistinct. However,        technique that reflects the rapidly varying          extracted. This initial field was extremely
it is possible to map this time horizon over     nature of the overburden geology adequate-           noisy; therefore, the raw field was
most of the study area, even where the           ly. For this interpretation project, two             smoothed with a 500-m Lowess filter and
reservoir section itself is absent.              methods were applied in parallel to provide          by manual point editing to remove isolated

34                                                                                                                                MAY 1998 •
                                    S E I S M I C               A P P L I C A T I O N S

anomalous values. This smoothed velocity        SEISMIC REPROCESSING                               ing the crossline time migration. This proce-
grid was then calibrated to tie to well val-    The original processed data were deter-            dure reduced the size of the data set on the
ues. Calibration required gridding of the       mined unsuitable for prestack depth migra-         computer system and improved the
well values and use of the smoothed veloc-      tion because of an abundance of low-ampli-         signal/noise ratio of the data. During the par-
ity grid as an external drift. Additional       tude random noise and the presence of              tial stack, the offset planes were regularized to
manual smoothing was also applied to pro-       high-amplitude noise bursts throughout the         a 150-m increment, producing superoffset
duce the map.                                   offset range. The data set was reprocessed to      planes. The resultant data set had a stacked
   The stacking-velocity technique indicated    clean it up and to improve the signal/noise        pseudofold of 144 and was used for the
higher relief across the central area of the    ratio. A combination of channel suppres-           remainder of the prestack work flow.
field but predicted steeper and deeper flanks   sion and function-of-x deconvolution was              Velocity analysis was accomplished with
than the interval-velocity method. Locations    used to improve the signal quality and to          iterations of travel-time tomography and
for development wells were chosen on the        facilitate prestack-domain use of the data.        depth focusing. The tomographic inversion
basis of commonality between the two depth         Velocity-analysis lines were extracted from     uses a common-reflection-point (CRP) -ori-
maps to minimize the risk of drilling a         the 3D volume with a proprietary 3D                ented ray-tracing technique rather than a
depth-conversion-induced anomaly.               crossline-migration program. This program          traditional common-midpoint (CMP) or
   The joint-venture members felt that,         compensates for out-of-plane events and repo-      common-receiver method. The CRP tech-
while the well-derived velocity values          sitions the 3D prestack data into a user-defined   nique traces rays reflecting on a known
could be regarded as hard data, the same        set of 2D lines suitable for detailed velocity     interface at a known location that originate
was not true of the stacking-velocity data.     analysis. The adopted approach involves bifur-     from a source/receiver pair with a known off-
Consequently, a trial reprocessing exercise     cating the migration operator into crossline                                     .
                                                                                                   set but an unknown CMP The main advan-
was initiated on only four lines chosen to      and inline components. The first workflow          tages of CRP ray tracing are the ability to
give a reasonable spatial coverage. This        stage (crossline migration) migrates the ener-     provide regular sampling along the inter-
trial was designed to generate improved         gy in the crossline direction and then is          faces (more appropriate for depth inversion)
stacking-velocity data and to produce a         applied to all input traces perpendicular to the   and the ability to simplify the management
number of high-resolution seismic pro-          inline plane. The second stage involves time or    of multiple arrivals.
files. To achieve these objectives, the rec-    depth migration that relocates the trace energy       After tomographic inversion, a 2D Kirchoff
ommendation was that these lines be             to its correctly migrated position. The original   common-offset depth migration was per-
reprocessed by use of prestack depth-           48-fold data (50-m offset increment) acquired      formed on each of the analysis lines.
migration software.                             over the PY3 field were partially stacked dur-     Retuning of the interval-velocity depth

       • MAY 1998                                                                                                                               35
                                   S E I S M I C             A P P L I C A T I O N S

                                                                                model was carried out with a series of focus-
                                                                                ing panels generated during the depth migra-
                                                                                tion. These fully migrated focusing panels
                                                                                were built by taking into account adjacent
                                                                                common-data points within the migration
                                                                                aperture. The migration-velocity grid is per-
                                                                                turbed in small increments and decrements
                                                                                of velocity, and the seismic traces are migrat-
                                                                                ed and their coherency calculated for each
                                                                                velocity perturbation. Adjustments to the
                                                                                depth-migration-velocity grid are made by
                                                                                picking the velocity that corresponds to the
                                                                                maximum reflector coherency. Several focus-
                                                                                ing and depth migrations are required before
                                                                                the velocity model is fully optimized.
                                                                                Velocity-depth picks were then merged and
                                                                                interpolated into maps and, subsequently,
                                                                                into an integrated full-volume, 3D velocity-
                                                                                depth and structure model (Fig. 3).

                                                                                The immediate impression from the
                                                                                reprocessed data is cleaner, sharper defini-
                                                                                tion compared with the original versions.
                                                                                Improved resolution was particularly
 Fig. 3—Three-dimensional structural model of the main picked depth surfaces.
                                                                                noticeable at and around the reservoir level
                                                                                and had a significant effect on the under-
                                                                                standing of reservoir distribution and prob-
                                                                                able small-scale faulting. These changes
                                                                                added many details to the reservoir model.
                                                                                   While the original stacking-velocity field
                                                                                is noisy (even after attempts to smooth it),
                                                                                its overall trend is in broad agreement with
                                                                                the trend derived during the tomographic
                                                                                analysis. However, if the well-calibrated
                                                                                velocity profile is compared with that of the
                                                                                smoothed original stacking velocities, the
                                                                                apex of the velocity profile on the original
                                                                                (in this case a velocity low) has shifted lat-
                                                                                erally some 2.5 km. This shift results from
                                                                                the variable correction required to tie the
                                                                                stacking-velocity field to the actual well-
                                                                                derived values (Fig. 4).
                                                                                   Therefore, the calibration of stacking
                                                                                velocities with actual well velocities has
                                                                                resulted in a distortion of the original trend
                                                                                information from the stacking velocities.
                                                                                Additional work is required to investigate
                                                                                the reasons for the wide variance between
                                                                                stacking and well velocities. In addition,
                                                                                the choice of geostatistical technique used
                                                                                to calibrate stacking with well velocities
                                                                                needs to be reviewed to maintain the maxi-
                                                                                mum retention of trend information from
                                                                                the stacking-velocity field.

                                                                                Please read the full-length paper for
                                                                                additional detail, illustrations, and ref-
                                                                                erences. The paper from which the syn-
                                                                                opsis has been taken has not been peer
 Fig. 4—Map showing shifts required to tie stacking velocity to well values.

36                                                                                                          MAY 1998 •
                                    S E I S M I C              A P P L I C A T I O N S

The U.S. Dept. of Energy (DOE) Class 2
Demonstration Project operated by Oxy
U.S.A. Inc. in the West Welch Unit was
designed to enhance economics of
improved-oil-recovery (IOR) projects in
lower-quality, shallow-shelf carbonate
reservoirs. Accurate reservoir description
is critical to effective evaluation and effi-
cient design of IOR projects in heteroge-
neous reservoirs. Therefore, most of the
preinjection effort was devoted to develop-
ing a geological model that allows a flow
simulator to match and predict reservoir
performance accurately. The basic geologi-
cal input for flow simulation is constructed     Fig. 1—Seismic-data-guided average              Fig. 2—Wellbore-data-guided average
from wellbore data (primarily log data with      porosity; contour interval = 1 p.u.             porosity; contour interval = 1 p.u.
occasional core information). In the DOE
project area, well spacing averaged more
than 600 ft. Although three-dimensional            Geological layers were combined to form      property values and their location between
(3D) -seismic data are often available, the     equivalent units equal to the seismically       well control.
vertical resolution is not suitable to match    defined intervals. With wellbore data as a
the layering in the flow simulator.             guide, the seismic values were propor-          Seismic Interpretation. Geophysical lay-
Geological layering divided the producing       tioned to the geological layers. This tech-     ers were used to interpret the 3D volume.
interval into nine layers of varying thick-     nique provided greater density control to       Once interpreted, various seismic attri-
nesses. Through use of seismic attributes, a    match the geology in the interwell areas.       butes were extracted from the volume for
map (grid) of the thickness and average                                                         the intervals at well locations. The Hilbert
porosity was generated for the producing        Process. The first step is to correlate         transform was used to compute instanta-
interval. Seismic data could reliably divide    defined layers through the model area.          neous amplitude and phase (these were
the reservoir interval into only two units:     Then, seismically definable layers are          summed over the interval to create reser-
upper and lower. The challenge is how to        identified with synthetic seismograms for       voir amplitude and reservoir phase).
proportion this information realistically       the reservoir layer. These layers are corre-    Frequency, isopach, structure, and relative
into the geological layers used in the flow     lated through and around the model area.        amplitude were also extracted from the
simulator. The accuracy of the seismically      The next step is to define the reservoir        data volume. Each parameter was crosscor-
generated porosity values has been con-         properties for all layers, both simulation      related to reservoir parameters obtained
firmed by subsequent infill drilling outside    and seismic layers. The values for average      from well-log data and core analyses.
the project area. The values agree with the     porosity, porosity/thickness (φh), average      Water-saturation and permeability parame-
log data from new wells to an accuracy of       permeability,      permeability-thickness,      ters proved to have no definitive correla-
less than 0.5 porosity unit (p.u.).             thickness, structure, and water saturation      tion with seismic attributes; however, a sig-
                                                are computed from reliable log and core         nificant correlation was found between
                                                data. To permit better interpretation of the    average porosity and the summed instanta-
This article is a synopsis of paper SPE         seismic response, porosity and permeabil-       neous amplitude, structure, and summed
39809, “Improving Flow Simulation               ity values are calculated without cutoff        instantaneous phase. These seismic attrib-
Performance With a Seismic-Enhanced             values because the response is for the total    utes were used to create a calibration func-
Geologic Model,” by G.D. Hinterlong,            section and will not reflect an arbitrary       tion to estimate average porosity by use of
SPE, A.R. Taylor, SPE, G.P Watts, Oxy
                            .                   reservoir cutoff. Without seismic input,        an overdetermined linear-regression solu-
U.S.A. Inc., and K.H. Kumar, SPE,               the averaged reservoir properties are con-      tion applied to the seismic properties in the
Smedvig Technologies Inc., originally           toured, then points from the contour are        final estimate of average porosity. The solu-
presented at the 1998 SPE Permian               entered into the simulation grid. The           tion was then applied to the data set cover-
Basin Oil and Gas Recovery Conference,          approach here uses the response of the          ing the model area. The result was an aver-
Midland, Texas, 25–27 March.                    seismic signal to the reservoir to derive the   age-porosity value for each seismically

38                                                                                                                         MAY 1998 •
                                       S E I S M I C              A P P L I C A T I O N S

defined interval at each bin location. These       structure. The option to re-enter openhole        block. The porosity and permeability mul-
data were gridded and exported to the geo-         completions is complicated by the history         tipliers were not applied as in the previous
logical workstation for incorporation into         of multiple acid treatments that greatly          model, which used only wellbore values.
the model. Fig. 1 shows that the seismical-        enhanced the porosity in the measurable           This enhanced model produced the correct
ly guided porosity displays considerably           near-wellbore area.                               volumes of total fluid, but at the wrong
more interwell variability than the average-                                                         WOR. Therefore, further changes to the
porosity map (Fig. 2) generated from well          Numerical Simulation. The reservoir was           geological model were limited to pay conti-
data alone.                                        modeled with a finite-difference reservoir-       nuity, relative permeability, and net-to-gross
   To use the seismic data, specialized vari-      fluid-flow simulator by use of an equation        pay multipliers.
ables are computed. These variables permit         of state. A preliminary history match was            The first change attempted was the addi-
proportioning seismic data to the individual       made for the base geological model, and the       tion of flow barriers on the basis of seismic
layers on the basis of the φh distribution.        results were used to make limited forecasts       data. Areas of rapid property changes were
The first step is to determine the percentage      for screening economics. Steady-state simu-       interpreted as the location of potential barri-
of total seismic-interval φh contained in          lations and production type curves were           ers. This modification did not produce suffi-
each simulation layer making up the equiv-         used to provide permeability and effective-       cient change in the produced-fluid ratio;
alent interval. The next step is to determine      thickness multipliers for the history match.      therefore, net-/gross-pay ratio was investigat-
the percent of seismic-interval total thick-       The multipliers varied from approximately         ed. Dimensionless type-curve analysis indi-
ness contained in each simulation interval.        0.1 to 10.5 across different areas of the pro-    cated that a net-/gross-pay multiplier needed
Once computed, these parameters are grid-          ject site. The largest multipliers were in the    to be applied to certain wells in the project
ded with the same nodal structure as the           northern portion of the project area, where       area. Multipliers reduced net pay by 50% in
seismic data. It should be pointed out that        an additional producing interval exists but       the northern area; better producing areas
the control for thickness far exceeded the         has little permeability data available.           needed almost no adjustment. Generally,
control for φh. Independent use of these           Steady-state simulations matched the late         more anhydrite is present in the north to cre-
parameters improves the overall reliability        waterflood history (January 1993 to April         ate the flow barriers, which is reflected by
of data redistribution.                            1994) when reservoir saturations were rela-       historical production. The changes allowed
   Once gridded, each layer-grid value is          tively constant, setting the permeability-        the model to match production more closely
multiplied by the appropriate seismic-grid         thickness needed for the history match.           than the previous model.
value. This generates thickness and φh val-        The type curves are plots of water/oil ratio         The type-curve analysis produced good
ues for each simulation layer at each seis-        (WOR) vs. fraction of oil recovered to            results when the production or injection
mic-bin location. Average porosity for each        determine the net-pay thickness needed to         wells were operating under reasonably sta-
layer is computed by dividing the φh value         modify the reservoir description to match         ble conditions, which prevents generation
by the thickness.                                  historical performance.                           of “noise.” Injection wells were generally
   Estimation of permeability proved more             The history match shows effective water        operated at injection pressures of 1,600 to
elusive; however, comparison of average            injection was approximately 60 to 70% dur-        1,800 psig, creating operating conditions
porosity to the logarithm of average perme-        ing most of the flood history. The model          stable enough for the type-curve analysis to
ability for each simulation layer provided a       shows that most losses occurred when sur-         be usable. Noise, in the producing wells, is
reasonable layer-dependent linear relation-        face injection pressures were at 1,800 psi dur-   usually caused by mechanical problems
ship. Individual-layer transforms were             ing the late 1970’s and 1980’s. After reducing    (e.g., scale problems, workovers) that inter-
computed and multiplied by the seismical-          injection pressures in 1990, injection-volume     rupt capacity production. Some producing
ly determined average porosity to obtain an        effectiveness has approached 100%. This           wells were suitable, while others were too
average-permeability value for each layer at       result correlates well with the fracture gradi-   noisy for the technique to work.
each seismic-bin location.                         ents from available step-rate tests.                 Combining net-/gross-pay multipliers
                                                      Relative Permeability. On the basis of         with minor relative permeability adjust-
APPLIC ATION                                       laboratory data, two relative permeability        ments allowed the model to produce at the
Two simulation models were developed to            curves were used in the simulation to             correct WOR. The changes, required to
evaluate various technologies applied to the       reflect different rock types in the reservoir.    model a higher WOR, caused a higher oil
reservoir description. The first model was         Minor changes were made to the simula-            saturation at the beginning of the CO2 flood.
constructed with only wellbore data used           tor’s water relative permeability curve that      The last adjustment to the relative perme-
for rock properties. Reservoir-data avail-         was still within the band of laboratory data.     ability curves was to assign one rock type to
ability was sparse through most of the             A radial model was set up to simulate the         the entire area. The resulting water relative
model area. Of the 64 wells in the project         water-alternating-gas injection test run on       permeability curve had a residual-oil satura-
area, only 11 were cored and only 10 have          Injection Well WWU 4816W. The objective           tion of 45% after waterflood and a slightly
modern logging suites (four wells offer            was to obtain a history match of the field        higher water relative permeability than the
both). The remaining wells have a gamma            test by adjusting the relative permeability       relative permeability used in the base simu-
ray/neutron, compensated neutron, or no            hysteresis curves.                                lation model. This adjustment is supported
logs at all. By use of a robust transform, reli-      Seismically Enhanced Model. The basic          by available core-saturation data.
able permeability data were estimated for          geological model was enhanced by incorpo-
wells with modern logs. The result is that         rating seismic data to define the interwell       Please read the full-length paper for
only 25% of the wells can be used as a             properties. Because seismic traces were on        additional detail, illustrations, and ref-
source of porosity and permeability data.          approximately the same spacing as model           erences. The paper from which the syn-
The 53 wells with correlation logs were            grids, reservoir properties of porosity and       opsis has been taken has not been peer
used to determine layer thickness and              permeability were available at each grid-         reviewed.

       • MAY 1998                                                                                                                               39
                                       S E I S M I C              A P P L I C A T I O N S

Since seismic-operations safety became a           the contractor to ensure that all aspects of      put into the contract, the next require-
major issue in 1983, safety has become             the operations had been considered before         ment was to get the local contractor to
health, safety, and environment (HSE). The         work started in the field.                        agree to the principles. This agreement
U.K.-based E&P Forum and the Intl. Assn.              The contracts for the two crews present-       was critical to change the cultural ap-
of Geophysical Contractors have provided           ed very different problems. One contract          proach to HSE as a fundamental part of the
guidance to contractors regarding opera-           was for a mountainous area that required          efficiency of the job. A presentation at the
tions management. This guidance enabled            helicopter support and dynamite opera-            head office in Athens was attended by all
HSE to achieve the same level of attention         tions. Weather was also expected to be a          senior personnel in the company and the
that the quantity and quality of safety data       factor and became a concern as winter             local enterprise manager. The result was
had received in the past. Initially, the role of   approached. The mountainous operation             positive, and the next step was to organize
the client (exploration company) was to            offered many opportunities for accidents.         the HSE management course for the crew.
audit the operation at the beginning of the        In contrast, the second contract could use        The main point focused primarily on the
job and make recommendations for                   a vibroseis crew and would have an easier         responsibilities in the management struc-
improvement. This process evolved into             task on level ground. The easier prospect         ture for the safety of the work, especially
audits of the contractor before work began,        was awarded to a local contractor, and the        because three HSE personnel had been
then into prequalification audits.                 northern, mountainous prospect was                appointed to the crew.
   Statistics on lost-time injuries indicate       awarded to an international seismic con-             The enterprise HSE adviser was on the
steadily improving operations. However, a          tractor. In addition, required environmen-        crew full-time, working with the contrac-
gap in preparations exists in the stage at         tal studies delayed both programs.                tor’s HSE manager to put together an HSE
which HSE requirements are considered in           Therefore, the approach was changed to            plan that covered all aspects of the opera-
the sequence of events that lead up to a           give the local contractor the assistance          tion that had been identified and incorpo-
crew working in the field.                         required to bring it up as close as possible      rated others as they arose. Necessary job
                                                   to international standards and to keep in         procedures had been identified during the
HISTORY                                            close contact with the international con-         management course, but getting the vari-
To evaluate two new Greek licenses,                tractor as its plans progressed for getting its   ous sections to write and present them for
Enterprise Oil set out to have a program           crew into the field.                              inclusion in the plan was difficult.
with two crews starting work simultane-                                                              Eventually the plan was produced, and it
ously in 1997. Many of the problems faced          THE COUNTRY                                       was submitted to contractor management
in establishing good HSE standards from            As a member of the European Community             for approval toward the end of October
the beginning of field work are caused by          (EC), Greece has an infrastructure not            1997. During preparation of the plan, the
the hurried award of work followed by fur-         found in many places where exploration is         whole crew was trained in awareness of
ther hurried mobilization to the field.            carried out. Membership in the EC carries         hazards, and initial audits were performed
Therefore, the idea was put forward that a         many responsibilities with respect to safety      on the vehicles and workshops.
dedicated HSE adviser should be part of the        and the environment. The “six pack” of               The northern prospect was postponed
planning team with the client while the fea-       European regulations covering manage-             until 1998 because the risks associated with
tures of the prospect areas were being con-        ment systems, workplace safety, machinery         the weather were deemed too great.
sidered. The adviser would then work with          safety, personal protective equipment, man-       However, preparation continued for the
                                                   ual handling, and visual-display units            intended startup. By use of the generic HSE
                                                   apply, as do many other EC regulations that       plan presented with the tender, the actual
This article is a synopsis of paper SPE            the Greek government has brought into             plan started to take shape with the inten-
46606, “Contrasting HSE Approaches                 law. In addition, personnel are civil servants    tion that it would be used for the startup
by an Oil Company to Concurrent                    and subject to labor laws drawn up by             audit in due course.
Seismic Operations in a New Country,”              recent socialist governments. Also, uncer-           On the southern prospect, the surveyors
by Rod C. Thonger, Geophysical Safety              tainty abounds as the country prepares for        started work in the field and were followed
Resources, originally prepared for pre-            a major privatization program, which              by the uphole crew and the recording oper-
sentation      at   the    1998     SPE            includes the national oil company.                ation 1 week later. All personnel went
International Conference on Health,                                                                  through startup safety meetings, which
Safety and Environment in Oil and Gas              SEQUENCE OF EVENTS                                were followed 1 week later by the first safe-
Exploration and Production, Caracas,               Once the broad strategy for approaching           ty-committee meeting. Up to this point, no
7–10 June.                                         HSE in the program was established and            lost-time injuries had occurred.

40                                                                                                                              MAY 1998 •
   Also on the southern prospect, one moun-
tain had to be crossed, which was too difficult
for vibrators. This section was drilled with
truck-mounted rigs and hand-carried ham-
mer drills. The client’s HSE adviser reviewed
the drilling activities in the south to ensure
application of the HSE plan. The adviser was
accompanied by a climbing expert to review
techniques and advise on training and equip-
ment. The helicopter contractor was also
audited in his Italian base to ensure that all
aspects of the helicopter operations had been
considered; to check the equipment; and to
review the training program for ground sup-
port, such as loadmasters.

The first lost-time injury occurred after
137,000 hours when a driver changed
gears. His hand slipped off the gear stick
and his elbow made hard contact with the
radio mounted between the seats. This
incident led to a hospital visit and time off.
A dispute developed whether a laborer’s
twisted ankle had been caused by falling
off a truck or playing basketball. The only
medical report received concerned an eye
infection, which was deemed not to be
work related.

Owing to the long lead time on both con-
tracts, one of the ideas put forward for the
startup of these jobs became redundant.
The suggestion had been made that the
frequent short time between award and
field mobilization had an adverse effect
on the HSE standards in the early days of
the work. Therefore, the proposal was
made that, on turnkey contracts, the con-
tractor should work temporarily on a
monthly basis to relieve pressure of get-
ting the first shot taken. While the cost to
the oil company would increase during
that period, use of that time to ensure that
all HSE (and technical) matters had been
sorted out would allow this cost to be
recovered during the more efficient
months that followed.

Early attention to HSE matters caused the
contractors’ HSE departments to become
involved in planning, leading to crews
prepared for the field from the first day
of production. The discipline required
for good HSE standards gave a structure
to the operations that benefited day-to-
day production.

Please read the full-length paper for
additional detail, illustrations, and ref-
erences. The paper from which the syn-
opsis has been taken has not been peer

       • MAY 1998                                 41
                                    S E I S M I C              A P P L I C A T I O N S

Achieving an incident-free operation is one
of the most important outcomes for any seis-
mic project. Many hours are spent examin-
ing work methods and understanding risks
in the planning stage to minimize the risk to
the individuals working in the field.
   The case history presented in the full-
length paper details three consecutive
three-dimensional (3D) surveys undertak-
en by Schlumberger Surenco de Venezuela          Fig. 1—Geographical area of opera-
(Geco-Prakla) between October 1995 and
September 1997 in the Orinoco delta on
behalf of BP Exploración de Venezuela           amounts of aerial-root systems, varying
(Figs. 1 and 2). These projects provided        mud depths, and an elevation generally less       Fig. 2—Three 3D-survey areas.
the opportunity to refine a number of           than 1 m. At high tide much of the area is
methods for both monitoring and manag-          under water.
ing the safety performance of the operation.                                                     Environmental. The major environmental
These methods may help open the door to         Shrub Dominated. As the saltwater fringe         hazard is the continual risk of injury from
achieving the next level of health, safety,     becomes brackish and eventually fresh, the       slips and falls. The environmental permit
and environmental (HSE) performance             environment changes from mangrove into           prohibits construction of any form of bridg-
toward which the industry is striving. By       shrubs and trees. The central area of brack-     ing. The workers are required to minimize
themselves, they will not necessarily deliv-    ish water contains only low shrubs. As the       the amount of cutting, resulting in signifi-
er an improvement, but their use may con-       mangrove dies off, it is replaced by fresh-      cant problems just to move along the seis-
tribute to providing a safer workplace for      water species. The ground elevation varies       mic line (Fig. 3). The severe variation in
all employees.                                  significantly over very short distances (e.g.,   surface conditions and water coverage can
                                                1 m elevation change in 0.5 m distance),         produce deep holes full of mud and water
ENVIRONMENT                                     with numerous holes under a fairly consis-       (Fig. 4). Examples of animal hazards in-
The environment encompassed by the                                                               clude scorpions, spiders, snakes, stingrays,
                                                tent level of water.
three surveys is varied.                                                                         bees, and crocodiles.
                                                                                                    These hazards are difficult to control
                                                Open Grassland. Large expanses of open
Water Dominated. Open water, with                                                                because very little can be done to reduce
                                                grassland, with a height of 1 to 2 m, exist
depths from 0 to 10 m. Tidal mud flats,                                                          the inherent risk. The focus for risk man-
                                                inside the shrub and mangrove areas. The
with areas of “quicksand.” River channels,                                                       agement is to increase the group and indi-
                                                grass covers a “muddy soup” of root matter
both narrow and wide, with water depths                                                          vidual awareness of their environment. As
                                                and mud, with little substantial soil until
from 0 to 10 m and currents up to 4 knots.                                                       teams move along the seismic line, they are
                                                approximately 10 m depth.
The tidal range is generally 2 m.                                                                continuously looking for hazards and com-
                                                                                                 municating the hazards to other team
Mangrove Dominated. Both freshwater             Inhabited Areas. Within the survey areas         members. Several procedures relating to
and saltwater mangrove areas with varying       are several populations. The two small           reducing the risk of attack from animals,
                                                towns, Capure and Pedernales (2,500              such as stingrays and bees, are also in place.
This article is a synopsis of paper SPE         inhabitants) occupy the only dry ground
46607, “Shooting Seismic Safely—A               in the area. Several small indigenous            Operational. The operational hazards are
Case History From the Orinoco Delta,”           Warao populations exist along the major          probably the best understood and easiest to
by A.J. Laven, BP Exploration                   river edges.                                     manage. Any activity that is part of the
Venezuela, and D. Pring and A.                                                                   operation can be modified by introducing a
McGrail,      Schlumberger Surenco              HAZARDS                                          procedure or by redesign of the activity. By
Venezuela, originally prepared for pre-         Two major types of hazards (environmental        providing detailed procedures for each
sentation at the 1998 SPE Inter-                and operational) are present in the area.        activity, training the work force in their use,
national Conference on Health, Safety           The environmental hazards are a natural          and providing the correct equipment, the
and Environment in Oil and Gas                  consequence of the working environment.          risk of injury can be reduced significantly.
Exploration and Production, Caracas,            The operational hazards are a consequence           In some activities, environmental risk
7–10 June.                                      of the activity that is being undertaken.        can be moved into operational risk. One

42                                                                                                                           MAY 1998 •
                                    S E I S M I C              A P P L I C A T I O N S

                                                                                                  serving to reinforce the message continual-
                                                                                                  ly. The induction is led by the heads of each
                                                                                                  group to demonstrate the responsibility of
                                                                                                  line-management for HSE performance.

                                                                                                  Definitions. LTI. Any accident where an
                                                                                                  individual suffers an injury that prevents the
                                                                                                  individual from returning to any form of
                                                                                                  employment at the next normal work period.
                                                                                                     Restricted-Work Case. Any accident
                                                                                                  where an individual suffers an injury that
 Fig. 3—Moving around in areas where             Fig. 4—The mud and water, which can              prevents the individual from returning to
 bridging is not allowed.                        be chest deep, contain invisible holes.
                                                                                                  normal employment at the next normal
                                                                                                  work period but allows the individual to
area where this was consciously done was        both new and experienced employees.               perform an alternative required function.
with regard to walking. In areas where          Office-based personnel visit the field regu-         Medical-Treatment Case. Any accident
walking is extremely difficult, helicopter      larly to listen to problems the crew and          where an individual suffers an injury that
transport was increased. Despite the            individuals are having and to conduct both        requires treatment by a doctor and does not
increase in helicopter hours and cost, heli-    formal and informal HSE audits.                   prevent the individual from returning to
copter use provides two significant bene-                                                         work the next day.
fits: safety and time spent working are         SAFETY MANAGEMENT                                    First-Aid Case. Any accident where an
increased. The risk is moved from trips and     Safety management relies on a number of           individual suffers an injury that may be
falls, something that can be difficult to       key factors. The first, and most important,       treated by a nonmedic and does not prevent
manage, to the risk related to helicopter       is that everyone believes that a safe, acci-      the individual from returning to normal
use, which is inherently more manageable.       dent-free operation is possible. The second       employment the next day.
                                                is to create a blame-free atmosphere that            STOP Card. Any reported occurrence
MANAGEMENT SYSTEM                               encourages people to report risks and not         that relates to a near miss or unsafe act but
The safety-management system (SMS)              hide incidents. Finally, it requires key indi-    does not result in any other incident classi-
plays a big role in ensuring that an opera-     viduals committed to ensuring that a high         fication. No accident actually occurred, but
tion takes place. The system should cover       level of HSE performance is delivered.            a recognized potential for damage to people,
not only safety, but also health and envi-                                                        the environment, or equipment occurred.
ronmental issues. The client wants to know      Commitment. The attitude taken by every-
that the system is complete and being used,     one, especially the client and senior man-        Reporting. The STOP cards are collected by
while the contractor wants to ensure that it    agement, is extremely important. Everyone         the heads of each group, who review the con-
is relevant to the project and being used. It   must feel committed to delivering a safe          tent and pass the cards on to the party chief,
is essential that an agreed-on set of com-      operation. Pushing production is unaccept-        who reviews them individually. Every
mon goals for the operation exists that         able if a major contributing factor to low        evening, the key reports are discussed with
allows the field operation to unite behind a    production is working conditions. Sending         the heads of the groups and the outcome is
goal of zero lost-time incidents (LTI’s).       a clear message that finishing safely and late    reported back down the line. This allows the
                                                rather than early but having someone hurt         work force to discuss the messages at their
BP BP uses an operational-integrity assur-      (and meaning it), sends a strong message of       toolbox meetings the next morning. Ensuring
ance system (OIAS). Rather than detail          HSE commitment.                                   a very quick response to issues and feeding
exactly what an operation has to do, this          The attitude of senior management dur-         the response back to the work force, sends a
system establishes expectations that should     ing visits, either on a routine basis or for an   clear message that reporting is important.
be fulfilled. To assure BP that the expecta-    audit or investigation, can have a large pos-
tions were met, a gap analysis was per-         itive or negative effect. Holding a fixed view    Meetings. In addition to crew and toolbox
formed, linking the contractor’s SMS to         or being unwilling to listen can be extreme-      meetings, the crew management attend
OIAS expectations. A “linkage” document         ly damaging to both morale and perfor-            weekly HSE meetings. The external groups
was produced that identified additional         mance. Listening and being seen to help           provide an opportunity to discuss risks in
procedures required. To support field oper-     can be very positive and deliver a measur-        detail. One group brought live examples of
ations, an ongoing series of third-party        able improvement in performance.                  the animals present in the work area,
audits took place.                                                                                including poisonous snakes and spiders.
                                                Training. The complete work force under-          Such action brings home the risks vividly
Geco-Prakla. Each operation creates a spe-      goes a 3-day induction that covers all            and ensures very active participation from
cific HSE plan for the project being under-     aspects of the operation and includes basic       the work force.
taken, identifying key risks and necessary      first aid, DuPont’s Safety Training
procedures. The plan is based around a          Observation Program (STOP), and addi-             SAFETY PERFORMANCE
simple “safety case” and includes plans for     tional specific training for more skilled         Measurement of safety performance has two
incidents at any level. The crew must be        positions. This induction is repeated in a        major purposes: it provides an understanding
provided with various types of support to       condensed format every time an individual         of the level of safety present in an operation
allow them to deliver a safe operation, in-     returns from break. On average, an employ-        and it allows comparison of safety between
cluding a complete training program for         ee receives a reinduction every 28 days,          companies and operations. Additionally, safe-

       • MAY 1998                                                                                                                            43
                                     S E I S M I C              A P P L I C A T I O N S

ty performance of an operation needs to be       ing his normal boots, he could not work           reducing the risk and mitigating the conse-
understood to form part of the feedback loop     and the incident was classified as an LTI.        quences of incidents. Safety is a product of
of action, reaction, and measurement.                                                              design, behavior, and procedures. In an ideal
                                                 Dislocated Shoulder. In this incident, a          world these would be in total balance.
Measurement. Normal reporting of safety          relatively new employee stood on a log,              Much of the residual risk is related
is generally related to reporting of both        fell, and knocked his shoulder. After a pre-      directly to the environment (e.g., animals
actual incidents and circumstances that          cautionary X-ray, he was diagnosed with a         or working conditions). Here, the focus of
could have become incidents (i.e., unsafe        dislocated shoulder. The employee was in          the HSE management system often
acts and hazardous situations). What often       great pain, and the shoulder could not be         changes. The primary focus should be on
happens is that an HSE group on the field        stabilized without surgery to insert a pin in     eliminating risk. If this is not possible, the
crew collates data from the reports and uses     the shoulder.                                     next step is to reduce the possible severity
these data to improve the level of safety in        Of these four incidents, two are clearly       of the outcome by providing local clinics.
the operation. These data are used to            related to the environment, one is totally        The problem with this change in focus is
understand which risks are more common           preventable, and the fourth is a combina-         that it accepts that accidents will happen,
and to manage those risks.                       tion of environment and procedures. The           which is not acceptable.
                                                 trapped finger and dislocated shoulder
Comparison. Similar project operations           showed an increase in severity between            Looking to the Future. To be truly safe,
are often compared simply on the basis of        diagnoses in the field and later at a medical-    changes in work procedures must be consid-
one indicator, LTI frequency rate (LTIFR).       treatment facility. These incidents might         ered. Changes may be as simple as ensuring
However, a problem arises when different         have been managed better if more sophisti-        that helipads are sufficiently large and bridg-
definitions are used by different crews. To      cated medical-treatment facilities were           ing is allowed. However, industry needs to
permit comparison, crew managers must            available on site.                                explore alternative methods for operations.
use and enforce the same definitions. The           This also clearly shows the coarseness of      Recent industry discussions indicate that
risk level for each individual project varies    the LTIFR as a measure of safety perfor-          light-weight equipment can save money and
depending on the associated hazards and          mance. Of the four LTI’s, a small change in       can also increase safety. Disposable self-posi-
must also be considered.                         emphasis might have reduced the number            tioning equipment could eliminate the
                                                 of LTI’s to one, the first stingray attack.       necessity for line cutting.
                                                 COMPARATIVE PERFORMANCE                           CONCLUSIONS
Four incidents resulted in LTI’s. Despite the
                                                 A demonstrable improvement in perfor-             The key to a safe operation lies in the use of
small number, it is possible to learn key
                                                 mance occurred during this series of projects;    an HSE management system that comprises
lessons from specific incidents, which may
                                                 when compared with similar operations,            commitment, training, and reporting. One
reduced the number of LTI’s.
                                                 however, the incident frequencies are signifi-    of the most important components is the
                                                 cantly better. Even though this comparison is     use of an incident-reporting system. Any
First Stingray Attack. This incident             based on imperfect data resulting from differ-    incident-reporting system provides the
occurred when a group was returning to           ent methods of reporting, an order-of-magni-      operation with data to analyze and manage
their boat over a mud flat in less than 30 cm    tude comparison is acceptable. The reporting      risks. Use of data can allow proactive man-
of water. They were following the correct        and the resultant feedback create an environ-     agement of safety. When the STOP program
procedures as far as possible. Stingrays are     ment that is clearly safer, with only 1 in 74     was implemented, fully collected data had a
not associated with these areas, and it is       incidents resulting in an LTI compared with       clear correlation with activity. Earlier re-
believed that the boat may have scared it        1 in 6 for similar operations.                    porting, analyzed at a later date, showed no
into shallow water where it was trapped by                                                         link, implying that action should have been
the group. It probably attacked out of fear.     RESIDUAL RISK                                     taken. The system not only supplies data on
The individual involved suffered a deep cut      It has not been possible to remove all the        specific risks, but can also provide a direct
across the front of his foot that damaged a      risk associated with an operation.                measurement of safety performance.
number of tendons.                                                                                    Industry needs to adopt a common
                                                 Conflict Between Environment and                  approach to safety statistics to eliminate
Trapped Finger. A kitchen worker maneu-          Safety. Seismic is often the first activity in    confusion. At a crew level, the use of LTI’s
vering a large glass bottle of drinking water    new areas, some of which have not been            as a performance measurement may be mis-
trapped the end of her finger. Correct tools,    previously accessed. Therefore, a serious         leading. The use of lower-severity incidents
including a stand, were not used. The            concern about our impact on the environ-          is more statistically relevant and accurate,
injury was diagnosed as a fracture to the        ment, both to plants and animals, exists.         and allows safety-performance manage-
finger tip requiring minor surgery.              This concern often creates a significant con-     ment. Even implementation of a full HSE
                                                 flict between acceptable and safe practices.      management system may not reduce the
Second Stingray Attack. This incident            Despite all the efforts to manage and reduce      risk to a totally acceptable level.
occurred when a group of shooters was            the risk of incidents to zero, it is clear that
crossing a flooded area inside the mangrove      certain activities have residual risk that may
where normal precautions cannot be fol-          be considered unacceptable. The level of          Please read the full-length paper for
lowed. On this occasion, the injury was rel-     unacceptability is likely to depend on an         additional detail, illustrations, and ref-
atively minor, a cut to the calf that required   individual’s background and point of view.        erences. The paper from which the syn-
a few stitches. However, because the treat-         Seismic activity is needed. Therefore, con-    opsis has been taken has not been peer
ment prevented the individual from wear-         siderable time, effort, and money are spent       reviewed.

44                                                                                                                             MAY 1998 •
                                    S E I S M I C              A P P L I C A T I O N S

Most E&P companies hire contractors to             • Personnel and training.                       The full-length paper details several key
acquire geophysical data. Therefore, the           • Operations and maintenance.                activities performed by EEC that have been
geophysical-services contractors have the          • Management of change.                      effective in reducing HSE incidents during
primary responsibility of managing opera-          • Third-party services.                      geophysical operations. The activities are
tions to prevent health, safety, and environ-      • Incident investigation and analysis.       checklist action items found in one of the
mental (HSE) incidents. However, the E&P           • Community awareness and emergency          management systems that form EEC’s pro-
company, as the client, should work with        preparedness.                                   ject management process. These activities
the contractor, especially when the opera-         • Operations-integrity assessment and        apply to all geophysical operations world-
tions are conducted on client-owned or          improvement.                                    wide, land or marine.
-operated property. The client has oversight       To define these elements, 60 specific
responsibility to ensure geophysical opera-     expectations have been developed. Each          PREBID PHA SE
tions are conducted properly to protect the     Exxon operating organization has devel-         The prebid activities begin when EEC’s geo-
public, the environment, client and con-        oped additional guidelines to clarify actions   physical-operations section receives a
tractor personnel, and client assets. The       needed to meet the OIMS expectations.           request to acquire data in a given area. A
client should have a process to verify the      Exxon Exploration Co. (EEC) has approxi-        project coordinator is assigned and imple-
overall effectiveness of the contractor’s HSE   mately 150 guidelines to direct HSE risk        ments the geophysical-project management
management plan. The client and contrac-        management. In 1993, EEC’s geophysical-         process, beginning with the prebid action-
tor should work together to identify poten-     operations section implemented OIMS and         item checklists. First, information about
tial HSE concerns, then develop ways to         developed a geophysical-project manage-         the project area (including terrain, climate,
prevent, or at least mitigate, those con-       ment process comprising the following           and governing laws and regulations) is
cerns. Also, fewer and less-severe HSE inci-    documented management systems.                  acquired, then potential hazards and con-
dents translate into more efficient opera-                                                      cerns about conducting the operation are
                                                   • OIMS implementation.
tions that result in cost savings for both                                                      identified. The project coordinator obtains
                                                   • Operated-by-others management.
client and contractor.                                                                          information about operating agreements,
                                                   • Risk assessment and management.
                                                                                                permit conditions, and results of previous
                                                   • Regulatory compliance.
APPROACH                                                                                        operations in or near the project area.
                                                   • Hazardous materials.
Exxon Corp. uses a structured, systematic                                                       Environmental requirements and concerns
                                                   • Personnel qualification and training.
approach called “operation integrity man-                                                       are identified by conducting interviews
                                                   • Environmental protection.
agement system” (OIMS) to manage risk in                                                        with personnel familiar with the project
                                                   • Change management.
all operations. The objective of OIMS is to                                                     area and followed by a literature search of
                                                   • Third-party management.
provide a framework for developing specif-                                                      public and EEC data. For most projects,
ic management systems with written proce-          • Incident investigation and analysis.       EEC personnel visit the project area and
dures, guidelines, and checklists to reduce        • Community awareness and emergency          conduct an on-site environmental survey or
the risk of HSE incidents. The elements or      preparedness.                                   assessment.
management areas of OIMS follow.                   A management system is a series of steps        Operational capabilities of potential con-
   • Management leadership, commitment,         taken to ensure that a stated objective is      tractors are evaluated as well as their HSE
and accountability.                             achieved. Each system has five main char-       management program and recent HSE per-
   • Risk assessment and management.            acteristics. First, the system has a defined    formance. Contractors with unknown
   • Facilities design and construction.        scope and objectives with specific expected     operating and HSE management capabili-
   • Information and documentation.             results. Second, the system includes or         ties are asked for written information about
                                                identifies specific Exxon or industry proce-    their general HSE management plan. An
                                                dures, checklists, guidelines, and standards    invitation-to-bid package containing tech-
This article is a synopsis of paper SPE         to be used to satisfy the objectives of the     nical-survey-design information and HSE
46608, “HSE Management of                       system. Third, responsible and accountable      requirements for the project is assembled.
Geophysical Operations: The Client's            resources (personnel) are identified for sys-   The complete disclosure of requirements
Role,” by Alan L. Dolezal, SPE, Exxon           tem maintenance and administration.             assists contractors in identifying and plan-
Exploration Co., originally prepared for        Fourth, verification and measurement para-      ning for gaps in their general HSE manage-
presentation at the 1998 SPE                    meters are identified to evaluate the perfor-   ment plan.
International Conference on Health,             mance of the system’s objectives and
Safety and Environment in Oil and Gas           expected results. Fifth, feedback and           PRESURVEY PHA SE
Exploration and Production, Caracas,            improvement recommendations are solicit-        The presurvey phase begins when the
7–10 June.                                      ed periodically to identify system upgrades.    contractor bids containing the technical

46                                                                                                                         MAY 1998 •
                                     S E I S M I C              A P P L I C A T I O N S

and HSE information are received and             hazardous-material handling procedures.            Ideally, HSE performance should be mon-
evaluated for acceptability. Frequently,         The procedures for handling, storing, and       itored on a real-time basis by both the con-
additional information is requested from         disposing of hazardous materials should be      tractor and the client. In the post-survey
the bidding contractors to clarify bid           determined and documented in the project        phase, the contractor should analyze the
components, including HSE management             HSE plan.                                       project HSE performance in detail and look
items. The experience and training cre-                                                          for trends or relationships to improve oper-
dentials of the contractors’ HSE advisers        SURVEY PHA SE                                   ating procedures or identify crew-training
and other field supervisory personnel are        The survey phase begins when the contrac-       needs. The client needs to evaluate the con-
closely scrutinized.                             tor crew and equipment move into the pro-       tractor’s overall HSE performance and com-
   Once a contractor is selected, a meeting      ject area. All components of the HSE plan       pare it with that of other contractors
of client and contractor management is           must be in place and understood by the          and projects.
held. EEC clearly communicates to the            crew before work begins. An HSE plan               A key objective of the close-out proce-
contractor the sincere expectation of com-       review with field supervisors is conducted      dure is identification of client-recommend-
pleting a successful project without an          to ensure that they are familiar with the       ed process improvements and new infor-
HSE incident. Another key item is the            plan details. The supervisors should be able    mation. The process improvements are
importance of the contractor’s develop-          to implement the plan and communicate           directed to EEC’s OIMS process custodian,
ment of a comprehensive, project-specific        pertinent plan information to the crew          who evaluates the recommended improve-
HSE management plan. This plan is a com-         effectively. The risk-assessment informa-       ments and implements process upgrades.
pilation of documents and references             tion, including identified hazards and pre-     Most projects provide valuable new infor-
describing the management commitment,            vention/mitigation measures, should be          mation that is documented and shared.
strategy, and procedures to use during the       discussed with the crew before field activi-
survey. The plan should reference the con-       ties begin. The crew’s input on potential       CONTRACTOR SAFETY
tractor’s HSE policies, operating proce-         hazards and their prevention should be          PERFORMANCE
dures, and applicable industry standards         encouraged to increase individual HSE           Since 1993, when Exxon implemented a
and provisions, such as those published by       awareness and commitment. Newly identi-         geophysical-project management process,
the Intl. Assn. of Geophysical Contractors       fied hazards and upgrades to prevention         the HSE performance of geophysical con-
and the E&P Forum.                               and mitigation measures should be added         tractors working on EEC projects world-
   Next, detailed project planning begins        to risk-assessment documents until com-         wide has significantly improved. One exam-
with development of the project-specific         pletion of field activities.                    ple of HSE performance improvement has
HSE management plan. First, a detailed              The quality-control personnel should         been EEC’s contractor on-the-job lost-time-
hazard analysis or risk assessment of the        monitor the contractor’s prestart audits of     incident rate. In 1992 and 1993, contractors
project operations is performed. Several         equipment and operating procedures, espe-       working on EEC projects experienced an
methods are used to perform risk assess-         cially emergency-response drills. The client    average of one lost-time incident every
ments, but the most common is the knowl-         HSE quality-control personnel should            200,000 exposure hours. In 1994, the lost-
edge-based “what-if” technique. For identi-      observe crew training previously identified     time-incident frequency was one every
fied hazards and concerns, the contractor        and agreed to in the project HSE plan.          400,000 hours, and in 1995 it was one every
explores potential consequences and the             Throughout field activities, quality-con-    2 million hours. Contractors working on
probability of incident scenarios. Then, the     trol personnel observe contractor opera-        EEC geophysical projects have not experi-
contractor identifies prevention (control)       tions and activities to ensure that all com-    enced a lost-time incident since May 1995,
and mitigation (recovery) measures needed        ponents of the project HSE plan function as     approximately 4 million hours. According
to reduce, if not eliminate, the conse-          written. Timely reporting of near-miss inci-    to E&P Forum’s 1996 accident report, the
quences and probability of each hazard and       dents and the corrective actions taken is       lost-time-incident frequency for exploration
concern. This risk-assessment process con-       required. Also important is the use of job-     contractors worldwide was approximately
tinues throughout the project whenever           safety analysis when an individual or small     14 incidents every 4 million hours.
new hazards or concerns are identified. The      work group identifies hazards associated
contractor maintains a complete record of        with performing a specific task.                CONCLUSION
all risk-assessment work and provides the                                                        E&P companies, as clients, benefit from
client with timely updates.                      POST-SURVEY PHA SE                              having a process in place to verify that geo-
   An important component of the plan is         Post-survey activities begin as field opera-    physical operations performed by contrac-
the level of on-site medical services to be      tions are nearing completion and are classi-    tors are conducted properly. EEC uses a
provided. Equally important is the develop-      fied into four main categories: complete        structured, documented process for man-
ment of a specific medical-evacuation pro-       project documentation, review of HSE per-       aging geophysical projects worldwide and
cedure for serious injuries or illnesses.        formance, performance feedback, and iden-       for working with contractors to lower the
Depending on transport time to quality           tified process improvements. EEC’s process      risk and number of HSE incidents. The
heath-care facilities, EEC may require the       has a prescribed list of activities necessary   OIMS provided the framework for devel-
contractor to provide a paramedic or physi-      to close out a geophysical project that must    opment of a geophysical-project manage-
cian at the project site. Telemedicine, direct   be conducted within 90 days after comple-
radio, satellite, or telephone communica-        tion of data acquisition. Close-out proce-      Please read the full-length paper for
tion with physicians on call for emergency       dures include client/contractor meetings to     additional detail, illustrations, and ref-
situations is also recommended.                  review HSE performance and discuss pro-         erences. The paper from which the syn-
   Other important components include            cedures that worked well and improve-           opsis has been taken has not been peer
environmental-protection measures and            ments for future projects.                      reviewed.

       • MAY 1998                                                                                                                          47
                                       S E I S M I C              A P P L I C A T I O N S

The increased emphasis on the industry’s           acceptable to a wide segment of the indus-        tractors who have a vested interest in them.
health, safety, and environment (HSE) perfor-      try. Audit reports and follow-up documents        Along with this release, approval should be
mance during the last decade has greatly           would be made available to client compa-          granted to release them to future clients.
accelerated the frequency of auditing in geo-      nies on request and would be accepted by          Contractors will become the repositories for
physical operations. As an integral part of        them on the basis of guideline conformance.       audits of their vessels and crews. Clients must
their internal business controls, most operat-     Client companies retain the right to conduct      become comfortable with audits commis-
ing companies and contractors now have HSE         verification of audits or conduct occasional      sioned by other client companies or internal
management systems that include audits.            audits themselves to verify performance.          audits commissioned by contractors. A level
E&P Forum’s 1994 “Guidelines for the De-                                                             of mutual trust is needed to promote overall
velopment and Application of Health, Safety,       Specific Objectives. The forum’s audit            efficiency of HSE auditing in the geophysical
and Environmental Management Systems”              guidelines are intended to address several        industry and reduce excessive auditing.
includes audits as a key element for a com-        issues and to establish a framework for con-
plete management system. Both client com-          ducting audits that achieve specific goals,       AUDIT STRUCTURE
panies and contractors commission different        which include the following.                      Scope and content should be clearly deter-
types of audits for a variety of purposes.            • Reduce excessive client auditing,            mined and agreed on by all parties before
   This proliferation of audits has resulted in    especially of seismic vessels, and create         establishing the specific audit purpose.
problems and inconsistencies throughout            consistency across land and marine geo-
the geophysical industry. The frequencies,         physical operations.                              Scope. The scope of an audit is determined by
standards, types, and purposes of audits vary         • Ensure compliance with operational poli-     the audit owner with input from the lead audi-
widely throughout the industry. Some               cies, procedures, and applicable regulations or   tor and auditee. Client and potential-client
marine vessels are subject to frequent audits      guidelines on HSE and analyze the existence       requirements should be taken into account
with short times between them, with reports        and effectiveness of management controls.         along with the nature and complexity of the
of some having more than one audit in a sin-          • Provide guidance to the geophysical          operation being audited. All parties should
gle day by different clients. In contrast, other   industry to implement audits that are con-        agree on a written audit scope, including audit
operations and crews are never audited.            sistent with the forum’s existing guidelines.     criteria, standards, rules, regulations, and
   The standards used for audit comparison are        • Improve acceptability of audits across       work instructions or guidelines used to assess
as variable as the frequencies of occurrence.      company boundaries.                               audit findings. Targeted locations, facilities,
Typically, audit reports and subsequent follow-       • Verify that operating systems the contrac-   and functions should be identified clearly and
up documents are closely held and do not read-     tor has in place optimize the well-being of all   include appropriate ancillary facilities.
ily transfer between companies. To address         personnel, clients, contractors, subcontrac-
auditing in the geophysical industry, E&P          tors, communities, and the environment and        Content. The minimum audit content
Forum’s Safety, Health, and Personnel-             that these systems are aligned across client,     should be consistent with the forum’s exist-
Competence Committee collaborated with             contractor, and subcontractor boundaries.         ing guidelines and should be supplemented
members of the Intl. Assn. of Geophysical             • Determine compliance of an auditee’s         with specific items from the contractor’s HSE
Contractors to develop the 1996 “Guidelines        HSE management system with audit criteria.        management system, supporting documents,
for HSE Auditing in the Geophysical Industry.”        • Determine whether the auditee’s HSE          and client requirements (if applicable). The
                                                   management system has been properly               full-length paper gives a suggested list of spe-
EXPECTATIONS AND OBJECTIVES                        implemented and maintained.                       cific topics to be included in audits and their
The guidelines establish minimum stan-                • Identify areas of potential improvement      applicability to management and operations.
dards for audits and auditors that are             in the auditee’s HSE management system.
                                                      • Assess the ability of the internal man-      Scheduling and Frequency. These guide-
                                                   agement review process to ensure continu-         lines do not set definitive or prescriptive fre-
This article is a synopsis of paper SPE            ing suitability and effectiveness of the audi-    quencies for conducting audits. However,
46739, “Guidelines for HSE Auditing                tee’s HSE management system.                      audit commissioners are expected to justify
in the Geophysical Industry,” by                      • Evaluate the contracting system.             the frequency.
Gordon R. Smith, Amoco, and
Thomas J. Dujmovich, Conoco, origi-                Release of Audit Reports. A new attitude is       Participant Roles. Several parties have
nally prepared for presentation at the             required that allows companies in the indus-      specific roles and responsibilities they must
1998 SPE International Conference                  try to share audit reports and follow-up docu-    fulfill to ensure a successful audit.
on Health, Safety and Environment in               ments. Audit owners (i.e., the entity commis-        Audit Commissioner. The commissioner
Oil and Gas Exploration and                        sioning an audit) must be willing to release      of an audit must establish the overall strat-
Production, Caracas, 7–10 June.                    reports and documents to clients and con-         egy and purpose for the audit and ensure

48                                                                                                                               MAY 1998 •
                                        S E I S M I C              A P P L I C A T I O N S

that adequate and competent auditors are               Lead Auditor. The lead auditor has over-      AUDIT PROCESS
used. The commissioner defines the audit            all responsibility to ensure efficient comple-   Successful and efficient completion of an audit
scope, criteria, and standards; creates a clas-     tion of the audit. The lead auditor ensures      that will add value and meet the needs of all
sification process for findings; and ensures        that planning is complete, well defined, and     parties requires several basic process steps.
that the follow-up process is completed.            communicated to all parties and that all
   Auditee. The auditee must cooperate with         logistic necessities are fulfilled. Obtaining    Preaudit. Before an audit, all parties should
the auditors and provide information,               necessary background information, direct-        obtain and review information concerning
resources, access, and facilities necessary to      ing the audit team, resolving problems, and      the operation, purpose, and scope of the
achieve the audit objectives. Auditees should       leading discussions with the auditee are         audit as well as the logistics arrangements.
inform their employees of audit plans, scope,       required functions. Responsibilities also        Operational information needed includes
and objectives and appoint responsible staff        include notifying the auditee of critical        the auditee’s HSE management system
to accompany the auditors. After receiving          findings immediately; timely and clear           along with supporting documents for
the audit report, the auditee should develop        completion of the audit report; ensuring         implementation of the system (e.g., policy
a corrective-action plan defining the steps         that recommendations are clear, concise,         and procedures manuals). The auditee’s
and responsibilities necessary to address the       and represent the team opinion; and ensur-       organizational structure, HSE staffing, and
audit findings. A follow-up plan to ensure          ing that objectivity and professionalism are     responsibilities for HSE management are
item completion should be included as part          maintained throughout the audit.                 necessary. Operation-specific hazard regis-
of the corrective-action plan.                         Auditors. Individual auditors must fol-       ters, incident reports, previous audits with
   Audit Team. Establishing a proficient audit      low the direction of the lead auditor,           follow-up reports, operational maps and
team is critical for a successful audit. The lead   maintain objectivity and professionalism,        descriptions, and training records should
auditor and audit team must have sufficient         and collect and analyze sufficient informa-      be included. Local regulations, the environ-
standing and experience to be credible and          tion and observations to draw definitive         mental-impact assessment, any permits or
authoritative. They should be trained in HSE        conclusions regarding the auditee’s system       government licenses, or other documents
audits and possess the range of skills, knowl-      and implementation. They are responsible         that establish restrictions on or require-
edge, and experience necessary to meet the          for preparing and safeguarding docu-             ments for the work are critical review infor-
audit requirements. All audit-team members          ments, recording and clearly reporting           mation. A clear audit-announcement letter
must be free of conflict of interest and bias       findings, and assisting in preparation of        detailing the scope and objectives should
toward the operation being audited.                 the final report.                                be transmitted to the location in advance.

50                                                                                                                               MAY 1998 •
                                       S E I S M I C               A P P L I C A T I O N S

On Site. Cooperation, efficiency, and under-       should include an overall description of the       CONCLUSIONS
standing are critical. An opening meeting          audit scope and objectives, identification of      E&P Forum’s “Guidelines for HSE
with the auditee’s local management and staff      the audit team, dates of the audit, and            Auditing in the Geophysical Industry” have
(including HSE staff) should be held before        description of the operation audited. The          established a framework for auditing that
audit activities begin. This meeting should        report should also include general observa-        will promote efficiency and value through-
reaffirm the scope and objectives of the audit,    tions along with positive findings and defi-       out the industry for HSE auditing activities.
agenda, and audit plans; establish the contact     ciencies noted with clear reference to applic-     Use of these guidelines will help ensure
and communications points; obtain informa-         able management-system components, regu-           proper planning, in-depth completion,
tion on special topics for inclusion or sensi-     lations, policies, stipulations, and guidelines.   timely reporting, clear follow-up, and clo-
tive areas to be aware of; and confirm the         Clear and understandable recommendations           sure of audits. Acceptance between client
schedule for the closing meeting. Actual           to address deficiencies should be stated.          companies of audits conducted in confor-
audit activities will be directed by the lead         The audit commissioner is responsible           mance with these guidelines will be
auditor. Physical inspection of the operations     for timely distribution of the report to all       enhanced. This acceptance should reduce
and work sites, review of documents and            necessary parties. The commissioner                excessive auditing of a particular operation
records, interviews with the auditee’s man-        should establish clear expectations for            or vessel and promote overall efficiency and
agement and staff, and assessment of training      action plans to address the recommenda-            cost-effectiveness of HSE auditing in the
implementation and effectiveness are critical      tions and follow-up activities to ensure           industry. Cooperation and trust between
to ensure audit completeness. Findings             implementation and closure. A schedule for         client companies and contractors should be
should be documented clearly and catego-           reports to monitor the status of action plans      promoted through use of and conformance
rized daily with analyses and recommenda-          should be agreed on.                               with these guidelines.
tions for the final report. A closing meeting to       The auditee and local operation establish
review the preliminary audit findings and          the action plans to address recommendations
recommendations should be conducted with           and furnish these plans to the audit commis-
the local management and staff.                    sioner. The plans should include clear identi-     Please read the full-length paper for
                                                   fication of steps to be taken, who is responsi-    additional detail, illustrations, and ref-
Post-Audit. It is imperative that the final        ble, and the anticipated timing of comple-         erences. The paper from which the syn-
audit report be clear, concise, and issued         tion. Periodic reports of progress toward clo-     opsis has been taken has not been peer
within an agreed-on time period. The report        sure are the responsibility of the auditee.        reviewed.

       • MAY 1998                                                                                                                               51
                                      S E I S M I C              A P P L I C A T I O N S

Today, crews working three-dimensional              • Some HSE knowledge, a cosmetic HSE           Lowest-Bid Culture. The lowest price does
(3D) -seismic surveys are larger and more         program in place, and some management            not necessarily mean the lowest cost.
complex than in the relatively straightfor-       commitment.                                      Companies are liable for the actions of their
ward two-dimensional-seismic operations.            • No HSE knowledge.                            subcontractors, and high numbers of acci-
A typical 3D crew, working in the                                                                  dents or incidents result in both long- and
Louisiana transition zone, may be staffed         CHALLENGE                                        short-term cost increases. When awarding a
by 200 or more personnel with many cul-           After deciding what equipment and person-        contract, the long- and short-term liabilities
tures and languages and may experience a          nel will be subcontracted, the problem           associated with the hiring of unsafe and
                                                  becomes ensuring that subcontractor per-         environmentally unaware subcontractors
high personnel-turnover rate. The terrain
                                                  sonnel and equipment perform to an               must be considered.
can change from swamp to open water, to
                                                  acceptable HSE standard. A big challenge is
marshland, to highland within the same
                                                  the large number of personnel involved and       Short-Term Contracts. Statistics indicate
prospect. Equipment required for these            the high turnover rate expected.                 that most accidents or incidents happen to
operations includes marsh and swamp                                                                new employees soon after their employ-
buggies, drills, rams, skiffs, ski barges, air-   KEY ISSUES                                       ment. For example, airboat drivers with
boats, helicopters, quarter boats, and crew       Before awarding a contract several key           many years of experience in open marsh-
boats. The variety of tasks requires person-      issues must be addressed.                        land must be considered as new employees
nel with different technical backgrounds,                                                          when required to work in open lakes or
including expertise in global-positioning-        Subcontractor HSE Policies. These poli-          swamp/bayou areas because they now are
system surveys, conventional surveys, nav-        cies must be scrutinized to ensure that the      working in a new environment. The
igation, pipeline-hazard surveys, cleanup,        fundamentals of good HSE are a part of the       assumption cannot be made that they are
camp management, catering, permitting,            culture of the subcontractor. The senior         capable of working safely in an area full of
equipment operation, and labor.                   person in the company should sign the pol-       new hazards; they must receive orientation
   Because projects and personnel vary, the       icy documents.                                   and be trained. The same idea applies to an
use of subcontractors is cost-effective and                                                        entire company that moves to a new envi-
provides specialized personnel and equip-         Subcontractor HSE Management. The                ronment. Short or long term should make
ment and local experience and expertise.          system must ensure that all basic elements       no difference. The same standards must
In addition, seismic crews traditionally          are in place and understood. At Geco-            apply to all contracts.
                                                  Prakla, these basic elements are leadership
have a high personnel-turnover rate
                                                  and commitment; policies and objectives;         “Must Have Them On Site Tomorrow”
because of natural attrition and frequent
                                                  organization, responsibilities, and re-          Culture. High personnel-turnover rates,
location moves.
                                                  sources; risk management; planning;              contractual changes, or weather problems
                                                  implementation and monitoring; and audit         can lead to plan changes on very short
TYPES OF SUBCONTRACTOR                            and review processes.                            notice. Crew management may be tempted
Subcontractors can be classified in one of                                                         to ignore procedures to get a person or a
the following groups on the basis of their        Adherence to Company Procedures. Lack            piece of equipment into the field to main-
health, safety, and environmental (HSE)           of adherence to company procedures by the        tain production. This action cannot be
awareness.                                        company awarding the contract can lead to        allowed because untrained, unaware indi-
   • A full HSE program with comprehen-           confusion and misunderstanding. Before           viduals are a hazard to themselves and the
sive policies in place and senior- and line-      awarding a contract, the subcontractor           rest of the crew.
management commitment.                            should be audited to ensure that it meets
                                                  the standards required as set out in the ten-    TRAINING RESPONSIBILITY
                                                  der documents.                                   Responsibility for training becomes a very
This article is a synopsis of paper SPE                                                            complicated issue if requirements are not
46749, “Subcontractor Management                  Unclear Specifications. Insufficient clarity     clearly stated in the contract. If a subcon-
in Today’s 3D Environment in                      of contract specifications can be a major        tractor arrives with an untrained crew that
Louisiana,” by Tony Dillane, Geco-                cause of misunderstanding. The contract          has not been drug and alcohol tested and
Prakla, originally prepared for presen-           should state clearly what is required from the   that does not have legally required licenses
tation at the 1998 SPE International              subcontractor and should include training,       and certificates, who is responsible for pro-
Conference on Health, Safety and                  legal requirements, reporting, personal pro-     viding training? Training and testing are very
Environment in Oil and Gas                        tective equipment, auditing, contingencies,      time consuming and must be completed
Exploration, Caracas, 7–10 June.                  and HSE management system requirements.          before the subcontractor is allowed on the

52                                                                                                                            MAY 1998 •
                                      S E I S M I C              A P P L I C A T I O N S

work site. Because training can take at least        • Knowledge of job-specific hazards.          Visible Commitment. The manager
3 days, it is in the interest of the company         Once on site, the subcontractor is con-       awarding the contract must be seen as ded-
awarding the contract to ensure that all sub-     sidered part of the crew; therefore, daily       icated to the HSE philosophy of the compa-
contractor personnel are fully trained, tested,   reports and statistics must include both         ny. He/she must participate in audits and
and licensed before they show up on site.         subcontractor and crew numbers. During           visit operations regularly to be seen as
   The issue of training must be specifically     crew operations, crew management moni-           someone who takes HSE seriously.
addressed at the tender stage and entered         tors the subcontractor’s performance.
into the final contract precisely. Geco-          Regular spot audits, cross-audits, and           Documents. Specific contract documents
Prakla trains all their employees and sub-        checks must also be carried out to ensure        dedicated to HSE requirements are essential
contractors in the U.S. gulf coast transition     HSE compliance.                                  and must lay out exact requirements for ref-
zone before they are allowed in the field.                                                         erence when questions arise.
The full-length paper details an extensive        TURTLE BAYOU
list of training topics required by the com-      Between June and October of 1997, Geco-          Specific Requirements. Specifying legal
pany. The list does not include job-specific      Prakla conducted a nonexclusive, propri-         and training requirements saves time and
training, such as defensive driving or boat       etary 3D survey covering 140 sq miles in         effort at the start of the project.
handling, which is done separately.               Turtle Bayou, southeastern Louisiana. The
                                                  prospect area encompassed highland,              Being Proactive. Rather than wait for prob-
SITE-SPECIFIC TRAINING                            marshland, swamp, open water, and indus-         lems to arise, management should be
Site-specific training must be done when          trial areas. A third-party seismic company       proactive from contract tender through end
the crew arrives on site, regardless of any       was contracted for the job. This company,        of project. Plan, discuss, and act with all
previous training the individuals have.           in turn, subcontracted with many different       parties involved from the beginning.
Personnel must be made aware of environ-          companies to survey and drill and to supply
mental issues and spill-response plans spe-       ski barges and airboats.                         Maintain Standards. Use the same stan-
cific to the area of operations. In Louisiana,       The challenge was to manage the main          dards for all companies and individuals and
several areas exist where a limited number        subcontractor and ensure that it, in turn,       make no exceptions. Standards cannot be
of passes are allowed with buggies and air-       managed its subcontractors in an HSE con-        dropped for one person and strictly
boats. Personnel must be shown, on a daily        ducive manner. At one time, the crew num-        enforced on another. Such action leads to
basis, the restrictions for any particular        bered more than 230 personnel on site from       lack of readibility and to creation of an
piece of property. Information is disseminat-     16 different companies. The contract was         atmosphere where people think they can be
ed every day at the safety briefing held for      completed without serious injury and with-       the exception to the rule.
every work group. Training and awareness          out a serious environmental incident.
is an ongoing process that continues daily        Careful subcontractor selection was a key        RESULTS OF NOT FOLLOWING
throughout the term of the project.               to this accomplishment.                          PROCEDURES
                                                     Before the contract was awarded to the        Not following corporate procedures when
SUBCONTRACTOR REQUIREMENTS                        main contractor, their HSE program and           hiring a subcontractor can result in several
Before awarding a contract, it must be            records were assessed. Then, a meeting was       problems.
established that the subcontractor meets          held to ensure that all parties understood         • Lack of corporate credibility.
the following standards.                          exactly what was required. The contract con-       • Liability caused by accidents and inci-
   • An ongoing HSE program.                      tained an HSE exhibit that specified all HSE     dents.
   • Management and line-management               requirements. All subcontractors were audit-       • Liability from not adhering to the law.
commitment.                                       ed before going into the field, and their per-     • Liability from not following written pro-
   • Financial stability.                         formance was monitored on a daily basis.         cedures and policies.
   • Experienced/trained personnel.                  Personnel were required to attend a
   • Modern/serviceable equipment.                meeting where they were informed about           CONCLUSIONS
   • A good HSE track record.                     all local safety and environmental issues,         • Clear, concise, and consistent contracts
                                                  and spot briefings were held on a daily          increase productivity, eliminate confusion,
ON-SITE MONITORING                                basis. Disciplinary action was taken as          and reduce downtime.
Once a contract has been awarded, sub-            required for violations of the HSE rules. A        • Subcontractors who fully understand
contractor performance must be moni-              Geco-Prakla HSE representative was on the        their contractual obligations will perform
tored. Auditing personnel perform this            crew at all times to ensure compliance and       their HSE tasks more efficiently.
monitoring and inspect all equipment on           to handle day-to-day problems.                     • No exceptions can be made for individ-
arrival at the work site. The audit should be        On the successful completion of the pro-      uals or companies.
conducted by crew management and the              ject, statistics were analyzed to establish        • Constant monitoring is necessary to
on-site subcontractor manager. Items to           what worked well and what did not. This          ensure that the subcontractor performs in a
audit include the following.                      information and experience was then              HSE conducive manner.
   • Line-management knowledge and com-           applied to the next contract.
   • Personnel licenses.                          MANAGEMENT ACTION                                Please read the full-length paper for
   • Training and certification of personnel.     To ensure compliance, management must            additional detail, illustrations, and ref-
   • Equipment condition.                         be visible; have specific documentation,         erences. The paper from which the syn-
   • Safety equipment.                            requirements, and a proactive attitude; and      opsis has been taken has not been peer
   • Knowledge of emergency procedures.           maintain consistent standards.                   reviewed.

       • MAY 1998                                                                                                                            53

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