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					RESERVOIR PETROPHYSICS

       PETE 311
         PETROPHYSICS

Petrophysics is the study of rock properties and
rock interactions with fluids (gases, liquid
hydrocarbons, and aqueous solutions).




                    Modified from Tiab and Donaldson, 1996, p. 1
RESERVOIR PETROPHYSICS
       PETE 311
           COURSE DESCRIPTION
Systematic theoretical and laboratory study of
physical properties of petroleum reservoir rocks
• Lithology
• Porosity
• Compressibility
• Permeability
• Fluid saturations
• Capillary characteristics
• Rock stress
• Fluid-rock interaction
RESERVOIR PETROPHYSICS
Course Objectives

By the last day of class, the student should be able to:
1.   Define porosity; discuss the factors which affect porosity and
     describe the methods of determining values of porosity;

2.   Define the coefficient of isothermal compressibility of reservoir
     rock and describe methods for determining values of formation
     compressibility;

3.   Reproduce the Darcy equation in differential form, explain its
     meaning, integrate the equation for typical reservoir systems,
     discuss and calculate the effect of fractures and channels, and
     describe methods for determining values of absolute
     permeability;
RESERVOIR PETROPHYSICS
Course Objectives

4.   Explain boundary tension and wettability and their effect on capillary
     pressure, describe methods of determining values of capillary
     pressure, and convert laboratory capillary pressure values to reservoir
     conditions;

5.   Describe methods of determining fluid saturations in reservoir rock
     and show relationship between fluid saturation and capillary pressure;

6.   Define resistivity, electrical formation resistivity factor, resistivity
     index, saturation exponent, and cementation factor and show their
     relationship and uses; discuss laboratory measurement of electrical
     properties of reservoir rocks; and demonstrate the calculations
     necessary in analyzing laboratory measurements;
RESERVOIR PETROPHYSICS
Course Objectives
7.  Define effective permeability, relative permeability, and
    permeability ratio; reproduce typical relative permeability curves and
    show effect of saturation history on relative permeability; illustrate the
    measurement of relative permeability; and demonstrate some uses of
    relative permeability data.
8. Describe three-phase flow in reservoir rock and explain methods of
    displaying three-phase effective permeability.
9. Demonstrate the techniques of averaging porosity, permeability, and
    reservoir pressure data.
10. Demonstrate capability to perform calculations relating to all
    concepts above.
11. Design and conduct experiments to determine porosity, rock
    compressibility, absolute and relative permeability, fluid saturation,
    capillary pressure, and electrical properties of reservoir rocks;
    analyze and interpret experimental data; and prepare laboratory
    reports.

                      (These are minimum skills to be achieved/demonstrated)
     PETROPHYSICS

• Why do we study petrophysics?
          Cross Section Of A Petroleum System
                              (Foreland Basin Example)
                         Geographic Extent of Petroleum System
                                                                  Extent of Play
                                                    Extent of Prospect/Field
         O
                                                               O                      O

                Stratigraphic
                  Extent of
                 Petroleum
                                                                     Overburden Rock
                   System




                                                                                          Sedimentary
                                                    Essential




                                                                                           Basin Fill
                                                    Elements         Seal Rock
                                                        of           Reservoir Rock
                                                    Petroleum
                                  Pod of Active      System          Source Rock
                                  Source Rock
                                                                     Underburden Rock
          Petroleum Reservoir (O)
                                                                     Basement Rock
          Fold-and-Thrust Belt                                       Top Oil Window
          (arrows indicate relative fault motion)
                                                                     Top Gas Window

(modified from Magoon and Dow, 1994)
                         PETROLEUM SYSTEM




                                                          From Schlumberger Oilfield Glossary




Timing of formation of the major elements of a petroleum system, Maracaibo basin, Venezuela.
DEFINITIONS - SEDIMENTARY ROCK

   Sedimentary Rock
     Rock Formed from the Weathered
     Products of Pre-Existing Rocks and
     Transported by Water, Wind, and
     Glaciers
     Clastic Sedimentary Rocks (Such as
     Shale, Siltstone, and Sandstone)
     Consist of Broken Fragments of
     Pre-Existing Rock (cf. Detrital)

     Carbonate Sedimentary Rocks (and
     Evaporites) May Form by Chemical
     Precipitation or Organic Activity
CLASTIC AND CARBONATE ROCKS

 Clastic Rocks
     Consist Primarily of Silicate Minerals

     Are Classified on the Basis of:

          - Grain Size
          - Mineral Composition

 Carbonate Rocks
     Consist Primarily of Carbonate Minerals
                                  -2
     (i.e. Minerals With a CO3 Anion Group)
         - Predominately Calcite (Limestone)
         - Predominately Dolomite (Dolomite
            or Dolostone)
     Classified by Grain Size and Texture
SEDIMENTARY ROCK TYPES
             Relative Abundances
                          Sandstone
                       and conglomerate
                            (clastic)
                              ~11%

                                Limestone and
                                   Dolomite
Mudstone
                                 (carbonate)
(Siltstone
                                    ~14%
and shale;
 clastic)
  ~75%
Grain-Size Classification for Clastic Sediments
    Name              Millimeters       Micrometers
                       4,096
   Boulder              256
   Cobble                64         Commonly, phi-sizes are used
                                    for sediment analysis
   Pebble                 4
   Granule                2
   Very Coarse Sand       1
   Coarse Sand            0.5                     500
   Medium Sand            0.25                    250
   Fine Sand              0.125                   125
   Very Fine Sand                                  62
                          0.062
   Coarse Silt            0.031                    31
   Medium Silt            0.016                    16
   Fine Silt              0.008                     8
   Very Fine Silt         0.004                     4
   Clay                                  (modified from Blatt, 1982)
DUNHAM’S CLASSIFICATION - CARBONATES




  Carbonate rocks can be classified according to the texture and grain size.

                                                      From Schlumberger Oilfield Glossary
 GENERATION, MIGRATION, AND
 TRAPPING OF HYDROCARBONS

                              Seal

    Fault
                                            Oil/water
(impermeable)
                                          contact (OWC)

                                                  Migration route
                                     Seal
                                                          Seal
        Hydrocarbon                                              Reservoir
       accumulation                                                rock
           in the
       reservoir rock
                        Top of maturity

                                        Source rock
DESCRIBING A RESERVOIR
    Structural Characterization
      STRUCTURAL HYDROCARBON TRAP




This structural trap is formed by an anticline and a normal fault.   From Schlumberger Oilfield Glossary
  DOMAL TRAP
• Are hydrocarbons in this field oil or gas?
• What is the volume of hydrocarbons
  In this trap?
• What are the reserves?

Closure. In map view (top),
closure is the area within the
deepest structural contour
that forms a trapping
geometry, in this case 1300
ft [390 m]. In cross section
A-A', closure is the vertical
distance from the top of the
structure to the lowest
closing contour, in this case
about 350 ft [105 m]. The
point beyond which
hydrocarbons could leak
from or migrate beyond the
trap is the spill point.


        From Schlumberger Oilfield Glossary
WATER DRIVE
              What is the Drive
               Mechanism?


               A reservoir-drive
               mechanism whereby
               the oil is driven
               through the
               reservoir by an
               active aquifer. As
               the reservoir
               depletes, the water
               moving in from the
               aquifer below
               displaces the oil
               until the aquifer
               energy is expended
               or the well
               eventually produces
               too much water to
               be viable.


               From Schlumberger Oilfield Glossary
GAS EXPANSION DRIVE
                            What is the Drive
                             Mechanism?

                              A gas-drive
                              system
                              utilizes the
                              energy of
                              the
                              reservoir
                              gas,
                              identifiable
                              as either as
                              free or
                              solution
                              gas, to
                              produce
                              reservoir
                              liquids.

                            Are there other
                            drive mechanisms?


                      From Schlumberger Oilfield Glossary
TYPES OF HYDROCARBONS

• Composition

• Molecular structure

• Physical properties
PHYSICAL PROPERTIES OF
   HYDROCARBONS

 • Color
 • Refractive Index
 • Odor
 • Density (Specific Gravity)
 • Boiling Point
 • Freezing Point
 • Flash Point
 • Viscosity
          FLUID DENSITY
˚ API =         141.5 - 131.5
                 g
• What are the standard reporting conditions?


˚ API = API gravity
    g   = specific gravity
  FLUID VISCOSITY

• Importance
• Units – centipoises (μ, cp)
• Strongly temperature dependent
• Standard reporting conditions
               DRILLING RIGS
Drillship   Semisubmersible   Jackup   Submersible           Land Rig




                                       From Schlumberger Oilfield Glossary
ROTARY DRILL BIT, WORN




              From Schlumberger Oilfield Glossary
Next Class:
  RESERVOIR POROSITY

  Definition: Porosity is the fraction of the
  bulk volume of a material (rock) that is
  occupied by pores (voids).

  • Origins and descriptions

  • Factors that effect porosity

  • Methods of determination

				
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posted:10/14/2012
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