Disposing Cuttings Piles material onshore - DOC

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					   TECHNICAL REPORT

                OLF
 DISPOSAL OF CUTTINGS PILES MATERIAL
ONSHORE CAPABILITIES, PRACTICALITIES AND
                IMPACTS




          REPORT NO. 00-4018
                REVISION NO. 01




          DET NORSKE VERITAS
DET NORSKE VERITAS




TECHNICAL REPORT
Date of first issue:                                   Project No.:                                                  DET NORSKE VERITAS
3 January 2001                                         58101666                                                      REGION NORGE AS
Approved by:                                           Organisational unit:                                          Safety and Environmental
                                                       Safety and Environmental Advisory                             Advisory Services, Stavanger
Hermann Steen Wiencke                                  Services                                                      Bjergstedveien 1,
                                                                                                                     P.O.Box 408,
Head of Section                                                                                                      N-4002 STAVANGER, Norway
                                                                                                                     Tel: +47 51 50 60 00
Client:                                                Client ref.:                                                  Fax: +47 51 50 60 80
OLF                                                    Bente Jarandsen                                               http://www.dnv.com
                                                                                                                     Org.No: NO 945 748 931 MVA

Summary:
This study contains an assessment of capabilities, practicalities and impacts associated with onshore
treatment and disposal of “old” drill cuttings from the Norwegian Continental Shelf.

The scope is, however, limited to the onshore part of the operation, i.e. areas of concern related to
recovery and transport to shore of drill cuttings materials are not considered.

Also some assumptions are made in order to carry out the study. The most important assumption is
that all cuttings associated with offshore fields where oil based- or pseudo based drilling muds have
been used will be removed. This gives the study a conservative approach, basing the assessments on
maximum volumes of cuttings.




Report No.:                           Subject Group:
00-4018                                                                Indexing terms
Report title:
Disposal of Cuttings Piles Material
Onshore capabilities, practicalities and impacts




Work carried out by:
Steinar Nesse and Anne Hovda                                                  No distribution without permission from the
                                                                              Client or responsible organisational unit
Work verified by:
Tim Fowler                                                                    Limited distribution within
                                                                              Det Norske Veritas
Date of this revision:    Rev. No.:          Number of pages:
                          01                 46                               Unrestricted distribution



Head Office: Veritasvn. 1, N-1322 HØVIK, Norway
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Table of Content                                                                                                                      Page

1            SUMMARY ................................................................................................................. 1

2            INTRODUCTION ....................................................................................................... 3
2.1          Background                                                                                                           3
2.2          Objective                                                                                                            3

3            SCOPE OF WORK ...................................................................................................... 4
3.1          Introduction                                                                                                         4
3.2          Approach                                                                                                             5
3.3          Assumptions and definitions                                                                                          5

4            CAPACITY EVALUATIONS .................................................................................... 8
4.1          Onshore reception and temporary storage                                                                   8
4.2          Pre-treatment                                                                                             9
4.3          Processing                                                                                                9
4.3.1           Processing capacity                                                                                  13
4.3.2           Critical factors for processing                                                                      14
4.4          Waste disposal                                                                                          16
4.4.1           Number of relevant sites                                                                             16
4.4.2           Legal requirements                                                                                   17
4.4.3           Capacity limitations                                                                                 18
4.4.4           Geographical location and logistics                                                                  19
4.4.5           Using treated drill cuttings as cover material on landfills                                          20

5            COST ASSESSMENT ............................................................................................... 21
5.1          Cost of pre-treatment                                                                                           21
5.2          Treatment costs                                                                                                 21
5.3          Disposal costs                                                                                                  21
5.4          Total costs                                                                                                     21

6            RE-USE OPPORTUNITIES ...................................................................................... 23
6.1          Use of untreated cuttings                                                                                   23
6.2          Recovered oil                                                                                               24
6.3          Recovered solid cuttings material                                                                           24
6.4          Recovered water                                                                                             26

7            IMPACT ASSESSMENT .......................................................................................... 28
7.1          Environmental Impacts                                                                                        28
7.1.1          Atmospheric emissions                                                                                      28
7.1.2          Discharges to sea/water including seepage from landfills                                                   29

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7.1.3          Waste disposal                                                                                                             31
7.1.4          Energy consumption                                                                                                         31
7.2          Impacts on local community                                                                                                   32
7.2.1          Noise                                                                                                                      32
7.2.2          Dust                                                                                                                       33
7.2.3          Odour                                                                                                                      33
7.2.4          Increased traffic                                                                                                          34
7.2.5          Employment effects                                                                                                         34

8            REFERENCES........................................................................................................... 35

APPENDIX 1. CUTTINGS DATA ......................................................................................... 37

APPENDIX 2. NORWEGIAN CUTTINGS PROCESSING TECHNOLOGY ...................... 40
SRD Technology                                                              40
TCC technology                                                              41
Incineration                                                                43

APPENDIX 3. CASE STUDY................................................................................................. 45




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1 SUMMARY
The scope of the present study does not include the entire loop associated with a possible
removal and onshore treatment of old drill cuttings, and is limited to the phase from the material
is delivered on quay to the material is finally disposed of. This means that it is outside the scope
of the present study to consider how the material is being recovered from the seabed and how the
transport to shore may take place. This will, however, have relevance to the first onshore
handling process and possibly also to the further treatment.
In order to carry out this study it has been necessary to make some assumptions. These
assumptions are however made conservative. The main assumption is that all remaining cuttings
associated with offshore fields where oil based- or pseudo based drilling muds have been used
will be removed. The cuttings volumes used as basis for the study thus represents maximum
values.
The estimated timetable for field cessation and subsequent recovery and processing of cuttings
pile material indicates a peak period of recovery activity between 2010 and 2020. The estimated
amount to be delivered for processing will generally not demand an increase in processing
capacity compared to the present/planned capability, however, there is a predicted shortage of
storage capacity.
There is quite a large difference in composition of the old cuttings material compared with fresh
recently drilled cuttings, as the older material is a mixture of different drilling campaigns and
have been subject to decomposition, water uptake, mixing etc. This represents an uncertainty
with regard to thermal processing of recovered cuttings in both operational regularity and
effectiveness of the processes.
Compared with total available landfill capacity and other sources of waste for disposal, the
volume of cuttings that theoretically could be taken ashore for disposal in the respective time
intervals is small. However, since the material will be processed in a limited geographical area
this could result in some pressure on local landfill capacity. With regard to processed material
quality, the current processing efficiency is improving and most material will be qualified for
disposal in landfills (<0.5mg/kg oil). With the present performance only a small fraction will
have to be sent for special disposal at Langøya. Such disposal is not considered necessary in the
future, as processing performance is likely to improve even further.
Processing onshore followed by landfill disposal of the dry residue will have a cost in the order
of 1500-3000 NOK/tonne (assuming the characteristics of the cuttings are similar to those for
fresh cuttings, and including temporary storage, pre-treatment, processing, transportation and
disposal). Other studies indicate, however, that lifting cuttings and transportation to shore has
significantly higher costs than assumed here (in the order of 1 magnitude higher).
Impacts on the environment should be limited due to the control systems applied and the
requirements given in the permissions to operate both processing plants and landfills.
Most processing operations will result in emissions to atmosphere. Taking CO2 emissions as an
example, the amount of emission will vary significantly from no emissions with the electrically
operated TCC method, through about 100kg emitted per tonne processed with the SRD unit and
in the order of 2500 kg per tonne emitted with the incinerator.


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Discharge of trace metals and organic material to sea recipient through leachate from landfills is
an issue. However, landfills are sealed and drainage is controlled, therefore a controlfailure must
occur to result in notable impacts on the environment.
Aesthetic impacts are generally found to be minor. This is due to the location of the presently
operating plants, but also mitigation measures that are in force to prevent dust spreading, noise
generation and odour. Visual intrusion following the processing and landfill is not expected,
again due to the localisation of the sites.
Other impacts on the local community, such as increased traffic will also be minor, as most
traffic will be at the industrial site.
Re-use opportunities for the products following processing have been studied. Some have
positive prospects and should be studied further. No single re-use alternative is identified that
can be guaranteed success.
The conclusion of the present study is that, given the assumptions made, the cuttings pile
material on the Norwegian Continental Shelf can be processed and disposed of onshore within
the present operating capacity. Impacts to both society and the environment are mitigated and
there should generally not be any significant negative impacts. The main drawback to the
onshore disposal option will be high cost and uncertainties related to the offshore recovery and
transport. The variable composition of material delivered for onshore processing may also
present difficulties.




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2 INTRODUCTION

2.1 Background
“Cuttings piles” is an issue that has come on the agenda during the last 3-4 years as a result, at
least in part, of decommissioning planning. It refers to residues from drilling operations (mainly
rock fragments and drill fluid residues) that have been licensed for discharge, and which have
accumulated on the seabed under and around fixed installations. The focus has mainly been on
“oily” cuttings, referring to cuttings produced when drilling with oil based mud (OBM) leaving
some oily residues when the cuttings are discharged.
From an industry point of view it is important to evaluate all risks associated with field cessation,
including aspects related to drill cuttings piles during disposal operations and following final
disposal. Typical uncertainties are:
    What will the risk be for the environment and fisheries?
    If the risk is considered too high, what are the possible mitigation measures and alternative
     disposal options?
In 1999, OLF initiated a process looking into these aspects with the objective to establish a basis
for decision making. One project has the scope to map existing piles as a basis for further risk
evaluations, and the study is being conducted by Rogaland Research (RF, 2000). Another study
has established a method for characterisation of cuttings piles (NIVA & NGI, 2000).
Land-based disposal is among several disposal alternatives suggested for the material, and DNV
was commissioned by OLF to study the practicalities and impacts associated with such disposal.
This work is based on findings from a similar study performed on behalf of UKOOA (DNV,
1999). The present study focuses solely on Norway and Norwegian conditions.

2.2 Objective
The objective of this study is to consider the practicalities and limitations of onshore handling of
old cuttings material, to evaluate the associated cost and impacts on the environment and society.
Together with results from other evaluations, this study will form part of the decision basis for
the industry with regard to disposal of old cuttings pile material.




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3 SCOPE OF WORK

3.1 Introduction
In 1999, DNV conducted a study on behalf of UKOOA as part of the UKOOA Cuttings Piles
R&D Programme, looking into the practicalities and impacts of disposing old cuttings material
onshore (DNV, 1999). Results from that study have formed the basis for the present project, with
the aim to achieve further knowledge, better data quality and more precise impact assessment,
and to focus on the Norwegian part of the cuttings piles issue.
The scope of the present study is limited to onshore activities and endpoints. This means that the
scope starts with cuttings material delivered on the quay, and ends when material is re-used or
finally disposed of.
A typical process flow is illustrated below:




Figure 1 Cuttings pile material onshore disposal route.

Information is gathered from OLF, literature and personal communication with representatives
from industry and authorities. Of special importance has been information submitted from
representatives from Norwegian cuttings processing industry and individual landfill sites.


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3.2 Approach
The objective of the study is, as presented above, two-fold; to evaluate practical matters and
capabilities, and to evaluate costs and impacts of relevant solutions.
The overall scope is to consider the total amount of cuttings pile material. In addition, to
exemplify the situation, a case study is performed to exemplify costs and impacts.
The basis for the assessment is the amount of cuttings material present on the Norwegian
Continental Shelf, associated with “cuttings piles” (see definition below). Together with an
assumption of cessation period for the individual fields, the total amount of cuttings material is
distributed in five-year time intervals. These five-year totals are used to assess any capacity
restrictions for the existing cuttings processing plants that may exist, and for landfill disposal of
residues.
Practicalities are evaluated on a general basis with respect to the disposal loop from quay to final
disposal, based on experiences with fresh cuttings and assumptions on differences with regard to
old cuttings.
Impacts are assessed based on experiences from processing cuttings and landfilling in general,
based on knowledge about processes and endpoint. Quantification is made for the total cuttings
volume, and for the case study, comparing the numerical values with relevant activities.

3.3 Assumptions and definitions
There are some words and expressions used in the context of drill cuttings that need to be
defined for the purpose of the present project. Also, there are many uncertainties related to old
cuttings, both amounts and composition, and some assumptions will therefore have to be made.
Cuttings pile. When cuttings are discharged at seabed or from the rig/installation the material
will spread. Many factors will affect this spreading, and in many cases there will never be any
visible mound of solids below the installation.
Among the factors considered important in evaluating if there is a pile (and its size) are:
    Type of discharge (WBM, OBM, PBM)
    Discharge regime (over board, dumping liner, at seabed)
    Field structure (fixed installation, floater/pre-drilling, satellite)
    Time since discharge
    Geographical location
    Water depth
    Currents


In this study, the focus is on cuttings piles (not the material that is widely spread). We have not
identified any globally accepted definition of a cuttings pile from literature. The study performed
by NIVA & NGI (2000) on cuttings characterisation, however, gives a definition that we adopt
in this study:


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“A mound of solids material gathered on the seabed underneath and around an offshore
installation due to the deposition of drilling waste material.”
Cuttings deposits representing a thin layer on the seabed are thus generally not considered a pile.
The reason for making this type of distinction is to focus on concentrated amounts in a limited
area. Environmental risk differences that arise as a result of material being concentrated in a
small area or spread out over a large area are not part of the scope of this study.
As mentioned above the question whether there is a pile and what the pile is made of is
important. When the wells are drilled with oil based mud (OBM), the mud will mainly stick to
the cuttings and accumulate under or near the installation. A similar situation will occur from the
use of synthetic or pseudo based mud (PBM). For water based mud (WBM) the situation will be
different as the mud will not be directly associated with the cuttings, thus as both the cuttings
and the mud particles are smaller (lighter) they will spread over a much larger area before they
settle. When individual fields are evaluated in the present study, there is therefore made
difference depending on the mud type used. This philosophy is also in line with the
recommendations for hazard classification for cuttings deposits, made by NIVA & NGI (2000).
In this study, therefore, the main priority is consideration of the piles derived from drilling
with diesel and mineral oil, and large piles from drilling with a combination of water based-
and synthetic based mud.
Old cuttings: This expression is used for cuttings (mixed with mud) that have been discharged
to sea. Fresh cuttings are used to describe cuttings from the drilling process that are taken
directly to shore for treatment.
Material composition. The quality of cuttings material delivered onshore is uncertain,
especially with regard to water content, but also with regard to oil content, chemical residues,
salt and trace metals. As a basis for evaluation, it is assumed that the material consists of50%
solids, 35% water and 15% oil (or other drill fluid residues). Field surveys indicate oil content in
the range of 5 to 22% oil (Cordah/RF, 1998), but for piles originating from drilling mainly
without OBM this content should be far less (e.g. Frigg DP2 with THC concentrations in the
order of 60-400 mg/kg (RF 2000-b)). This distribution is then assumed to be the same for both
the material forming a pile on the seabed, and for recovered material following removal of water
(“de-watering”).
Volume cuttings material. Many studies have been conducted to try to establish the volume of
residual cuttings material under offshore installations (e.g. Andersen et al. 1996, Cordah 1999,
Cordah/RF, 1998). The most recent study performed by Rogaland Research (RF 2000) for OLF,
has tried to quantify all discharges from Norwegian fields since they started operations in the
sixties, based on discharge data from operators and regulators. The study has however not
succeeded in quantifying the amount of cuttings present today. Several models have been
developed to try to make such estimates e.g. the UKOOA model (Cordah 1999) and the Ekofisk
model (RF 1999). The UKOOA model is used to quantify the total amount of cuttings piles
material on the UK North Sea, and cannot be used for individual fields. It can however be used
as a reference when estimating the total amount of Norwegian North Sea cuttings. The “Ekofisk
model” is developed as a result of field studies at Ekofisk, but is here considered to be “not-
applicable” to other areas which have different water depth, current regime, and drilling history.
In the present study, an estimate of the amount of cuttings on individual fields and in total is
important input data to evaluate the capacity limitations and impacts. Since none of the existing

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models could be used for this purpose, effort is made to make a best “guestimate” based on
information on parameters assumed to be important. The method is not scientifically proven, but
the uncertainties are considered acceptable, giving indicative results serving the purpose of this
study. The method of estimation and associated assumptions are given in Appendix 1.
The result of this exercise is presented below. It must be noted that these data are indicative only,
and data should not be extracted and used on evaluations for individual fields or otherwise used
without consulting and evaluating all the assumptions given in appendix 1.

    180000
    160000
    140000
    120000
    100000
     80000
     60000
     40000
     20000
            0
                 2000-2005 2005-2010 2010-2015 2015-2020 2020-2025 2025-2030                                        2030+


Figure 2 Cuttings material distribution (m3) in five-year “recovery and treatment”
intervals.

A conversion factor of 1.8 is used when converting from volume (m3) to mass (tonnes).
The figures included in the assessment include cuttings derived from drilling partly or fully with
OBP or PBM. The discharge figures are also totals for mud and cuttings, mud representing 78%
of this (RF, 2000). The percentage split between cuttings and mud after many years on the
seabed is not known, and is not taken into consideration.




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4 CAPACITY EVALUATIONS

4.1 Onshore reception and temporary storage
Old cuttings recovered could possibly be transported to shore in skips (directly or in big-bags*),
in barges or as bulk in other vessels. De-watering should possibly take place offshore to save
transportation capacity and cost. Vertical centrifuges with large capacities are one example of an
effective dewatering process.
At present fresh cuttings are normally transported by supply ship back to the base, and further
shipped with the same/other vessels to the processing location. Old drill cuttings and mud will
most probably be transported from the different fields directly to the processing sites onshore in
Norway by a designated vessel.
The onshore destination will depend on the location of sites for further treatment or disposal. As
of today the three operating processing plants in Norway are located west of Bergen (cf.
Figure 4).
The most commonly used containers have a capacity of 3-5 m3 net volume of drill cuttings
contained, and containers characterised as big can take 10 m3. It is outside the scope of the
present study to consider how this transport may take place, however it will have relevance to the
first onshore handling process. The relevant first step upon onshore reception will either be
placing containers on a quay area or pumping material to temporary storage units onshore. It
should be noted that Swaco is now looking into transportation of fresh cuttings in bulk by supply
vessel from the rigs to the treatment facility. This concept also be applied to old cuttings, which
are recovered in large quantities.
When received onshore, further handling will depend on the next or ultimate destiny of the
cuttings, the way they were brought to shore, their condition with respect to water content etc.
Temporary storage in containers or larger waste storage tanks is possible, but capacity will be a
limitation in many places. The storage capacity at the present processing facilities varies from
about 1000 tonnes to 7000 tonnes (For fresh cuttings these “tanks” are used for mixing drill
cuttings and mud to a preferred composition of pumpable material). When considering individual
fields on the Norwegian Continental Shelf (NCS), and assuming all material is delivered onshore
within a short period of time, the relevant volumes arriving will be of the order of some hundreds
to 35,000 m3 (cf. Appendix 1). Compared to handling fresh cuttings (receiving some hundreds of
cubic meters at a time) temporary storage of old cuttings represent a challenge.
If cuttings from large piles are recovered and delivered to shore in bulk there is therefore at
present not sufficient storage capacity. The storage area for containers is also quite limited,
generally speaking accommodating some 10 to 100 of containers. There are also at present not
that many containers available (though that is a demand question only), and normally containers
are returned to the ship before it leaves the quay.




*
    It should be noted that one of the three cuttings processing plants has problems with the used big bags, spending much time and
       money on cleaning them before disposal.

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A study performed by Østlandskonsult for OLF in 1993 (ØK, 1993) looked into the capacity of
processing fresh cuttings, including storage facilities. The cost of constructing storage tanks was
estimated as:
                 Tank size (m3)                               Cost per m3 (NOK)                     Cost per tank (NOK)
                      200                                        2,000-2,500                          400,000-500,000
                      400                                        1,500-2,000                          600,000-800,000
                     1000                                        1,100-1,200                        1,100,000-1,200,000


It will not be practicable, within all the existing processing localities to construct and place
enough large temporary storage tanks. Such investment will also depend on the flow of old
cuttings material. If cuttings are received on a regular basis, and over many years, at least two of
the three plants will have available space for some tanks. However, the investment cost will also
have consequence on the total processing cost.
For rental of areas for skip storage ØK (1993) estimated the cost to 90 NOK/m2 (time period not
mentioned, assumed to be per month). As the use of base area will be limited or not relevant to
old cuttings this cost is not considered further.

4.2 Pre-treatment
Onshore pre-treatment before processing or disposal is possible and will again depend on the
final destination, the process/disposal site to be used, the means of transportation etc. Further
dewatering before transport could be a cost saving measure. Pre-treatment associated with
thermal processing is mainly associated with water content. It is important to keep this content
below about 40% to achieve acceptable results. Further, the size and hardness of particles could
be important, as large and hard particles will lead to an ineffective operation. A mix of hard and
soft particles may also reduce the efficiency of the operation. Centrifugation is suggested as a
useful pre-treatment step to de-water, reduce particle size and reduce hardness of particles.
Chemical parameters such as pH, wettability characteristics and content of trace metals could
also affect thermal processing and some chemical pre-treatment could be necessary.
Washing with freshwater to avoid elevated salt concentrations in the dry residue is another issue
with relevance to reuse of the dry solids.
As all these issues are very dependent on the cuttings condition when received onshore, as well
as the further process/disposal no detailed evaluation is made.

4.3 Processing
As part of the work conducted for UKOOA in 1999, operational and planned cuttings processing
technologies and plants were mapped. For further introductions on these technologies please
consult DNV (1999) or go to the web site: www.oilandgas.org.uk.
In the present report, the focus is on the cuttings processing technologies that are operational
(and planned) in Norway at present. It is fair to state that the existing Norwegian processing
companies have developed very good systems, and have modified and improved their
technologies during the last 10 years. To our knowledge they represent the best cuttings
processing competence in Europe at present. They are also working to continuously improve and
further develop their processes.

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The technologies applied in Norway at present are based on three different principles:
 Thermal distillation
 Thermal distillation following hammer-mill processing
 Incineration


For used drilling mud one biological treatment process is also available, while the other
processes work with a mix of mud and cuttings to optimise their process operation.




Figure 3 TCC (left) and SRD thermal processes.

The companies comprising this industry in Norway are:
    Franzefoss, located at Eide (Sotra) has two different thermal distillation technologies. Three
     conventional “Soil Recovery Denmark” (SRD) units and one modified unit with a higher
     temperature interval. They normally run two units depending on capacity needs.
    Soilcare AS (Thermtec) located at the Mongstad base has two conventional SRD units and
     one “Thermo-mechanical cracking and conversion” (TCC) unit – often referred to as a
     “Hammer-mill” unit.
    Sløvåg located in Gulen (across the Fensfjorden from Mongstad) has an incinerator process
     for cuttings mix, and a biological process for used mud.
The locations of the plants are indicated in Figure 4.
A more detailed description of the technologies is given in Appendix 2, and a short description
of each the operating processing plants is given below.




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Figure 4 Location of cuttings processing industry.



Soilcare AS:
The plant is located at the Mongstad Base in the municipality of Lindås, some 1hour drive from
the city of Bergen.
Their most important customers are oil companies operating in the Norwegian part of the North
Sea, refineries and other process industries.
Technologies used are SRD and TCC, and as described in Table 1, the largest amount of treated
drill cuttings is by using the TCC technology.
After treatment the dry residue may contain different residue amounts of oil depending on the
technology used. By using the TCC technology the residue of oil will be about 0.1 w %, and by
using the SRD technology about 0.5 w % of oil.
Permission for treating oily waste at the location is given by the county governor and the SFT.


Franzefoss Gjenvinning AS:
The company is located at Eide in the municipality of Fjell (Hordaland).
Their main customers are Statoil, Hydro, (Saga) and Esso which all deliver oily waste for
treatment. The processing site normally uses three machines, and every single of them is able to
treat about 1 ton of drill cuttings and/or mud per hour. The main task for these three machines is
to retrieve the oil added in the mud and drill cuttings. A future target is to regain the oil added,
and make the mud companies reuse it. At present time this oil may only be used as fuel.
They process 425 tonnes of oily cutting and mud each week, and residues of oil in the dry treated
waste are 0.8 - 1.0 w %. This residue of oil is higher than the limit for disposal of dry treated
waste in an ordinary landfill site, and the dry waste must at present be transported to Langøya for
disposal.



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The technology used is SRD - the same technology as Soilcare is using, but Franzefoss has
recently invested in three new modified machines to increase the temperature of the process.
By using a higher temperature for the treatment of drill cuttings (500C instead of 340C), more
oil may be retrieved from the material getting the residue of oil below 0.5 w %. The landfill site
located on the property of Franzefoss may then be used for disposing of the dry treated waste.


Sløvåg Industriservice AS
The company is located in the municipal of Gulen in the county of Sogn- og fjordane. As for the
others, it is located by the sea and in the vicinity of deep-sea quays.
The technologies used differ from the two others and are based on incineration and biological
treatment. Sløvåg Industriservice treat 40,000 tonnes of mud by using biological treatment and
15,000 tonnes of cuttings by incineration. They have firm plans to install a new incineration unit
replacing the existing one, within a time frame of approximately 2 years. The capacity of the
new incinerator will be similar to the present.
The residue of oil after treatment is less than 0.1 w %, and the treated waste is disposed of in
their own dedicated landfill site.


Planned processing plants in Norway
Research and testing for developing new and better technology for treatment of drill cuttings and
mud is a continuous process. In Norway, as well as in other countries, effort is made on
developing new technology.
At present time there is one cuttings processing plant at the planning stage in Norway. They
expect a permit given by the government in the very next future (though the first application was
returned). First processing is planned for November 2001, but the schedule is assumed to be
delayed. The location of this processing facility is Jøssingfjord in the municipality of Sokndal
(Rogaland).
The technology planned to be used is the already described above under SRD-technology, with
some slight modifications.
The capacity of each unit will be approximately 5 tons per hour (about 800 tons per week).
For the first phase in the development an annual treatment capacity of 40,000 of tons is planned
– but the ultimate goal is an expansion to treat 300,000 tons of oily waste each year.
The residue of oil in the dry treated waste are claimed to be between 0.1 and 0.3 w % - for
presently operating plants this is 0.5-1%. The processing site will be located in the vicinity of
Titania AS, a mining company extracting illmenite. The associated landfill is planned to be used
also for the dry residue from the cuttings processing.

Other relevant treatment plants
It should be mentioned that Soilcare is planning a new step in their processing, named MARSEP
technology. The objective is to crack heavy oil components by using special temperature


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intervals (60-90 ˚C) before the SRD process. The technology is expected to enhance the
delivering of high quality oil and will save substantial quantities of energy per unit processed.
The company SWACO which presently is involved in e.g. reinjection, mud separation and
reception of mud/cuttings waste onshore, has established co-operation with Soilcare using the
TCC unit for processing muds for reuse of the base oil.
Other waste companies have indicated plans for treating cuttings, but without being specific.
These are therefore not considered further.


NOAH, Brevik and Norcem’s cement kiln.
As an alternative to NOAH (Norsk Avfallshandtering AS) Langøya as the final disposal site of
the dry treated waste containing more than 2 w% oil, NOAH Brevik has opened a processing site
for special waste in Brevik (summer 1999). The processing site accepts different types of organic
special waste, which separately require special treatment.
The process consists of sequential steps including grinding pulverisation, separation of solids and
liquids, re-use and washing of metals, mixing with wood chipping and fractionation.
The solid waste is filled in containers and brought by tankers the short distance to Norcem’s
processing plant. The liquid part is pumped directly from the storage tanks to the cement kiln.
This transmission is controlled by Norcem and is based on their need of fuel for their cement
production.
NOAH Brevik is licenced to accept and treat 31,000 tonnes of special waste. The processing site
has just started their operation and has, so far not tested the processing site for handling drill
cuttings. At the present time there is no operative quay at the processing site in Brevik, but
NOAH hope to have most of the waste transported to them by boat in the near future.

4.3.1 Processing capacity
In order to evaluate the processing capacity in Norway only the presently operated plants are
considered. This represents a conservative approach as other plants are planned (see above).
To evaluate the capacity we have studied the following issues:
 Presently licenced volume
 Actual capacity
 Planned additional capacity

The maximum annual cuttings processing capacity of the three presently operating processing
plants is 95,000 tons of cuttings-mud mix and 40,000 tons of mud, however the licensed amount
is less (about 70,000 tons). In 1999 about 50,000 tons cuttings mix were processed (Table 1).




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Table 1 Cuttings processing capacity and normal annual processing amount.
Processing plant               Soilcare AS                         Franzefoss Gjenvinning      Sløvåg Industriservice AS
Licence volume                 11,200 tonnes*                      30,000 tonnes               35,000 m3
Present capacity               SRD: 13,000 tonnes                  25,000 tonnes**             Incineration: 15,000 m3 (30,000 T)
                               TCC: 26,000 tonnes                                              (Biological: 20,000 m3 mud)
Planned additional             0                                   20,000 tonnes               0
capacity
Annual Fresh cutting           15,000 tonnes (1999)                23,000 tonnes (1999)        15,000 T cuttings (1999)
processing                                                                                     17-18,000 m3 mud (1999)
Spare capacity                 24,000 tonnes                       22,000 tonnes               15,000 tonnes
* Permission is expected to be extended to 30,000 tonnes a year
**They have however space to expand with more machines and these (mobile units) will be rented from Denmark on demand.
    Their capacity could thus easily be doubled at low relatively cost.


The annual gap between capacity and fresh cuttings produced is of the order of 40,000 tonnes
over-capacity at present, but this could easily double in the near future.
If old cuttings are to be recovered and brought to shore, the annual rate will generally be in the
order of 1000-15,000m3, with peak values following individual fields at a maximum of
35,000m3, and five year totals at a maximum 200,000m3 (40,000m3/y). (Data based on
assumptions given in Appendix 1).
Processing capacity will thus, in a course evaluation such as here, be higher or of the same order
of magnitude as the demand. The demand will only be greater than the capacity for a few single
years. With the uncertainty associated with these numbers this is not considered significant, and
no capacity build-up is considered recommendable.


4.3.2 Critical factors for processing
Due to the different technologies used, the companies having processing plants in Norway have
been asked to give an indication of the critical factors that may influence on the processing of
drill cuttings and mud. Grain size, water content, material composition/consistency, salt content,
heavy metals are all factors which in one way or another may affect the processing line. All these
factors are described below, indicating how they may cause problems during processing or
towards the final product after processing.


Grain size
Small particles may cause problems during thermal distillation processing. The problem is that
small particles may reduce the ability to separate oil from the solids. Processing experience
indicates that the smallest particles, ranging from 0.010 - 0.001 mm, cause the biggest problems
in the processing line. For old cuttings, that have been on the seabed for a long time, it is
considered possible that some of these small particles may have been removed by current
movement/erosion, making this less of a problem compared to fresh cuttings. No evidence has
been found supporting this theory, and it could also be very much dependent on local conditions.
Below is presented a grain size distribution for the Ekofisk 2/4 B pile as an example.
Unfortunately there is no analysis below the silt limit (particle size less than 0.063 mm).

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However, one can assume that 5-10 w% of the total weight of material may be in the particle size
range (0.010 - 0.001 mm) known to cause problems in thermal processing.
Table 2 Grain size distribution in pile underneath the installation 2/4 B. 0 – 50 cm.
       Size (mm)                   Weight (%)                  Cumulative weight (%)
          > 4.0                        2.7                            100.0
           2.0                         3.8                             97.3
           1.0                         9.9                             93.5
           0.5                        11.1                             83.6
          0.25                        12.9                             72.5
         0.125                        19.3                             59.6
         0.063                        12.4                             40.3
        < 0.063                       27.9                             27.9


Heavy metals
There are no indications that heavy metals may cause problems during processing. However
when it comes to reuse or final disposal of the dry residue, heavy metals could both represent a
limiting factor and a cost element.
Several attempts have been made to use the dry residue from processing as part of structural
material or as roofing tile. Elevated concentrations of heavy metals (associated with barite) are
one of the factors effectively preventing such use to date (RF, 1998-b).


Salt
For thermal or mechanical processes salt enhance corrosion but is otherwise not found to cause
any problem. (The SRD and the TCC processes are able to handle a mixed material containing
up to 11 % brine).
For the biological treatment of mud, salt may influence the disintegration rate in an aqueous
environment. The disintegration rate of hydrocarbons may decrease due to increasing content of
salt. Tests performed by Ward and Brock (1978) gave results indicating this inconvenience. This
effect is expected and is connected to a general reduction in microbial metabolic rates at high
concentrations of salt (Østgaard et al. 1996).
The Norwegian processing site using biological treatment claim not to have any problems with
salt in the processing of drill mud. As a basis for the culture of bacteria they use the naturally
occurring culture in the drill cuttings and by developing this culture it might become a culture of
salt tolerating bacteria.
Too high a content of salt may also cause problems when trying to reuse the dry residue in
asphalt and construction material.


LSA Scale
If cuttings material contain scale (low activity radioactive material) the processed waste products
cannot be disposed of in landfills. There is no general indication that cuttings piles contain scale,

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and the scale problem is also very variable between fields. The presence of radioactivity should
be identified before material is recovered and delivered for processing.


High water content
For the SRD and the TCC technology, several tests have been performed to find the most
suitable mixture of water, oil and cuttings. To get a continuous flow in the processing line the
following composition is preferred:
    50 – 55 % dry material/cuttings
    15 % oil
    35 % water
A de-watering pre-treatment will ensure an optimal or working composition of the fed, and water
will thus not directly limit the process.


Consistency and composition
One of the biggest problems when treating drill cuttings and mud is the consistency of the
material. A glutinous consistency may cause problems in the process line and continuous flow
may be hindered. Accumulation of both treated and untreated material may occur if the mixture
of drill cuttings and mud is not carefully controlled and monitored. The right balance between
mud, cuttings and water is thus very important. Ensuring such a balance for “old” cuttings could
be more difficult than for fresh cuttings, as they are already mixed. Mixing “old” cuttings with
fresh cuttings could be one way to try to reduce this problem.



To conclude this section on critical factors for processing, the most important issue will be the
difference in composition of the pile material. All the above mentioned aspects could be relevant
but none is considered to be a general limiting factor. To overcome all these uncertainties some
test trials should be run testing material of different quality and with different processes.

4.4 Waste disposal
4.4.1 Number of relevant sites
In most counties in Norway there are several municipal, inter municipal and private landfill sites.
The current trend is that the number of municipal landfill sites is decreasing, leaving fewer but
larger landfills.
Only a few of these landfill sites are permitted to accept oily waste, and have landfill areas that
fulfil the requirements of the SFT to deposit such material. Some landfill sites may have
permission to accept oily waste but due to their geographical location and their capacity
limitations, they will not take residues from oily cuttings (presently accept no other oily waste
other than from domestic waste and from oil separators). Landfill sites located at the processing
site or nearby are most likely to accept the dry residue of the treatment of drill cuttings. The three


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main processing sites in Norway have their own landfill site or have an agreement with a landfill
site located nearby. There is no experience of transporting this waste far from the processing
location. This may be one of the reasons why landfill sites which could be suitable for accepting
such waste, have never considered it.
The three main processing sites in Norway are located just outside Bergen, and local waste
disposal sites are assumed most relevant. However, to check the capacity and willingness to
accept such waste, landfill sites in the county of Vest Agder, Rogaland, Hordaland, Møre og
Romsdal, Sogn og Fjordane and Sør-Trøndelag have been contacted (totally 44 landfill sites).
19 of these landfill sites are either permitted to accept oily waste, or are considering the
possibility to use this material as cover material for their disposal sites. More details about
location and capacity are found in the report following the UKOOA phase I study (DNV 1999).




Figure 5 Special landfill for treated solid cuttings residues.

4.4.2 Legal requirements
With reference to the regulation of special waste (Miljøverndepartementet, 1996), untreated oil
contaminated drill cuttings (more than 1 w% oil) are classified as special waste and must be
delivered to an approved receiving station for treatment. NORSAS (Norwegian Resource Centre
for Waste Management and Recycling) has the responsibility for implementing the system for
special waste. The treatment of this kind of waste includes material recovery, energy recovery
and depositing. For some of the types of special waste special collection systems have been
established. During the past years there has been an increase in the amount of waste delivered to
the special waste system (In 1990 it was 60,000 tonnes, in 1998 it was 140,000 tonnes. In 1998
the oily waste constituted 44 % of the special waste).
Final oil content of the dry residue after treatment is normally between 0.01 and 0.5 w%* for the
operating plants in Norway (CORDaH, 1997). This material is then no longer looked upon as
special waste and may be deposited on any approved landfill site (there are however also other


*
    At present the Franzefoss plant has problems to reach this level and are often in the interval 0.8-1%. Their high temperature
      technology is however believed to change this situation to the better.

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conditions – see below). The county governor gives this approval to landfill sites fulfilling
certain requirements.
The disposal of waste with an oil content between 0.5 and 2 w% is not permitted in regular
landfill sites for oily waste. Inorganic special waste (less than 2% organic content) is sent to
NOAH’s (Norsk avfallshåndtering AS) treatment site on Langøya for stabilisation and
neutralisation before final disposal.
One of the processing sites have just recently been able to treat the drill cuttings to such an
extent that the oil content of the dry residue is below 0.5 w%. Currently the oil content from this
plant is between 0.8 % and 1.0 %, and the dry residue is delivered to Langøya for final disposal.
With an oil content over 2w% the dry residue can not be disposed of in Norway and will be
incinerated or exported.
Limits of hydrocarbon content and associated disposal requirements are summarised below:
     Hydrocarbon content (%)                      Disposal
            <0.5 (1)                              Specially licenced landfills
              0.5-2                               Langøya
               >2                                 Export or combustion


In the above discussion of processing drill cuttings the oil content has been the initial focus.
However, it is also possible to classify some drill cuttings as special waste on account of their
generic attributes with regard to the threshold values for various risk phrases detailed in
Schedule 2 part III of the Special waste regulations (MD, 1996). This will then be a case by case
evaluation, but it is an important issue especially with regard to the processing technologies and
the possible use of the residual dry solids.
Even if the upper limit is 1w% oil there is not an uniform level of oil content in oily waste at
which landfill disposal is permitted. Each landfill site has to get permission from SFT, and the
level will then be at or below 1%. Such a permit will, of course, consider many more aspects
than oil concentrations, e.g. design of landfill, plan for drainage of seepage water, emissions,
monitoring programme etc.
Regulation for export of waste gives the opportunity to transport waste across the Norwegian
border and to processing sites in the EEA/OECD area. SFT may normally give permission for
export of waste for recycling. Exporting waste for final treatment will not be permitted if there is
a Norwegian processing site able to handle the waste. This is in accordance with the “vicinity
and self-supporting principles” applied in the EEA (SFT, 1999).

4.4.3 Capacity limitations
Norsk Renholdsverksforening (Norwegian association for waste companies) has made an
overview of landfill sites permitted to receive special waste (listed in DNV, 1999). Their total
annual disposal capacity (not only oily waste) is estimated to be approximately 560,000 tonnes.
However, looking at the sites that receive oily waste, a total annual waste capacity of 360,000
tonnes per year is considered more realistic.
As previously mentioned the volume of cuttings on the NCS of the North Sea is of the order of
700,000 tonnes. Offshore field cessation will take place spread over several decades. If cuttings
are to be recovered and brought onshore, this could be phased together with field cessation. The

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annual demand for landfill capacity from these cuttings will be of the order of tens of thousand
tonnes rather than hundred thousand tonnes. Landfill capacity on a national level is thus not
considered to be a limitation. However, as processing plants are located in the same region there
could be some pressure on local landfill capacity.


4.4.4 Geographical location and logistics
Two of the processing plants in Norway have landfill sites located on their own land and the
transport route is uncomplicated. The third processing plant uses an inter-municipal landfill
located 15km away.
At the present time there is thus no processing plant in Norway that has to transport the end
product over a long distance to the landfill site. This also includes the planned processing plant
in Jøssingfjord, using Titania AS’s landfill.
If large volumes of cuttings are recovered and treated at the present processing plants the
residues will possibly have to be transported some distance for disposal (as local sites will not
have sufficient capacity for large volumes). Railroads and road systems in western Norway are
not very well developed due to topography, scattered settlement and since other dominant
transportation routes exist. As both processing plants and most relevant landfills are located
along the coastline, sea transportation is considered the most relevant transportation route for
cuttings.
Table 3 Most relevant landfilling sites for present processing plants.
Processing site                       Soilcare AS                           Franzefoss Gjenvinning             Sløvåg Industriservice
                                                                                                               AS
Landfill site used                    Kjevikdalen landfill,                 The landfill site is located       The landfill site is located
                                      Nordhordaland and Gulen               in the same area as the            in the same area as the
                                      inter-municipal waste                 process is performed               process is performed
                                      company..                             (Eide) - on the property of        (Sløvågen) – on the
                                                                            Franzefoss.                        property of Sløvåg
                                                                                                               Industriservice.


As the dry residue containing more than 0.5w% oil may not be disposed of in a regular landfill
site, it has to be transported to NOAH’s landfill site for special waste on Langøya. The transport
to Langøya is by boat (about 350 nm). As discussed under the processing section, this is not very
likely to happen as the 0.5% limit will be met in the future.




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Figure 6         Waste disposal sites in coastal areas of Hordaland county.



4.4.5 Using treated drill cuttings as cover material on landfills
Many operators of landfills have responded positively to the idea of using dry residues from
thermal processing of cuttings as top cover on their landfills. The material must obviously meet
the requirement of hydrocarbon content (<0.5%), but there is still some problems getting
permission for such use. As discussed under “Legal requirements” hydrocarbon content is not
the only area of concern for the authorities when classifying hazardous waste. As the
composition of old cuttings material is believed to vary between fields, it seems difficult to find a
general acceptance for such use, and analysis of every shipment of material plus consideration of
the requirements of the relevant authorities will be required for each case. At the moment such
use is only permitted on a few landfill sites.
The reason why operators find this idea attractive is the fact that they have a demand for
covering masses, which they normally will have to pay for and which also could be a limited
resource. Using the dry residue of processed cuttings for this purpose could therefore be both
economically and logistically favourable. In the opinion of the author of this report, however, the
challenge is to obtain more general acceptance for such reuse. This concerns the perception of
reusing something that was originally “special waste”. A dialogue with authorities following the
proper testing of material and documenting the demand could ease acceptability for such reuse.




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5 COST ASSESSMENT

5.1 Cost of pre-treatment
The cost of dewatering has not been studied as this is assumed taking place offshore. If
performed onshore it will be performed as the first step in the processing chain, adding
operational costs assumed to be of the order of 10-20% (100-150 NOK/tonne). Capital expenses
are not estimated.
If fresh water washing for removing salt becomes relevant this will also add a new step in the
processing chain. The additional cost again, could be in the order of 10-20%, but it is not
calculated.

5.2 Treatment costs
The three Norwegian processing plants have average costs of processing oily waste of about
1300 NOK per tonne treated (1000-1500 NOK).
The unit costs may vary significantly however due to the characteristics of the waste, processing
effectiveness, capacity etc.
The processing capacity is highly dependent on the amount of water in the feed. A normal
processing rate for the SRD technology unit could be roughly close to 1.5 tons/hour for a feed
with an oil wet feed of about 30 – 35 % water and with a fair amount of high molecular weight
chemicals. High content of chemicals can, in some instances, lead to operational problems.
The processing capacity can be increased by a decrease in water content, and similarly be
reduced to below 1 tonne/hour if the feed is too wet.
A TCC 400 kW unit can process roughly 3 tonnes/hour of oily cutting with a water content
roughly 20- 25 %. With this technology an increase in the water content can also lead to a
significantly reduced processing capacity.

5.3 Disposal costs
The costs gathered for hazardous waste delivery (destruction) in Norway vary between 780
NOK/tonne and 1200 NOK/ton, with an average cost at 1030 NOK/ton (DNV, 1999).
For conventional waste the cost is significantly lower. The landfill site Kjevikdalen Avfallsplass,
NGIR, which is a non-profit inter-municipality owned company, accepts dry residue from
processing at a cost equal to the disposal tax i.e. 200 NOK/ton (+23% VAT).
Disposal at Langøya for this type of waste is said to be in the order of 600 NOK/ton, including
transportation from Hordaland (about 1000 tons waste per shipment).

5.4 Total costs
Following from the data presented above, processing onshore followed by landfill disposal of the
dry residue will have a cost in the order of 1200-2500 NOK/ton cuttings (assuming the
characteristics of the cuttings are similar to fresh cuttings, and including temporary storage, pre-
treatment, processing, transportation and disposal, see Table 4).



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Table 4 Cost per activity for onshore handling, processing and disposal.
Cost activity                                                        Cost per tonne (NOK)
Pre-treatment and local transport                                            0-300
Treatment                                                                  1000-1500
Disposal                                                                   200-1000
Total cost                                                                 1200-2500


Applying the cost data for treatment and disposal documented in this report, the cost of disposing
of the total 700,000 tons of cuttings material will be about 850 – 1750 million NOK
For the total cost picture (not limited by the scope of the present study) there are additional costs
for recovery from seabed, de-watering and transport to shore. Cost estimates developed under the
UKOOA R&D programme phase 1 suggest recovery unit cost in the range of 380-2760
NOK/ton, but the estimates are very course. For the total amount of cuttings this means an
additional cost in the range of 300-2000 million NOK.
The offshore de-watering issue is currently not looked into, thus no cost estimate is produced.
Cost for transport to shore will depend on type of transport, vessel and amount of material. For
bulk transport a course estimate was made back in 1988 (COWI, 1988) indicating cost per tonne
in the order of 150-300 NOK. Transport in containers (skips) will have cost for vessel use and
rent of containers. The cost will depend mainly on the vessel day-rate and duration, depending
on the amount to be transported.
Logistics associated with lifting containers/pumping bulk material are assumed to have a cost in
the order of 30-70 NOK/ton (COWI 1988). Possible storage onshore has a cost in the order of 5-
10 NOK/day/m3.
Previous studies (Phillips, 1999) have concluded that costs for the entire loop (from seabed to
final onshore disposal) have a unit cost in the order of 30,000 NOK/tonne. For small volumes the
unit cost is far higher (DNV, in prep.).




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6 RE-USE OPPORTUNITIES
There is no experience with using recovered “old” cuttings for any purpose. There are however
some examples of studies and trials with re-use of some fractions of “fresh” cuttings.
The possible use as top cover on landfills is discussed above. Presently it is only permitted on
“special” landfills. There is, however, generally a demand for such material, and the issue should
be looked further into and discussed with relevant authorities.
Other types of re-use of cuttings waste products were studied as part of the UKOOA study (DNV
1999). In addition to this, through the present project Statoil has shared some results from studies
looking into re-use opportunities of fresh cuttings.
Presented below is an extraction of results from the UKOOA study and the different Statoil
studies follows. These include a discussion of possibilities for using fractions of cuttings
(oil/solid phase) following processing, or directly without any treatment.
In general, the products of the processing consist of oil, water and a dry residue or mud
depending on what kind of treatment is used. The percentage distribution from the processing of
fresh oily cuttings is normally in the region of 10 % oil, varying water content between 30 and
50 %, and the content of dry residue/mud varying between 40 and 60 %.
The product of the processing is very much dependent on the material which is fed into the
processing machines. As long as the relative distribution of the old cuttings is not exactly known,
it is difficult to give any indications of the content of the end product. It is therefore assumed to
be similar to fresh cuttings, probably with somewhat higher water contents.

6.1 Use of untreated cuttings
In the UK it has been proposed that untreated cuttings are used as feed for coal fired power
stations. There is no similar opportunity in Norway, however it seems likely that the energy
content is significantly lower than normal, meaning that much more “fuel” must be fed into the
system. The possible use/treatment in the cement kiln was addressed above but, with regard to
the cement product, cuttings are generally not considered a useful material, rather the opposite.
On behalf of Statoil, Norcem studied this opportunity. Problems identified are:
 Cuttings material with large particles must be crushed
 The energy content is very low compared to normal fuel, i.e. large amounts must be
    used/mixed with other fuels
 The consistency of the material was very inconvenient with regard to handling prior to
    feeding.
Their conclusion is that it could technically be used, but it will introduce many new uncertainties
and problems.
The use in cement production was also considered and tried by Sløvåg, representing both a
cuttings processing industry and a cement producer. The main problem they found was that
cuttings lack strengthening properties. This is ensured by silica in normal cement production.
Also the barite content represented some problem.



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Statoil has also engaged Jordforsk (1999; in prep.) to look into the possibilities of using cuttings
in different type of soil, and also for enhancing crop production.
Their conclusion is very optimistic (positive) and recommends cuttings mixed with sand and/or
other organic material.
Problems identified are associated with high pH (pH 10), which should be about pH 7 to give
optimal (neutral) conditions, but this could be mitigated by introducing about 50% composted
material. Another problem is the balance between magnesium (Mg) and potassium (K), which
represents a challenge.
There has been a lot of speculations about content of trace metals in cuttings material. Based on
the evaluation done in these studies, the values are found comparable with normal Norwegian
agricultural soil. This should therefore generally not be an important limiting factor.

6.2 Recovered oil
For fresh cuttings the oil phase from the SRD (low temperature version) can be reused as drilling
mud oil without further treatment. Under these circumstances there would be no discolouring of
the recovered oil (brownish colour). From a compositional point of view the recovered oil can be
classified as a light fuel oil. Such classification is approved by the Norwegian environmental
authorities (SFT), as the oil recovered from the cuttings does not contain any priority pollutants
in the form of chlorinated organic compounds, phthalates or any other type of organic toxins.
The oil phase from the SRD (higher temperature version) will lead to an oil quality which can
not be reused as mud oil without removing the cracked products. Higher sulphur values in the oil
due to cracking may make a detailed analysis necessary if the oil is to be used as a fuel oil.
Depending on the chemical content of the feed stock recovered, “TCC oil” in a normal
operational mode will probably contain some by-products and some fine solid particles making it
necessary to clean up the oil before re-use.
Recovered TCC oil in a plasma mode operation could remove the necessity for further clean up
of the oil.
For old cuttings, the oil is usually assumed to be mixed with different chemicals or oils, it could
be at different degradation states, and is not considered applicable for use in new mud.
Depending on the oil quality, the oil could possibly be collected and sent to refineries for
processing with crude and finally used for normal consumption. Alternatively, the recovered oil
could be used as fuel for the processing plant or used for energy recovery (oil burnt to free its
energy content which normally is used for heating purposes in industry or households).

6.3 Recovered solid cuttings material
For reuse of the solid residue it can be important to remove as much salt as possible associated
with the cuttings, as salt is identified as an important hindrance for most reuse opportunities.
The UKOOA study identified the following potential re-use areas for dry solid residues:
    Construction of coastal or river defences
    Lining of sewer trenches
    A variety of landscaping projects and the construction of berms/dikes


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    Blending with organic composts
    Construction of cycle paths
    Roof tiles
    Mixture with aggregate used for trench cover or other engineering purposes
    Use as cover material on landfills


In addition the Statoil sponsored studies suggest (RF 1998):
 Brick Manufacturing
 Absorbents
 Clay Pipes
 Terra-Cotta
 Aggregates
 Rubber filler
 Fibre glass composites and other plastics
 Fire brick (Refectories)
 Ceramics
 Mineral wool


The majority of these options require a minimal salt content. For civil engineering projects the
reason is that rain will extract the salts, destroying the robustness and integrity of the material.
The agricultural uses of the cuttings are also not enhanced by salt. If reuse becomes a reality it
would be necessary to invest in cutting washing equipment that can be used to remove salt. In
principle this could be done by the use of heated freshwater. Such washing will add costs, and
the magnitude of this will depend on the purity needed for the new purpose.
On the contrary, for use of such material in roof tiles production (together with clay material) it
will be an advantage not to take out the salt. This is due to the chemical characteristics of clay
materials used for such purposes, where salt is important to make a compact product.
The Statoil sponsored work concluded that the vitrified clay materials i.e. the construction
bricks, roofing tiles and pipes are best suited to the reuse of drill cuttings. These products turned
out to be most technically feasible and are all high volume products.
Previous studies (1990/91) looked into the possibility of using cuttings as an additive to asphalt
production for road coverage. The main problem was found to be release of sulphur to water
during the processing, which is believed to be due to creation of barium chloride from barite
after processing above 800 °C. This is no longer considered to be a problem, anyway not for the
low temperature thermal processes. What is considered important for the use of solids in asphalt
production is particle size and to add an emulsifier to integrate and solidify the material.
The possibility for reuse can also depend on the prior processing methodology. The TCC
technology leaves behind solids in a powder form with small particle sizes. In the early 1990’s a
study was performed at the University of Bergen to investigate the properties of the TCC
generated solids. The conclusion from this study was that it was difficult to wet these solids, but
once wetted they will keep the moisture under harsh conditions, such as under desert like
conditions.


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One suggestion from this study was to use this solid material as planting soil and even as
agriculture soil in warm desert surroundings (see also Statoil sponsored studies performed by
Jordforsk that support use in soils). For old cuttings, salt content could complicate such use.
Other options are use in asphalt pavement and alternatives as described for the SRD above.
Discussion with the industry has also identified ideas like using the incinerated residue (ash) as
new weight material in new mud, replacing barite. How realistic this suggestion is has not yet
been studied, but it is launched as an idea to the offshore operating and service industry for
further investigation.


6.4 Recovered water
The water recovered from the thermal distillation processes is a waste stream that must be treated
either for reuse or disposal. The quantity of water recovered is equal to that entering the process
with the cuttings. The water quality obtained reflects the ability of the process to destroy the
chemicals on the oily cuttings. The best results are obtained with the TCC technology operated
in a plasma mode leaving behind non-emulsified water that is fairly easy to treat.
The SRD in a low temperature version leaves behind emulsified water which can be difficult to
treat properly.
The SRD in a high temperature version and the TCC in a normal mode operation will leave
behind a water quality somewhere in between the two process treatments mentioned above.
Normally the water phase from the treatment of cuttings (SRD or TCC) is treated in a waste-
water facility (see below) and thereafter discharged to sea. This water is generally not reused.




Figure 7 Chemical/physical waste water treatment following thermal processing.

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If the temperature is elevated (normally about 40 °C, but this could be planned as appropriate)
there could be a potential for getting energy benefits from this to be used for heating purposes
(buildings, offices). Similarly, heat from the solids could also be utilised in a heat pump system
if found appropriate and economically viable.




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7 IMPACT ASSESSMENT
The environmental impacts considered are atmospheric emissions, discharges to sea/water
including seepage from landfills, waste disposal, and energy consumption. Impacts to local
society are evaluated in terms of noise, dust, smell, and increased traffic. More national societal
issues are considered related to economy (cost) only, and are not studied.



7.1 Environmental Impacts
Processing plants in Norway have specific permissions from SFT which they must operate
within. Among emissions/release parameters given, are: particles, CO, HCl, SO2, Cd, Cu, Pb, Zn,
other trace metals, HF, dioxins, oil, esters and other polar compounds.


7.1.1 Atmospheric emissions
The main source of emissions onshore will be from the processing. As most transportation is
local, the associated emissions of exhaust gases are small. There are some differences in
performance between different type of processing technologies, which are presented below.


TCC (Hammermill) unit
For the presently used TCC unit the energy is supplied by electricity and it has no direct
emission of carbon dioxide (CO2), sulphur dioxide (SO2) and nitrous oxides (NOX). Emissions
associated with such processing will then depend on the electricity generation. In Norway,
atmospheric emissions from electricity production are generally not considered relevant as the
vast majority is generated from hydro electric power stations.

SRD unit
Because of external heating with thermal oil the SRD technology gives rise to emission of
carbon dioxide (CO2), sulphur dioxide (SO2) and nitrogen oxides (NOX).
An average low temperature version SRD unit, by reusing the recovered base oil as a fuel, has an
emission of carbon dioxide (CO2), sulphur dioxide (SO2) and nitrogen oxides (NOX) of
approximately 98 kg, 0.005 kg and 0.006 kg per tonne processed respectively. If diesel is used in
stead of recovered base oil, the sulphur dioxide emissions will increase significantly. This is
however not normal, but could be so for old cuttings with low oil content.
In the case of using recovered oil from the high temperature version SRD the monthly emission
of SO2 could increase by a factor of >10 as high temperature cracking of chemicals leads to more
sulphur compounds in the recovered oil.




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Incineration
According to Cordah (1997) and in situ measurements (Jebsens Miljøteknikk, 2000) the emission
from the incineration plant is about 2675 kg CO2 /ton, 0.2 kg SO2/ton and 61.6 kg NOX/ton. In
addition there is emission of small particles, in the order of 200mg/Nm3 or less.


Emission estimate for the total amount of cuttings.
Based on the present capacity and the split between the different thermal processes used, a total
estimate of emissions is made. The process split is:
TCC: 27%              SRD: 41%               Incineration: 32%
The total amount of emissions for the 700,000 tonnes of material processed is then calculated as
presented in Table 5 below.
Table 5 Emissions from processing all the NCS cuttings piles material (tonnes)
                                                   CO2                                       NOX                                    SO2
Total amount (tons)                              640,000                                    14,000                                   50
Annual amount (tons)                            500-80,000                                 10-1700                                 0.1-6.0


It is important to note that the above calculations only represent the steps from onshore handling
through processing and landfilling. Offshore recovery, dewatering and transport are considered
to emit more, but are outside the scope of the present study.

7.1.2 Discharges to sea/water including seepage from landfills
With the exception of the incinerator which emits water as steam, the thermal processes leave a
waste water that needs to be treated before release. SFT has granted special permits with
measures regulating this individually.
Regular environmental monitoring is taking place in the plants aqueous discharge receiving
media (sea). They give no indication on contamination that can be tracked back to the cuttings
processing.
Assuming a processing distribution as for the atmospheric emissions (above), an oil content of
maximum 20 mg/l water, and a water content of 35% (of total cuttings weight) the total
discharge of oil will be about 3-4 tonnes from the two locations divided on 30 years.
Seepage water
There is a risk due to pollution of leachate from landfills after disposing of cuttings material.
This will depend on the nature of the material disposed of, and of course the design of the
landfill. Landfills are now designed with a containment system for leachate, and they are sealed.
Any pollution will then be a result of failure of the sealant or drainage system.
Biological and chemical processes in landfill sites may cause releases of organic material and
nutrient salts to the leachate. If a failure occurs, such releases may be transported with the
seepage water to ground water, river systems and fiords. The content of contamination of the
leachate varies strongly due to waste content, landfill site age, management and degradation rate.



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An extensive survey programme has been performed for two of the landfill sites accepting dry
residue from the processing of drill cuttings (Niva, 1999; IFM, 1996). The results indicate
contamination, but as these landfills receive different type of waste and have done so for many
years, there is no reason to relate this contamination to the dry cuttings solids disposed of.
Contents of the disposed material, which could represent a source of problem or contamination,
are discussed in general below.


Soluble salts (e.g. chloride)
At too high a level, chloride can become a problem in landfills since the bacteria will be
seriously disrupted. This occurs at around 5000 mg/kg as a proportion of the waste mass
(Robinson-Todd, 1999). Thus the input rate of drill cuttings needs to be limited in line with this
level.
Most chlorides are easily water soluble, and could be washed out with the leachate from
landfills. The majority of such soluble salts are however considered to be removed with the
water phase during pre-treatment or thermal processing.
From the presently used landfills, the receiving media will be sea, and no salt problem of
freshwater is thus foreseen.


Metals
Depending on the time in sea and the water depth from which the piles material is retrieved
from, variable water solubility of metals is anticipated. Since most of the cuttings have been
under the sea for several years, the majority of metals will be insoluble in water (most will be
bound in the crystal structure of barite, and will hardly be water soluble). Metals should therefore
not appear in significant concentrations in the leachate. However some tests on processed
residues (see below) indicate elevated levels just after disposal. Generally however this should
not cause a significant environmental effect.
Most of the organic material is destroyed by thermal processing/combustion of drill cuttings, and
the dry residue will mainly contain inorganic material. Analysis of the dry residue shows that it
contains large amounts of barium, sulphur, iron and aluminium. High values of the trace metals
lead, copper, nickel, tin, zinc and strontium have been discovered. The amount of non-
combusted organic material constitutes 0.12-0.16 % (SFT, 1994) and the possible amount of
dioxins is very low. The combusted material is strongly alkaline.
Tests have been done to control the amount of pollution from seepage water from landfills into
water recipients. The tests indicate that seepage water contains large amounts of copper, chrome,
lead, barium, strontium and sulphate for a short time period after deposit. With the exception of
the amount of barium the level for the other components decreases rapidly (SFT, 1994).
The amount of barium and strontium supply to the recipient may be considerable. Both of these
components are found naturally in relatively large amounts in seawater. Strontium is one of the
main elements in seawater and as such is not an unfriendly element to marine organisms. Barium
is not classified as environmentally hazardous in the marine environment. Any barium-ions in



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the seepage water will react with some of the naturally high content of sulphate and will
precipitate as almost insoluble barium sulphate.
A short period of time after depositing, the seepage water could contain relatively high
concentrations of lead (SFT, 1994), which is an environmentally hazardous compound. Even
though the concentrations will be reduced quite rapidly, attempts to avoid such leakage of lead
are needed. The leakage of other trace elements seems to be so small that any effects are not
expected. Some of these trace elements are potentially environmentally hazardous, and should
however be monitored according to the authorisation from SFT (in Norway).
Tests that have been done of the dust/particulate material show that the ash following
combustion is toxic (SFT, 1994). The toxicity of the seepage water depends on the degree of
particle transport from the depositing area.


Oil/hydrocarbon content
SFT has established limits for oil content from the waste-water treatment process from the
thermal and biological processing plants. Monitoring the outlet from the biological process
indicate hydrocarbon concentrations in the range of 1-5 ppm, the requirement being 20 ppm. It
has then been through both mechanical and chemical treatment.
When ready for landfilling the concentration of oil should be below 0.5w%. These oily residues
will have survived thermal processing. They are therefore not assumed easily removable or water
soluble, and should not represent a significant environmental factor.
The residue could also contain other organic material (included in TOC analysis). Residuals are
expected to be about 1-3% after thermal distillation, far less from incineration (indicated as about
0.2%).
As the concentrations generally are low, the leachate controlled impacts on the environment are
generally expected to be small.

7.1.3 Waste disposal
Considering the total amount of old cuttings in the NCS – some 700,000 tons with the time
distribution as suggested in this report, this suggests an annual waste volume for disposal in the
order of 600-100,000 tons (normally 8,000 tons). About 50w% of this are solids.
The annual Norwegian disposal of industrial waste is in the order of 2-3 million tons, and annual
landfill capacity for oily waste is about 360,000 tons. With the exception of the peak period
between 2015-2020 there will generally not be any effect on the waste disposal capacity from the
old cuttings.

7.1.4 Energy consumption
Energy factors studied are: Local handling, waste transport and processing. As for the emissions
it should be noted that the main energy use is assumed associated with offshore recovery,
dewatering and transport that are not part of the present scope.
For the present processing plants, the distance from shore to the plant is insignificant with regard
to transportation. The distance is 100-300m, and mainly on own property. Energy consumption
in local transport on quay by forklift and lorries will be trivial compared to overall energy


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consumption associated with retrieval, transport and final treatment. For one of the plants this is
calculated to 0.0002 GJ/ton based on their actual fuel consumption records and processed
material (data from Franzefoss).
The energy consumption of road transport is also low per tonne compared to other processes in
the loop from seabed to final destination, normally in the order of 0.001 GJ/tonne per km
(Institute of Petroleum, 2000). With the current processing rate the actual distances for two of the
sites are 2km and 15 km, for the third it is only a matter of hundreds of meters.
The energy consumption by processing drill cuttings is dependent on water content in the
material fed into the processing plant. This water content varies, and the amount of water each
technology is able to handle is also variable.
For fresh cuttings the content and the distribution within the material fed into the processing
plant varies due to reservoir type and, to a lesser extent because of the time of storage.
The numbers given below, are estimates for material which have been treated under the existing
conditions.
For the SRD technology, an energy consumption in the order of 1.6 GJ/tonne material processed
is calculated. It should be noted however that this process also recovers oil (oil on cuttings are in
the range of 5-22%) that is reused or used for heating purposes.
For some SRD units process the temperature is elevated using electrical heating. The electricity
demand is about 100 kW (i.e. about 100 kW per ton processed or about 0.36 GJ/ton).


For the TCC technology an energy consumption in the order of 0.5 GJ/ton processed is
calculated (electricity).


Incinerating processes normally have high energy consumption (reported up to 34 GJ/ton).
However for the actual plant the energy consumption is calculated by using data from RF (1998)
to be about 1.7 GJ/ton. The company claims they only uses electricity and at a level of 45 kW.
The energy consumption for the three different technologies is then found to be 0.5, 1.6 (+0.4)
and 1.7GJ/ton respectively. For the total mass of cuttings piles to be recovered the energy
consumption associated with onshore handling, processing and transport will be in the range of
400,000-1.200,000 GJ! The latter equals to 3 months electricity consumption of the municipality
of Stavanger. Assuming a processing split between the processes as calculated for atmospheric
emission, the total energy consumption will be about 1 million GJ.

7.2 Impacts on local community
7.2.1 Noise
None of the presently operating processing sites seem to have a noise problem in the processing
area. The SRD machines are located in half-closed industry halls, and the monitoring of the
process is done in separated control rooms shielded against noise from the machines. The SRD
machine can not be characterised as noisy, and one can easily have a conversation while standing
in the processing hall.


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For companies having both SRD and TCC technology, these two processing methods may be
compared, and the TCC machine seems to cause more noise than the SRD machines. The mixer
associated with the TCC machines is notable noise source, though it cannot be considered either
annoying or at a sufficient level to cause health problems.
The activity causing most noise are loaders transporting drill cuttings between boat and storage
halls, and to/from processing machines etc.
All of the processing sites are located in heavily industrialised areas, and the nearest neighbours
to the processing sites are located some 800 meters from the processing area. There is no reason
to believe that they will be disturbed by noise from the treatment of drill cuttings.


7.2.2 Dust
As most of the process systems are closed systems through the whole processing train, dust
might only occur as a problem when the dry residue has just been created and before it has been
moistened. Some of the processing sites solve this problem by combining moistening and
packing as the final part of the process. They thereby avoid dust problems and get the dry residue
packed in big bags ready for transportation to landfill sites.
Dust has previously been a problem to one of the landfill sites accepting dry residue. They
solved the problem by adding some moisture to the residue before disposing it.
Moistening is now a part of the treatment done by the processing sites, and this reduces the dust
problem considerably, both for the processing site and for the landfill sites.




Figure 8 Examples on systems preventing dust spreading. The “fume” to the right is
mainly water steam.

7.2.3 Odour
All of the four types of treatment processes used for drill cuttings and mud at the present time
have been built as closed process systems and odour does not generally seem to be a problem.
Even close to the processing machines, the smell can not be characterised as disturbing. The
processing area is within closed or partially closed industrial halls. The nearest settlement is
about 800 meter from the processing site.

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The biological treatment (Sløvåg) of the mud could be expected to cause some annoying smell.
No such smell is notable on the processing property, and seems to be a limited local problem in
the very near vicinity to where this method is being used.
For the TCC unit smell is said to be a potential issue, however it is not observed during present
operations. Depending on the storage “history” of the cutting material, it can produce some
odorous compounds when it is processed in a thermal unit. For fresh cuttings the concentrations
of these compounds are normally very low, but the odour recognition thresholds for these
materials are normally extremely low. The end result can be the production of offensive odours,
even if the concentrations of these compounds are not measurable.


7.2.4 Increased traffic
Negative impacts on local society could include increased traffic due to local transport of waste.
This is however considered of low importance at the relevant sites, as most transport probably
will go by sea or by lorries mainly within the processing site. It is relevant for Soilcare
transporting their solid residue with lorries 15km, but in a scattered populated area. In 1999 they
delivered 4,200 tons for disposal, representing about 400 return trips (or on average about one
per day). The negative effect of increased traffic is therefore very limited.


7.2.5 Employment effects
The processing plants are located in rural areas where 10-20 man-years are considered important
to the local community (and generally also according to Norwegian rural settlement strategies).
The capacity of the present plants is, however, considered to be sufficient to receive the old
cuttings, and increases in employment are thus assumed to be low if any at all. The planned new
plant could give some tens of new jobs in an area with high demand for employment and new
business.
To summarise, the overall employment effect from this industry is insignificant in a wider
perspective.




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8 REFERENCES
Andersen et al., 1996. Review of drill cuttings piles. Study for UKOOA/DTI by Altra safety and
environmental ltd.
Cordah & RF, 1997. Review of drill cuttings piles in the North Sea. Final report to ODCP.
Cordah, 1997. Environmental assessment of using onshore disposal of drill cuttings as
management Tool, for BP. September 1997.
DNV 1999. Impact from onshore disposal – study item 7.1. UKOOA drill cuttings R&D
program. DNV report 99-4029.
DNV, in prep. Frigg Field Cessation. Environmental Impact Assessment. DNV report 99-4030.
IFM 1996. Miljøundersøkelse ved Eide Avfallsplass, Fjell Kommune. IFM Rapport nr.14.
Jordforsk, 1999. Bruk av borekaks. Vekstmedier, Report no. 19/99, April 1999.
Jordforsk, in prep. Borekaks i dyrkningsmedier, Biologiske, kjemiske og økotoksiologiske
undersøkelser, (Roald Sørheim, Carl Einar Amundsen, Roar Linjordet, Freddy Engelstad og
Birger Volden), Jordforsk report no. 25/00, February 2000
MD, 1996. Regulation on special waste.
NIVA & NGI 2000. A guidance document for physical, chemical, and biological characterisation
of offshore drill cuttings piles. Version 2, 10 May 2000.
Niva,1999. Resipientgranskning i Lurefjorden 1998. Rapport Lnr 4051-99.
NOAH, Norsk Avfallshandtering AS, Advertising leaflet: “- active cooperator for an improving
environment”.
Østgaard, K., et al. 1996. Miljøbioteknologi, del III: Andre Anvendelser.
Phillips, 1999. Ekofisk 1 Drill Cuttings Piles Characterisation and Management plan. Vers.2.
1999.
RF 1998-a. Industrial uses of drill cuttings.
RF 1998-b. Recycling oil based mud drill cuttings in industrial applications, RF 1998/304,
Vers.1/10. 1298
RF, 1997. Disposal of oil-based cuttings. Rogaland Research Report RF-97/281.Vers.1.1997.
RF, 1998-c. Cripps, S.J, Picken,G., Aabel, J.P., Andersen, O.K., Heyworth, C., Jakobsen, M.,
Kristiansen, R., Marken, C., Paulsen, J.E., Shaw, D., Annand, A., Jacobsen, T.G., and Henriksen,
I.B. Disposal of oil-based cuttings. Report Rogaland Research, RF-98/097.
RF, 2000. Survey of information on cuttings piles in the Norwegian sector. RF –2000/151.
Robinson-Todd, D., 1999. Evaluation of processes in landfills, in DNV (1999).
SFT, 1994. Krav til fyllplasser – Retningslinjer til Fylkesmannen.
SFT, 1994. Utslippstillatelse for deponi for industriavfall på Stangneset, Gulen kommune. 3. mai
1994.


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SFT, 1999. Carroll, M., Evenset, A., Kögeler, J., Langfeldt, J.N, and Johansson, T., 1999.
Sanering av akutt forurensning på strand. Del 1: Teoretisk grunnlag for anbefalte praktiske tiltak
og organisering.
SSB, 1999. Naturressurser og Miljø 1999, Statistics Norway.
Stortingsmelding nr.8 1999-2000. Hovedlinjer i miljøvernpolitikken.
Ward, D.M. & Brock, T.D., 1978. Hydrocarbon biodegradation in hypersaline environments.
Appl environ microbiol 35:353-359.




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APPENDIX 1. CUTTINGS DATA
Rogalandsforskning (2000) has conducted a study to quantity the total amount of cuttings
discharged on the Norwegian Continental Shelf. The study also intended to quantify residual
cuttings materials left under/around the installations. The latter task was attempted by means of
using data from mapped piles and applying these to all fields, and by using existing models
(from Ekofisk and UKOOA R&D). It was concluded to be an impossible task based on available
data.
For this study however it is considered important to have at least an estimate of the amount of
cuttings piles materials left around the installations. The uncertainty in the data is recognised, but
a conservative approach is taken to allow for an evaluation of a reasonable “Worst case”
scenario. The wording “reasonable” then refers to a process of making the best evaluation of the
data for the individual fields with regard to discharge history, water depth and location.
Among the factors considered important are:
    Type of discharge (WBM, OBM, PBM)
    Discharge regime (over board, dumping liner, at seabed)
    Field structure (fixed installation, floater/pre-drilling, satellite)
    Time since discharge
    Geographical location
    Water depth
    Currents


Since the scope of the present study does not include these calculations (supposed to be an input
to the study) only a coarse evaluation based on the above factors is made.
The few piles that have been mapped give some indications on the order of magnitude of
materials remaining versus that discharged. There is no scientific documentation for this, but it
seems to be fair to generally accept that in the order of 20% material is left at a “normal” field.
This number also corresponds well with results from the models available (UKOOA and
Ekofisk). Based on this, every single field is evaluated on the above parameters and with the
indicative percentile as a basis. Large water depth and the use of water based mud are the two
most important factors reducing the percentile, oil based mud and low water depth the two single
parameters increasing the percentile most. Anyway, this exercise is done to produce input data
for the onshore evaluation, and the individual field data are less important. The cuttings data
listed below should therefore not be cited or used for any other purpose than this.
To make the data workable for the onshore processing capability evaluation, a split into 5 year
time intervals is made. This is based on a subjective evaluation of the time of field cessation,
assuming possible cuttings removal to be phased with this activity.
This is only done with respect to fields where OBM or PBM are used (partly or fully).


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Table 6 Data for estimating remaining amount of cuttings material at individual fields.
Field                                                                 Remaining volume, DNV method
                    Volume (m3)Depth (m) Drill fluid More/less than average       Pile?             Comment
Aasgard               24774      300         W             0.05          1239       N         15 templates, WBM
Albuskjell            144000      70         O                           4200       Y                Mapped
Balder                26272      125         W             0.15          3941       N     Drilling in large area, WBM
Brage                 98783      137          P            0.25         24696       Y      SBM, 30 wells, long wells
Cod                   20000       79         O                            600       Y                Mapped
Draugen               45950      251         W              0.1          4595       N                  WBM
Edda                  54000       73         O                           1000       Y                Mapped
Ekofisk I (center)    120000      73         O              0.1          7600       Y                Mapped
Ekofisk II (center)    8000       76         W              0.2          1600       Y
Ekofisk 2/4 A         72800       70          P                          5300       Y                Mapped
Ekofisk 2/4 B         88000       71          P                          4235       Y                Mapped
Ekofisk 2/4 K         54000       71       O, W             0.2         10800       Y
West Ekofisk (2/4D) 60000         67         W                           1000       Y                Mapped
Eldfisk               240000      72          P             0.2         48000       Y
Embla                 20000       71          P             0.2          4000
Frigg                 71435      100       W/O                            400       N                Mapped
East Frigg            13158      100       O, W             0.1          1316       N                 Satelite
North East Frigg      20622      100         W              0.1          2062       N
Frøy                  47312      120          P                           490       N                Mapped
Gullfaks A            126895     136       O/W             0.25         31724       Y
Gullfaks B            137619     143       O/W             0.25         34405       Y
Gullfaks C            113760     216       O/W             0.25         28440       Y
Gullfaks Sat          11286      135       W, P             0.1          1129       N             WBM, 5 SBM
Gyda                  29008       66         O              0.1          3430       Y                Mapped
Heidrun               28277      350          P            0.05          1414       N      Predrilled, satelitte, SBM
Heimdal               31816      120         W              0.1          3182       N
Hod                    6538       72          P             0.2          1308
Husmus                 2330      230         W              0.1           233
Jotun                  5425      125         W             0.15           814       N                 Satelite
Lille Frigg           30215      100         W              0.1          3022       N            WBM, satelitte
Loke                   1957       85       W, P             0.2           391
Mime                    0         80         W
Njord                  5766      330       O, W             0.1           577                No discharge of OBM
Norne                 16270      380         W             0.05           814                  Predrilled, Satelites
Odin                  19481      103         W              0.1          1948       N
Oseberg A               0        110                                                N
Oseberg B             101788     103      O/W/P                          6550       Y                Mapped
Oseberg C             67287      108      O/W/P                          1100       Y                Mapped
Oseberg Øst            2044      100         W              0.1           204                          WBM
Oseberg Sør            7213      100       W, O             0.1           721                          WBM
Rogn Sør               4580      286         W              0.1           458                        Satelite?
Sleipner              35338       82       P/W              0.2          7068       Y
Sleipner West         25078      106         W              0.2          5016
Snorre                120950     310       W, P            0.25         30238       Y              WBM, SBM
SOP                    4580      277                        0.1           458
Statfjord A           64340      145      O/W/P            0.25         16085       Y
Statfjord B           67143      144      O/W/P            0.25         16786       Y
Statfjord C           63630      146      O/W/P            0.25         15908       Y
Statfjord East        14633      110       W, P             0.1          1463       N                 Satelite
Statfjord North+      14681      120         W              0.1          1468       N                 Satelite
Tommeliten             3894       70         W              0.1           389       N
Tor                   64000       67       P/W              0.2         12800       Y
Tordis                38449      200       P/W              0.1          3845                         Satelite
Troll Gas             39409      303         W             0.15          5911                          WBM
Troll Oil             137801     320         W              0.1         13780       N                Satelites
Ula                   19927       70          P              1          24000       Y                Mapped
Valhall               54051       69         O             0.45         25000       Y                Mapped
Varg                  14585       85         W              0.1          1459                          WBM
Veslefrikk            50066      175       O, W             0.2         10013       Y
Vigdis                29327      282          P             0.1          2933               SBM, drilled from floater
Visund                15064      335         W              0.1          1506                          WBM
Yme                   23203       93       W/P             0.15          3480       Y                  WBM
TOTAL                2878810                                            448540

                      2878810                  313354                          448540




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Table 7 Distribution per 5 year time interval (assumed time of field cessation).
                               Year of cuttings removal
Field                          2000-2005 2005-2010 2010-2015 2015-2020 2020-2025 2025-2030 2030+
                    Field cessation
Aasgard                   2025
Albuskjell                1998                                    4200
Balder                    2012
Brage                     2012                          24696
Cod                       1998                                     600
Draugen                   2012
Edda                      1998                                    1000
Ekofisk I (center)        1998                                    7600
Ekofisk II (center)       2028
Ekofisk 2/4 A             2028                                                        5300
Ekofisk 2/4 B             2028                                                        4235
Ekofisk 2/4 K             2028                                                      10800
West Ekofisk (2/4D)       1998
Eldfisk                   2028                                                      48000
Embla                     2009                                    4000
Frigg                     2004       400
East Frigg                1998
North East Frigg          1996
Frøy                      2000       490
Gullfaks A                2016                                  31724
Gullfaks B                2016                                  34405
Gullfaks C                2016                                  28440
Gullfaks Sat              2021                                              1129
Gyda                      2010                           3430
Heidrun                   2016                                    1414
Heimdal
Hod                       2005                 1308
Husmus
Jotun                     2005
Lille Frigg               1999
Loke
Mime
Njord                     2013                            577
Norne                     2012
Odin                      1996
Oseberg A                 2018
Oseberg B                 2018                                    6550
Oseberg C                 2018                                    1100
Oseberg Øst               2014
Oseberg Sør               2030                                                                   721
Rogn Sør
Sleipner                  2007                 7068
Sleipner West             2038
Snorre                    2014                          30238
SOP                                                       458
Statfjord A               2013                          16085
Statfjord B               2020                                  16786
Statfjord C               2020                                  15908
Statfjord East            2007                 1463
Statfjord North+          2014
Tommeliten                1997
Tor                       2028                                                      12800
Tordis                    2014                           3845
Troll Gas                 2046
Troll Oil                 2016
Ula                       2010                          24000
Valhall                   2011                          25000
Varg                      2005
Veslefrikk                2009                10013
Vigdis                    2012                           2933
Visund                    2028
Yme                       2003      3480
TOTAL                               4370      19852   130802   153726       1129    81135        721




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APPENDIX 2. NORWEGIAN CUTTINGS PROCESSING TECHNOLOGY


SRD Technology
The SRD (Soil Recovery Denmark) unit is a process unit based on distillation and evaporation
with a large rotary heat exchanger. The feed (oily cuttings, raw or pre treated) enter the process
through a hopper followed by a set of conveyors which between them act as a gas seal. This is
necessary because the process operates slightly above atmospheric pressure to minimise the
ingress of oxygen. Thermal oil is heated by a gas fired boiler and pumped through a rotating
shaft and a series of hollow discs to heat up the cuttings to between 280 and 320 C. More
recently there is also a new version of the SRD unit that can take the temperature up to
approximately 500° C where the extra energy needed to go from 320°C to 500°C is supplied
electrically. The cuttings inside the unit tend to “flow” rather like “ chalk powder”, and their
passage through the unit is controlled more by new feed displacing them through the process,
rather than by any mechanical conveying.
The new material feed rate is dictated by three temperature sensors. Once the final sensor
indicates that the cuttings are comfortably above the final boiling point of the base oil then more
cuttings are fed in and now oil free cuttings are displaced out. A water-cooled screw conveyor
reduces their temperature after which a small quantity of recovered water from the process is
used to quench them and eliminate the dust hazard.
The vapours boiled off the cuttings are fed across a counter rotating auger to lead any entrained
dust into the rotor chamber, condensed and separated prior to being pumped out. All non-
condensable gases are routed back into the gas boiler for incineration. The process is rather
clean, and the emissions can be compared with those from a large domestic central heating
system. All the operating parameters, temperatures, pressures and the electrical current drawn by
the various internal motors are continuously monitored and the data recorded by a computer,
which controls the process.

Advantages
The SRD process (lower temperature version) achieves a stable and valuable composition of the
recovered oil that can be reused. No cracking is involved as the temperature is kept below
350°C.
By using the high temperature version of the SRD technology, the product of the processing – a
dry residue is even more clean and the weight percentage of oil is estimated to be appr. 0.1 %,
which is far below the limit for acceptance. However, the oil recovered from this high
temperature treatment can not be reused (which can be seen as a disadvantage).
Disadvantages
1. Performance efficiency.
   The weak point about the technology is the fact that the cuttings are still defined as a
   hazardous waste after leaving the unit even at 500°C. The reason is that heavier hydrocarbons,
   pitch, coke and added chemicals / modified chemicals are still present in concentrations > 0.1
   w%.


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2. Air Emission.
   Because of external heating with thermal oil this technology also gives rise to emissions of
   carbon dioxide (CO2), sulphur dioxide (SO2) and nitrous oxides (NOX).
3. Space requirements.
    The SRD unit is big and definitely not a compact unit and would require allocation of quite a
    large volume of operational space.
4. Reuse opportunities
    The SRD (higher temperature version) where the feed is subjected to high temperature
    cracking at 500°C with a residence time in the reactor of approximately 1 hour, will lead to an
    oil quality which can not be reused as mud oil without further treatment to remove cracked
    products.



TCC technology
The TCC (Thermo-mechanical cracking and conversion) technology is a unique process
compared to most other processes in the way that heat transfer to the solids takes place. Located
within the reaction chamber which has a close resemblance to a hammer mill, is a rotational shaft
with hinged hammers that deliver the energy and mechanical forces to the material (oil, water
and solids). The heat is created within the solids themselves by means of the mechanical shear
forces from the hammers. This is achieved by whipping and crushing the oil/water wet solids in
such a way that it generates heat in-situ by internal friction and hydrodynamic forces within the
reactor. No external heating is necessary if the energy is supplied by a motor operating on
electricity. The rotation of the hinged hammers combined with the motion of the particles in
solid-liquid suspension in the reactor breaks the particles, destroys the capillary forces and
reduces the interfacial tension in the solids and thereby exposes the fluids for evaporation.
In this way the oily material not carried away by instant evaporation as a vapour or mist can also
be subjected to a total energy environment (heat and mechanical). This will lead to a ”special”
cracking mechanism under plasma conditions with virtually no gas or coke production given the
right process conditions in the TCC unit.


Advantages
1. Performance efficiency.
   The TCC technology can turn hazardous oily waste material (oily cuttings) into a non-
   hazardous material with less than 0.01% hydrocarbons in the solids after treatment if needed.
   TCC technology in addition to virtually recovering all of the base oil hydrocarbons from the
   cuttings, can also degrade (destroy) added chemicals when operating in a special cracking
   mode.
2. Environmentally acceptable technology, with only trace emission of CO2, SO2, NOX and
   other gases with the use of electricity as the energy source.
3. Compact unit with high capacity, which takes up little space.



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Disadvantages
1. The TCC technology leaves behind solids with smaller particle sizes than the SRD
   technology due to a high degree of turbulence (rotational speed > 600 rpm) in the TCC
   reactor compared to the SRD reactor. Because of smaller particle sizes, there is also a
   greater chance of incomplete separation of liquid (oil/water) and solids from a TCC unit than
   from a SRD unit where the turbulence level is very low (rotational speed of 6 rpm). This
   does not represent a special problem with cuttings materials as a feed material, but it is a
   definite challenge when organophilic bentonite or other clay materials make up the main part
   of the solid feed material.
2. The TCC technology cannot handle non-condensable gases including volatile odour
   compounds as the SRD technology does by routing them back into the gas boiler for
   incineration. In the TCC technology they have to be treated separately.


Differences between the TCC and SRD technology
There are many operational differences between the TCC and SRD technology. These manifest
themselves in:
 Residence time in the reactor;
    seconds for the TCC reactors and up to 1 hour for the SRD reactor.
 Way of delivering heat to the bulk mass in the reactor.
    In the TCC unit the heat is created in-situ within the solids themselves by means of
    mechanical shear forces from the hammers which are put in action by a rotating shaft driven
    by electricity. Normally, operational bulk temperature in the TCC unit is around 380-390°C.
    In the SRD unit the initial bulk temperature increases to 320°C, by means of thermal oil
    heated by a gas fired boiler. Finally, the temperature is increased up to 500°C supplied by
    electricity.
 Different modes of operation.
    The TCC technology also has the ability to establish plasma conditions (if needed) in the
    reactor which gives rise to a very high treatment efficiency. This is not possible with the
    SRD technology.
 Heat and mass transfer possibilities.
    More efficient heat and mass transfer possibilities in the TCC technology than in the SRD
    technology.
 The extracted oil from the SRD process is more likely to be reused because no cracking has
    occurred, but to make the dry residue as clean as possible and with a w % of oil to be as low
    as possible, the TCC process is preferable.
From a practical users standpoint the main difference between the units (SRD and TCC) is the
treatment efficiency. The TCC unit can achieve very clean dry solids with a remaining organic
content of < 100 ppm if operated in a plasma mode. This means that the TCC unit in addition to
recovering the base oil (diesel or low toxicity oil) also can efficiently handle (destroy) high
molecular weight chemicals when operating in a plasma mode.
When the cutting materials are subjected to thermal cracking at 500°C combined with a long
residence time in the reactor as in the SRD unit it is not possible to achieve the extensive
cleaning efficiency as with the TCC unit because of the formation of high molecular weight by-
products.

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Consideration of operational constraints of TCC and SRD Technologies
Operational constraints in the TCC and SRD reactor are:
1. Temperature limitations in the reactors.
   In the TCC reactor a bulk temperature of 380-390°C will be needed in order to ensure an
   efficient treatment with destruction of high molecular weight chemicals under plasma
   conditions without creating unnecessary by-products. A higher temperature in the reactor
   can lead to decreased efficiency.
   In the SRD unit it will be necessary to keep the temperature high in the range of 400- 500°C
   to sustain an efficient treatment that can be more than 100°C higher than the TCC unit.
2. Amount of high molecular weight/sticky chemicals in the feed.
   With a high amount of high molecular weight chemicals, efficient treatment with a TCC unit
   can only be achieved in plasma mode which destroys the chemicals. No higher temperature
   in the bulk phase is required to attain plasma conditions in the reactor, but a minimum solids
   content (> 50 vol. %) and a minimum rotational speed (> 1000 rpm) is needed.
   Even without plasma condition in the TCC reactor, it performs better with chemicals than in
   the SRD reactor, since operating in a thermal-mechanical way, with much shorter residence
   times in the reactor thereby creating less by products.
   In the SRD unit this creates a very difficult situation, as the high temperature version would
   thermally degrade (transform) the chemicals to both compounds of lower molecular weight,
   but also to other types of high molecular weight materials. This include new polar products,
   pitch and coke (by-products) which will stick to the solid material making it difficult to
   comply with current regulations for efficient treatment and with possible reuse of the solid
   material.
   Both technologies are fluidised bed technologies requiring a maximum limit for the amount
   of water in the feed. Dilute feeds can prohibit plasma conditions, and too dilute feeds can
   create bed flooding and even dangerous situations in a SRD reactor with long residence time
   and a high temperature. The TCC technology does not function properly either with too
   dilute feeds.



Incineration
Incineration is a relatively inexpensive disposal option and is a good alternative for treating
retrieved oily drill cuttings. The technique requires high temperature purpose-built plants, and is
used for the disposal of organic waste which is normally highly toxic, highly flammable and/or
resistant to biological breakdown in landfill sites. The process, other than for liquid wastes,
normally leaves a solid residue or ash, which is finally disposed of at landfill.
In Norway there is one company, Sløvåg Industriservice, that uses combustion for the treatment
of oily cuttings. As the energy requirements is directly related to water content, costs for
incineration of materials such as drill cuttings, with a high water content, will be more expensive
than those with a low water content (Rogaland Research, 1998).
Sløvåg Industriservice use a combustion kiln of the “Fluidised bed” type. In the combustion
chamber air is blown with high velocity into a sand-bed at the bottom of the combustion
chamber, so that a fluidised bed is made where the waste is burned. In the lower part of the

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combustion chamber the temperature is between 500 and 800 degrees Celsius. The waste gases
from the combustion chamber are lead into a cleaning process which includes hot water boiler,
multi-cyclone fabric filter and a gas cleaning unit where respectively heat, fly ash, dust,
hydrochloric acid and SO2 is separated from before emission (SFT, 1994).
During the combustion process the temperature in the combustion kiln is carefully monitored and
kept fairly stable at 900 C. To avoid releases of dioxins from the process, it is important to keep
the temperature below 1100  C.
The inorganic product of the combustion process is normally disposed of at a landfill, though the
intention should be to reuse the remaining products of the treated drilling muds.
Analysis of the dry residue indicates high content of barium, sulphur, iron and aluminium. Some
trace metals are found in elevated concentrations, e.g. lead, copper, nickel, tin, zinc and
strontium. Toxity tests of the dry residue indicate that the ash after combustion of the drill
cuttings is toxic. However it may be possible to reuse the remaining inert material.
Another option is the burning of cuttings in cement kilns. In Brevik there is a processing plant
treating all types of organic special waste which have their origin in Norway, including oily
waste. The special waste is pre-treated at NOAH’s processing site and the organic content is
used as an energy source, while the burnt solids go into the cement product. Norcem AS (cement
producer) uses the pre treated material as combustibles instead of coal. This co-operation makes
sure that a total energy reuse is made for the special waste.
Low oil, high water and/or high chloride content could restrict old cuttings for such treatment,
but some cuttings could have potential to be treated this way.




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DET NORSKE VERITAS


                                                                              Report No: 00-4018, rev. 01
TECHNICAL REPORT



APPENDIX 3. CASE STUDY

To exemplify the results, a case study is performed, using the impact and cost data on some
selected piles. This is based on the reference pile as defined by OLF (RF 1997)
Table 8 is summarising the characteristics of the OLF reference pile.


Table 8 Reference pile constitution as defined by OLF Steering Committee (RF 1998).
Parameter                                              Value
Form                                                   Cone
Height (m)                                               7.5
Radius (m)                                               25
Volume (m3)                                            4906
Water (% by weight)                                      40
Oil (% by weight)                                         2
Barite (% by dry weight)                                 10
Density of cuttings (kg/L)                                2
Density of oil (kg/L)                                   0.83
Density of water (kg/L)                                1.027
Pile bulk density (kg/L)                                1.54
Total pile content (tonnes)
Oil                                                      143
Cuttings                                                3780
Water                                                   2850
Barite                                                   413
Total                                                   7186


In addition to these constituents, piles may contain a range of debris resulting from years of
maintenance, construction and remediation. This includes scaffolding poles and clips, welding
rods, bolts, spanners, gloves, boots, wire rope, rigging and various construction materials. This
material can be buried in the piles or may protrude out from the pile surface.
Due to the various fluids and material incorporated into a pile, there is a large variation in shear
strength of the piles ranging from near liquid to hard cement layers (Anderson et al., 1996).
(Disposal of oil-based cuttings, Report RF- 97/281)


Processing 7200 tons of cuttings mix will take about 4-8 months at any of the present plant
working at today’s capacity.
About 4200 tons of solids will have to be disposed of. This is about the same amount as was
delivered to Kjevikdalen (from Soilcare) for disposal in 1999; i.e. about 400 lorry loads.
The energy consumption for processing will be in the order of 10,000 GJ.

                                                                                                                                    Page 45
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DET NORSKE VERITAS


                                                                              Report No: 00-4018, rev. 01
TECHNICAL REPORT

The total emission of CO2, applying the processing split as used in the main report gives 6400
tons. The corresponding values for NOX and SO2 are 140 tons and 0.5 tons.
Cost will be in the range of 10 - 25 million NOK for the onshore handling, processing and
disposal.


                                                                     - o0o -




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