Produced Water

Produced water (formation and injected water containing production chemicals) represents the largest volume waste stream in oil and gas production operations on most offshore platforms. In 2003, an estimated 667 million metric tons (about 800 million m³) of produced water were discharged to the ocean from offshore facilities throughout the world. There is considerable concern about the ocean disposal of produced water, because of the potential danger of chronic ecological harm. Produced water is a complex mixture of dissolved and particulate organic and inorganic chemicals in water that ranges from essentially freshwater to concentrated saline brine. The most abundant organic chemicals in most produced waters are water-soluble low molecular weight organic acids and monocyclic aromatic hydrocarbons. Concentrations of total PAH and higher molecular weight alkyl phenols, the main toxicants in produced water, typically range from about 0.040 to about 3 mg/L. The metals most frequently present in produced water at elevated concentrations, relative to those in seawater, include barium, iron, manganese, mercury, and zinc. Upon discharge to the ocean, produced water dilutes rapidly, often by 100-fold or more within 100 m of the discharge. The chemicals of greatest environmental concern in produced water, because their concentrations may be high enough to cause bioaccumulation and toxicity, include aromatic hydrocarbons, some alkylphenols, and a few metals. Marine animals near a produced water discharge may bioaccumulate metals, phenols, and hydrocarbons from the ambient water, their food, or bottom sediments. The general consensus of the International Produced Water Conference was that any effects of produced water on individual offshore production sites are likely to be minor. However, unresolved questions regarding aspects of produced water composition and its fate and potential effects on the ecosystem remain. Multidisciplinary scientific studies are needed under an ecosystem-based management (EBM) approach to provide information on the environmental fates (dispersion, precipitation, biological and abiotic transformation) and effects of chronic, low-level exposures to the different chemicals in produced water.

The measurement of oil in produced water is important for both process control and reporting to regulatory authorities. The concentration of oil in produced water is a method-dependent parameter, which is traditionally evaluated using reference methods based on infrared (IR) absorption or gravimetric analysis, although Gas Chromatography and Flame Ionisation Detection (GC-FID) have recently become more accepted. This chapter will give a brief overview of hydrocarbon chemistry and discuss the definition of oil in produced water and the requirement for its measurement. Reference and non-reference (bench-top and online monitoring) methods for the measurement of oil in produced water are reviewed. Issues related to sampling, sample handling and calibration, as well as methods of how to accept a non-reference method for the purpose of reporting, are discussed.

Chemistry and toxicity of produced water (PW) from offshore platforms operated by Petrobras in Brazil were investigated. Three studies – PW monitoring, detailed composition and temporal variability – were conducted during 1996, 2001 and 2006 in the Campos, Santos and Ceara Basins. For approximately 50 samples the median concentrations were ammonia 70 mg L^–1, barium 1.3 mg L^–1, iron 7.4 mg L^–1, BTEX 4.7 mg L^–1, PAH 0.53 mg L^–1, TPH 28 mg L^–1, phenols 1.3 mg L^–1, ²²⁶Ra 0.15 Bq L^–1 and ²²⁸Ra 0.09 Bq L^–1. Acute toxicity median values were LC50_96 h = 3.57% for Mysidopsis juniae, LC50_48 h = 52.55% for Artemia sp., EC50_72 h = 8.43% for Skeletonema costatum and EC50_15 min = 16.05% for Vibrio fischeri. Median chronic toxicity using Lytechinus variegatus showed a NOEC = 1.3%. These results for Brazilian PW are similar to those for the North Sea, Gulf of Mexico, Australia and other regions of the world. Dispersion plumes modelled using CORMIX and CHEMMAP predicted that PW can be diluted rapidly after discharge and that permissible levels for all chemical parameters in seawater cited in the Brazilian Resolution CONAMA 357/05 are attained within 500 m of the discharge point. Over 10 years (1998–2010) of monitoring in the vicinity of the Brazilian platforms did not show alterations in sea water quality, supporting the predictions of the dispersion plume modelling. Despite no observed alteration in seawater quality around oil and gas production platforms, the authors recognize the importance of continuous evaluation of the impact of PW discharges from a risk assessment perspective, and studies of bioaccumulation and the use of biomarkers, among other initiatives currently implemented by Petrobras in areas with large volumes of PW discharge. Up to and including 2011, Petrobras remains the major producer of oil and gas in Brazil and the total discharge of produced water by the country is essentially the volume that is discharged by offshore Petrobras operations. In 2005, the average total volume of PW discharged offshore on the Brazilian coast was 73 million m³/year, representing less than 3% PW discharged onto other oceans worldwide.

The concentrations of organic acids in produced water are highly variable. Because of the information shown in others chapters of this book about the toxic effects of organic acids, it is of major interest to understand the mechanisms controlling the occurrence of this compound group in produced water. This chapter focuses on in-reservoir biogeochemical processes which may produce organic acids as products or by-products. The biodegradation processes inside reservoirs decrease the hydrocarbon content of petroleum. Additionally, an increase in oil acidity as measured by total acid number (TAN) is frequently observed. Since the formation waters of reservoirs are in close contact with these processes, the production of smaller, more polar petroleum constituents will also have an effect on the composition of organic molecules in the produced water. This manuscript reviews the literature with respect to acids production of petroleum biodegradation and the effects of water re-injection on such processes.

High concentrations of Ba in produced water have been linked to adverse biological impacts during toxicity testing. This observation, along with interest in modelling chemical processes during produced water discharges to the ocean, led to the present study. Essentially all the Ba in produced water collected for this study was dissolved and passed through 0.4-μm pore size filters and 1-KDa ultrafilters. Using 1:99 and 1:199 mixtures of produced water with seawater, initial amounts of dissolved Ba of 180–600 μg/L did not change over 72 h and were oversaturated with respect to BaSO₄ by factors of ~5–16. For 1:9 mixtures of produced water with seawater, precipitation was observed to either start immediately or be delayed for as long as 12 h; however, the dissolved Ba that remained after 24–72 h in these mixtures ranged from 340–1,200 μg/L, or ~10 to >30 times above apparent saturation. Field sampling of a discharge in the Gulf of Mexico showed that >98% of the Ba added to seawater via produced water was still dissolved 5 min after discharge at a distance of 20 m from the source and at >1,600-fold dilution. Overall, the results show the importance of considering both dilution and precipitation when interpreting the behavior or impact of Ba based on laboratory and field studies.

Water column samples for trace metal and nutrient analysis were collected in the vicinity of the Hibernia offshore oil and gas platform on CCGS Hudson cruises in July 2005 and June 2006 as part of an investigation of chemical tracers of produced water discharges. Measurements of metals and nutrients in two produced water samples from the Hibernia platform show that produced water concentrations for SiO₂, NH₃, Ba, Fe and Mn are >100 times those in seawater. The concentrations of dissolved Fe and Mn increase with depth in the waters outside the platform’s exclusion zone, with highest concentrations in deep water samples immediately south and west of the platform. Particulate Ba, Fe and Mn are elevated compared to Al in a number of the deep and bottom water samples located in the vicinity of the platform in 2005 and 2006. Elevated concentrations of SiO₂, NH₃, Fe and Mn were also found within 150 m of the platform at 10 m depth in 2005.

It is widely accepted that toxicity tests on environmental samples should commence as soon as possible after sample collection. However, constraints involved with sampling and transporting produced water (PW) from offshore oil and gas facilities can cause lengthy delays, during which time some of the toxic constituents may degrade. This can lead to an underestimation of PW toxicity. The objective of this study was to determine whether storage conditions (time and temperature) affected the toxicity and chemical constituents in undiluted PW over a 4-day period from the time of sampling. In addition, the toxicity and chemical composition of PW diluted in seawater, when stored under natural day/night conditions in open and closed test containers, was also assessed. Toxicity was determined after 0, 4, 15, 24, 48, 72 and 96-h storage, using the Microtox^® bacterial bioassay. When undiluted PW was stored in the dark for 96 h, refrigeration was not required to prevent changes in PW toxicity indicating that storage temperature was not important for reducing chemical degradation of the PW. For PW that was diluted in seawater, many measured PW constituents were readily degraded (by up to 90%) due to volatilization (BTEX and TPHs C6–C9) and/or photodegradation (PAHs, TPHs C10–C28, phenols). Despite this degradation, there was only a small decrease in toxicity of PW for both open and closed tests (i.e. the EC₅₀ increased from 2 to 4% PW for both tests) over the 96-h period, indicating that some toxicant(s) persisted. While it was beyond the scope of this project to identify the cause of toxicity in the PW, it was unlikely that BTEX, naphthalene or ammonia were contributing to toxicity. Phenols, TPHs (in the C10–C14 fraction) and production chemicals were possible toxicants.

The aim of this chapter is to introduce an compact system for produced water treatment that is under development, the CFS (Centrifugal Flotation System) which combines the classic flotation and centrifugal separation processes. In the CFS, the bubbles generation, the flocculation and the droplet-bubble contact pass through a pneumatic flocculator, while the separation of the gas phase and the phase rich in oil is achieved using a cylindrical hydrocyclone. In the quest for new produced water treatment concepts, this chapter aims to evaluate the preliminary performance of a Centrifugal Flotation prototype with a feed flow rate of 10 m³/h, designed and built at Petrobras Research and Development Center (CENPES) to remove dispersed oil, sulphide and soluble compounds such as benzene and toluene, using hydrogen peroxide as oxidant. During the field tests, it was possible to achieve a sulphide removal above 95% and considerable removal values for benzene and toluene from the produced water using a hydrogen peroxide concentration of 100 ppm and a gas flow rate of 10 Nm³/h.

DREAM (Dose-related Risk and Effect Assessment Model) is a three-dimensional, time-dependent numerical model that computes transport, exposure, dose, and effects in the marine environment. The model can simulate complex mixtures of chemicals. Each chemical component in an effluent mixture is described by a set of physical, chemical, and toxicological parameters. Because petroleum hydrocarbons constitute a significant fraction of many industrial releases, DREAM incorporates a complete surface slick model, in addition to the processes governing contaminant behavior and fates in the water column. The model can also calculate exposure, uptake, depuration, and effects for fish and zooplankton simultaneously with physical–chemical transport and fates. The Environmental Impact Factor (EIF), first developed for the water column, has been extended to include ecological stresses in the benthic community. The EIF is a standardized method for marine environmental risk assessment that does not require explicit information on the local biological resources. This makes the methodology relatively easy to apply to new geographical areas, and it has been used in northern and southern European, as well as in North American, South American, and African waters. This chapter gives an overview of the model system and a summary of ongoing developments.

The ready availability of plume models allows analysts to predict plume behavior and performance of wastewater outfalls. Such models need inputs describing the flow rate of effluent; the number, diameter, and depth of discharge ports; and fluid properties of the effluent and receiving water and the water depth. Unfortunately, there is a crucial step in outfall design that is oftentimes neglected—hydraulic analysis of the outfall. Hydraulic analysis predicts the flows from each port of a diffuser and the hydraulic head needed to drive the diffuser for a required total effluent discharge rate. Hydraulic analysis is especially important to a relatively new class of wastewater outfall suitable for offshore oil and gas facilities, the vertical spiral diffuser. This chapter describes the rules of thumb for outfall design, the influence of the major design parameters on vertical diffuser behavior, the methodology for calculating the hydraulic performance of vertical diffusers, and an illustration of vertical spiral diffuser performance. The reconciliation of current regulatory practices in US federal waters with correct hydraulic analysis is also discussed.

A probabilistic based steady state model, PROMISE, was developed to predict the mixing behaviors of produced water in the marine environment. The model was also coupled with a MIKE3 model to study the dispersion in non-steady state conditions. Laboratory experiments were conducted in a 58 m towing tank to calibrate the near field model. Field experiments using an Autonomous Underwater Vehicle (AUV) were also performed to test the ability of an AUV in produced water plume mapping.

This chapter describes a method for simulating the dispersion of produced water in the marine environment. A near field model, PROMISE, has been coupled with the MIKE3 model using the passive offline coupling method. A hypothetical case study has been conducted to evaluate the method and it has been shown that model coupling is critical in accurately simulating the dispersion. A minimum grid size must be maintained in the far field model to introduce the source term from the near field model correctly.

It has been recently discovered that precipitates form when produced water is diluted with seawater. These precipitates are more toxic than the dissolved fraction, can flocculate and sink to the bottom, or can coalesce onto microscopic oil droplets and rise to the surface. This represents new pathways that could bring potentially toxic substances to the surface or bottom where marine life is concentrated. The surface or bottom concentration of toxins and their slow two-dimensional dispersion present potential biohazards that should be evaluated. We present a novel, proven, patent-pending technology specifically designed to trace near-surface or near-bottom particulates to greater distances and dilutions than other measurement technologies can achieve, and present preliminary results demonstrating the effectiveness of the system. We propose a method to experimentally determine the pathways and dilution factors of particulates from oil production platform produced water discharges.

There is paucity of data regarding hydrocarbon exposure of tropical fish species inhabiting the waters near oil and gas platforms on the Northwest Shelf of Australia. A comprehensive field study assessed the exposure and potential effects associated with the produced water (PW) plume from the Harriet A production platform on the northwest shelf in a local reef species, Stripey seaperch (Lutjanus carponotatus). This field study was a continuation of an earlier pilot study which concluded that there were “warning signs” of potential biological effects on fish populations exposed to PW. A 10-day field caging study was conducted deploying 15 individual fish into 6 separate steel cages set 1-m subsurface at 3 stations in a concentration gradient moving away from the platform. A battery of biomarkers were evaluated including hepatosomatic index (HSI), total cytochrome P450, bile metabolites, CYP1A-, CYP2K- and CYP2M-like proteins, cholinesterase (ChE) activity, and histopathology of liver and gill tissues. Water column and PW effluent samples was also collected. Results confirmed that PAH metabolites in bile, CYP1A-, CYP2K-, and CYP2M-like proteins and liver histopathology provided evidence of significant exposure and effects after 10 days at the near-field site (~200 m off the Harriet A platform). Hepatosomatic index, total cytochrome P450, and ChE did not provide site-specific differences by day 10 of exposure to PW. CYP proteins were shown by principal component analysis (PCA) to be the best diagnostic tool for determining exposure and associated biological effects of PW on L. carponotatus. Using a suite of biomarkers has been widely advocated as a vital component in environmental risk assessments worldwide. This study demonstrates the usefulness of biomarkers for assessing the Harriet A PW discharge into Australian waters with broader applications for other PW discharges. This approach has merit as a valuable addition to environmental management strategies for protecting Australia’s tropical environment and its rich biodiversity.

In Western Australia, the discharge of produced water (PW) by the offshore petroleum production facilities is acceptable under specific conditions. Little is known on the effects of PW discharge on the health of marine organisms attracted to the submerged structures. Three offshore facilities have been selected for studying the impact of exposure to PW discharge on fish health, as measured by a suite of biomarkers of fish health. Physiological indices (liver somatic index, condition factor) as well as biochemical markers of exposure (EROD activity, biliary metabolites) and of effect (DNA damage, stress proteins) have been assessed on three different fish species captured in the vicinity of the facilities. Condition factor was slightly reduced at one site only, but liver somatic index was elevated in fish captured at two of the three locations. EROD activity and DNA damage levels were high only at one facility discharging high volumes of PW. Naphthalene and pyrene biliary metabolites were detected at significant levels at all locations. Stress proteins HSP70 were also elevated at all locations. The results suggest that while the chemical characteristics of PW are important, consideration of the loading (concentration × volume) of PW is crucial in assessing environmental effects and risks of PW discharge.

The Hibernia production platform is the largest oil producing platform off the east coast of Canada. The produced water is the major source of contamination from the platform into the ocean. A comprehensive study on the potential impact of the produced water discharge is needed. Microorganisms can rapidly respond to change, whether negative or positive, and at the population level, are powerful indicators of change in their environment. The objective of this study was to characterize the indigenous microbial community structure, by denaturing gradient gel electrophoresis (DGGE), in the produced water and in seawater around the production platform, and to determine whether the release of produced water is impacting the natural ecosystem. The DGGE results showed that the production water did not have a detectable effect on the bacterial populations in the surrounding water. Cluster analysis showed a >90% similarity for all near surface water (2 m) samples, ~86% similarity for all the 50 m and near bottom (NB) samples, and ~78% similarity for the whole water column from top to bottom across a 50 km range, based on two consecutive yearly sampling events. However, there were distinct differences in the composition of the bacterial communities in the produced water compared to seawater near the production platform (~50% similar), indicating that the effect from produced water may be restricted to the region immediately adjacent to the platform. Specific microorganisms (Thermoanaerobacter for eubacteria and Thermococcus and Archaeoglobus for archaea) were detected as significant components of the produced water. These particular signature microorganisms may be useful as markers to monitor the dispersion of produced water into the surrounding ocean.

Microbial production and activity in produced water directly recovered from the discharge stream of offshore oil and gas production facilities off the east coast of Canada were examined before and after aeration in a series of concentrations to determine the effect of dilution at sea. Aeration and dilution resulted in reduced toxicity due to volatilization and oxidation of the lighter hydrocarbons including polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, benzene, toluene, ethylbenzene, xylene, and short-chain alkanes (C₁₀–C₁₄). A fraction of the detrimental effects on microbial productivity and activity could also be attributed to the elevated salinity associated with produced water. These results suggest that caution should be used in the manipulation of produced water samples used for toxicity/risk assessment studies.

Bioindicators or health effect indicators have the potential to identify adverse health conditions in fish in advance of effects on populations. A commercially valuable species, American plaice (Hippoglossoides platessoides), was chosen by the oil industry in consultation with Fisheries and Oceans Canada as an important species for Environmental Effects Monitoring (EEM) programs on the Grand Banks. We report here on fish health studies carried out at the Terra Nova Offshore Oil Development site before and after discharge of produced water, which began in 2003. These studies constitute one component of the overall Terra Nova EEM program. Fish were collected in the near vicinity of the Terra Nova Development site as well at a Reference site located approximately 20 km southeast of the development. Approximately 500 fish were studied in total over 5 survey years from 2000 to 2006. The health effect indicators studied included fish condition, visible skin and organ lesions, ethoxyresorufin O-deethylase (EROD) activity, haematology (differential cell counts) and a variety of histopathological indices in liver (e.g. nuclear pleomorphism, megalocytic hepatosis, foci of cellular alteration, macrophage aggregation, neoplasms) and gill (e.g. epithelial lifting, oedema, fusion and aneurysms). Although a slight elevation of EROD activity was observed in fish from the Development site in 2002, before discharge of produced water, and in 2006, the suite of other health bioindicators were found to be generally absent or similar between the Development and Reference sites. Overall, on the basis of the various indicators studied, the results support the hypothesis of no significant project effects on the health of American plaice.

Barite is composed largely of barium sulfate, and the high density of this particular compound lends support to the use of barite as a weighting agent in oil well drilling fluids, which are often released into the environment in conjunction with petroleum exploration and development. The discharge of produced water can also be an important source of barium sulfate around petroleum development sites. Barium sulfate is practically insoluble in seawater and is commonly indicated to have little toxicity potential. However, there is limited information on the chronic toxicity potential of the compound. We have carried out a long-term chronic toxicity study on the effects of barium sulfate, as barite, on fish health. Cunners (Tautogolabrus adspersus) were exposed on a weekly basis for 10 months to dispersions of 200 g of barite in a tank containing 1800 L of water. A range of health effect indicators were investigated, including visible skin and organ lesions, fish and organ condition indices, histopathological alterations in liver, gill, and kidney tissues, and levels of ethoxyresorufin O-deethylase (EROD), a catalytic activity associated with induction of cytochrome P4501A1. No differences were noted between the control and experimental groups other than a slight induction of EROD. Given the prolonged and high-level exposure to barite, results support the hypothesis that the relatively insoluble barium sulfate associated with the disposal of drilling fluids and produced waters does not pose a significant toxicity risk to finfish.

The Minerals Management Service (MMS) is the bureau within the US Department of the Interior that offers for lease areas of the Outer Continental Shelf for mineral extraction and regulates the offshore oil and gas industry. As part of its mission, the agency collects information about the environmental impacts from these regulated activities through a program of funded research. Since its inception in 1973, the MMS Environmental Studies Program has collected baseline information about the marine environment and examined the potential impacts of the industry, such as the effects of produced water. The Gulf of Mexico is the primary area for offshore oil and gas activities, contributing about 27% of the domestically produced oil and 17% of the natural gas. In Southern California, 23 platforms are currently operating. Over the years, MMS has funded studies examining the impacts from this produced water in coastal areas and offshore. Generally, studies have focused on the contamination in the sediments as the ultimate sink rather than measurements in the water column. A few studies have examined the genotoxicity on specific species or life stages. One recent study examined the contribution of produced water to the hypoxic zone that forms off the coast of Louisiana. The information gathered through these studies is used by MMS in the preparation of Environmental Impact Statements, which support both offshore leasing decisions and permits promulgated by the US Environmental Protection Agency.

As a result of aging offshore fields discharging higher volumes of produced water, and after the discharge of oil contaminated cuttings was terminated on the Norwegian Continental Shelf (NCS) in 1993, oil originating from produced water has become the dominant contributor of the Norwegian E&P industry to hydrocarbon and chemical input to the marine environment. To reflect the present situation, the environmental monitoring programmes have also changed. The Norwegian requirements related to offshore environmental monitoring are given in the HSE regulations for the petroleum activity. The water column monitoring consists of two parts: the condition monitoring and the effects monitoring. The programmes have developed through dialogue between the authorities, the scientific community, consultants, and the E&P industry, but will still be subjected to revision and improvement in the years to come.

At the request of the U.S. Environmental Protection Agency (USEPA), the Gulf of Mexico Offshore Operators Committee sponsored a study of bioconcentration of selected produced water chemicals by marine invertebrates and fish around several offshore production facilities discharging more than 731 m³/day of produced water to outer continental shelf waters of the western Gulf of Mexico. The target chemicals, identified by USEPA, included five metals (As, Cd, Hg, ²²⁶Ra and ²²⁸Ra), three volatile monocyclic aromatic hydrocarbons (MAH), benzene, toluene, and ethylbenzene, and four semivolatile organic chemicals (SVOC), phenol, fluorene, benzo(a)pyrene, and di(2-ethylhexyl)phthalate (DEHP). Additional MAH (m-, p-, and o-xylenes) and a full suite of 40 parent and alkyl-PAH and dibenzothiophenes were analyzed in produced water, ambient water, and tissues at some platforms.

Concentrations of MAH, PAH, and phenol were orders of magnitude higher in produced water than in ambient seawater. All MAH and phenol were either not detected (>95% of tissue samples) or were present at trace concentrations in all invertebrate and fish tissue samples, indicating a lack of bioconcentration of these relatively soluble, low molecular weight produced water chemicals. Concentrations of several petrogenic PAH, including alkyl naphthalenes and alkyl dibenzothiophenes, were slightly, but significantly higher in some bivalve molluscs, but not fish, from discharging than from non-discharging platforms. These PAH could have been derived from produced water discharges or from tar balls or small fuel oil spills. Concentrations of individual and total PAH in mollusc, crab, and fish tissues in this study are well below concentrations that might be harmful to the marine animals themselves or to humans who might collect them for food at offshore platforms.

The first oil on the Norwegian continental shelf was found at the Ekofisk field in the southern North Sea in 1969. Several new discoveries were made in the years after, and from 1973, the Norwegian Pollution Control Authority (SFT from 2010 Climate And Pollution Agency (Klif)) required that all the licensed companies should submit annual reports on the environmental conditions in their impact areas. This requirement was one of the conditions for discharge permits, and guidance was given on the minimum scope and content of the environmental surveys to be performed. The annual reports quickly demonstrated that there was a need for better harmonisation of the monitoring methods to be used. In 1987 SFT and the offshore operators jointly hosted a 2-day workshop to agree on a common strategy and methodology for offshore baseline and monitoring surveys. On the basis of the workshop outcome, an expert group appointed by SFT developed a guideline document for sediment monitoring that was subsequently discussed in an open forum with the offshore operators. The guidelines were put into force in 1988 and in the same year they were adopted by the Paris Commission for use in the convention waters (PARCOM 1989). In 1991 the guidelines (SFT 1990) were made mandatory for monitoring around Norwegian fields. In 1997 the guidelines were revised. A concept of regional monitoring was introduced, and guidelines for monitoring of the water column were included (SFT 1997). The latter was a response to the change in impact focus from discharge of drilling waste to produced water (PW). In 1993 strong restrictions ended regular discharges of oily drill cuttings. At the same time, national prognoses estimated an increase in PW discharges from around 25 million m³/yr in 1993 to more than 250 million m³/yr in 2009. Subsequent minor guideline revisions were made in 1999, (SFT 1999) and 2010 (Klif 2009).

In recent years, the large volumes of produced water discharges from offshore petroleum production activities have been identified to be an issue of concern by regulators and environmental groups. In the majority of the existing risk assessment research of produced water discharges, local environmental guidelines have been used as the evaluation criteria. However, these guidelines are mostly impractical and cannot be implemented. In this chapter, a fuzzy-stochastic risk assessment approach has been developed to predict the risks and to examine the uncertainties associated with produced water discharge and the related regulated values for the heavy metal, lead, in the marine environment. Specifically, the concept of fuzzy membership is established to reflect the suitability of local standards for produced water risk assessment. The Monte Carlo method has been used to address system uncertainties and provides stochastic simulation of pollutant dispersion associated with produced water discharges. The developed risk assessment approach is applied to an offshore petroleum facility located on the Grand Banks of Canada. As an extension of the previous risk assessment studies, the proposed approach will contribute to the development of effective decision tools for the assessment and management of produced water discharges in the marine environment.

The Dose-related Risk and Effect Assessment Model (DREAM) was developed through a JIP in the period 1997–2000 and was implemented for produced water (PW) management in the Norwegian sector of the North Sea as a part of the ‘Zero discharge work’, 2000–2005. The initial version of DREAM included two approaches to PW management, the Environmental Impact Factor (EIF) and a body burden related risk assessment model focusing on selected PW compounds. The EIF, addressed in the present chapter, has found broad application in the North Sea and has also been used in other offshore production areas by different companies. The produced water EIF is based on the risk assessment principles described in the EU Technical Guidance Document (TGD), comparing the Predicted Environmental Concentration (PEC) and the Predicted No Effect Concentration (PNEC) of PW compounds. The quantitative risk element in the model is represented by the water volume where PEC exceeds PNEC, including the combined risk of all major PW constituents, both naturally occurring compounds and industry-added chemicals. The EIF is used as a management tool, primarily to identify and perform cost–benefit analyses of PW mitigation measures and best available technology (BAT). The method enables the operator to identify the compounds posing the most significant environmental risk in PW, and further to rank different PW discharges with respect to environmental significance and risk. This chapter describes the EIF method and focuses on examples of application of the tool on specific offshore production fields. A description of how the EIF fits into Statoil’s environmental management system is also given, including the link between risk assessment, selection of BAT and field validation through environmental monitoring.

Increasing offshore oil and gas activities in the European Arctic have raised concerns of the potential anthropogenic impact of oil-related compounds on polar marine ecosystems. For the Barents Sea, the Norwegian government has therefore enforced a zero discharge policy which does not allow any discharges to sea. This policy poses some challenges to routine operations, and it has been questioned whether this is the overall best environmental strategy. An alternative could be to handle the Barents Sea in the same way as the rest of the Norwegian shelf, which is to apply the zero harmful discharge strategy. This strategy involves performing risk assessments of harm made to the environment by petroleum-related activities. However, risk quantification procedures for petroleum operations were originally established on scientific knowledge derived from investigations mainly performed on temperate living organisms. Before risk calculations can be performed in Arctic areas, basic knowledge of sensitivity of Arctic species has to be in place, and risk assessment procedures need to be adapted to Arctic environments. This chapter describes current procedures and discusses key challenges to performing risk assessments in the Arctic, with special focus on the Barents Sea. For Arctic organisms there is a general lack of information concerning possible effects of oil-related compounds at all levels of biological organization. Further research is needed to understand sub-lethal and long-term impacts of acute and chronic exposure to petroleum compounds as well as to increase basic ecosystem understanding.

Produced water is by far the largest volume by-product or waste stream associated with oil and gas exploration and production. Because of the large volumes involved, management of produced water presents important costs to the industry. This chapter describes the broad range of options that may be used to manage produced water. In some situations, technologies can be employed to reduce the volume of water that is managed within the well or at the platform deck. In other situations (primarily at onshore wells), produced water can be treated and then reused for various purposes. Produced water can be disposed using discharge, injection, removal to an offsite disposal facility, and evaporation. These management options are described along with numerous technologies currently used by the international oil and gas industry for treating produced water. Because this book focuses primarily on offshore produced water, this chapter will emphasize technologies for treating and managing offshore produced water. However, the chapter will include summary descriptions of other management practices and technologies used for onshore wells, too.

Produced water (PW) is the most significant source of waste discharged in the production phase of oil and gas operations. The management of PW provides distinct challenges for the oil and gas industry. There are number of technologies to treat and manage the PW, but selection of the best alternative often involves competing criteria and needs sophisticated decision-making tools. This chapter introduces a decision-making tool for selecting the best PW management option by utilizing a multi-criteria decision-making (MCDM) approach. The methodology introduces several important concepts, and definitions in decision analysis related to PW management. These are the trade-offs among technical feasibility, environment, cost and health and safety. The Analytical Hierarchy Process (AHP) and additive value model is integrated with MCDM to enhance the decision-making process. The proposed methodology is applied to a hypothetical example, and its efficacy is demonstrated through an application dealing with the selection of PW management technology for oil and gas operations.