The Norwegian government issued in 1998 White Paper No. 58 followed by the"Zero discharge report" requiring the oil industry operating in the Norwegian sector of the North Sea to develop a strategy for reaching "zero environmental harmful discharges" of produced water (PW) within 2005. As a result Miljøsok proposed to develop a management tool based on environmental risk and hazard assessment to identify the most potential environmentally harmful discharges of PW, and to quantify the environmental benefit of different actions to reduce these. The Norwegian OilIndustry Association (OLF) working group for PW was asked to develop the Environmental Impact Factor (EIF), and the tool has sofar been applied for PW management on a single platform level. The plan is to elevate this work to a regional scale in order to compare the potential benefit of measures to reduce PW discharges in the whole area, and to form a basis for a cost-effective total approach to PW management. The EIF is based on a combined environmental risk and hazard assessment of PW discharges, accounting for both composition and amount of the discharge. The EIF is also linked to the environmental impact assessment (EIA) studies in the area and the environmental monitoring programme for the water column, initiated in1999. Determination of the EIF for a single platform allows the operator to rank the available technologies for PW discharge reduction on a cost-benefit basis. The EIF identifies the source of potential environmental damage and quantifies the benefit of any action taken to reduce this. Technologies like PW re-injection, treatment and removal or replacement of process chemicals can thus be ranked based on cost and environmental benefit. Introduction Produced water management in the Norwegian waters is currently based on the"Zero impact" mindset, meaning that the ultimate objective is to remove all potential environmentally harmful discharges (1). In general, a number of technological approaches are being considered and developed to meet this challenge;*Re-injection*Treatment*Water shut off*Down-hole separation*Removal or replacement of process chemicals

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Reduced environmental impact is the goal when choosing produced water treatment technologies. On the Norwegian sector the method used for quantifying this impact is the Environmental Impact Factor, EIF. This method is computerized in a tool that calculates the environmental impact from each of a number of chemical component groups that are present in produced water. Re-injection of produced water is the preferred option, and mostly used when pressure support is required. This paper, however, describes new treatment technologies aimed at produced water being released to sea. The technologies are suitable for different produced water compositions. The components in the produced water that contribute to the environmental impact are mainly: aliphatic hydrocarbons, heavy aromatic compounds (PAH), alkylated phenols and man added production chemicals. At several Statoil operated fields the corrosion inhibitor and H2S scavenger are giving a significant contribution. Several new technologies will be described. Statoil has had a leading role and actively participated in the development and qualification of most of these technologies. The results from this work will be presented. The technologies will include the CTour process, Epcon CFU, droplet coalescing technologies as well as new technologies to reduce discharge of production chemicals. The main conclusion is that knowledge is needed about which compounds contribute to the environmental impact of produced water before deciding which technology to use. Introduction The main focus in reducing the possible pollution from produced water to the sea has traditionally been on reducing the content of dispersed oil. Even though some countries have placed their attention on other compounds, international regulations like the new OSPAR regulations [1] still focus mainly on dispersed oil content in produced water. The new OSPAR regulations demanding less than 30 mg/l dispersed oil, and a 15 % reduction in total oil from year 2000 level will be implemented by 2006. On the Norwegian sector of the North Sea, all operators must, in addition to fulfilling and reporting according to the dispersed oil regulations, report the total environmental impact of the produced water release to the sea to the Norwegian Pollution Control Authorities (SFT) [2]. This reporting is done on an annual basis and is based on thorough (GC-MS) analysis of the produced water to quantify the content of all compounds of interest. The method for quantifying the environmental impact is the Environmental Impact Factor, EIF [3], which relies on DREAM (Dose Related Risk and Effect Assessment Model) [4]. In this model a comparison is made between the concentrations of possible environmentally harmful compounds and the predicted no effect concentration, based on an environmental risk assessment approach. The EIF is not only a valuable tool for quantifying the total environmental impact from one platform or a group of them, but also for evaluating the contribution from the different constituents in the produced water. In this paper three different technologies for produced water purification will be presented. The CTour process that is a liquid-liquid extraction process, the Epcon Compact Flotation Unit and Mare's Tail that is an oil droplet coalescer. In addition to these three technologies measures to reduce the environmental impact from production chemicals will be presented. Produced Water Purification Processes The compositions of produced water from different fields vary significantly. Hence, each field should be evaluated with respect to which compounds contribute to the environmental risk. When selecting produced water treatment technologies, one should focus on the major contributors to reduce the total environmental impact. Experience has shown that the major contributors to the EIF are dispersed oil, volatile aromatics, heavy aromatics, alkylated phenols, and added chemicals.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractReduced environmental impact should be the goal when choosing produced water treatment technologies. On the Norwegian sector the method used for quantifying this impact is the Environmental Impact Factor, EIF. This method is computerized in a tool that calculates the environmental impact from each of a number of chemical component groups that are present in produced water.Reinjection of produced water is obviously an option that should be considered if the reservoir needs pressure support. This paper, however, describes four new treatment technologies aimed at produced water being released to sea. The technologies are suitable for different produced water compositions.The four technologies described are the PECT-F (Performance enhancing coalescence technology) for enhanced removal of dispersed oil, the MPPE (Macro Porous Polymer Extraction) technology for removal of volatile aromatics, the CTour technology for the removal of heavy aromatics and alkylated phenols, and the Framopure C100 injection system for H 2 S scavenger.The potential of these technologies has been illustrated by choosing typical produced water compositions where one of these technologies has a significant potential to reduce the environmental impact. Given an estimated efficiency of these technologies, the EIF is calculated before and after applying the technology to show the reduced environmental impact obtained.The main conclusion is that knowledge is needed about which compounds contribute to the environmental impact of produced water before deciding which technology to use.Results are also presented that correlate the content of dispersed oil and PAH (poly aromatic hydrocarbons).

Reduced environmental impact should be the goal when choosing produced water treatment technologies. On the Norwegian sector the method used for quantifying this impact is the Environmental Impact Factor, EIF. This method is computerized in a tool that calculates the environmental impact from each of a number of chemical component groups that are present in produced water. Reinjection of produced water is obviously an option that should be considered if the reservoir needs pressure support. This paper, however, describes four new treatment technologies aimed at produced water being released to sea. The technologies are suitable for different produced water compositions. The four technologies described are the PECT-F (Performance enhancing coalescence technology) for enhanced removal of dispersed oil, the MPPE (Macro Porous Polymer Extraction) technology for removal of volatile aromatics, the CTour technology for the removal of heavy aromatics and alkylated phenols, and the Framopure C100 injection system for H2S scavenger. The potential of these technologies has been illustrated by choosing typical produced water compositions where one of these technologies has a significant potential to reduce the environmental impact. Given an estimated efficiency of these technologies, the EIF is calculated before and after applying the technology to show the reduced environmental impact obtained. The main conclusion is that knowledge is needed about which compounds contribute to the environmental impact of produced water before deciding which technology to use. Results are also presented that correlate the content of dispersed oil and PAH (poly aromatic hydrocarbons). Introduction The main focus in reducing the possible pollution from produced water to the sea has traditionally been on reducing the content of dispersed oil. Even though some countries have placed their attention on other compounds, international regulations like the new OSPAR regulations [1] still focus mainly on dispersed oil content in produced water. On the Norwegian sector of the North Sea, all operators must, in addition to fulfilling and reporting according to the dispersed oil regulations, report the total environmental impact of the produced water release to the sea to the Norwegian pollution authorities (SFT) [2]. This reporting is done on an annual basis and is based on thorough (GC-MS) analysis of the produced water to quantify the content of all compounds of interest. The method for quantifying the environmental impact is the Environmental Impact Factor, EIF [3], which relies on DREAM (Dose Related Risk and Effect Assessment Model) [4]. In this model a comparison is made between the concentrations of possible environmentally harmful compounds and the predicted no effect concentration, based on an environmental risk assessment approach. The compounds of interest are: PAH, NPD (naphthalenes, phenanthrenes and dibenzo-thiophenes), BTEX (Benzene, Toluene, Ethylbenzene and Xylene), phenol, alkylated phenols, metals, and added chemicals. The later being substances such as: production chemicals, corrosion-, scale-, and hydrate-inhibitors, separation chemicals, and H2S scavenger. The EIF is not only a valuable tool for quantifying the total environmental impact from one platform or a group of them, but also for evaluating the contribution from the different constituents in the produced water. The compositions of produced water from different fields vary significantly. Hence, each field should be evaluated with respect to which compounds contribute to the environmental risk. When selecting produced water treatment technologies, one should focus on the major contributors to reduce the total environmental impact. Experience has shown that the major contributors to the EIF are dispersed oil, volatile aromatics, heavy aromatics, alkylated phenols, and added chemicals.