Development of a Product Screening Protocol for Evaluating Environmental Effects of Oilfield Chemicals

Abstract

North Sea operators are now faced with more stringent forthcoming regulations concerning usage and discharges of chemicals. The Paris Commission (PARCOM) Working Group on Oil Pollution (GOP) is trying to harmonize procedures for approval, evaluation, and testing of offshore chemicals and drilling muds. PARCOM has proposed that a series of tests covering toxicity testing of a marine algae and a marine copepod, biodegradation in seawater, and bioaccumulation are performed for all compounds in chemical products used in offshore production. The development of these regulations depends upon a more thorough understanding of the fate of chemical products during processing and discharge than we presently have. This affects economic and environmental aspects of chemical selection, process technology selection and daily offshore operation. The PARCOM proposed procedures, which are based on existing or proposed OECD or ISO standards, do not take into consideration that the chemicals used offshore are often slightly water soluble and complex mixtures of ill-defined components, and that modification in procedure or special sample preparation is needed. Therefore Conoco Norway (CNI), in 1989, initiated the development of a products screening protocol for evaluation of environmental effects of oil field chemicals discharged to the marine environment. The protocol includes test procedures for determination of the oil/water partitioning of chemicals, the biodegradation and bioaccumulation potential of the chemicals, and to assess and classify complex chemical products according to environmental risk. In addition to the marine environment, the oil field chemicals can also reach the air, due to volatile fractions in the compounds and they can go to marine sediments. The test protocols developed should also take this information into account. In a complete test protocol, acute and chronic toxicity also need to be addressed. However, existing published biodegradation and toxicity test procedures for surfactants and non-water soluble chemical products are not suitable, since homogeneous samples are very difficult to prepare, making reproducibility a significant problem.