Aggregative environmental risk of produced water from offshore oil & gas platform - A fuzzy based approach

Produced water, which includes formation water, injected water, small volumes of condensed water, and any chemical added down hole or during the oil/water separation process, is extracted during oil and gas production. Produced water is the highest volume waste generated in association with oil and gas production operations, which can be more than 10-folds of the oil produced in a particular well during its economic period of life. Despite treatment before discharge to satisfy regulatory limitations, produced water contains a certain amount of toxic chemicals, which make the assessment of their effects very important to environment in the oil and gas producing industries. Produced water discharged from offshore oil and gas industries contains several chemicals that are harmful to human health and ecology. Although, most of the contaminants fall below the detection limits within a short distance from the discharge point, few of the remaining contaminants are of concern due to their bioavailability in the media and bioaccumulation characteristics in finfish and shellfish species used for human consumption. In this study, a framework for evaluating aggregative risk from produced water is presented. The fuzzy based approach has been incorporated to deal with the uncertainties associated with different risk item assessment. The very popular method, called analytic hierarchical process (AHP) with fuzzy aggregation has been employed in this study.