Improving Environmental Performance by Sharing Information on Offshore Drilling Discharge Environmental Science and Drill Cuttings Treatment Technology

Abstract

Abstract This paper describes literature reviews commissioned by the International Association of Oil and Gas Producers (IOGP) and initiated by the IOGP Drilling Waste Management Task Force that address recent environmental science related to the discharge of drill cuttings into the marine environment. The focus is on the environmental effects of discharge of cuttings drilled with non-aqueous drilling fluids, and recent developments in the technology of drilling waste management. The objectives of these reviews are to provide industry with information for improving environmental performance of offshore drilling and to facilitate communication between industry and stakeholders concerning environmental effects of offshore drilling and factors to be considered in decision making related to drilling waste management. Environmental consultants were engaged to prepare an update of a 2003 review and synthesis of environmental fate and effects of drilling discharges and to prepare a review of recent technology developments applicable to the management of drilling waste. Information sources used in the preparation of the reviews included published and gray literature as well as discussions with industry and technology subject matter experts. The concept of classifying base fluids according to aromatic content, introduced in 2003, continues to provide a useful framework for discussing the environmental effects of cuttings drilled with nonaqueous drilling fluids. Several large multiyear monitoring programs, covering operations in four geographic regions, where cuttings drilled with very low aromatic content base fluids were used, were reviewed as part of this effort. In most studies, recovery usually began shortly after drilling was completed and was often advanced within a year. Organic loading of sediments was a significant contributor to effects, suggesting that recently introduced treatment technology, such as centrifugal cuttings dryers and thermomechanical cuttings treatment systems, will improve environmental performance in offshore drilling by reducing the organic content of discharged cuttings. Differences among technologies in processing rates, power consumption, air emissions, and requirements for deckspace on drilling rigs are factors for consideration in the selection of cuttings treatment technologies. Sharing this information among companies involved in offshore drilling provides opportunities for improving industry environmental performance.