Statistical Risk Methodology: Application for Pollution Risks for Canadian Georges Bank Drilling Program

Abstract

ABSTRACT Risk analysis assessment techniques have not been applied previously to determining environmental risks at specific locations for offshore exploratory drilling programs in Canada. Rational analysis of the potential causes of failure, combined with probabilistic methods, provides a quantitative measure of the risk of an oil spill and consequent pollution from exploratory drilling which has not been available previously. This approach has demonstrated that the risk of oil pollution is very small much smaller than is perceived by the general public. Methods are also suggested by which operators can further reduce this risk. INTRODUCTION In recent years, there has been increasing public concern about protecting the marine environment from the effects of accidents in offshore oil and gas exploration and development activity. This concern attained a very high profile over a proposal for exploratory drilling on Georges Bank, a seaward extension of the continental shelf that projects into the Atlantic Ocean between Cape Cod and Nova Scotia. Georges Bank supports a rich fishery which is important to fishing interest in both Nova Scotia and Massachusetts. Much of this concern stems from the public's perception about the risk of environmental damage. When Texaco Canada Resources Ltd. (Texaco Canada) announced plans to seek regulatory approval to drill two exploratory wells on the Canadian side of the bank, the issue of risk to the environment was paramount in the minds of the interest groups lobbying against such activity. In the public debate over the issue, the potential risks of drilling activity on the bank became badly distorted. Without site specific information to answer the concerns of critics, Texaco Canada was unable to respond directly to the allegations that its proposal presented an unacceptable risk to the environments and fisheries of the bank. To provide a factual basis for discussing these risks, Texaco Canada contracted Energy & Maritime: Claims and Appraisals, Inc. (EMCA) and Noble Denton & Associates, Inc. (NDA) to develop a methodology to quantify the risks of an oil spill resulting in environmental damage, and apply it to the Georges Bank area. The objective of this study was to put the potential pollution risk in proper perspective and then develop recommended strategies for managing this risk. Data were collected on blowout casualties, oil spill events and combined with an existing database on nondrilling hazards for the years 1955-1987. The goal was to present the hazards in a simplified graphical form, together with quantification of the probabilities of occurrence of the initiating events that could lead to an oil spill. Probabilistic techniques were used to verify the roost likely size of such an oil spill, if it were to occur, from both historical data and rational analysis. Information on previous accidents was used to assist in formulating appropriate hazard mitigation techniques.