A Method To Estimate the Pollution Risk and Cost of OCS Oil Transportation
Authors: Donovan L.J. , Owen J.J. 
Published: December 2007

Energy developers are concerned with the potential added development expenses resulting from environmental restrictions in transporting Outer Continental Shelf oil. This paper presents a method for combining the available cost and spill risk data into a format that can be used for rational decision-making.

Introduction

Since the Arab oil embargo, considerable attention has been focused on our Outer Continental Shelf (OCS) lease sales. The Dept. of the Interior's Bureau of Land Management and the several affected states have spent a great deal of time and effort on assessing the environmental impact associated with developing the oil and gas lease areas.

An area that has not been treated extensively in an analytical fashion is the transportation component of the over-all system. No objective and thorough comparison has been made of the economic and environmental merits and risks of these alternatives.

This paper presents the method used during a study of four hypothetical production sites in the Gulf of Alaska, as shown in Fig. 1. In addition, the results of one site analysis are presented relative to the environmental and economic trade-offs that must be considered by those involved with OCS planning and development.

Description of the Scenario

Site 3 in the Gulf of Alaska is used in this paper to demonstrate the approach used to evaluate the options available for transporting the energy products produced offshore. Site 3 is about 13 miles offshore in water 95 fathoms deep. Reserve estimates for the lease area are highly uncertain, so a range of reserves from 25 million to 2 billion bbl of oil recoverable over 20 years was investigated.

It is not contemplated that oil produced in the Gulf of Alaska will be refined or consumed in Alaska or adjoining parts of Canada, nor is it anticipated that the oil will parts of Canada, nor is it anticipated that the oil will be moved to refining or consuming areas over land. This implies that Gulf of Alaska oil will be transported by tanker over sea routes to locations as distant as the U.S. West Coast. However, the use of tankers entails a requirement for substantial offshore storage capability that is not necessary if pipelines are used for transfer to shore, because production continues while the tanker is in transit. Thus, costs and spill risks associated with offshore storage must be considered when evaluating tanker alternatives, and such storage facilities effectively become part of the tanker transportation subsystem. Hence, integrated transportation and storage systems were designed for each hypothetical production site.

Three general concepts of transportation and storage systems were utilized: tanker transshipment, pipeline transshipment, and direct shipment. Each of these concepts is outlined below.Tanker transshipment. Offshore oil is stored temporarily at the production site, where it is picked up by a small shuttle taken This tanker carries the picked up by a small shuttle taken This tanker carries the oil to a port facility near the Gulf, and offloads to shore storage. Next, the oil is loaded aboard a 90,000-DWT tanker for shipment to the U.S. West Coast.Pipeline transshipment. A pipeline links the production site to a shore port facility. Oil is production site to a shore port facility. Oil is produced offshore and pumped through the pipeline to onshore produced offshore and pumped through the pipeline to onshore storage at the port. It is then transported to the U.S. West Coast by a 90,000-DWT tanker.

JPT

P. 639