An oilspill risk analysis for the Diapir Field (June 1984), outer continental shelf lease offering

Abstract

10,000 barrels in size. Nakassis (1982) conducted a statistical analysis of the record, 1964-1979, and concluded that the platform spill rate did not remain constant since 1964, but had decreased significantly. Using this trend analysis and updating for the 1980 data, the spill rate for platform spills of 1,000 barrels or larger is 1.0 spills per billion barrels produced; and the spill rate for platform spills of 10,000 barrels or larger is 0.44 spills per bill ion barrels produced. As with platform spills, the spill rate for pipelines is based on the record for the U.S. OCS from 1964 through 1980. Two spills of 10,000 barrels or larger are in the data base, along with 6 spills of 1,000 to 10,000 barrels in size. No trend in the pipeline spill rate is evident. The spill rate for pipeline spills of 1,000 barrels or larger is 1.6 spills per billion barrels transported, and the rate for spills of 10,000 barrels or larger is 0.67 spills per billion barrels transported. For tanker spill rates, previous OSTA models for Alaska used data for years prior to 1973. Using a new data base (The Futures Group, and World Information Systems, 1982) covering the years 1974 through 1980, Lanfear and Amstutz (1983) concluded that the tanker spill rate (expressed as spills per billion barrels transported) since 1974 was only about a third of that found prior to 1973. Thus, this oilspill analysis uses a significantly lower tanker spill rate than the earlier models. From 1974 through 1980, the data base contains records of 57 tanker spills of crude oil of 10,000 barrels or larger and another 57 spills of 1,000 to 10,000 .barrels. During this period, approximately 88 billion barrels of oil were transported. Lanfear and Amstutz (1983) were able to separate the 114 tanker spills into those occurring in port (i.e., inland of the breakwater, etc.) and those occurring at sea. While this information does not affect predictions of the overall occurrence rate, it does affect assumptions about where spills are likely to occur, and the appropriate weights were assigned along tanker routes to account for "at sea H/ Hin port" spills. The overall spill rate for tanker spills of 1,000 barrels, or larger, is 1.3 spills per billion barrels transported (0.90 at sea, and 0.40 in port), and the rate for spills of 10,000 barrels, or larger, is 0.65 spills per billion barrels (0.50 at sea, and 0.15 in port). In summary, the spill rates, expressed as number of spills per billion barrels produced or transported, used in this report are: >1,000 bbl ^10,000 bbl Platforms 1.0 0.44 Pipelines 1.6 0.67 Tankers (at sea) 0.9 0.50 Tankers (in port) 0.4 0.15 Oil spill occurrence estimates for spills greater than 1,000 barrels and greater than 10,000 barrels (Table 1) were calculated for production and transportation of oil over the 27-year expected production life of the DiapirField Leases. Similar estimates were also calculated for production and transportation of oil from existing leases and for transportation of Canadian oil. Oil spill Trajectory Simulations Oil spi...