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Geological and Geophysical Differences between Shelf and Deep Water Hydrocarbon Environments, Implications For Mms Field Designation and Deep Water Royalty Relief in the Gulf of Mexico OCS Region

Richard H. Fillon, Paul Weimer, Oil & Gas Development on the Outer Continental Shelf (2002)

The geology of the Texas-Louisiana continental slope reflects the structural modification of layers of sediment by the gradual vertical and lateral movements of large masses of salt, originally deposited when the water in ancient Jurassic seas evaporated. Over the last 15 years, a large body of technical work has established that, although the salt on the continental slope probably derives from the same Jurassic formation as salt on the continental shelf, the dominant hydrocarbon-trapping geologic structures it creates in the two areas are significantly different.

This review, (1) summarizes geological/geophysical contrasts between hydrocarbon-trapping environments on the continental shelf and continental slope, and (2) examines whether MMS field designation guidelines sufficiently meet accepted technical standards of continental slope geological classification. The guidelines are necessary to support the de-termination of field status for deep-water portions of the outer continental shelf (OCS) protraction area covered by the Outer Continental Shelf Deep Water Royalty Relief Act of 1995. MMS field status decisions are important to commercial development because they may qualify or disqualify production from royalty relief.

Provisions of the Outer Continental Shelf Deep Water Royalty Relief Act apply only to hydrocarbon accumulations in deep water, i.e., on th