Abstract: Revisiting Our Predictions of Petroleum Reservoir Properties, U.S. East Coast Mesozoic Offshore

Samuel A. Epstein

In the early 1980's the major international oil corporations were focusing on potential giant oil fields in the U.S. frontiers. The offshore U.S. East coast Mesozoic shelf edge was one such frontier play area. The oil industry was preoccupied by an apparent continuous Mesozoic shelf edge build-up which appeared in seismic records. At the time there were no wells that penetrated the seismic build-up. Additionally, the shelf edge prospects were in water depths exceeding 1500 meters making difficult drilling technological problems and associated extremely high expenses.

What made the U.S. East Coast so attractive was that if carbonate reservoirs did exist the oil potential would be in the ten's of billions of barrels range. For example, in the Baltimore Canyon Trough, the Mesozoic shelf margin carbonates form a sublinear trend extending 650 km. from the Carolina Platform to the Long Island Platform. Similar carbonate shelf edge carbonates exist up to NewFoundland, all with mappable closures at various horizons.

In the June 1983 issue (volume 67/6) of the A.A.P.G. Bulletin, Gerald Friedman and the author published an article applying modern carbonate diagenetic findings in conjunction with the global seismic stratigraphy of P.R. Vail et. al.. Our article predicted porous carbonate build-ups formed during low sea-level stands in the Middle Jurassic, Late Jurassic, and Lower Cretaceous Age rocks.

In the mid 1980's, Shell Oil Corporation drilled seaward off the continental shelf edge. While working for Shell, B. E. Prather described their well findings in the February 1991 A.A.P.G. Bulletin (vol. 75/2). The wells encountered Jurassic and Cretaceous carbonate shelf edge oolitic grainstones, coral stromatoporoid grainstones and boundstones. Core, and log analysis reveal that reservoir quality carbonates do exist with the Jurassic and Cretaceous Age carbonate rocks. He suggested the porosity was formed during various subaerial exposures caused by low sea level stands.

In summary, our integration of global seismic stratigraphy and modern carbonate diagenetic models help predict reservoir quality in a totally undrilled area of continental proportions. Unfortunately, thus far the tested prospect was water saturated (wet). In the foreseeable future, with the price of crude oil at its current level it is unlikely any further drilling will take place.

AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York