The Lower Cretaceous James Lime Play of the Northeast Gulf of Mexico: A New Trend Discovery Made on the Mature Gulf of Mexico Shelf

B. Thomas Himes
Chevron, New Orleans, LA

In the early 1990's Chevron recognized that only 10 wells targeting the Lower Cretaceous had been drilled in the Northern Gulf of Mexico. This lack of drilling was despite the fact that over 3 billion barrels of oil and oil equivalent gas had been produced from Lower Cretaceous carbonate reservoirs in East Texas, North Louisiana, and Southern Mississippi. A regional geologic study of the Lower Cretaceous Carbonate platform of the Northern Gulf of Mexico basin was conducted and indicated that one area south of Mobile Bay (Viosca Knoll) had Lower Cretaceous exploratory potential. Using the newly developed geologic model, sparse well control, and high quality seismic data, a number of Lower Cretaceous prospects where identified.

The prospects that were identified all had similar characteristics. The targeted objective was the James Lime Formation deposited in a back reef platform environment. The prospects were defined as stratigraphic traps with porous grainstone shoals draped over southwest plunging structural noses. The depth to the James objective ranged from -14,000' ss to -15,500' ss.

In 1994 Chevron and partner Samedan drilled the first discovery well, finding a porous carbonate grainstone within the Lower Cretaceous James Formation that was 65' gas full averaging 15% porosity. On test it was determined that the well was capable of producing in excess of 30 MMCFGD. Four years later four additional James discoveries had been made and first production began. This new James Formation production was the first commercial production from the Lower Cretaceous in the U.S. Gulf of Mexico. To date eight James fields have been discovered with a cumulative production total of 250 BCFG. Exploratory and development drilling continue in the offshore James trend.