From BAHA to Jack, Evolution of the Lower Tertiary Wilcox Trend in the Deepwater Gulf of Mexico

Abstract

Since the 1920's, the Lower Tertiary Wilcox Formation (Lower Eocene/Upper Paleocene) has been a significant hydrocarbon resource producing primarily gas from fluvial, deltaic, and shallow marine sandstone reservoirs from southwest Louisiana through south Texas to northeast Mexico.The total estimated recoverable reserves from this present-day onshore trend are approximately 30 trillion cubic feet gas or 5 billion barrels of oil equivalent (bboe). Not until 80 years later, with the drilling of the BAHA 2 well in March 2001, did industry begin to realize the full extent of linkages within the Wilcox depositional systems, from widespread shelf deposits to extensive deepwater turbidite sands. Ensuing drills in deep, offshore United States territorial waters (Perdido Fold Belt of the Alaminos Canyon Area) led to successes at the Trident and Great White prospects, demonstrating the significant potential of the Lower Tertiary Wilcox section more than 250 miles basinward of its onshore depocenter. In 2002, the Cascade discovery well extended the deepwater Wilcox trend another 275 miles east into Walker Ridge and 350 miles down dip from the shelf deltas. Then in 2006, two years after the 2004 Jack discovery, results of the test well were released. The Jack test established flow rates of over 6,000 barrels of oil per day from only 40% of the reservoir, thus confirming the Deepwater Wilcox as a world-class depositional and potential petroleum system. Currently, we estimate that the Wilcox Trend covers over 34,000 mi2 of deepwater in northwest Gulf of Mexico (GoM) and has potential recoverable reserves of 3-15 bboe. If these projections hold, the Deepwater Wilcox could increase proven reserves from GoM deepwaters by 94% to 30 bboe. This would account for a 17% overall increase for the entire GoM basin reserves, which also include the onshore areas (35 bboe) and continental shelf (35 bboe).