The Trident Discovery: Play Opener of the Perdido Foldbelt, Deepwater Northwestern Gulf of Mexico

Jon F. Blickwede, Mich W. Damm, Michael J. DiMarco, Eddie Doré, Barry L. Gouger, James G. Hawkins, John W. Hidore, and Skip Walden 
Unocal Corporation, Sugar Land, TX

The successful drilling and discovery of significant hydrocarbons during 2001 at the Trident #1 wildcat in the Perdido Foldbelt of Alaminos Canyon area proved the exploration viability of this deepwater frontier in the northwestern Gulf of Mexico. The well also set a world record for water depth, at 9,687 feet, and was the first announced discovery in the Paleogene of the deepwater Gulf. Trident #1 reached a measured depth of 20,500 feet in hemipelagic shales of the Lower Paleocene Midway Formation.

The Perdido Foldbelt is characterized by water depths reaching more than 10,000 feet and difficult drilling conditions exacerbated by a low pore pressure to fracture gradient margin in some prospects. The Trident discovery helped to increase industry’s understanding of how to effectively manage the drilling of such features.

Geologic insights gained from Trident #1 include the discovery of high-quality light oil, the recognition of multiple hydrocarbon source rocks, the age of key seismic markers, and the presence of abundant and well-developed deep-marine sandstone reservoirs in the Upper Paleocene portion of the Wilcox Formation. The prediction of reservoir presence prior to drilling utilized several seismic-based techniques, which have since been refined and improved with the calibration of well log data to the seismic response.

In the past three years additional discoveries have been made in the Perdido Foldbelt. Because of the extreme water depths, remote location, and technological challenges, cooperation amongst all operators will help ensure the economic development of this prolific trend by the end of the decade.

AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004