Exploration NW gulf's Perdido fold belt due deep exploratory test

API Monthly U.S. Well Completions* [18189 bytes] A four company group appears close to drilling a deep well on the untested Perdido fold belt in the Gulf of Mexico. The site likely will be in 6,000-9,000 ft of water east of Brownsville, Tex., in the Alaminos Canyon area and near Mexican waters. Much of the belt lies in Mexican waters, but it covers more than 3,000 sq km in the southern part of the Alaminos Canyon area, according to a paper published last fall by the Gulf Coast Association of

Feb. 26, 1996

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API Monthly U.S. Well Completions* [18189 bytes]

A four company group appears close to drilling a deep well on the untested Perdido fold belt in the Gulf of Mexico.

The site likely will be in 6,000-9,000 ft of water east of Brownsville, Tex., in the Alaminos Canyon area and near Mexican waters. Much of the belt lies in Mexican waters, but it covers more than 3,000 sq km in the southern part of the Alaminos Canyon area, according to a paper published last fall by the Gulf Coast Association of Geological Societies.

Authors of the paper characterize reserve estimates as highly speculative due to the lack of deep borehole data in the area. However, they cite individual structures with areal closures as large as 400 sq km with more than 2,000 m of section under closure. Such structures could contain as much as 6 billion bbl of oil and more than 10 tcf of gas in place, they wrote citing estimates by earlier authors.

The anticlinal crests of the Perdido fold belt are the primary targets for any future exploration, with potential for stratigraphic pinchout plays on the flanks of some structures, they wrote. The authors hail from University of Colorado, Boulder, and Shell, Texaco, Amoco, and Mobil.

The authors indicated potential reservoirs in Upper Jurassic/Lower Cretaceous carbonates, Upper Cretaceous chalks, and Lower Tertiary (Paleocene/Oligocene) turbidite sandstones.

Mature source rocks are predicted in Upper Jurassic and Upper and Lower Cretaceous. Extensive oil seeps have been recorded along with chemosynthetic communities at active seep sites on the seabed across the belt.

The authors describe the belt as a series of northeast to southwest trending, sub-parallel, concentric, box folds cut on one or both of their flanks by high angle reverse faults. The Perdido fold belf is defined by a series of large scale fold structures that extend southwest into Mexican waters and northeast beneath the well defined Segsbee salt escarpment.

Major exploration risks are adequate seal over the faulted crest of the major anticlines and the presence of good reservoirs in a deep marine setting.