Abstract: Petroleum Geology of the Reforma Area, Southeastern Mexico

By

Eduardo J. Guzman

Most of Mexico's oil has come from Cretaceous and Jurassic carbonate rocks, although there was no production from these formations in southeastern Mexico until the significant 1972 Pemex discoveries. By the end of 1977, 15 to 20 onshore and 3 offshore Mesozoic producing sites had been drilled in the Reforma area and Campeche Gulf. Eight of these pools are producing and several can be recognized as giant fields. Conservatively, proved reserves exceed 5 billion bbl of liquid hydrocarbons and 7 tcf of gas. The additional potential in view of the extent and number of favorable structures is enormous.

Daily production in January 1978 was 810,000 bbl of oil and condensate, and about 900 mmcf of gas. Cumulative production at the end of 1977 was about 580 million bbl of oil, approximately 60 million bbl of condensate, and 840 bcf of gas. The number of wells drilled at the time was 249 (202 successful). Three of the wells drilled were offshore.

New reservoirs are mainly Cretaceous and Jurassic dolomites and microfractured limestones at an average depth of 12,500 ft (3,750 m). Trapping conditions are complexly faulted and, locally, overthrust anticlines covered by a thick Tertiary shale and sandstone sequence. Salt tectonics also are involved. Miocene sandstones have produced in the area since 1960, but Mesozoic discoveries were not made until the development of more sophisticated geophysical and drilling techniques.

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