Guillermo Mora¹, Alex Iparrea¹, Adan Oviedo¹

(1) Pemex Exploracion y Produccion, Villahermosa, Tabasco, Mexico

ABSTRACT: Petroleum Geology of the Salina del Istmo Basin

Salina del Istmo basin is located in the southern Gulf of Mexico where onshore production has been established since early 1900. The Neogene stratigraphy varies from deep-water to transitional sediments associated with compressional-extensional salt-related tectonics. The main Jurassic source rock began to be active in the Middle Eocene westward, and from the Miocene to the present at the eastern and northern parts. Compressional faults bring the charge from source rock into the structures being involved sand bodies, normal faults and salt. Vertical seal includes multiple shale intercalations within sands. Four provinces can be identified based on the salt behavior that produces different play types. At the western part, a thick shallow salt canopy bound both pinch out and truncated deep-water sediments. At the central part, compressional salt plugs and roller faults created an intraslope mini-basin, which is the main structural feature. The production comes from lobate sheet sands, sinuous channel-levee systems and shingle turbidites. Production is also associated with a progradational shelf and transitional deltaic facies. At the northern part, where the tabular salt canopy is located, a sub-salt play in Miocene deep-water conglomerates was discovered in 1976. Above the salt, turbidites are also productive. The eastern part is associated with a salt withdrawal basin where thick transitional sediments are related to listric, and counter-regional faults. According to seismic amplitude extractions and horizon slices the reservoir distribution denotes structural control. Offshore continuity has been explored while onshore and offshore Mesozoic sub-salt plays still wait for better seismic resolution.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado