Facies Architecture of a Kimmeridgian Mixed Carbonate-Siliciclastic System in the Akal Block, Cantarell Field, Campeche Bay Area: Implications for the Distribution of Reservoir Ooid Shoal Strata

The mature Cantarell oil field in the Campeche Bay is still an important petroleum-producing area. An integrated study of the Kimmeridgian strata in the Akal block, the overthrusting block, at the Cantarell field was completed utilizing seismic data, well logs, and core analysis. The studied Upper Jurassic interval reaches a thickness of 500 m and consists of a sedimentary succession of interbedded calcareous and terrigenous facies. The calcareous facies, almost totally dolomitized, include: silty-shaly mudstone, mudstone, silty skeletal wackestone, coated grains-skeletal packstone, and ooid grainstone. The depositional settings interpreted for these carbonate facies vary from quiet marine environments (outer platform and “lagoon”) to high-energy shallow subtidal environments (carbonate sand shoals and lagoon). The siliciclastic facies consist of greenish gray shales, white arkoses, and reddish brown shales. The interpreted settings for these siliciclastic facies include: outer platform (offshore), “lagoon”/shoreface and probably alluvial plain, respectively. Overall, the facies stack forming terrigenous-carbonate cycles equivalent to parasequences which also stack forming higher hierarchy cycles equivalent to third-order(?) depositional sequences. Three depositional sequences were recognized and their thickness varies from 50 m to 140 m. Ooid-rich facies are the Kimmeridgian reservoir strata. The oldest depositional sequence contains the thickest package of ooid-rich interval (50 m to 100 m). Facies heterogeneity and stacking patterns resulted in the stratigraphic compartmentalization of the ooid-rich horizons. Both stratigraphic correlations throughout the field, utilizing at least 55 wells, and isopach maps indicate that the carbonate successions represent homoclinal ramps developed in the NW and central parts of the field. Relative sea-level changes related to tectonic movements and/or eustasy associated to the terrigenous input controlled the development and diminish of the carbonate ramps. A Jurassic to Early Cretaceous extensional event has been documented throughout the Campeche bay region including the underthrusting block (Sihil) in the Cantarell field and nearby fields. The distribution of the Kimmeridgian ooid shoals throughout the field and their correlation with adjacent fields support the extensional scenario during their deposition. The origin of the extensional event may be related to salt-driven tectonics or just extensional tectonics.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California