Abstract: Stratigraphy, Source Rocks, Reservoir and Seals in the Oil Provinces of Cuba

J. Sanchez-Arango, J. Lopez-Quintero, S. Valladares-Amaro, R. Segura-Soto

Two Major oil provinces are recognized in Cuba. The Northern Oil Province includes the overthrust belt whose rocks correspond to the syn-rift and drift stages of a stable continental margin. Deposition of syn-rift terrigenous sediments occurred from the Lower Jurassic to Lower Oxfordian and are about 3000m thick. Lagoonal strata were deposited in Middle Jurassic with no less than 1500m thick.

Carbonate sedimentation dominated the Upper Oxfordian and persisted into the Turonian, including several tectono-stratigraphic units with distinct facies. Thickness in starved basin sediments ranges from 1200 to 1800m and 4000m for the carbonate bank.

In north-central Cuba, one or several paleo-seaways existed at least from the Early Albian to the Maestrichtian south of the Bahamas Platform as a result of the retrogradation of the Ramedios-Cayo Coco Platform.

The Southern Oil Province includes the Zaza Terrane with the Cretaceous volcanic arc rocks and the ophiolites and the Turquino Terrane with the Paleogene volcanic arc rocks. Flyah-type pelagic deposition predominated in foreland basins developed between the Campanian and Middle Eocene.

The main proven source rocks are related to the basin sediments in sequences of Kimmeridgian to Turonian age with predominance of organic matter type II and high values of T.O.C. as high as 15%. Organic matter type III is associated with terrigenous-clayey sediments from Lower Jurassic to Kimmeridgian age.

These Cuban source rocks are the primary reservoirs with secondary type porosity (fractured-cavernous type). The Matrix exhibits its intergranular character. The presence of karstification is discussed.

Paleogene siltstones, shales and clays form good regional seals in several oil fields. Ultramatic rocks that are non-fractured and/or highly altered to shale are also seals.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994