--> Abstract: Characterization of the Generative Subsystems of Productive Northern Mexico Basins, by J. R. Román-Ramos, V. L. Bernal, G. H. Ramos, and J. A. Cuevas-Leree; #90933 (1998).

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Abstract: Characterization of the Generative Subsystems of Productive Northern Mexico Basins

Román-Ramos, J. R.; Bernal, V. L.; Ramos, G. H.; Cuevas-Leree, J. A. - Pemex

The study is focused to characterize and establish the correlation between source rocks and hydrocarbons of the four petroleum basins of northern Mexico: Sabinas, Burgos, Tampico-Misantla and Veracruz (Fig. 1, 2).

Sabinas Basin (SB) is located in the northernmost portion of Sierra Madre Oriental Fold Belt (SMOFB). The stratigraphic section comprises rocks from Oxfordian to Maastrichtian, reaching 5-6 Km thickness. The main sources are Kimmeridgian-Tithonian siliciclastic shales, which have 400m average thickness. The average TOC is 2.5%. The original kerogen was a type III. Nowadays all organic matter is overmature. The calculated hydrocarbon charge (SPI) is 7.5 ton/m². SB produces dry gas from fractured upper Jurassic sandstones and barremian limestones. Carbon and Hydrogen isotopic data suggests two families of thermogenic no-associated gases. Generation was developed on late Cretaceous-Paleocene. Preserved gases are the products of last syn- and post-orogenic expulsion and remigration.

Burgos Basin (BB) is located eastern from SB in a tertiary depression bounded by Mesozoic highs to west. The stratigraphic column consists of a tertiary progradational to Gulf of Mexico growth fault controlled marine-delta sequence, overlying Mesozoic carbonates. Thickness section reaches 12 Km. The main sources are Paleocene-Eocene shales, which contains type III mature-overmature kerogen. The average TOC is 1.0% and SPI reaches 7.5 ton /m². BB produces gases and condensates. Isotopic data suggests two families of thermogenic gases: Biomarkers of condensates indicate a deltaic origin. Hydrocarbon generation started at Eocene.

Tampico-Misantla Basin (TMB) is located southern from BB within foreland area associated with the early Tertiary compressional Laramide event. The stratigraphic column comprises from Lower Jurassic to Tertiary, reaching 7-Km thickness. The main sources are Upper Jurassic shaly carbonates with an average thickness of 550m. The TOC is 2.5%. Kerogen is a Type II, mature and very mature. The SPI is more than 15 ton/m². TMB produces predominantly heavy oils and associated gases with high sulfur. Their characteristics are related with low maturity, biodegradation, and segregation. Biomarker data suggests three marine oil families. Generation was developed during Paleogene, onshore, and during Neogene, offshore.

Veracruz Basin (VB) is located southern from TMB. Western VB portion the main sources are Lower Cretaceous and Turonian shaly carbonates. The SPI reaches 6.0 ton/m². Oils and associated gases with high sulfur are produced from fractured Cretaceous rocks. Biomarker and isotopic data suggests two oil families and two gas families: thermogenic gases associated with oil and mixed thermogenic-biogenic gases. Hydrocarbon generation carried out during Tertiary. Eastern portion column consists of a Tertiary progradational to Gulf of Mexico marine fan complex. Dry gases and condensates are produced from Miocene sandstones. Isotopic data suggests three gas families: thermogenic gases associated with condensates, correlated with Paleogene sources, Biogenic and mixed gases, correlated with Miocene shales.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil