TALUKDAR, SUHAS C., DGSI, The Woodlands, TX, and FERNANDO MARCANO, Maraven, S.A., Caracas, Venezuela

ABSTRACT: Petroleum Systems of the Maracaibo Basin, Venezuela

The La Luna-Misoa(!) petroleum system covering an area of about 47,500 sq km, contributes to several giant oil fields and over 98% of the total recoverable oil reserves of 52.20 x 10 bbl and gas reserves of 51.97 x 10 cu ft in the Maracaibo basin. The system developed in two phases. Each phase has the characteristics of an unique petroleum system, but both share the Upper Cretaceous La Luna source rock. The development of each phase is related to two separate, mature-overmature pods of the La Luna source rock. Based on biological markers, the oil in this system is correlated to the oil-prone, type-II kerogen of the La Luna Formation, a marine source rock. Reservoir rocks of Eocene and Miocene age are the most important as they contribute 50% and 44% respectively, of the total recovera le oil in the basin. Based on average total organic carbon content and consumed hydrogen from hydrogen indices, the mass of hydrocarbons generated by the La Luna source rock is 2.50 x 1014 kg, and the in-place hydrocarbons in known oil fields are estimated at 352.25 x 1011 kg. These calculations indicate that 14% of the hydrocarbons generated from the La Luna source rock actually accumulated in known traps.

The Orocue(.) petroleum system, located in the southwestern part of the basin, contributes to less than 2% of the total hydrocarbon reserves in the basin. The geographic extent of this system covers 10,500 sq km and encompasses the mature-overmature pod of Paleocene Orocue Formation, a coaly source rock containing type-III kerogen, and the genetically related oil accumulations. Sometimes these accumulations contain a mixture of oils from the Orocue and La Luna source rocks.

AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.