Maracaibo Oil and Gas Basin

one of the largest oil and gas basins in northwestern Venezuela; its southern margin extends into Colombia. Lake Maracaibo, with maximum depths of 250 m, occupies the southern part of the basin. The Maracaibo oil and gas basin is confined to the Maracaibo intermontane basin, which is enclosed between the Sierra de Perijá and the Cordillera de Mérida, which are composed of highly dislocated Paleozoic, Mesozoic, and Cenozoic rocks. The intermontane basin is formed by Cretaceous and Cenozoic deposits up to 10 km thick. The basement of the basin is made up of Precambrian crystalline rocks and, in certain places, Paleozoic metamorphic rocks. The Cretaceous limestones and sandstones, Paleogene and Neocene sandstones and, in part, the fissured metamorphic rocks of the basement (La Paz, Totumo), are all oil-bearing.

The Maracaibo oil and gas basin has more than 35 oil fields located in the marginal areas of the basin. Explored oil reserves are estimated to be approximately 2 billion tons (1972).

The Bolívar field, which is one of the largest oil fields in the world, has an oil pool with an area of 70 × 20 km; it is confined to Miocene and Eocene deposits at depths of 1,000-1,100 m and stretches along the northeastern shore of Lake Maracaibo, extending into the latter for 10-15 km. The rest of the large fields in the Maracaibo oil and gas basin (Mene Grande, La Paz, Mara, Boscan, and La Concepcion) are situated in the northern part of the western margin. Oil production on a commercial scale began in 1917 with the development of the Mene Grande field. Oil production in the Maracaibo oil and gas basin amounts to approximately 77 percent of Venezuela’s overall oil production. In 1969, oil produced in Venezuela accounted for 78 percent (187 million tons) of the continent’s total production of 239 million tons. The oil is sent via pipeline to petroleum refineries and to ports for export. A considerable amount of the oil is refined at refineries on the islands of Aruba and Curasao (Netherlands Antilles). Production is controlled by companies of the USA and Great Britain.