Gulf of Mexico Oil and Gas Basin

located within one of the largest depressions in the earth’s crust, whose lowest part is occupied by the Gulf of Mexico. The basin has an almost isometric form, with a diameter of about 1,800 km, and is filled with Cenozoic and Mesozoic deposits up to 15 km thick. The land portion of the basin occupies the Gulf Coastal plain that stretches across Texas, Louisiana, Arkansas, Mississippi, and parts of Alabama, Georgia, and Florida in the USA and the states of Tamaulipas, Veracruz, and Tabasco in Mexico. In the southeast the basin is bounded by a fracture separating it from the Antilles geosynclinal system.

In the north the basin is rimmed by outcrops of Paleozoic deposits in the Appalachian and Ouachita folded systems or protrusions of the Precambrian basement (Nashville and Pascola arches). In the southwest the basin is connected with the Permian basin, and in the east its boundary passes through the Ocala arch of Florida. The western and southern rim of the basin is formed by the Laramide mountain structure of the Sierra Madre Oriental.

The land portion is composed of a series of large depressions and rises. The submarine part of the basin includes a shelf, a continental slope, and an abyssal plain descending to 4 km. Salt dome tectonic activity, with Early Jurassic or Permian salt, extends throughout the entire basin.

More than 2,000 petroleum and gas deposits have been discovered, including more than 200 in the submarine part. The oil and gas is associated with Miocene, Paleogene, Cretaceous, and, to a lesser extent, Pliocene and Jurassic deposits. The reservoir rocks are primarily sandstones in Cenozoic rocks and limestones in Cretaceous rocks. In the northwest Carbonaceous and Ordovician sandstones and limestones also contain oil and gas. Most of the deposits are associated with local uplifts of the platform type, salt-dome structures, and zones where sandy deposits taper out. In the Mexican part of the basin petroleum deposits are also associated with linear folding anticlines and extended reef zones. There are several extremely large deposits, such as the petroleum deposit in East Texas and the gas deposits at Monroe (Louisiana) and Carthage (Texas).

Petroleum production in the basin began in Mexico in the early 20th century (around Tampico) and in the USA in the 1920’s. The use of sea transport for shipping petroleum contributed to the rapid expansion of the oil industry. Natural gas has been extracted on a large scale since World War II. In the 1960’s and 1970’s offshore drilling has been conducted in the shoals off the coast of Texas and Louisiana. Petroleum reserves in the shelf are estimated at 374 million tons (1969). Oil extraction from the sea floor is also being developed in southeastern Mexico. Reserves of natural gas in the USA are dispersed in small deposits, making exploitation more difficult. The basin yields 30 percent of the petroleum produced in the USA, totaling more than 140 million tons in 1971. (Production in Louisiana increased greatly in the 1960’s and 1970’s.) It also provides all of Mexico’s petroleum (21.9 million tons in 1971) and gas (18.2 million cu m).

A large petroleum-refining industry, using both local and imported oil, has arisen in the basin. The basin’s petroleum refineries account for about one-third of the output of US refineries (about 200 million tons in 1971) and three-fourths of Mexico’s output (22 million tons in 1971). The major petroleum-refining centers are Houston, Beaumont, and Port Arthur in the USA and Tampico, Ciudad Madero, and Minatitlan in Mexico. The petrochemical industry has also expanded rapidly. Petroleum, natural gas, and petroleum products are shipped through pipelines to other parts of the USA and Mexico.