Reexploration of old fields in mature hydrocarbon provinces, such as the Permian Basin of West Texas and New Mexico, may significantly increase known oil and gas reserves.

Shallow-water-platform carbonate reservoirs of Permian age have accounted for more than half of the oil production in the Permian Basin, one of the largest oil-producing regions in the United States.

The ooid-sand shoals of the Joulters Cays area of Great Bahama Bank were chosen for detailed sedimentologic study to investigate patterns of internal heterogeneity within a modern carbonate sand deposit and to develop criteria for predicting the lateral extent of porous and permeable carbonate gr

The East Penwell San Andres Unit produces from a depth of approximately 3,400 ft (1,040 m) on the east flank of a broad, low-relief anticline on the east side of the Central Basin Platform of the Permian Basin in Ector and Crane Counties, West Texas.

Unrecovered mobile oil is oil that is movable at reservoir conditions but is prevented from migrating to existing we1 l bores because of geologic complexities or heterogeneities.