The West Black Bay, Black Bay, and East Black Bay fields are in the prolific upper-middle Miocene oil- and gas-producing trend of Plaquemines Parish, Louisiana.

The stratigraphic section in the area consists mainly of strata of Miocene age. In wells drilled to sufficient depth, three distinct facies were found: (1) shallow-water, massive upper Miocene nearshore to continental sandstone facies; (2) an intermediate facies consisting of alternating sandstone and marine shale of the early late Miocene and middle Miocene continental shelf; and (3) a massive shale or deep-water facies composed of a dark marine shale facies of the early middle Miocene continental slope.

The West Black Bay-Black Bay and East Black Bay structures are elongate simple anticlinal closures on the downthrown side of a regional growth fault. These structures have a northwest-southeast alignment, are of low relief, and exhibit a southwestward shift and growth with depth. There is no evidence of salt piercement. Buried faulting occurs on the southeastern end of the West Black Bay-Black Bay structure. This faulting is down-to-the-southeast and does not appear to penetrate early Bigenerina 2 sediments.

Massive sandstone deposition is found as low in the section as the lower Bigenerina 2 sediments. However, sandstone deposition in the lower Bigenerina 2 and Textularia W zones was erratic, making electric-log correlations difficult in this zone.

The production is from sandstone beds of late and middle Miocene ages between the depths of 5,980 and 11,200 ft. A total of 218 producing wells has been completed in the three fields and cumulative production from them through December, 1964, was 31,318,202 bbls. of oil and condensate and 63,131,616 Mcf. of gas. The estimated recoveries for all reservoirs range from 455 bbls./acre-ft. to 692 bbls./acre-ft. An estimate of recoverable reserves is 72 million bbls. of liquid hydrocarbons. The reservoir mechanism is water drive.

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