Deep Miocene sediments strike east-west across southeast Louisiana. Generally, regional dip and total thickness of sediments increase southward. Deep Miocene hydrocarbon traps include deep-seated and piercement salt domes, faultline closures, and combination structural-stratigraphic phenomena. Drilling below 15,000 ft indicates two major, distinct east-west trends in the southern parts of Terrebonne and Lafourche Parishes. The northern trend is essentially an alignment of faultline structures with upthrown and downthrown production; the deep producing sediments are in the strata of the Cibides carstensi zone. The southerly trend is a series of salt domes and related down-to-the-north faulting; deep production is downthrown and from the Textularia "L" zone. Recognition of hese trends will become more difficult as they are extended.

Some deep tests have been disappointing failures because they were located on young structures. Others have found buried faults and related deep sandstone which encourage additional drilling. Production possibilities from stratigraphic pinchout traps have been indicated in several areas, but economic factors of deep drilling inhibit this type of hydrocarbon exploration.

The limits of deep Miocene prospecting and production are imposed by technological and economic considerations. Production has been found below 21,000 ft and sandstones capable of producing may be projected to 30,000 ft and deeper. Prospecting above 17,000 ft has proved to be profitable, but at greater depths the economic potential is reduced by greater risks and costs.

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