Production Potential of Deep Miocene Rocks in Southeastern Louisiana

Abstract

Deep Miocene strata strike east-west across southeastern Louisiana. Generally, regional dip and total thickness of sedimentary rocks increase southward. Hydrocarbon traps include deep-seated and piercement salt domes and combination structural-stratigraphic types. Drilling below 15,000 ft indicates three east-west trends. The more southerly trend is a series of piercement salt domes and related up-to-the-basin faulting; deep production is from the downthrown Textularia L zone. A second trend is essentially an alignment of deep-seated salt domes; production is from both upthrown and downthrown strata on down-to-the-basin faulting. Productive formations are from sandstones in the Textularia L and Cibicides carstensi zones. The third trend, on the north, has one pierceme t salt dome and several deep-seated structures; production is from sandstones in the Robulus 43 and Nummulites (Camerina) operculinoides zones. Some deep tests have been disappointing failures because they were located on young structures. Others have encountered buried faults and related deep sandstones, or unexpected shallow productive sandstones--finds which encourage additional drilling. Production has been found below 21,000 ft and a prospective sandstone section may be projected to 30,000 ft and deeper. Prospecting above 17,000 ft has proved profitable, but at greater depths the economic potential is reduced by greater risks and costs.