Roger D. Shew, 1991. "Mid-Dip Tuscaloosa Trend: Analog Geological, Geophysical, and Engineering Data for Prospect Evaluation and Field Development", The Integration of Geology, Geophysics, Petrophysics and Petroleum Engineering in Reservoir Delineation, Description and Management, Robert Sneider, Wulf Massell, Rob Mathis, Dennis Loren, Paul Wichmann
Download citation file:
The Upper Cretaceous Mid-Dip Tuscaloosa trend occurs in southwestern Mississippi and parts of northeastern Louisiana (Figure 1). It is located on the south rim of the Mississippi Salt Basin and occurs updip of the Lower Cretaceous shelf margin. The Mid-Dip Tuscaloosa is primarily composed of terrigenous clastics derived from the Ouachita orogenic belt. Braided and meandering fluvial deposits unconformably overlie the Lower Cretaceous Washita-Fredericksburg Group. These initial progradational deposits were followed by an overall transgressive depositional sequence composed, from base to top, of fluvial, deltaic, and nearshore sediments encased in a dominantly shale-rich interval. These lenticular sandstones, particularly point-bar and channel deposits, are prospective for hydrocarbons in stradgraphic or combined structural/stratigraphic traps. The encasing mudstones and shales are excellent lateral and top seals for the hydrocarbons. Marine shales of the Middle Tuscaloosa cap the transgressive sequence and are interpreted to be the source rock. The mature Mid-Dip Trend has been estimated to have contained greater than one billion barrel equivalents of oil.
Three Shell fields, Little Creek, Olive, and Liberty, provide important analog data for further exploratory and enhanced recovery operation in the trend. Little Creek is by far the largest field with OOEP of 102 MMBO in a combined structural/stratigraphic trap. Olive (8 MMBO) and Liberty (7 MMBO) are typical of the remaining smaller stratigraphically-trapped accumulations. Detailed seismic stradgraphic interpretations, in combination with core and wireline data, are critical to the discovery, delineation, and development of these smaller reservoirs. Mappable seismic anomalies are associated with these porous, “soft” sandstones.