Coordination of geological and engineering research in support of the Gulf Coast Co-Production Program. Final report, June 1987-November 1988

Shallow-marine sandstones in Northeast Hitchcock field having high porosities and permeabilities contain abundant authigenic kaolinite and have acted as preferential conduits for fluid migration. Authigenic clay creates fluid production problems because of its delicate structure. Dislodged clay will obstruct pore throats at high production rates. A maximum safe rate of fluid production will need to be determined for co-produced wells. Middle and lower Miocene barrier-island sands in Northeast Hitchcock field have the potential for receiving large volumes of co-produced brines. These sands have permeabilities in excess of 2,000 md, are internally homogeneous, and are laterally extensive in the field area. Detailed geologic analyses of two reservoirs in Seeligson field delineate heterogeneous, fluvial sandstones that probably contain isolated, undrained reservoir compartments. Zone 15 can be subdivided into at least four genetic sandstones, and Zone 18-C can be subdivided into two separate sandstones. Two new pool discoveries (Miocene) in Tom O'Connor field developed during growth-fault activity along the Vicksburg Fault Zone. Deposition of these sandstones, as part of an offshore system during initial parasequence deposition, was confined between the Vicksburg Fault Zone and the Tom O'Connor anticlinal crest.