Ronald K. Zimmerman¹, David E. Pope², Aaron S. Bass², Chacko J. John²
(1) Louisiana State University, Baton Rouge, LA
(2) Louisiana Geological Survey, Baton Rouge, LA

Abstract: A new look at potential exploration targets in Lake Pontchartrain

Lake Pontchartrain covers an area of approximately 390,400 acres in southeastern Louisiana. Its subsurface strata range in age between Late Jurassic and Recent, exhibiting a wide variety of inner-to-middle shelf environments in the Tertiary and outer shelf-to-deeper environments in the Mesozoic. Structurally, the Tertiary beds dip southward at a rate of approximately 2 degrees across the lake, ranging between 2134 m and 3658 m at the Miocene-Anahuac contact. The Jurassic and much of the Cretaceous sections may be over-matured and rendered economically risky below 6100 m.

Field development has been between approximately 1250 m and 3353 m, with 9 being productive from reservoirs of the Middle and Lower Miocene. Five fields remained productive in 1998. Production comes from fault-closure traps on the downthrown (south) side of generally east-west trending faults. Four fields have produced both oil and natural gas, and four others, natural gas and condensate.

Several potentially prospective hydrocarbon targets remain: (1) untested fault-closure traps, (2) unconformity traps, including one area of about 8760 acres, (3) unconformity and/or possible porosity traps associated with the Heterostegina lime, (4) the fractured Austin Chalk, and (5) Lower Tuscaloosa sands on structure and possibly the “Tuscaloosa marine shale” stratigraphic zone in the northern part of the lake. Additional targets may exist in conjunction with possible field extensions. Since a moratorium on new leasing in the lake was imposed in 1991, there has been only one field well drilled and no 3-D seismic profiling.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana