AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Examination of the Post-Ouachita Paleozoic Successor Basin Strata for Undiscovered Oil and Gas Resources, Arkansas, Oklahoma, and Texas, USA
(1) Department of Interior, U. S. Geological Survey, Reston, VA.
(2) Department of Interior, U. S. Geological Survey, Denver, CO.
The U. S. Geological Survey (USGS) recently concluded an assessment of the undiscovered, technically recoverable, oil and natural gas resources of the Arkoma Basin Province and related geological areas. One of these areas is the Post-Ouachita Successor Basin Assessment Unit (AU) of northeast Texas, south Arkansas, and northern Louisiana. This AU is composed of Upper Paleozoic strata resting unconformably above the Ouachita Thrust Belt and extending in age from Pennsylvanian Desmoinesian to Permian Guadelupian. The AU is defined to the north by the updip pinchout of the post-Ouachita strata in Arkansas and northeast Texas and within structurally elevated areas of the Arkansas-Louisiana-Texas (ARKLATEX) salt basin where deep wells have penetrated Paleozoic sedimentary strata. This area is currently non-productive, but has hints that a viable petroleum system may still exist within the Paleozoic strata. Several wells have reported oil and/or gas shows and several intervals contain marginal source rocks.
Potential reservoir rocks in south Arkansas include Upper Pennsylvanian fluvial-deltaic and marginal marine sandstones, with minor limestone. Thin coals have been reported from some wells; these coals may be the source for some of the reported petroleum shows. Permian limestones overlie the Pennsylvanian in the deeper parts of the basin in Arkansas and on the Sabine Uplift along the Texas - Louisiana border and also may be potential reservoirs.
Very limited seismic and well data are not sufficient to point to any viable, untested structural or stratigraphic traps large enough to contain resource volumes greater than the 0.5 MMBOE or 3 BCFG minimum for the assessment. These factors, coupled with the lack of established production or significant, flowing hydrocarbon shows, led the assessment team to conclude that this area should not be quantitatively assessed at this time.