EAST TEXAS EMBAYMENT

PROJECT OVERVIEW

The primary objective of this integrated exploration project is to identify structurally-controlled traps and faults that localize Jurassic production. Identification of structures, many of which are basement related, where Smackover production may be found, has been accomplished primarily by utilizing an exclusive, high-intensity, low altitude aeromagnetic survey with closely spaced flight lines. Additionally, shelf breaks that control the locations of Cotton Valley-type production may be identified by using closely-spaced gravity data. Thus, this project focuses on an integrated geophysical/geological analysis for, not one, but several prolific petroleum reservoirs.

GEOLOGIC INTERPRETATION

The East Texas Embayment is a Mesozoic-aged depression that is bounded on all sides by major tectonic features. These features are portions of regional structural trends. To the west and north, the embayment is bordered by the Mexia-Talco Fault Zone. The Mexia-Talco system is a series of south-southeast dipping normal faults and grabens. Geologically, the project area extends from above the updip pinchout of the Jurassic Smackover Formation, through the Mexia-Talco Fault System, and downdip into the western portion of the East Texas Embayment. Within this geologic trend, wells with cumulative productions of over ten billion cubic feet of gas have been drilled.

SEEWALD ENERGY COMPANY has already completed a geologic evaluation of this area integrating the above-described exclusive aeromagnetic survey with available subsurface information. This evaluation has identified 32 prospect leads thought to represent basement-related structure. The identified leads are scattered throughout the area that has been flown and are found below, along, and above the updip limit of the Smackover Formation. Now, the integration of gravity data is to be added to this interpretation to expand its scope to include the Cotton Valley Limestone play. Delineation of geologically similar production in the Midland Basin has already proven successful by the same means.

Underlying both the Cotton Valley and Smackover Formations is an entire system of Paleozoic rocks, the Ouachita Structural Belt, about which very little is known within this area. What is known, though, is that many large structures exist in this belt which should be conducive to hydrocarbon accumulation. Potential field geophysics has been extremely useful in detecting these large Paleozoic structures to the immediate west in the Strawn Basin, and should similarly be of considerable use in the East Texas Embayment.