ABSTRACT: Results of Horizontal Well Site Evaluations in Fractured Devonian Shale Reservoirs

Thomas H. Mroz, William A. Schuller

The U.S. Department of Energy, Morgantown Energy Technology Center, is presently active in applying horizontal drilling technology to enhance production from fractured reservoirs in the Devonian shales of the Appalachian basin, The reservoirs under study occur in the Middle Devonian sequence of black organic shales, mudstones, siltstones, and carbonates. Fracturing in the shales had developed as a result of compressional and tensional tectonic stresses and uplift with differential movement over basement faults. This complex burial and deformational history is unraveled with the development of detailed three-dimensional geologic models from geological, geophysical, geochemical, and remote sensing data.

The evaluation of four horizontal well sites in the Appalachian basin using the three-dimensional geologic models has resulted in the development of an exploration rationale for fractured reservoirs. Detailed well production and pressure data, well logs, and down-hole video were used to define enhanced fracture porosity in the shale section. Surface and subsurface geology maps, seismic sections, and geochemical surveys were integrated to develop a three-dimensional reservoir model. Remote sensing and shallow resistivity surveys were combined to map major joints and faults at surface.

The integration of the results from all of these efforts has allowed for the evaluation of each method and its effectiveness in defining enhanced fracturing at the reservoir level.

AAPG Search and Discovery Article #90998 AAPG Eastern Section Meeting, London, Ontario, Canada, September 10-12, 1990