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ABSTRACT: Horizontal Exploitation of the Upper Cretaceous Austin Chalk of South Texas

Rick Borkowski, Linda Hand, Danny Dickerson, Shane Bird

Horizontal drilling in the fractured Austin Chalk of south Texas has proven to be a viable technology for exploiting reserve opportunities in mature trends as well as in frontier areas. To date, the results of an interdisciplinary approach to the regional analysis of structure and stress regimes combined with studies of the depositional characteristics of the Austin Chalk and Eagleford Shale have been a success. Productive characteristics of the Austin Chalk indicate the influence of regional fractures on the preferential flow direction and partitioning in the Pearsall field area of the trend.

Well bore orientation and inclination are designed such that multiple fracture swarms at several stratigraphic horizons are intersected with a single horizontal well bore. As a result of the greater frequency of fracture contacts with the well bore, there is a significant increase in the ultimate recovery of hydrocarbons in place. Conventional vertical drilling techniques are frequently ineffective at encountering these laterally partitioned fracture sets, resulting in lower volumes of recoverable hydrocarbons. Additionally, horizontal well bores may increase ultimate recovery of hydrocarbons by lowering the pressure gradient to the well bore and maximizing the reservoir energy.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990