Horizontal permeability anisotropy can significantly affect the performance of wells stimulated with vertical hydraulic fractures in low permeability reservoirs. The purpose of this paper is to demonstrate, using simulated and actual data, the effect permeability anisotropy can have on the apparent fracture half-length calculated from well test data, on well performance, and on optimal fracture treatment design.

For example, in a well with a horizontal permeability anisotropy ratio of 20:1 and a 500 ft propped hydraulic fracture (oriented in the same direction as the largest component of horizontal permeability), the apparent fracture half-length calculated from a conventional well test would be about 240 ft. If anisotropy can be identified and quantified, this information can be used to modify the design of stimulation treatments, to compute more realistic estimates of fracture half-length and long-term well performance, and to modify development well spacing patterns.

Examples are presented using simulated and field data.

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