This paper details the acquisition and application of laboratory rock mechanical data, in situ stress measurements, dipole sonic logs, and pre- & post-fracture well test data to characterize hydraulic fracture performance in the Ozona Canyon and Penn sands, Ozona Field, Crockett County, Texas. The in situ stress measurements (micro-fracs) showed sand stresses from 0.55 to 0. 75 psi/ft, while shale stresses ranged from 0.8 to 0.85 psi/ft. These data were used to calibrate dipole sonic logs that ultimately resulted in lithology based (gamma-ray) stress profiles for fracture modeling studies. The variations in measured sand stresses using micro-frac tests indicated the need for small-volume water mini-fracs prior to many fracture treatments to measure local sand stresses.
Excessive treating pressures (high net pressures) indicated the possibility of complex fracturing (or multiple fractures) and this interpretation was supported by the short "effective" fracture half-lengths (+/- 200 ft) calculated from subsequent fracture modeling and pre- & post-fracture well tests. The post-fracture well tests unexpectedly showed very low fracture conductivity that was also attributed to complex fracturing. The inability to significantly improve "effective" fracture length with increasing fluid & proppant volumes resulted in reduced treatment sizes (and treatment costs) and improved well economics.