This paper presents an overall summary of the in-situ stress data obtained through the Gas Research Institute (GRI) Tight Gas Sands Research Program. Data of this type can be invaluable to anyone designing a hydraulic fracture treatment in a complex, multi-layered reservoir. Correlations are presented that allow the in-situ stress gradient to be calculated from openhole log data as a function of reservoir pressure.

Results from thirty-four (34) stress tests in five wells in the Travis Peak formation of east Texas are presented. Twenty of these tests were conducted as part of the 1986 GRI Staged Field Experiment in the Waskom (Travis Peak) Field in Harrison County, Texas. The primary purpose of these tests was to determine the in-situ stresses of the various lithologies in this multi-layered, complex reservoir. Knowledge of the vertical stress profile can help to make estimates of vertical fracture growth as a function of excess pressure in the fracture.

Formation pressures were obtained in many zones with either wireline formation testers or pressure buildup tests. These estimates of reservoir pressure were then correlated with the actual measured values of in-situ stress to determine the effects of pressure depletion on the in-situ stress. Calculated values of in-situ stress from logs were calibrated using the measured values of reservoir pressure and in-situ stress.

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