Evaluating pressure and temperature effects on permeability and elastic properties of wolfcamp formation - an experimental study

Changes in in-situ stress and/or temperature of the unconventional reservoirs, which occur during production and stimulation stages, alter their permeability and elastic properties. In this study, effects of confining pressure and temperature on permeability and other properties (Young's modulus, Poisson's ratio, brittleness, and bulk compressibility) of outcrop and downhole core samples from Wolfcamp reservoir were investigated. The permeability of the core samples was measured at a constant confining pressure of 5.17 MPa and five different temperatures (20°C to 100°C with an increment of 20°C) using the complex transient method. Additionally, the ultrasonic velocities of the core samples were measured at five different confining pressures (7 to 34 MPa with an increment of 7 MPa) and temperatures (20°C, 40°C, 60°C, 80°C, and 100°C). The results revealed that increasing the confining pressure resulted in increase in the elastic properties of the core samples and decrease in their permeability and bulk compressibility. Whilst, increasing the temperature caused increase in the ductility of the core samples and decrease in their permeability. The results also demonstrated that the elastic properties of the downhole core samples were more significantly affected by temperature than the outcrop core samples.