Laboratory Geomechanical Investigation of Less Productive Mowry Shale

Hydraulic fracturing has enabled commercial production from shale reservoirs. The goal of this paper is to provide insight into the mechanical properties of Mowry shale exposed to stimulation fluid. For this study, samples were obtained from well S505 in Wyoming, with cores stored at the United States Geological Survey (USGS), at a depth of approximately 3250 meters. A total of eight specimens were prepared: four with a diameter of 12.5 mm and four with a diameter of 25 mm, with lengths twice their diameters. Specimens were aged with either brine or brine+stimulation fluid for 30 days. Triaxial compression tests were performed on the specimens at three confining pressures of 12, 26, and 40 MPa, along with a pore pressure of 9 MPa at a temperature of 96 °C. This paper discusses the stress-strain behavior of Mowry shale specimens exposed to varying effective confining pressures and treatment conditions. Selected specimens were characterized using X-ray diffraction and thermogravimetric analysis to understand the change in minerals resulting from the different treatment conditions. The results will enhance the understanding of the mechanical behavior and properties of Mowry shale, which are crucial for oil production in unconventional reservoirs.