Shale Gas Geomechanics and Insights into Hydraulic Fracturing Stimulation

Geomechanical characterization of shale gas reservoirs is a key factor for understanding the mechanical behavior of the shale strata and to help predict reactions to hydraulic fracturing stimulation (HF) at a large scale. Small-scale geomechanical data provide the first-order information for establishing a large-scale robust geomechanical model which can guide stress-strain analysis of fracturing processes. Because of issues such as stress-shadowing (changes in fracture orientation in later stages because of induced stress change), stress-strain analysis can improve interpretation of microseismic information and lead to more reliable HF design. We summarize briefly some of the major components of a scientific geomechanical characterization approach including the determination of various mechanical properties of the reservoir rock, the estimation of in-situ stresses, the evaluation of the role of natural fractures and discontinuities, the investigation of the shear dilation mechanism, and so on. Also, the roles of these properties in affecting HF processes and the related mechanisms are discussed and placed in a Geological Sciences context.