Zhi Ye, Mewbourne School of Petroleum and Geological Engineering, The University of Oklahoma
What to Expect
Shear reactivation of faults/fractures caused by pressurized fluid injection is quite important in many subsurface engineering problems and geological phenomena, such as reservoir stimulation, wastewater disposal, geologic carbon storage, and induced seismicity. Specifically, inducing fracture self-propping by slip has been viewed as an effective means of permeability enhancement in the development of subsurface energy, which has led to the concept of shear stimulation or hydroshearing. However, there are some concerns on an increase in seismic hazard triggered by fracture slip. Although fracture slip and seismicity caused by fluid injection are routinely studied by theoretical and numerical models, the fundamental investigations through laboratory tests and field measurements have been limited. In this study, laboratory injection experiments were conducted to probe the physical mechanisms governing permeability evolution and seismic response during fracture slip by injection. The results demonstrate that fracture slip and mixed-mode fracture propagation are two important and often integral mechanisms of permeability enhancement within shear stimulation. Moreover, the experimental results indicate a sequence of aseismic-seismic-aseismic deformation during fracture reactivation by injection. It is observed that the aseismic-seismic transition was accompanied by the changes of slip velocity, fluid flow, and fault constitutive behavior (slip weakening vs. slip strengthening). A strong slip heterogeneity was noticed in the shear experiments, indicated by a spatially heterogeneous distribution of AE(acoustic emission) hypocenters. Consideration of the fracture surface topography revealed a direct link between slip heterogeneity and fracture surface roughness.
Zhi Ye is a rock mechanics experimentalist, and currently a Postdoctoral Research Associate at The University of Oklahoma after earning his PhD degree in Petroleum and Geological Engineering from the same university. His research is on rock mechanics and geomechanics with applications to subsurface energy recovery, induced seismicity, and fluid flow in fractured reservoirs. Specifically, his current research focuses on exploring the deformation, failure, friction, permeability, and seismic response of natural or man-made rock fractures during pressurized fluid injection under high pressure and high temperature condition. He has over 6 years’ research experience in rock mechanics laboratory. He is the winner of the 2019 Rock Mechanics Research Award from the American Rock Mechanics Association (ARMA). He has authored/co-authored more than 30 referred journal and conference papers.