Events

Speaker: Dr. James William Carey, Earth and Environmental Sciences Division, Los Alamos National Laboratory

Title of Seminar: "Fracture and Fluid Flow in Low Permeability Materials"

Abstract: Fracture permeability at subsurface conditions is poorly understood. In contrast to most idealized experiments, natural fractures are likely to be rough, non-planar and multistranded. In this study, we use a triaxial direct-shear coreflood method combined with simultaneous x-ray radiography/tomography to observe fracture formation, permeability evolution, and fracture aperture behavior as a function of stress. Our results show the impact of stress at the time of fracture formation on initial fracture permeability and subsequent reactivated fracture permeability. In some materials, we see a distinct transition from relatively permeable toimpermeable fractures as stress increases, while in others we see more gradual loss of permeability. The experiments yield distinctive, non-planar fractures with en echelon structures. We develop theory that shows why these form rather than simple planar structures and discuss the implications of these results for understanding of fracture roughness and aperture.

Biography: Dr. Carey is currently a Staff Scientist in the Environmental Sciences Division of Los Alamos National Laboratory. He is the principle investigator for Basic Energy Sciences study of fracture-permeability behavior. He is also the principle investigator for a portfolio of DOE-Fossil Energy projects in unconventional oil and gas and CO2 sequestration. Dr. Carey’s research emphasizes understanding fluid-rock interactions in geomaterials. His current work focuses on fluid-induced fracture generation, permeability and subsequent reactive chemistry as applied to unconventional oil and gas recovery (hydraulic fracturing) and CO2 sequestration (caprock integrity and wellbore integrity). Earlier work in CO2 sequestration included considerations of multiphase fluid flow and reaction in CO2-brine systems, geochemical deterioration of wellbore cement, corrosion of wellbore steel, and the reaction of CO2 with minerals. Dr. Carey earned his B.Sc. in Geology from the University of Wisconsin, his M.Sc. in Geology from the University of Oregon, and his Ph.D. in Earth Sciences from Harvard University.