Back

Hosung Shin

Hosung Shin

University of Ulsan, South Korea

Title: Hydraulic fracturing in soils with immiscible and miscible fluids

Biography

Hosung Shin has his expertise in development of numerical simulators. He has developed multi-dimensional FEM simulator Geo-COS (Geo-Coupled Simulator) specifically developed to investigate coupled phenomena in porous media and jointed rock-mass subjected to multi-phase flow.

Abstract

Fluid-driven hydraulic fracturing in soils has been explained either as tensile failure or shear failure. It is in part due to similar fracture pattern and simple explanation from fracture mechanics on solid materials. However, these hypotheses contradict the inherent effective stress frictional behavior of soils and fail to justify experimental observations. In this study, experiments, particle-scale analyses and macro-scale simulation provide unprecedented insight into hydraulic fracture initiation and growth in granular materials. Distinct particle-level analysis develops whether the invading fluid is miscible or immiscible with the host fluid. The miscibility of the invading fluid with the host fluid leads distinct localization processes that depend on the balance between particlelevel skeletal forces (effective stress-dependent), capillary forces (the invasion of the interfacial membrane when immiscible fluids are involved) and seepage drag forces (associated with fluid flow velocity). Positive feedback mechanisms at defects on the soil surface and fracture tips that promote fracture initiation and sustain fracture propagation. These include increased porosity at the tip due to strains preferentially normal to the fracture alignment, either eased membrane invasion (immiscible fluids) or higher hydraulic conductivity (miscible fluids) and the emergence of particle-level forces that promote opening-mode particle displacement. This effective stress compatible sequence of events helps identify the parameters that govern fluid-driven fracture formation in soils, and explain experimental observations.