Identification Of Hydraulically Conductive Fractures From The Analysis Of Localized Stress Perturbations And Thermal Anomalies

A number of key questions need to be addressed before the relationship between stress and<br>fluid flow in the Earths crust can be understood. First, how is fluid flow related to the current<br>stress field in highly fractured crystalline rock? Second, is enhanced permeability and permeability<br>anisotropy principally the result of flow along joints (Mode I failure) or shear faults (Mode II<br>failure) or both? Is it possible that answer is neither - that in highly fractured crystalline rock,<br>flow is dominated by the orientation of faults and fractures introduced into the rock mass during its<br>long geologic history and the orientation of these structures bears no strong relation to the current<br>stress field?<br>It is well known that relatively few fractures in fractured rock serve to conduct fluids<br>through the rock. The use of fracture geometry to predict hydrologic flow in the crust is therefore<br>severely limited by the lack of knowledge of which fractures measured in a given survey actually<br>provide conduits for fluid flow. This study examines the relationship between in situ stress and<br>fluid flow using data from detailed analyses of wellbore breakouts and fracture geometry in<br>conjunction with precision temperature logs.