Studies of Earth Stress and Hydraulic Fracturing with Applications in the Stimulation of Unconventional-Gas Reservoirs

摘要

Lawrence Livermore National Laboratory has a multi-year program to study the mechanics of hydraulic fracturing for enhanced gas recovery. We are also using a minifrac technique for stress measurements at coal mines in the Appalachian and Rocky Mountain regions, to be used to help design fracturing techniques to recover gas from gassy coal beds. Research to date indicates that fracture propagation is strongly influenced by existing stresses and that the stress gradient in a non-uniform stress field may stop or turn the fracture. Field evidence shows that anisotropic rock properties due to rock fabric can be a major factor in fracture geometry and in calculated stress values. 12 figures. (ERA citation 08:035098)