Laboratory study of hydraulic fracturing behavior in unconsolidated sands for methane hydrate production

Methane hydrates (MH) is expected to be a huge source of energy. However, for commercial gas production from MH reservoir, new technology should be developed. Potential scheme for gas production from MH reservoirs is considered to achieve three objectives, i.e., to bring the pressure and temperature conditions around hydrate particles outside the hydrate-stability zone, to sustain the energy required for the endothermic reaction, and to provide a means to transfer the products of dissociation to production wells. Hydraulic fracturing technique is applied to induce large fractures artificially in strata and it can be applied now even if the targeted strata are located below seafloor. Hydraulic fracturing behavior in sand and mud layers was studied using silica sand mixing kaolinite flour as a particulate material to form matrix of specimens. Water was diffused uniformly into the mixture as its water weight content to be 10 Wet kaolinite flour were prepared with water weight content of 10 % so as to form mud layers of specimens. The phenomena caused by injecting fluid inside of the specimen subjected to triaxial compressive stresses were examined. The fluid injection induced a fracture-like structure at the interface between sand and mud layers and the fracture-like structure contributed to drive the invasion of fracturing fluid along the interface. This is an abstract of a paper presented at the Offshore Technology Conference - "Waves of Change" (Houston, TX 5/5-8/2008).