Seismic Studies of a Massive Hydraulic Fracturing Experiment

Abstract

During a massive hydraulic fracturing experiment carried out at Fenton Hill, New Mexico, 850 microearthquake, ranging in magnitudes from -3 to 0, were located reliably using arrival times recorded at a set of 5 downhole geophone stations. A subset of these events was located using an upgraded hodogram technique. The seismicity defines a tabular zone with horizontal extent of 900 m, vertical extent of 800 m and thickness of 150 m. This zone strikes N340°E, and dips 75° to the east; its position indicates that no hydraulic connection between the two predrilled wells could be achieved by the fracturing. The distribution of locations obtained from arrival times shows good agreement with those derived from hodograms. Well constrained fault plane solutions were determined for 26 of the larger microearthquakes observed at a surface seismic net. Most solutions display one nearly vertical nodal plane that strikes close to E-W in agreement with regional indicators of the least principal stress direction.