The hydraulic fracturing technique is an important method for enhancing hydrocarbon recovery, geothermal energy extraction, and solid waste disposal. Determination of the geometry and growth process of a hydraulic fracture zone is important for monitoring and assessing subsurface fractures. A relative‐source‐location approach, based on a waveform correlation and a grid search method, has been developed to estimate relative hypocenter locations for a cluster of 157 microearthquakes induced by hydraulic fracturing at the Los Alamos Hot Dry Rock (HDR) geothermal site. Among the 157 events, 147 microearthquakes occurred in a tight cluster with a dimension of 40 m, roughly defining a vertical hydraulic fracture zone with an orientation of N40°W. The length, height, and width of the hydraulic fracture zone are estimated to be 40, 35, and 5 m, respectively. Analysis of the spatial‐temporal pattern of the induced microearthquakes reveals that the fracture zone grew significantly, averaging 0.2 m/minute in a two‐hour period toward the northwest along the fracture zone strike.
Natural gas massive hydraulic fracture research and advanced technology project. Quarterly report, August 1976--October 1976. [Fracture orientation determination]