Does Hydraulic Fracturing Theory Work in Jointed Rock Masses?
- Key words
- Hot Dry Rock; USA; New Mexico; Hydraulic; Fracture; Homogeneous; Heterogeneous; Microearthquakes; Pore Pressure; Permeation
- Conference
- Geothermal Resources Council Transactions
- Year
- 1983
- Session
- HDR/EGS; Hydraulic fracturing; Microseismicity; Fractures
- Language
- English
Abstract
The hypocenter location of microearthquakes (acoustic emissions) generated during fracturing typically are distributed three dimensionally suggesting that fracturing stimulates a volumetric region, rather than the planar fracture theoretically, expected. In this paper the hypocenter maps generated at six operating, or potential, HDR reservoirs in the U.S., Europe and Japan are examined in detail and the fracture dimensions are correlated with fracture injection volumes and formation permeability. Despite the volumetric appearance of the maps we infer that the induced fractures are mainly planar and may propagate a seismically. The induced seismicity stems from nearby joints which are not opened significantly by fracturing, but are caused to shear slip because of local pore pressure.
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