Microseismic data and coring studies suggest that hydraulic fractures interact heavily with natural fractures, creating complex fracture networks in naturally fractured reservoirs such as the Barnett shale, Eagle Ford shale, and Marcellus shale. Because direct observations of subsurface hydraulic-fracture geometries are incomplete or nonexistent, properly scaled experimental research and computer modeling based on realistic assumptions are used to help understand fracture-intersection geometries. Observations of cores from the Barnett and other shale plays suggest that most natural fractures are cemented. The most significant finding of this research was that fracture-intersection geometries are complex. Results showed that bypass, separation of weakly bonded interfaces, diversion, and mixed-mode propagation are likely in hydraulic-fracture intersections with cemented natural fractures.
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