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Hydraulic fracturing to determine the regional in situ stress field, Piceance Basin, Colorado

Journal Article · · Geol. Soc. Am., Bull.; (United States)
Using specially designed equipment, the state of stress was determined on a regional scale in the Piceance Oil Shale Basin of NW. Colorado. Seven oil-shale test holes scattered throughout the Piceance Basin were logged with an acoustic borehole televiewer to select unfractured solution-free intervals. Fracture-free intervals, ranging in depth from 60 to 460 m, were isolated between packers and hydraulicaly fractured. Induced fractures were propped with ground lucite and relogged with the televiewer to determine their strike and dip. These data, combined with pressure measurements made during the fracturing experiments, were used to compute the orientation and magnitude of the stress tensor. Field observations showed that in a tectonically relaxed area, vertical fractures can be induced at hydraulic pressures as low as 0.6 of the overburden stress. Below a depth of 120 m, the induced fractures were approx. vertical, with a prominent strike of N70/sup 0/W. (18 refs.)
Research Organization:
Geological Survey
OSTI ID:
6553037
Journal Information:
Geol. Soc. Am., Bull.; (United States), Journal Name: Geol. Soc. Am., Bull.; (United States) Vol. 87:2; ISSN BUGMA
Country of Publication:
United States
Language:
English