Enhanced gas recovery program. Third annual report, October 1977--September 1978
- eds.
Massive hydraulic fracture mapping field experiments continued in FY 78 with the major activity being an improvement program for the surface electrical system. The potential measurement boxes were modified to accept two different radial inputs and to be continuously calibrated. Hydraulic and explosive fracturing experiments have been conducted adjacent to an existing tunnel complex at DOE's Nevada Test Site and have been directly observed by subsequent mineback activities. Evaluation of a proppant distribution experiment has revealed a complex fracture system created in a complex geologic region with numerous faults and sharp variations in in-situ stress. Evaluation of an experiment to examine hydraulic fracture behavior at a geologic formation interface is underway. Initial mineback has revealed that a fracture initiated in an ashfall tuff formation broke upwards into an overlying welded tuff formation with significantly different properties, most notably an order of magnitude higher modulus; coring is underway to further delineate the fracture systems. The question of fracture propagation at an interface is being addressed by analytical, numerical and experimental techniques. Small volume hydraulic fracturing is being developed as a diagnostic tool to measure in-situ stresses and to evaluate expected fracture behavior. In conjunction with a nuclear containment program, it has been confirmed that confined explosive detonations produce containment cages of high residual stress around the cavity which severely inhibit the formation of radial fractures in communication with the cavity. In conjunction with a development program, it was shown that a tailored impulse from a propellant can create multiple fractures from a wellbore; twelve fractures (0.6 to 8 ft) were produced from a 20 lb propellant charge which gave pressure loading rate of 20 psi/sec and a peak pressure of 13,800 psi and no evidence of wellbore enlargement or crushing.
- Research Organization:
- Sandia Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- EY-76-C-04-0789
- OSTI ID:
- 6171480
- Report Number(s):
- SAND-79-0056
- Country of Publication:
- United States
- Language:
- English
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