Stimulation and Mineback Experiment Project. The direct observation of hydraulic and explosive fracturing tests
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 through the experimental area. A proppant distribution fracture experiment revealed a very complex fracture system. Observed fracture lengths were only 5 and 25 ft at the depth of the fracture interval and these differ significantly from the design lengths of 175 ft. The fracture interacted with numerous geologic faults, fractures, and bedding and parting planes. Variations of the in situ stresses and orientations were found in subsequent testing in this experiment region. An experiment was designed and conducted which examined the behavior of hydraulic fractures at an interface between an ashfall tuff and a welded tuff formation interface. These formations have significant differences in their elastic moduli (0.24 x 10/sup 6/ and 3.8 x 10/sup 6/ psi), Poisson's ratios (0.312 and 0.238) and porosities (45 and 13%). One fracture has been located via exploratory coring and mineback along the fracture is under way. In conjunction with a nuclear containment program, the residual stress effects around a contained explosive detonation have been studied. Mineback through a region surrounding a 256 lb TNT detonation indicated that no radial fractures extended from the main cavity. The use of small volume (<50 gal) hydraulic fractures in tunnel boreholes has been evaluated for determining in situ stresses and orientations in conjunction with this project.
- Research Organization:
- Sandia Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- EY-76-C-04-0789
- OSTI ID:
- 6704806
- Report Number(s):
- SAND-78-0682C; CONF-780825-2
- Country of Publication:
- United States
- Language:
- English
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