Actions for Application of hydraulic fracturing to determine virgin in situ stress state around Waste Isolation Pilot Plant - in situ measurements

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Application of hydraulic fracturing to determine virgin in situ stress state around Waste Isolation Pilot Plant - in situ measurements

Author
Wawersik, W. R.
Published
United States : [publisher not identified], 1985
Springfield, Va.: National Technical Information Service, [approximately 1985]
Physical Description
microfiche : negative ; 11 x 15 cm
Additional Creators
Stone, C. M.

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Summary
Hydraulic fracturing tests were carried out in horizontal drillholes in rock salt in the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. It was determined that the virgin in situ stress field is isotropic or nearly isotropic. The inferred magnitude of the isotropic in situ stress falls between bounds of 14.28 MPa and 17.9 MPa for the average breakdown/reopening pressures and driving pressures. The best estimate from instantaneous shut-in pressures is 16.61 MPa. Given some uncertainties about the interpretation of hydraulic fracturing data in salt, all of the foregoing values are in acceptable agreement with an average calculated isotropic in situ stress of 14.9 MPa at an average depth of 657 m below surface. Interpretations of breakdown and reopening pressures are based on finite element analyses of the relaxed stress field around a borehole in salt. This stress field varies little between approximately 50 and 200 days after drilling. The finite element analyses were also used to interpret the observed stable pressure-time signatures with little or no pressure drops during primary breakdown of the salt formation. The conclusion about the isotropic nature of the virgin in situ stress field is supported by observations of the induced fracture patterns. The report includes a comparison of the hydrofrac data in the WIPP with the published results of hydraulic fracturing tests in salt at three other locations. 75 refs., 21 figs., 4 tabs.
Report Numbers
DE86002096; SAND-85-1776
Other Subject(s)
Collection
NTIS collection.
Note
DOE contract number: AC04-76DP00789
OSTI Identifier 5187865
Research organization: Sandia National Labs., Albuquerque, NM (USA).
View MARC record | catkey: 47359497