In-situ stress measurement in the Carnmenellis granite. I. Overcoring tests at South Crofty mine at a depth of 790m

Journal Article · Fri Apr 01 04:00:00 EST 1983 · Int. J. Rock Mech. Min. Sci. Geomech. Abstr.; (United States)

DOI:https://doi.org/10.1016/0148-9062(83)90327-3· OSTI ID:6983592

Pine, R J; Tunbridge, L W; Kwakwa, K

A programme of overcoring rock stress measurement was conducted at South Crofty mine, Camborne, at a depth of 790m in the Carnmenellis granite to obtain information required for the Camborne School of Mines hot dry rock Geothermal Energy Research Programme at Rosemanowes quarry in Cornwall, U.K. The measurements at South Crofty were undertaken to obtain an independent confirmation of stress magnitudes measured by hydraulic fracturing at the quarry and an indication of stress directions. Before the overcoring test were undertaken, the geological and tectonic setting of the two sites were reviewed and it was concluded that the stress regimes should be similar. Both the Commonwealth Scientific and Industrial Research Organization (CSIRO) of Australia and the United States Bureau of Mines (USBM) designed overcoring systems were used, with a loca contractor providing the drilling services. A total of six CSIRO and seven USBM tests were successfully completed in two separate nearly horizontal boreholes with a 100/sup 0/ azimuth difference. Agreement between the CSIRO tests and the USBM tests was good. It is considered that the significant stress anisotropy must be due to the tectonic forces of the Alpine orogeny, and it is likely that the principal stress directions are similar at Rosemanowes and South Crofty.

• Research Organization: Golder Associates, Maidenhead, England
• OSTI ID: 6983592
• Journal Information: Int. J. Rock Mech. Min. Sci. Geomech. Abstr.; (United States), Journal Name: Int. J. Rock Mech. Min. Sci. Geomech. Abstr.; (United States) Vol. 20:2; ISSN IRMGB
• Country of Publication: United States
• Language: English

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ANISOTROPY
AUSTRALASIA
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COMPARATIVE EVALUATIONS
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DIRECTIONAL DRILLING
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