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Volume 30 Number 6
  • E-ISSN: 1365-2478

Abstract

A

A suite of electrical, radiation, and mechanical borehole probes were run in a 76‐mm‐diameter borehole drilled to a slant depth of 380 m in leptite and granite. The hole is located in Precambrian bedrock in central Sweden where a site is dedicated to in‐situ experiments pertaining to the disposal of radioactive wastes. The challenge to borehole logging methods for such site investigations is to resolve geological features and fluid flow parameters in geological sites which are initially chosen for their homogeneity, low porosity, and minimal fracturing. The Stripa borehole is characterized by high electrical resistivity values in the 20–100 kΩm range, by acoustic velocities around 5800 m s‐1 (which is close to laboratory values on intact specimens), and by total porosity of around one volume percent. In this context, probe resolution was adequate to produce interpretable information on almost all of the logs.

Two principal rock types were encountered in the hole: granite, of quartz monzonitic composition, and leptite. The granite and leptite intercepts are subdivided into units characterized by mafic mineral content, sulfide mineral content, and electrical and radiation properties. Iron‐rich zones in the leptite are highly anomalous on the gamma‐gamma and neutron logs; thin mafic zones in the granite can also be distinguished. Occurrences of a few percent pyrite are detected by the electrical, gamma‐gamma, and neutron logs. Although overall porosity is quite low throughout the hole, analysis of the resistivity and neutron logs indicates the porosity increases by a few volume percent at fracture zones. The differential resistance and caliper probes detect borehole diameter roughness of less than 1 mm, helping to confirm acoustic waveform anomalies which are indicative of fracture zones. Compres‐sional wave transit time and shear‐wave interference patterns usually occur coincident with open fractures observed in core, the correlation being especially good at major fracture zones.

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2006-04-27
2024-04-24

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References

  1. Brace, W. F.1980, Permeability of crystalline and argillaceous rocks, International Journal of Rock Mechanics, Mineral Science and Geomechanics17, 241–251.
    [Google Scholar]
  2. Brace, W. F. and Orange, A. F.1968, Further studies of the effects of pressure on electrical resistivity of rocks, Journal of Geophysical Research73, 5407–5420.
    [Google Scholar]
  3. Brace, W. F., Orange, A. S. and Madden, T. R.1965, The effect of pressure on the electrical resistivity of water saturated crystalline rocks, Journal of Geophysical Research, 70, 5669–5678.
    [Google Scholar]
  4. Dzeban, I. P.1970, Elastic wave propagation in fractured and vuggy media, Bulletin of the Academy of Sciences of the USSR, Earth Physics, 10, 31–38.
    [Google Scholar]
  5. Fritz, P., Barker, J. F. and Gale, J. E.1979, Geochemistry and isotope hydrology of ground‐waters in the Stripa granite: results and preliminary interpretation, Lawrence Berkeley Laboratory Report LBL‐8285, SAC‐12, University of California, Berkeley .
    [Google Scholar]
  6. Glenn, W. E. and Nelson, P. H.1979, Borehole logging techniques applied to base metal ore deposits, pp. 273–294 in Geophysics and Geochemistry in the Search for Metallic Ores, ed. P. J.Hood , Geological Survey of Canada, Economic Geology Report 31, Ottawa .
    [Google Scholar]
  7. Keys, W. S. and MacCary, L. M.1971, Applications of borehole geophysics to water‐resources investigations, Chap. E1 in Techniques of Water‐Resource Investigations of the United States Geological Survey, US Geological Survey, Washington , DC .
    [Google Scholar]
  8. King, M. S., Stauffer, M. R. and Pandit, B. I.1978, Quality of rock masses by acoustic borehole logging, Proceedings of the III International Congress, IAEG, 156–164.
    [Google Scholar]
  9. Magnusson, K. and Duran, O.1978, Permeabilitetsbestämnigar och geofysik borholsmatning, KBS (Karnbransle‐Sakerhet) Teknisk rapport 61, Stockholm .
    [Google Scholar]
  10. Nelson, P. H. and Glenn, W. E.1975, Influence of bound water on the neutron log in mineralized igneous rocks, Society of Professional Well Log Analysts, 16th Annual Logging Symposium, M1–M9.
    [Google Scholar]
  11. Nelson, P. H., Rachiele, R. and Smith, A.1980, The effect of radon transport in groundwater upon gamma ray borehole logs, Lawrence Berkeley Laboratory Report LBL‐11180, SAC‐30, University of California, Berkeley .
    [Google Scholar]
  12. Nelson, P. H., Paulsson, B., Rachiele, R., Andersson, L., Schrauf, T., Hustrulid, W., Duran, O. and Magnusson, K.1979, Preliminary report on geophysical and mechanical borehole measurements at Stripa, Lawrence Berkeley Laboratory Report LBL‐8280, SAC‐16, University of California, Berkeley .
    [Google Scholar]
  13. Norton, D. and Knapp, R.1977, Transport phenomena in hydrothermal systems: The nature of porosity, American Journal of Science277, 913–936.
    [Google Scholar]
  14. Paillet, F. L.1980, Acoustic propagation in the vicinity of fractures which intersect a fluid‐filled borehole, Society of Professional Well Log Analysts, 21st Annual Logging Symposium, Houston , Texas , DD1–33.
    [Google Scholar]
  15. Paulsson, B. N. P. and King, M. S.1980, A cross‐hole investigation of a rock mass subjected to heating, in Ultrasonic and Acoustic Emission Results from the Stripa Heater Experiments, Lawrence Berkeley Laboratory Report LBL‐10975, SAC‐32, University of California, Berkeley .
    [Google Scholar]
  16. Paulsson, B. N. P., Nelson, P. H. and Kurfurst, P.1981, Characterization of discontinuities in the Stripa granite—Full scale heater experiments, Lawrence Berkeley Laboratory Report LBL‐9063, University of California, Berkeley .
    [Google Scholar]
  17. Sjögren, B., Ofsthus, A. and Sandberg, J.1979, Seismic classification of rock mass qualities, Geophysical Prospecting27, 409–442.
    [Google Scholar]
  18. Waxman, M. H. and Smits, L. J. M.1968, Electrical conductivities in oil‐bearing shaly sands, Society of Petroleum Engineers' Journal, Transactions AIME243, 107–122.
    [Google Scholar]
  19. Witherspoon, P. A., Cook, N. G. W. and Gale, J. E.1980, Progress with field investigations at Stripa, Lawrence Berkeley Laboratory Report LBL‐10559, SAC‐27, University of California, Berkeley .
    [Google Scholar]
  20. Wollenberg, H. A., Flexser, S. and Andersson, L.1980, Petrology and radiology of the Stripa pluton, Lawrence Berkeley Laboratory Report LBL‐11654, University of California, Berkeley .
    [Google Scholar]
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