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Special Issue of Journal of Applied Geophysics “Non-Petroleum Applications of Borehole Geophysics”
Journal of Applied Geophysics 55 (2004) 1 – 2 www.elsevier.com/locate/jappgeo
Preface
Special Issue of Journal of Applied Geophysics ‘‘Non-Petroleum Applications of Borehole Geophysics’’ Equipment and data analysis techniques for the geophysical investigation of geological strata adjacent to boreholes have evolved over many decades, primarily in the search for petroleum. For much of this period, these existing techniques commonly known as ‘‘well logging’’ or ‘‘formation analysis’’ in the petroleum exploration literature were also applied to non-petroleum objectives by adapting them to the specialized environments of shallow, small-diameter boreholes common in other disciplines such as hydrogeology and mineral exploration. However, today, we see the appearance of fully digital downhole geophysical sensors and the capability of signal processing with microprocessors. This has largely freed geotechnical applications of borehole geophysics from the restriction of adapting measurement techniques developed in the petroleum industry. This special issue of the Journal of Applied Geophysics devoted to Non-Petroleum Applications of Boreholes Geophysics was undertaken in an effort to explore the new directions and new data processing potential of borehole geophysical measurements in such fields as hydrogeology, civil engineering, mining and environmental remediation. Probably the single most important rationale for bringing these diverse applications of borehole geophysics together in one volume is the recognition of the potential for technology transfer. For example, recent advances in ground water exploration may be applicable to mine engineering and environmental site characterization. Specialists in these fields do not often attend each other’s conferences or read each other’s journals but the many common aspects of borehole geophysics indicate that new techniques in one of these fields may find useful application in 0926-9851/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jappgeo.2003.06.002
some of the others. There are also completely new and unique technologies being developed for geotechnical applications that are distinctly different from those used in petroleum environments. These include high-resolution borehole flow logging, optical imaging in clear fluids or air, and mineralogical analysis in igneous (crystalline) rock environments. The new technological developments will provide even more opportunities for ‘‘cross-fertilization’’ between various non-petroleum applications of borehole geophysics. Another important aspect of recently developed equipment and data analysis techniques is the ability to control the volume of investigation. The nearsurface or shallow (with respect to mine drifts and shafts) environments of geotechnical geophysics can now be investigated from both the borehole and the surface region. The once clearly defined boundary between conventional well logging and surface geophysical sounding no longer exists. The sophisticated digital electronics of modern geophysical equipment and the advances in digital signal transmission present a wealth of options for the number and geometric configuration of downhole sensors, blurring the distinction between surface, borehole and cross-borehole geophysics. Borehole geophysics thus introduces the ability to extend surface geophysical sounding methods into the subsurface, reducing the effects of surface weathering on geophysical signal penetration. Borehole geophysics likewise provides the option of calibrating surface soundings using the correlation of borehole geophysical logs and mechanical or geochemical analyses of core samples. The 10 papers in this Special Issue of the Journal of Applied Geophysics provide excellent examples of
2
Preface
the various new directions in the application of borehole geophysics to non-petroleum subjects. These include reviews of the latest signal processing techniques for digital borehole image logs (Williams and Johnson; Deltombe and Schepers) and detailed case studies of the calibration of geophysical logs in mining applications (Mwenifumbo et al.; Fullager et al.). Cunningham and Cunningham et al. describe some of the specific applications of image and borehole radar logs in hydrogeology. Clark et al. present a thorough review of borehole geophysics applied to igneous basalt aquifers. Koizumi describes new results in the theory and practice of nuclear log interpretation. Serzu et al. review the results of borehole directional radar methods applied to hydrogeology and engineering studies in a mine environment. Paillet discusses the technical problems associated
with using high-resolution borehole flow measurements to relate geophysical properties to hydrogeology in situ. Together, these papers provide an instructive introduction to the current range and potential of non-petroleum applications of borehole geophysics. Frederick Paillet University of Maine, Orono, ME, USA Patrick Killeen Geological Survey of Canada, Ottawa, Ontario, Canada George Reeves University of Newcastle upon Tyne, Newcastle upon Tyne, UK
Preface
Special Issue of Journal of Applied Geophysics ‘‘Non-Petroleum Applications of Borehole Geophysics’’ Equipment and data analysis techniques for the geophysical investigation of geological strata adjacent to boreholes have evolved over many decades, primarily in the search for petroleum. For much of this period, these existing techniques commonly known as ‘‘well logging’’ or ‘‘formation analysis’’ in the petroleum exploration literature were also applied to non-petroleum objectives by adapting them to the specialized environments of shallow, small-diameter boreholes common in other disciplines such as hydrogeology and mineral exploration. However, today, we see the appearance of fully digital downhole geophysical sensors and the capability of signal processing with microprocessors. This has largely freed geotechnical applications of borehole geophysics from the restriction of adapting measurement techniques developed in the petroleum industry. This special issue of the Journal of Applied Geophysics devoted to Non-Petroleum Applications of Boreholes Geophysics was undertaken in an effort to explore the new directions and new data processing potential of borehole geophysical measurements in such fields as hydrogeology, civil engineering, mining and environmental remediation. Probably the single most important rationale for bringing these diverse applications of borehole geophysics together in one volume is the recognition of the potential for technology transfer. For example, recent advances in ground water exploration may be applicable to mine engineering and environmental site characterization. Specialists in these fields do not often attend each other’s conferences or read each other’s journals but the many common aspects of borehole geophysics indicate that new techniques in one of these fields may find useful application in 0926-9851/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jappgeo.2003.06.002
some of the others. There are also completely new and unique technologies being developed for geotechnical applications that are distinctly different from those used in petroleum environments. These include high-resolution borehole flow logging, optical imaging in clear fluids or air, and mineralogical analysis in igneous (crystalline) rock environments. The new technological developments will provide even more opportunities for ‘‘cross-fertilization’’ between various non-petroleum applications of borehole geophysics. Another important aspect of recently developed equipment and data analysis techniques is the ability to control the volume of investigation. The nearsurface or shallow (with respect to mine drifts and shafts) environments of geotechnical geophysics can now be investigated from both the borehole and the surface region. The once clearly defined boundary between conventional well logging and surface geophysical sounding no longer exists. The sophisticated digital electronics of modern geophysical equipment and the advances in digital signal transmission present a wealth of options for the number and geometric configuration of downhole sensors, blurring the distinction between surface, borehole and cross-borehole geophysics. Borehole geophysics thus introduces the ability to extend surface geophysical sounding methods into the subsurface, reducing the effects of surface weathering on geophysical signal penetration. Borehole geophysics likewise provides the option of calibrating surface soundings using the correlation of borehole geophysical logs and mechanical or geochemical analyses of core samples. The 10 papers in this Special Issue of the Journal of Applied Geophysics provide excellent examples of
2
Preface
the various new directions in the application of borehole geophysics to non-petroleum subjects. These include reviews of the latest signal processing techniques for digital borehole image logs (Williams and Johnson; Deltombe and Schepers) and detailed case studies of the calibration of geophysical logs in mining applications (Mwenifumbo et al.; Fullager et al.). Cunningham and Cunningham et al. describe some of the specific applications of image and borehole radar logs in hydrogeology. Clark et al. present a thorough review of borehole geophysics applied to igneous basalt aquifers. Koizumi describes new results in the theory and practice of nuclear log interpretation. Serzu et al. review the results of borehole directional radar methods applied to hydrogeology and engineering studies in a mine environment. Paillet discusses the technical problems associated
with using high-resolution borehole flow measurements to relate geophysical properties to hydrogeology in situ. Together, these papers provide an instructive introduction to the current range and potential of non-petroleum applications of borehole geophysics. Frederick Paillet University of Maine, Orono, ME, USA Patrick Killeen Geological Survey of Canada, Ottawa, Ontario, Canada George Reeves University of Newcastle upon Tyne, Newcastle upon Tyne, UK