Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Chapter 1 Introductory observations
- Chapter 2 Gravity surveying
- Chapter 3 Magnetic surveying
- Chapter 4 Seismic surveys
- Chapter 5 Self-potential surveying
- Chapter 6 Resistivity and induced polarization surveys
- Chapter 7 Electromagnetic surveys
- Chapter 8 Ground-probing radar
- Chapter 9 Radioactivity surveys
- Chapter 10 Geothermal surveying
- Chapter 11 Geophysical borehole logging
- Chapter 12 Inversion theory and tomography
- Appendix A Analytical continuation of potential fields
- Appendix B Gravity and magnetic attraction of finite vertical or horizontal cylinder
- Appendix C Magnetic anomaly of a right rectangular prism with an arbitrary direction of magnetization vector
- Appendix D Fourier series, transforms, and convolution
- Appendix E Poynting vector resistivity and the Bostick inversion
- Index
Chapter 11 - Geophysical borehole logging
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Chapter 1 Introductory observations
- Chapter 2 Gravity surveying
- Chapter 3 Magnetic surveying
- Chapter 4 Seismic surveys
- Chapter 5 Self-potential surveying
- Chapter 6 Resistivity and induced polarization surveys
- Chapter 7 Electromagnetic surveys
- Chapter 8 Ground-probing radar
- Chapter 9 Radioactivity surveys
- Chapter 10 Geothermal surveying
- Chapter 11 Geophysical borehole logging
- Chapter 12 Inversion theory and tomography
- Appendix A Analytical continuation of potential fields
- Appendix B Gravity and magnetic attraction of finite vertical or horizontal cylinder
- Appendix C Magnetic anomaly of a right rectangular prism with an arbitrary direction of magnetization vector
- Appendix D Fourier series, transforms, and convolution
- Appendix E Poynting vector resistivity and the Bostick inversion
- Index
Summary
Introduction
Geophysical borehole logging involves measuring the physical properties of surrounding rocks with a sensor located in a borehole. The record of measurements as a function of depth is called a borehole log (or well log). Many of the methods of geophysical surveying (described in previous chapters), with some modifications, can be adapted for use in borehole logging. Downhole geophysical measurements greatly increase the value of the hole to the interpreter by their ability to provide more direct information about formation thickness and lithology, dip of strata, porosity, formation fluid content, permeability, and temperature. In addition, they provide a means of correlating geological formations from one borehole to another. Geophysical logging techniques have been widely used in the investigation of wells drilled for hydrocarbon exploration, as they provide important in-situ properties of possible reservoir rocks.
This chapter focusses on the application of geophysical logging techniques that are of special relevance to environmental investigations. These are related mainly to the current and future stability of the site and the possible migration of contaminants in the groundwater. In particular, environmental impact studies at proposed landfill sites and potential nuclear waste repositories have concentrated much attention on detecting fractures as possible conduits for rapid transport of toxic chemicals. Conventional logging techniques (such as those used in exploratory wells for oil/gas and water) can be applied to define the hydrogeological regime at hazardous waste sites, but special interpretation procedures must be applied in those areas where the logging zone of interest is above the water table, or where the rock has an extremely low permeability.
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- Environmental and Engineering Geophysics , pp. 375 - 399Publisher: Cambridge University PressPrint publication year: 1997
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