USGS

APPLICATION OF BOREHOLE GEOPHYSICS TO WATER-RESOURCES INVESTIGATIONS

U.S. Geological Survey, Techniques of Water-Resources Investigations Book 2, Chapter E1

By W. Scott Keys and L. M. MacCary

Abstract

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This manual is intended to be a guide for hydrologists using borehole geophysics in ground-water studies. The emphasis is on the application and interpretation of geophysical well logs, and not on the operation of a logger. It describes in detail those logging techniques that have been utilized within the Water Resources Division of the U.S. Geological Survey, and those used in petroleum investigations that have potential application to hydrologic problems. Most of the logs described can be made by commercial logging service companies, and many can be made with small water-well loggers. The general principles of each technique and the rules of log interpretation are the same, regardless of differences in instrumentation. Geophysical well logs can be interpreted to determine the lithology, geometry, resistivity, formation factor, bulk density, porosity, permeability, moisture content, and specific yield of water-bearing rocks, and to define the source, movement, and chemical and physical characteristics of ground water. Numerous examples of logs are used to illustrate applications and interpretation in various ground-water environments. The interrelations between various types of logs are emphasized, and the following aspects are described for each of the important logging techniques: Principles and applications, instrumentation, calibration and standardization, radius of investigation, and extraneous effects.

 

Table of Contents

Preface

Glossary

Abstract

Introduction

Background.

Purpose and scope

Why log?

Limitations

Lithologic parameters

Resistivity

Formation factor

Permeability.

Porosity

Specific yield

Grain size

Fluid parameters

Fluid conductivity

Fluid temperature

Fluid movement

Moisture content

Log interpretation

Qualitative interpretation

Quantitative interpretation

Log calibration

Standardization and log accuracy.

Composite interpretation

Geometric effects

Radius of investigation

Bed-thickness effects

Borehole effects

Hole-diameter effects

Casing effects

Drilling effects

Logging equipment

Spontaneous-potential logging

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

Resistance logging

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

Resistivity logging

Normal devices

Principles and applications

Instrumentation

Calibration and standardization

Bed-thickness effects

Lateral devices

Principles and applications

Instrumentation

Bed-thickness effects

Wall-resistivity devices

Focused devices

Induction device

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

Nuclear logging

Fundamentals of nuclear geophysics

Characteristics of radiation

Radiation statistics

Radiation detection

Quantitative interpretation

Natural-gamma logging

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

Gamma spectrometry

Gamma-gamma logging

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

Neutron logging

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

The use of radioisotopes in well logging

Acoustic logging

Principles and applications

Continued Instrumentation

Calibration and standardization

Radius of investigation

Extraneous effects

Caliper logging

Principles and applications

Instrumentation

Calibration and standardization

Radius of investigation and extraneous effects

Temperature logging

Principles and applications

Instrumentation

Calibration and extraneous effects

Fluid-conductivity_logging

Principles and applications

Instrumentation

Calibration and extraneous effects

Fluid-movement logging

Principles and applications

Instrumentation

Calibration and extraneous effects

Casing logs

Selected references

Index

 


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Last modified: Thursday, September 01 2005, 03:31:55 PM
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