Case Histories of an Electromagnetic Method for Petroleum Exploration

The results of a five-year feasibility study of the utility of electrical measurements in petroleum exploration are very encouraging. Electrical anomalies were measured over 66% of the 29 oil and gas fields involved in the study. The fact that these fields represent both stratigraphic and structural traps at a wide range of depths, with varying production characteristics, and in diverse geologic environments, provides a particularly favorable indication that this technique can be used as a reliable exploration tool, complementing existing seismic and subsurface geology programs.

Case histories of five field projects are presented in this volume in order to illustrate both the advantages and limitations of the method in the context of known geology. The field projects involve a variety of field characteristics. The results delineate the following general observations: 1) repeatable anomalies can be measured over oil and gas fields; 2) two types of anomalies are measured-an electrically conductive "deep anomaly," and a polarizable "shallow anomaly;" 3) the anomalies correlate relatively well in plan view with the limits of hydrocarbon production; 4) the anomalies are partly dependent on specific geologic characteristics of the stratigraphic sequence.

As is the case in seismic interpretations, data processing techniques are crucially important in extracting the maximum of information from electrical data. Proprietary data processing techniques have been developed for this purpose. Great care must be taken during interpretation to evaluate effects of pipelines, well casings, topography, and subsurface geology, since many of these effects may result in spurious anomalies unrelated to alteration due to hydrocarbons. The case histories demonstrate the necessity for this type of evaluation.

Table of Contents, list of PDF files:

IP-Petro_1.pdf

• PART ONE: SUMMARIES
  • Executive Summary
  • Summary and Conclusions

• PART TWO: DATA INTERPRETATION
  • 1. Introduction to the Data
    • 1.1 Introduction
    • 1.2 Definitions and Plotting Conventions
    • 1.3 Electrical Noise
    • 1.4 Instrumentation
    • 1.5 Resistivity/Phase Data Acquisition and Field Logistics
    • 1.6 Harmonic Complex Resistivity Data Acquisition and Field Logistics
    • 1.7 Controlled Source AMT Data Acquisition and Field Logistics
    • 1.8 Data Processing Techniques, Resistivity/Phase and Complex Resistivity Data
    • 1.9 Parameters Used in Resistivity/Phase and Complex Resistivity Interpretation
    • References
  • 2. Interpreting Hydrocarbon Anomalies
    • 2.1 Introduction
    • 2.2 Statistical Analysis of Zonge Engineering Hydrocarbon Surveys, 1977 - 1982
    • 2.3 The Direct Detection of Hydrocarbons
    • 2.4 The Origin of Electrical Anomalies over Hydrocarbons
    • 2.5 Well-Casing Effects
    • 2.6 Surface Culture Effects
    • 2.7 Topographic Effects
    • 2.8 Subsurface Geologic Effects
    • 2.9 Anomalies Due to Hydrocarbon Alteration - What to Look For
    • References

• PART THREE: CASE HISTORIES
  • 3. Ryckman Creek and Whitney Canyon Fields, Uinta County, Wyoming
    • 3.1 Introduction
    • 3.2 Geologic Background
    • 3.3 Detailed Discussion of the Data
    • 3.4 Summary and Conclusions
    • References

• PART THREE: (continued)
  • 4. Desert Springs, Playa-Lewis, and Desert Springs West Fields, Sweetwater County, Wyoming
    • 4.1 Introduction
    • 4.2 Geologic Background
    • 4.3 Detailed Discussion of the Data
    • 4.4 Summary and Conclusions
    • References

• PART THREE: (continued)
  • 5. Little Buck Creek Field, Niobrara County, Wyoming
    • 5.1 Introduction
    • 5.2 Geologic Background
    • 5.3 Detailed Discussion of the Data
    • 5.4 Summary and Conclusions
    • References

• PART THREE: (continued)
  • 6. Lisbon Field, San Juan County, Utah
    • 6.1 Introduction
    • 6.2 Geologic Background
    • 6.3 Detailed Discussion of the Data
    • 6.4 Summary and Conclusions
    • References

• PART THREE: (continued)
  • 7. Trap Spring Field, Nye County, Nevada
    • 7.1 Introduction
    • 7.2 Geologic Background
    • 7.3 Detailed Discussion of the Data
    • 7.4 Summary and Conclusions
    • References

• PART FOUR: ADDITIONAL INFORMATION
  • 8. Mechanisms of Current Flow in the Earth
    • 8.1 Introduction
    • 8.2 Physical Mechanisms of Galvanic Current Flow
    • 8.3 The Origin of Inductive Coupling
    • References
  • 9. Principles of Electromagnetic Theory as Applied to Petroleum Exploration
    • 9.1 Introduction
    • 9.2 Maxwell's Equations
    • 9.3 Development of the Vector Wave Equation
    • 9.4 Boundary Conditions
    • 9.5 DC Solutions to the Vector Wave Equation
    • 9.6 AC Solutions to the Vector Wave Equation
    • 9.7 Complex Impedance of the Electric Field
    • References

• PART FOUR: (continued)
  • 10. A Short History of Electrical Techniques in Petroleum Exploration
    • 10.1 Introduction
    • 10.2 The Early Years: 1900 - 1940
    • 10.3 Continued Development: 1940 - 1960
    • 10.4 Recent Electrical Work
    • 10.5 Into the Future
    • References