Technologies and Practices for Plugging and Remediating Orphan Oil and Gas Wells (2026)
Chapter: Appendix D: Well Logging Tools
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Appendix C: Questionnaire to State and Tribal Agency Representatives
Appendix D
Suggested Citation:
"Appendix D: Well Logging Tools." National Academies of Sciences, Engineering, and Medicine. 2026. Technologies and Practices for Plugging and Remediating Orphan Oil and Gas Wells. Washington, DC: The National Academies Press.
doi: 10.17226/29343.
Appendix D
Well Logging Tools
This appendix presents a review of well logging tools, how they are used, and what they are designed to determine. It builds on information in the study’s associated white paper (Simmers et al. 2024).
- Gamma ray logging tools detect gamma rays from naturally occurring sources. This information may then be used to identify formations and possible hydrocarbon shows.
- Nuclear logging tools may be used to help identify formation density and hydrogen content. They may be useful in identifying and differentiating liquids and gases.
- Resistivity logs are primarily used to characterize fluids and formation properties. They can test orphan wells if casing has been pulled and they are run in openhole sections.
- Cement bond logs may help with the interpretation of the quality of a cement bond to the casing and/or formation, identification of cement tops, and channelization, or micro-annuli, in the cement. Various types are utilized in the field:
- Acoustic: measures the amplitude of the sonic signal, which may provide a qualitative assessment of the cement
- Variable density: measures the full wave form of the sonic signal, which may provide a more detailed analysis of the cement
- Segmented bond: more detailed than traditional logs
- Ultrasonic: uses high-frequency sound waves, which is more accurate than acoustic methods
- Temperature logs are used to identify temperature anomalies in a well.
Suggested Citation:
"Appendix D: Well Logging Tools." National Academies of Sciences, Engineering, and Medicine. 2026. Technologies and Practices for Plugging and Remediating Orphan Oil and Gas Wells. Washington, DC: The National Academies Press.
doi: 10.17226/29343.
- Noise or sonic logs are used to measure “noise” caused by the turbulent flow of fluids or gases behind casing, indicating cement issues.
- Downhole video logs are used to visually inspect the wellbore. The downhole camera is typically run on wireline or coiled tubing and can provide real-time or high-resolution stills of casing damage, obstructions, or lost tools.
Suggested Citation:
"Appendix D: Well Logging Tools." National Academies of Sciences, Engineering, and Medicine. 2026. Technologies and Practices for Plugging and Remediating Orphan Oil and Gas Wells. Washington, DC: The National Academies Press.
doi: 10.17226/29343.
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