Technologies and Practices
for Plugging and Remediating
Orphan Oil and Gas Wells

_______

Committee on Technologies and Practices
for Plugging and Remediating Orphaned
and Abandoned Oil and Gas Wells

Earth Systems and Resources Program
Area

Center for Health, People, and Places

Physical Sciences, Systems,
and Infrastructure Program Area

Center for Advancing Science and
Technology

Consensus Study Report

NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001

This study was supported by contract #140D0423C0125 between the National Academy of Sciences and the U.S. Department of the Interior Orphaned Wells Program Office. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.

International Standard Book Number-13: 978-0-309-60276-1
Library of Congress Control Number: 2026945816
Digital Object Identifier: https://doi.org/10.17226/29343

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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2026. Technologies and Practices for Plugging and Remediating Orphan Oil and Gas Wells. Washington, DC: National Academies Press. https://doi.org/10.17226/29343.

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COMMITTEE ON TECHNOLOGIES AND PRACTICES FOR PLUGGING AND REMEDIATING ORPHANED AND ABANDONED OIL AND GAS WELLS

MARY H. FEELEY (Co-Chair), ExxonMobil Exploration Company (retired)

JAMES A. SLUTZ (Co-Chair), National Petroleum Council

JAMES L. BOLANDER, JR., JLB Engineering, LLC

WALTER S. GUIDROZ, U.S. Geological Survey (emeritus)

MARY KANG, McGill University

THOMAS A. KROPATSCH, Wyoming Oil and Gas Conservation Commission

GEOFFREY M. LANDRY, SLB

D. NATHAN MEEHAN, Texas A&M University

ADAM S. PELTZ, Environmental Defense Fund

DAVID M. PERRIN, Chevron U.S.A. Inc.

MILEVA RADONJIC, Oklahoma State University (resigned from committee October 2025)

EILIS J. ROSENBAUM, Department of Energy National Energy Technology Laboratory

Study Staff

NOEL WALTERS, Study Director, Earth Systems and Resources Program Area

CAMERON OSKVIG, Director, Physical Sciences, Systems, and Infrastructure Program Area (until October 2025)

DEBORAH GLICKSON, Senior Program Director, Earth Systems and Resources Program Area

SAMUEL KRAFT, Senior Program Assistant, Earth Systems and Resources Program Area

STACEY GIROUX, Senior Program Officer, Earth Systems and Resources Program Area (from October 2025)

Reviewers

This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.

We thank the following individuals for their review of this report:

SCOTT ANDERSON, Oxy

KENNETH E. ARNOLD, K Arnold Consulting, Inc.

TRAVIS BAER, Railroad Commission of Texas

SUSAN L. BRANTLEY, Pennsylvania State University

JESSE FREDERICK, WZI Inc.

NICK GIANOUTSOS, U.S. Geological Survey

MIKE HICKEY, Colorado Energy and Carbon Management Commission

DREW HUNGER, Seashore Petroleum, LLC

GREG LACKEY, National Energy Technology Laboratory

SUSAN NASH, American Association of Petroleum Geologists

LUKE PLANTS, Plants & Goodwin

DAVID B. SPEARS, Virginia Department of Mines, Minerals, and Energy (retired)

HARI VISWANATHAN, Los Alamos National Laboratory

Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of

this report, nor did they see the final draft before its release. The review of this report was overseen by DAVID ALLEN, University of Texas at Austin, and CHRISTINE EHLIG-ECONOMIDES, University of Houston. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.

Contents

PREFACE

SUMMARY

States Are Central to the Solution

Verifying Barriers

Continued Efforts and Funding Support

Root Cause Analysis of Plugged Well Failures

Monitoring Plugged Wells

Remediation and Reclamation

New Technologies and Well Plugging in the Future

Workforce Readiness

A Pathway Forward

1 INTRODUCTION

Federal Support for Plugging Orphan Wells

Report Approach and Statement of Task

Key Terms and Definitions

Report Scope

Report Organization

2 THE ORPHAN WELL PROBLEM

History of Well Regulation

Technical History of Well Development

Health, Safety, and Environmental Issues Linked to Orphan Wells

Plugging Orphan Wells

Conclusion

3 HOW A WELL IS PLUGGED AND PLUGGED WELL FAILURES

How Wells Are Plugged

Causes, Predictability, and Root Cause Failure Analysis

Predicting Plugged Well Failures

Conclusions and Recommendations

4 MONITORING PLUGGED WELLS

Monitoring Implementation and Risk Factors

Types of Potential Contamination

Surface Monitoring Techniques and Tools

Subsurface Monitoring Techniques and Tools

Monitoring Costs, Uncertainty, and Strategic Guidance

Conclusion and Recommendation

5 REMEDIATION AND RECLAMATION

Subsurface Considerations

Surface and Near-Surface Considerations

Reclamation Methods

Reuse of Orphan Well Sites and Wellbores

Conclusion

6 EMERGING TECHNOLOGIES AND APPROACHES

Challenges to Applying New Technologies

Geologic and Wellbore Conditions Assessment

Barrier and Plug Technologies

Emerging Alternatives to Cement and Advanced Materials

Novel Concepts and Advanced Technologies

Collaborative Partnerships to Advance Plugging Technologies

Workforce Development in Plugging and Abandonment

Conclusions and Recommendations

REFERENCES

APPENDIX A COMMITTEE MEMBER BIOGRAPHIES

APPENDIX B GLOSSARY

APPENDIX C QUESTIONNAIRE TO STATE AND TRIBAL AGENCY REPRESENTATIVES

APPENDIX D WELL LOGGING TOOLS

Preface

U.S. oil and natural gas production through drilled wells began in 1859 with the first successful oil-producing well in Pennsylvania. State regulation of oil and gas production dates to around the 1890s, with continuing evolution of regulatory programs since then.

The orphan well problem has existed since some of the earliest wells ceased producing hydrocarbons in commercial quantities. While their risks and hazards will vary based on geology, geography, and land use, when left unattended, orphan wells can cause public health and safety, economic, and environmental problems.

At the request of the Department of the Interior’s Orphaned Wells Program Office, the National Academies of Sciences, Engineering, and Medicine convened an ad hoc committee of volunteer experts to address the regulatory, technical, and environmental challenges and solutions to orphaned hydrocarbon wells in the United States. Committee membership represented experience from major oil and gas companies, service companies, state regulators, environmental firms, academia, and federal agencies.

The National Academies efforts began with a workshop in July 2024 that brought together a broad set of stakeholders and informed the design and implementation of the consensus study. The workshop and this report were informed by a commissioned white paper compiling statutory and regulatory standards, methods, and design of plugging plans and requirements for such activities. We thank white paper authors Richard Simmers, John Fleming, Marlene Hall, Scott Kell, and Robert Worstall and all the speakers, panelists, and participants at the workshop.

Expert panel sessions were held over the course of the study period. Industry experts and state representatives participated in these information-gathering sessions; discussions informed and influenced all aspects of the study charge. To inform its deliberations, the committee examined academic literature, state regulatory standards, and industry-governing standards.

The members of the study committee brought a range of disciplinary backgrounds, viewpoints, experience, and practice to the discussions. It has been a great privilege to work together to advance understanding of the complex issues around the U.S. domestic oil and gas legacy. We thank the committee members for their commitment, thoughtfulness, and professionalism throughout the project.

The committee is grateful for the competence and efficiency of the National Academies staff assigned to this project. In particular, we thank Noel Walters for her tireless efforts, without which this study would not have been successful. Complex logistical arrangements were handled with ease and efficiency by Sam Kraft, and Stacey Giroux and Sarah Jo Peterson assisted with writing. We are indebted to Deborah Glickson for her experience and sage advice during our meetings and deliberations.

James A. Slutz, Co-Chair
Mary H. Feeley, Co-Chair
Committee on Technologies and Practices for Plugging and Remediating Orphaned and Abandoned Oil and Gas Wells
May 2026

Acronyms and Abbreviations