124 Fixing the Silent Leak: Identifying, Quantifying, Prioritizing, and Mitigating the Environmental and Health Impacts of Legacy Oil and Gas Drilling in North America

This session invites abstracts applying field studies, laboratory experiments, process-based and machine learning modeling, or multidisciplinary datasets to identify, quantify, and mitigate impacts from oil/gas wells of all types and statuses (active, abandoned, orphaned).

Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 214A

The Magnitude and Origin of Methane Emissions from Kentucky’s Legacy Oil and Gas Infrastructure

Paper number: 124-8
Program: Technical Sessions
Time: 3:35 PM – 3:50 PM

Authors

Abstract

Kentucky’s long tradition of oil and gas development spans 200 years, with the first discovery of oil in 1818. This historical legacy has resulted in nearly 15,000 known orphaned oil and gas wells (OOGWs), which emit methane, hydrogen sulfide, and other pollutants detrimental to human health. However, methane emission rates from OOGWs are inconsistent in behavior and origin. The Kentucky Geological Survey is collaborating with the Kentucky Division of Oil and Gas to measure methane emissions from OOGWs in an effort to identify the factors driving these emissions and ascertain their origin—information that could ultimately be used to maximize methane abatement through the plugging of OOGWs. 

To identify driving factors behind methane emissions and determine the genesis of emitted methane, we have employed several methods. We have completed methane emission measurements on 236 OOGWs located in the Kentucky portions of the Appalachian Basin, Cincinnati Arch, and Illinois Basin geologic provinces and categorized wells based on geologic and infrastructural characteristics. Geologic categories include the type of hydrocarbons produced, the producing formation, and the presence of coal-bearing strata. Infrastructure-related categories include the age of the wellbore, the degree of wellbore openness, and the presence of historical coal mining activity near the well. To better understand the origin of methane emissions, we have initiated a sampling campaign focused on analyzing the isotopic composition of methane emitted from OOGWs. Gas samples are being analyzed for wetness and carbon isotopic composition of methane (δ¹³C-CH₄). In parallel, water samples are being collected from OOGWs to investigate potential subsurface communication pathways that may influence gas migration.  

Our measurements indicate a wide range of emission rates, from 6.0 × 10⁻⁸ to 1,131.5 g/hr. The 10 highest emitting OOGWs measured make up 81% of the total measured emission rate. Ongoing isotopic analysis shows a mixed origin of gases from wells completed in close proximity in the same geologic formations. This is influenced by the producing geologic formation and the presence of historical underground coal mining operations in proximity to OOGWs. Thus, our preliminary results suggest that both geologic and anthropogenic factors contribute to mixed-origin methane emissions from OOGWs. 

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413339

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.