124-8 The Magnitude and Origin of Methane Emissions from Kentucky’s Legacy Oil and Gas Infrastructure

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

Presenting Author:

Deron Zierer

Authors:

Zierer, Deron¹, Washburn, Alex Matthew², Fryar, Alan E.³, Walton, Zachary⁴, High, Madison⁵, Hawksley, Andrew⁶, Parris, Thomas⁷

(1) Kentucky Geological Survey, Lexington, KY, USA; Univ Kentucky, Earth and Environmental Sciences, Lexington, KY, USA, (2) Kentucky Geological Survey, Burlington, KY, USA, (3) Univ Kentucky, Earth and Environmental Sciences, Lexington, KY, USA, (4) Kentucky Geological Survey, Lexington, KY, USA, (5) Kentucky Geological Survey, Horse Cave, KY, USA, (6) Kentucky Geological Survey, Lexington, KY, USA, (7) Kentucky Geological Survey, Lexington, Ky, USA,

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 Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8699

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