| Autor: |
Lackey G; National Energy Technology Laboratory, 626 Cochrans Mill Road, P.O. Box 10940, Pittsburgh, Pennsylvania15236-0940, United States.; NETL Support Contractor, 626 Cochrans Mill Road, Pittsburgh, Pennsylvania15236, United States., Pfander I; National Energy Technology Laboratory, 1450 Queen Avenue SW, Albany, Oregon97321, United States.; NETL Support Contractor, 1450 Queen Avenue SW, Albany, Oregon97321, United States., Gardiner J; National Energy Technology Laboratory, 626 Cochrans Mill Road, P.O. Box 10940, Pittsburgh, Pennsylvania15236-0940, United States.; NETL Support Contractor, 626 Cochrans Mill Road, Pittsburgh, Pennsylvania15236, United States., Sherwood OA; Department of Earth and Environmental Sciences, Dalhousie University, Halifax, Nova ScotiaB3H 4R2, Canada., Rajaram H; Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland21205, United States., Ryan JN; Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado80309, United States., Dilmore RM; National Energy Technology Laboratory, 626 Cochrans Mill Road, P.O. Box 10940, Pittsburgh, Pennsylvania15236-0940, United States., Thomas B; National Energy Technology Laboratory, 1450 Queen Avenue SW, Albany, Oregon97321, United States. |
| Abstrakt: |
Fluids leaked from oil and gas wells often originate from their surface casing─a steel pipe installed beneath the deepest underlying source of potable groundwater that serves as the final barrier around the well system. In this study, we analyze a regulatory dataset of surface casing geochemical samples collected from 2573 wells in northeastern Colorado─the only known publicly available dataset of its kind. Thermogenic gas was present in the surface casings of 96.2% of wells with gas samples. Regulatory records indicate that 73.3% of these wells were constructed to isolate the formation from which the gas originated with cement. This suggests that gas migration into the surface casing annulus predominantly occurs through compromised barriers (e.g., steel casings or cement seals), indicative of extensive integrity issues in the region. Water was collected from 22.6% of sampled surface casings. Benzene, toluene, ethylbenzene, and xylenes were detected in 99.7% of surface casing water samples tested for these compounds, which may be due to the presence of leaked oil, natural gas condensate, or oil-based drilling mud. Our findings demonstrate the value of incorporating surface casing geochemical analysis in well integrity monitoring programs to identify integrity issues and focus leak mitigation efforts. |
