Composition and Origin of Surface Casing Fluids in a Major US Oil- and Gas-Producing Region.
Environ Sci Technol
; 56(23): 17227-17235, 2022 12 06.
Article
em En
| MEDLINE
| ID: mdl-36379467
ABSTRACT
Fluids leaked from oil and gas wells often originate from their surface casingâa 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 Coloradoâthe 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.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Contexto em Saúde:
2_ODS3
Base de dados:
MEDLINE
Assunto principal:
Poluentes Químicos da Água
/
Água Subterrânea
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2022
Tipo de documento:
Article