Alteration of natural gas during leakage from a North Sea salt diapir field

Clayton, Chris; Hay, Stephen; Baylis, S.A.; Dipper, B.

doi:10.1016/s0025-3227(96)00080-1

Cited by 46 publications

(21 citation statements)

References 11 publications

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“…1). Moreover, stray gases have the same C 1 -C 5 composition as production gases (SI Appendix), which suggests relatively rapid transport via wellbores because geological seepage tends to strip gases of heavier alkanes during migration (35).…”

Section: Resultsmentioning

confidence: 99%

Groundwater methane in relation to oil and gas development and shallow coal seams in the Denver-Julesburg Basin of Colorado

Sherwood

Rogers

Lackey

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

104

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Unconventional oil and gas development has generated intense public concerns about potential impacts to groundwater quality. Specific pathways of contamination have been identified; however, overall rates of contamination remain ambiguous. We used an archive of geochemical data collected from 1988 to 2014 to determine the sources and occurrence of groundwater methane in the Denver-Julesburg Basin of northeastern Colorado. This 60,000-km2 region has a 60-y-long history of hydraulic fracturing, with horizontal drilling and high-volume hydraulic fracturing beginning in 2010. Of 924 sampled water wells in the basin, dissolved methane was detected in 593 wells at depths of 20–190 m. Based on carbon and hydrogen stable isotopes and gas molecular ratios, most of this methane was microbially generated, likely within shallow coal seams. A total of 42 water wells contained thermogenic stray gas originating from underlying oil and gas producing formations. Inadequate surface casing and leaks in production casing and wellhead seals in older, vertical oil and gas wells were identified as stray gas migration pathways. The rate of oil and gas wellbore failure was estimated as 0.06% of the 54,000 oil and gas wells in the basin (lower estimate) to 0.15% of the 20,700 wells in the area where stray gas contamination occurred (upper estimate) and has remained steady at about two cases per year since 2001. These results show that wellbore barrier failure, not high-volume hydraulic fracturing in horizontal wells, is the main cause of thermogenic stray gas migration in this oil- and gas-producing basin.

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Section: Resultsmentioning

confidence: 99%

Groundwater methane in relation to oil and gas development and shallow coal seams in the Denver-Julesburg Basin of Colorado

Sherwood

Rogers

Lackey

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

104

View full text Add to dashboard Cite

show abstract

“…ethane being preferentially oxidized when compared to the heavier hydrocarbons (Clayton et al, 1997;Pallasser, 2000;Stadnitskaia et al, 2006). At Isis MV ethane oxidation does not seem to occur.…”

Section: Anaerobic Oxidationmentioning

confidence: 94%

Differential aerobic and anaerobic oxidation of hydrocarbon gases discharged at mud volcanoes in the Nile deep-sea fan

Mastalerz

Lange

Dählmann

2009

Geochimica et Cosmochimica Acta

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“…As leaks occur to gas reservoirs, the carbon isotopic values for the remaining methane becomes less negative, and the residual gas is enriched in 13 C with increasing diffusion time in proportion to the progress of the leakage process (Clayton et al, 1997;Prinzhofer and Pernaton, 1997;Zhang and Krooss, 2001). Furthermore, some workers have attributed large (>5‰) changes in d 13 C to migration effects (Prinzhofer and Huc, 1995;Prinzhofer and Pernaton, 1997), although an investigation by Fuex (1980) convincingly demonstrated that isotopic fractionation during gas migration is negligible.…”

Section: Post-genetic Effect On Gas Geochemistrymentioning

confidence: 99%