Spatiotemporal variability of fugitive gas migration emissions around a petroleum well

Fleming, Neil; Morais, Tiago A.; Mayer, U.; Ryan, M. Cathryn

doi:10.1002/essoar.10507208.1

Cited by 2 publications

(2 citation statements)

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“…19 If surface testing suggests that GM may be present, in-soil samples are taken in a cross-pattern up to 6 m around a well; 53,57 however, testing methods and their results can apparently vary significantly. 60,61 GM is classified as "serious" where the emissions pose safety hazards, when a well has already been abandoned, or when groundwater wells are in the vicinity; otherwise, they are considered "non-serious". Like SCVFs, serious emissions require immediate repair, while the nonserious ones may be deferred to the time of abandonment.…”

Section: Methodsmentioning

confidence: 99%

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Highly Uncertain Methane Leakage from Oil and Gas Wells in Canada Despite Measurement and Reporting

Seymour,

Xie,

Kang

2024

Energy Fuels

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Leakage of fluids from oil and gas wells is a source of the key greenhouse gas methane, and presents environmental risks, including groundwater contamination. A loss of well integrity can result in fluid leakage into the annular space between subsequent well casings (which is often vented to the atmosphere) or into the surrounding subsurface. In Canada, industry reporting on well integrity is often incomplete, leading government inventories to disagree on emission magnitudes. In this study, we model wellbore methane emissions using industry data in British Columbia and Alberta, Canada, finding that differing model assumptions to handle unclear/missing data have a strong influence on estimated emissions. Considering estimates derived from industry reporting and from independent measurement, wellbore emissions in the two provinces range anywhere from 23 to 176 kt of methane, representing 1.7−11.4% of their upstream sector methane emissions. Further, finding over 130 examples of measured leaks seemingly missing from industry reporting, we conclude that wellbore emissions, groundwater contamination, and broader environmental risks are underestimated. We provide recommendations to improve well integrity tracking through data quality assurance measures and increased testing. Finally, we find that ongoing optical gas imaging camera surveys could be an effective tool to augment wellbore testing requirements to minimize industry burden.

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Section: Methodsmentioning

confidence: 99%

“…It has been suggested previously that GM testing requirements also need improvement considering that inconsistent industry test methods reportedly result in different observed GM occurrence rates. 60,61 3.5. Measurement Comparison.…”

Section: Evaluating Model Assumptionsmentioning

confidence: 99%

Highly Uncertain Methane Leakage from Oil and Gas Wells in Canada Despite Measurement and Reporting

Seymour,

Xie,

Kang

2024

Energy Fuels

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Soil surface flux measurements are a reliable means for assessing fugitive gas migration across soils and seasons

Argento

Henderson²,

Lewis

et al. 2022

Elementa: Science of the Anthropocene

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As oil and gas wells age and the number of wells drilled increases to meet demand, we may see more instances of fugitive soil gas migration (GM) and associated methane (CH4) emissions. Due to the immense spatiotemporal variability of soils and uncertainty in measurement practice, the detection and quantification of GM emissions is a challenge. Two common measurement techniques include the shallow in-soil gas concentration approach and soil surface flux measurements using flux chambers. In this numerical modeling study, both methods were compared to determine how soil texture, environmental conditions (water content, temperature), and CH4 leak rates into the soil profile influenced in-soil CH4 concentration and surface CH4 flux rates. We observed that in-soil CH4 concentration was strongly controlled by soil texture and environmental conditions, whereas surface CH4 flux rates were far less sensitive to those same parameters. Flux measurements were more useful for determining severity of the CH4 leak into the soil and allowed us to differentiate between leak and nonleak scenarios in soils with biological CH4 production which could complicate a GM assessment. We also evaluated field measurements of carbon dioxide from an enhanced oil recovery site to demonstrate how seasonal conditions can influence concentrations of trace gases in shallow soil. Based on our model results and supplemental field measurements, we propose that flux chamber measurements present a more reliable tool to assess the incidence and severity of fugitive GM.

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Spatiotemporal variability of fugitive gas migration emissions around a petroleum well

Cited by 2 publications

References 0 publications

Highly Uncertain Methane Leakage from Oil and Gas Wells in Canada Despite Measurement and Reporting

Highly Uncertain Methane Leakage from Oil and Gas Wells in Canada Despite Measurement and Reporting

Soil surface flux measurements are a reliable means for assessing fugitive gas migration across soils and seasons

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