Analysis of gas leakage occurrence along wells in Alberta, Canada, from a GHG perspective – Gas migration outside well casing

Bachu, Stefan

doi:10.1016/j.ijggc.2017.04.003

Cited by 73 publications

(58 citation statements)

References 20 publications

(37 reference statements)

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“…Studies focusing on the causes of gas migration have shown that a combination of factors likely contributes to the development of fugitive gas release confirming the issue to be a complex, region‐specific, and multifaceted problem . For example, Bachu investigated the occurrence up to 2013 of GM outside wellbore casings in Alberta by assessing records obtained from the Alberta Energy Regulator (AER). Factors potentially affecting well integrity and GM, such as completion type, cementation, well orientation, status, and production type, were individually evaluated and descriptive statistics were produced.…”

Section: Key Knowledge Gaps Relating To Gas Migration and Fugitive Gasmentioning

confidence: 99%

Advancing knowledge of gas migration and fugitive gas from energy wells in northeast British Columbia, Canada

et al. 2019

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Petroleum resource development is creating a global legacy of active and inactive onshore energy wells. Unfortunately, a portion of these wells will exhibit gas migration (GM), releasing fugitive gas (FG) into adjacent geologic formations and overlying soils. Once mobilized, FG may traverse the critical zone, impact groundwater, and emit to the atmosphere, contributing to greenhouse‐gas emissions. Understanding of GM and FG has increased in recent years but significant gaps persist in knowledge of (1) the incidence and causes of GM, (2) subsurface baseline conditions in regions of development required to delineate GM and FG, and (3) the migration, impacts, and fate of FG. Here we provide an overview of these knowledge gaps as well as the occurrence of GM and FG as currently understood in British Columbia (BC), Canada, a petroleum‐producing region hosting significant reserves. To address the identified knowledge gaps within BC, the Energy and Environment Research Initiative (EERI) at the University of British Columbia is implementing several field‐focused research projects including: (1) statistical analyses of regulatory data to elucidate the incidence and causes of GM, (2) characterization of regional hydrogeology and shallow subsurface conditions in the Peace Region of the Montney resource play, and (3) investigation of the migration, impacts, and fate of FG in the shallow subsurface through controlled natural‐gas release. Together, the EERI investigations will advance understanding of GM and FG, provide scientific data that can inform regulations, and aid development of effective monitoring and detection methodologies for BC and beyond. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Section: Key Knowledge Gaps Relating To Gas Migration and Fugitive Gasmentioning

confidence: 99%

Advancing knowledge of gas migration and fugitive gas from energy wells in northeast British Columbia, Canada

et al. 2019

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“…Other regions rely on baseline groundwater sampling to detect gas migration from faulty oil and gas wells (Bachu, 2017;Sherwood et al, 2016). While SfCP and SCVF indicate integrity loss, not all wells with compromised structural integrity contaminate groundwater (Bachu, 2017;Lackey et al, 2017;Watson & Bachu, 2009). Of the 446,289 wells in Alberta, approximately 4.9% (~21,868) have exhibited SCVF and 0.73% (3,276) have exhibited gas migration.…”

Section: Anthropogenically Induced Pathways Of Methane Migrationmentioning

confidence: 99%

“…Thermal heavy oil and bitumen wells in Alberta are more prone to gas migration than conventional wells, and the majority (90%) of wells exhibiting gas migration are drilled through shallow coal seams (Bachu, 2017), which is suggestive of anthropogenically induced migration of methane gas along well annuli from coal deposits to the surface. Watson and Bachu (2009) and Bachu (2017) analyzed SCVF and gas-migration records collected by the Alberta Energy Regulator, and found that wells installed with intervals of uncemented casing or deviated wellbores are more prone to losing integrity and developing SCVF (Watson & Bachu, 2009). Similarly, Lackey et al (2017) electronically mined SfCP test data from reports in the COGCC database and analyzed SfCP in a subset of the Wattenberg Field in Colorado.…”

Section: Anthropogenically Induced Pathways Of Methane Migrationmentioning

confidence: 99%

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Groundwater‐quality hazards of methane leakage from hydrocarbon wells: A review of observational and numerical studies and four testable hypotheses

et al. 2018

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Methane leakage from hydrocarbon wells plays an important role in the groundwater‐quality impacts of hydrocarbon development and presents a more likely hazard than hydraulic fracturing or formation fluids. Methane released from contaminated water wells has been linked with combustion risks and degraded water quality. Potentially, methane can serve as a precursor to other fluids associated with hydrocarbon extraction, such as volatile organics. In this review, we surveyed studies relating to contamination of drinking‐water aquifers by methane gas from leaking hydrocarbon wells. Challenges associated with linking methane in groundwater to hydrocarbon extraction are identified, highlighting the need for groundwater‐quality and well‐integrity databases. Science‐based policy recommendations are made, including deeper surface casings and greater cement coverage for wells with deviated wellbores, remediation of faulty abandoned wells, and increased gas‐migration monitoring. We suggest four hypotheses to quantify risks to groundwater quality from methane leakage. First, differentiation between thermogenic methane occurring in groundwater due to natural migration and thermogenic methane present due to hydrocarbon development can be used to alleviate the need for baseline measurements of methane in groundwater. Second, methane newly discovered in freshwater aquifers is unlikely to have originated from leaks beginning decades ago. Third, pertaining to the zone separating methane leakage from groundwater, relative permeability will have a larger impact on plume diameter than heterogeneity in intrinsic permeability. Fourth, thermogenic methane in groundwater will serve as a precursor to benzene, toluene, ethybenzene, and xylene (BTEX) under conditions where methane and BTEX coexist in a hydrocarbon reservoir and leakage is transported primarily in the aqueous phase. This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water Quality

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“…One of the main concerns is the potential migration of natural gas (composed mostly of methane, CH 4 ) toward freshwater resources (e.g. Jasechko and Perrone, 2017;Lefebvre 2017;Rice et al, 2018;Bachu, 2017;Cahill et al, 2017;DiGiulio and Jackson, 2016;Harkness et al, 2017;Nicot et al, 2017;Wolfe and Wilkin, 2017). According to the terminology of Milkov and Etiope (2018), methane in natural environments can have biotic or abiotic origins.…”

Section: Introductionmentioning

confidence: 99%

A geochemical and multi-isotope modeling approach to determine sources and fate of methane in shallow groundwater above unconventional hydrocarbon reservoirs

Humez

Osselin

Kloppmann

et al. 2019

Journal of Contaminant Hydrology

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Due to increasing concerns over the potential impact of shale gas and coalbed methane (CBM) development on groundwater resources, it has become necessary to develop reliable tools to detect any potential pollution associated with hydrocarbon exploitation from unconventional reservoirs. One of the key concepts for such monitoring approaches is the establishment of a geochemical baseline of the considered groundwater systems. However, the detection of methane is not enough to assess potential impact from CBM and shale gas exploitation since methane in low concentrations has been found to be naturally ubiquitous in many groundwater systems. The objective of this study was to determine the methane sources, the extent of potential methane oxidation, and gas-water-rock-interactions in shallow aquifers by integrating chemical and isotopic monitoring data of dissolved gases and aqueous species into a geochemical PHREEQC model. Using data from a regional groundwater observation network in Alberta (Canada), the model was designed to describe the evolution of the concentrations of methane, sulfate and dissolved inorganic carbon (DIC) as well as their isotopic compositions (δ 34 S SO4 , δ 13 C CH4 and δ 13 C DIC) in groundwater subjected to different scenarios of migration, oxidation and in situ generation of methane. Model results show that methane migration and subsequent methane oxidation in anaerobic environments can strongly affect its concentration and isotopic fingerprint and potentially compromise the accurate identification of the methane source. For example elevated δ 13 C CH4 values can be the result of oxidation of microbial methane and may be

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Analysis of gas leakage occurrence along wells in Alberta, Canada, from a GHG perspective – Gas migration outside well casing

Cited by 73 publications

References 20 publications

Advancing knowledge of gas migration and fugitive gas from energy wells in northeast British Columbia, Canada

Advancing knowledge of gas migration and fugitive gas from energy wells in northeast British Columbia, Canada

Groundwater‐quality hazards of methane leakage from hydrocarbon wells: A review of observational and numerical studies and four testable hypotheses

A geochemical and multi-isotope modeling approach to determine sources and fate of methane in shallow groundwater above unconventional hydrocarbon reservoirs

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