A review of physical, chemical, and hydrogeologic characteristics of stray gas migration: Implications for investigation and remediation

Molofsky, Lisa J.; Connor, John A.; Ven, Cole J.C. Van De; Hemingway, Mark P.; Richardson, Stephen D.; Strasert, Brian A.; McGuire, Travis M.; Paquette, Shawn M.

doi:10.1016/j.scitotenv.2021.146234

Cited by 31 publications

(31 citation statements)

References 83 publications

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“…The monitoring of people and equipment in buildings must be objective and consider various random factors. Objectivity is important because different equipment has different properties [6], which leads to the variation in sensor type and location. In order to ensure the improved type of the monitoring system, the development needs of the improved space and related instruments should be reserved when designing the system.…”

Section: Introductionmentioning

confidence: 99%

An Indoor Positioning and Prewarning System Based on Wireless Sensor Network Routing Algorithm

2021

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One of the most important means to position abnormal devices is to efficiently utilize the resources of wireless sensor network (WSN) and make proper analysis of the relevant data. Therefore, this paper constructs an indoor positioning and prewarning system that utilizes energy efficiently and achieves a long lifecycle. Firstly, the adjacent round iteration load balancing (ARILB) routing algorithm was proposed, which elects the cluster heads (CHs) by the adjacent round strategy. In this way, the random components were eliminated in CH election. Next, a short-distance multifrequency routing strategy was constructed between CHs to transmit the information to the sink, and a positioning algorithm was designed called ARILB-received signal strength (RSS). The ARILB-RSS positioning algorithm traverses the triangles formed by anchor nodes, forming multiple sets of ranging points; then, the optimal anchor node is recorded, and the path loss factor is iterated to reduce the positioning error. Simulation shows that the network survives 54.5% longer using ARILB than using the distributed energy-efficient clustering (DEEC) algorithm; the packet delivery rate using ARILB was about 139% higher than that of low energy adaptive clustering hierarchy (LEACH) algorithm and 35% higher than that of uneven clustering routing algorithm based on chain-cluster type (URCC) algorithm; ARILB-RSS reduced the ranging error by 14.31% and then the positioning error by 26.79%.

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Section: Introductionmentioning

confidence: 99%

An Indoor Positioning and Prewarning System Based on Wireless Sensor Network Routing Algorithm

2021

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Section: Introductionmentioning

confidence: 99%

“…Stray (or "fugitive") gas release is the upward escape of subsurface gases (hydrocarbon or non-hydrocarbon), often induced by oil and gas development [1]. A primary pathway for stray gas migration is oil and gas wells with compromised cement seals or casings [1,2]. Stray gas can impact the groundwater quality of shallow aquifers and contribute to atmosphere emissions because of the preferential transport of buoyant free-phase gas (FPG) within high permeability pathways [1], such as faults, fractures, and wellbores [1,3,4].…”

Section: Introductionmentioning

confidence: 99%

“…A primary pathway for stray gas migration is oil and gas wells with compromised cement seals or casings [1,2]. Stray gas can impact the groundwater quality of shallow aquifers and contribute to atmosphere emissions because of the preferential transport of buoyant free-phase gas (FPG) within high permeability pathways [1], such as faults, fractures, and wellbores [1,3,4]. FPG is inclined to migrate vertically through large, connected pore spaces (i.e., high permeability pathways) because of relatively low capillary entry pressures [1].…”

Section: Introductionmentioning

confidence: 99%

“…Stray gas can impact the groundwater quality of shallow aquifers and contribute to atmosphere emissions because of the preferential transport of buoyant free-phase gas (FPG) within high permeability pathways [1], such as faults, fractures, and wellbores [1,3,4]. FPG is inclined to migrate vertically through large, connected pore spaces (i.e., high permeability pathways) because of relatively low capillary entry pressures [1]. Free-phase stray gas migrating along preferential pathways can spread laterally into the surrounding aquifers [1], displacing groundwater from the pore spaces with FPG.…”

Section: Introductionmentioning

confidence: 99%

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Electrical Imaging of a Shallow Free-Phase Stray Gas Plume from an Abandoned Exploration Well

2021

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Geophysical imaging of free-phase gas (FPG) within aquifers is an emerging method for understanding the mechanisms controlling stray gas migration from oil and gas wells. Crystal Geyser is an unsealed and partially cased well that transports stray CO2 gas to the shallow subsurface. Accumulations of subsurface CO2 FPG near Crystal Geyser have been inferred, but the actual location and dimensions remained unclear. Here, the subsurface FPG distribution surrounding Crystal Geyser was characterized by interpreting 2D electrical resistivity images with previous drilling records and field mapping. An approximately 70-metre-wide FPG plume was located laterally between Crystal Geyser’s conduit and the Little Grand Wash Fault. The FPG plume spanned the vertical extent of approximately 20 to 55 metres below the ground surface, located within the Slick Rock Member sandstone with the relatively low permeability Earthy Member silty sandstone acting as a caprock. The FPG plume was identified from an anomalously high resistivity zone within the Slick Rock Member that was not caused by lateral lithofacies changes or fault displacement. The conceptual FPG migration pathways beneath Crystal Geyser are presented, based on the interpreted FPG distribution from the electrical resistivity images combined with previous site characterization and the principles of buoyant FPG migration. FPG accumulates within the Slick Rock Member by buoyant up-dip migration beneath siltstone capillary barriers of the Earthy Member. FPG leaks to the ground surface within high permeability preferential pathways along the Little Grand Wash Fault and the conduit of Crystal Geyser.

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Low-Cost Sensors Provide Insight into Temporal Variation in Fugitive Methane Gas Concentrations Around an Energy Well

Fleming

Morais

Ryan

2022

Preprint

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Effective measurement of the presence and rate of methane gas migration (GM) outside the casing of energy wells is important for managing social and environmental impacts and financial liabilities in the upstream petroleum industry. Practitioners typically assess GM by above-background methane gas concentrations in-soil or at-grade; however, factors influencing the potential variation in these measurements are not well represented in industry recommended best-practices. Inexpensive chemoresistive sensors were used to record a one-minute frequency methane gas concentration time series over 19 days. Time series were recorded at three soil depths (0, 5, and 30 cm) at two locations <30m cm radially from a petroleum well with known GM, in addition to two 'control' locations. Observed concentration variations ranged over several orders of magnitude at all depths, with generally lower concentrations and more variation observed at shallower depths. Varying concentrations were correlated to meteorological factors, primarily including wind speed and shallow groundwater table elevation. The gas concentration patterns were affected by a 3.5 mm rainfall event, suggesting soil moisture changes affected preferential gas migration pathways. Results indicate potential variability in repeated snapshot GM test results. Although currently recommended GM detection methods would have effectively identified the presence/absence of GM, they would not have quantified order of magnitude changes in concentration. GM detection success at this site was increased with measurement at more than one location spatially within 30 cm of the well casing, lower concentration detection limits, and greater measurement depth. These findings indicate that meteorological factors should be considered when conducting gas migration surveys (particularly for improving at-grade test reliability). The low-cost approach for long-term concentration measurement facilitates insight into variable gas concentrations and may be advantageous in comparison to snapshot measurements in some circumstances.

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A review of physical, chemical, and hydrogeologic characteristics of stray gas migration: Implications for investigation and remediation

Cited by 31 publications

References 83 publications

An Indoor Positioning and Prewarning System Based on Wireless Sensor Network Routing Algorithm

An Indoor Positioning and Prewarning System Based on Wireless Sensor Network Routing Algorithm

Electrical Imaging of a Shallow Free-Phase Stray Gas Plume from an Abandoned Exploration Well

Low-Cost Sensors Provide Insight into Temporal Variation in Fugitive Methane Gas Concentrations Around an Energy Well

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