Uncertainty analysis: influence of hydraulic fracturing on overlying aquifers in the presence of leaky abandoned wells

Brownlow, Joshua W.; James, Scott C.; Yelderman, Joe C.

doi:10.1007/s12665-018-7586-0

Cited by 2 publications

(1 citation statement)

References 69 publications

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“…Gas migration into shallow freshwater aquifers through faulty oil and gas wellbores is a decades‐old issue (e.g., Denver Post Editorial Board, ; Harrison, , ) that threatens groundwater in regions with oil and gas development and has recently reemerged as major concern in the United States in light of the expansion of unconventional oil and gas drilling (Brownlow et al, , ; Darrah et al, ; Davies et al, ; Dusseault & Jackson, ; Ingraffea et al, ; Jackson et al, ; Jackson, ; Lackey et al, ; Llewellyn et al, ; Rice, Lackey, et al, ; Sherwood et al, ). Leaked gas from a wellbore flaw or an improperly isolated gas‐bearing formation can migrate vertically along a well through the annuli between the well casings (steel pipes), if the annular cement is faulty (Figure b) or if the annulus is left uncemented (Figure c).…”

Section: Introductionmentioning

confidence: 99%

Modeling Gas Migration, Sustained Casing Pressure, and Surface Casing Vent Flow in Onshore Oil and Gas Wells

Lackey

Rajaram

2019

Water Resources Research

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Faulty oil and gas wellbores are a primary pathway of concern for gas migration from the deep subsurface into shallow freshwater aquifers. Leaked gases migrating vertically along wellbores either collect and build a pressure at the wellhead known as sustained casing pressure (SCP) or escape into the atmosphere as surface casing vent flow (SCVF). SCP and SCVF are valuable indicators of integrity loss that provide insight into the potential for groundwater contamination through gas migration. Previous models of SCP and SCVF have focused on offshore wells and have not considered the relationship between SCP/SCVF and gas migration away from onshore wells. We present the first modeling framework for SCP and SCVF that is applicable to onshore oil and gas wells constructed with outermost annuli that are hydraulically connected or “open” to the surrounding formation. Our results show that SCP behavior is unique in onshore wells with open annuli, because steady state SCP is not achieved in an open annulus unless gas escapes the wellbore via gas migration (Darcy Flow), a wellhead leak, or a controlled bleed‐off test. We show that appropriately modeling gas leakage along the wellbore and SCP/SCVF helps to constrain methane leakage fluxes from faulty wells and could be integrated with subsurface flow and transport models of stray gas contamination. By relating gas fluxes to SCP/SCVF, our model can provide information used to support regulatory actions informed by SCP/SCVF, which are easy to measure and monitor.

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Section: Introductionmentioning

confidence: 99%

Modeling Gas Migration, Sustained Casing Pressure, and Surface Casing Vent Flow in Onshore Oil and Gas Wells

Lackey

Rajaram

2019

Water Resources Research

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Uncertainty analysis on environmental impacts of hydraulic fracturing

et al. 2022

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Uncertainty is an undeniable aspect of underground operations, such as wellbore stimulation treatments, where combined rock and fluid interaction add a layer of complexity to the uncertainty. There are social and environmental concerns about the probable outcome of operations like hydraulic fracturing. Hydraulic fracturing treatments may affect the integrity of sub-surface geological strata or might initiate unexpected potential risks to the environment when the created fracture extends beyond its engineered design. Therefore, it is necessary to investigate a range of possible scenarios by which the fracture may experience a deviation from its planned behaviour. In this study, we model the uncertainty associated with hydraulic fracturing using fracture growth simulation. The uncertainty of a range of treatment parameters, such as pumping flow rate, injection duration and mechanical properties of the underground geological layer, is investigated. Monte Carlo simulation is used to examine different probable fracturing scenarios and numerous fracturing simulations with numerical and analytical models. The probability analysis is performed in a case study to identify the cumulative distribution functions (CDFs) of fracture growth. The emerging least, median and most likely situations of fracture growth are analysed to evaluate the fracturing uncertainty. Our results indicate that the numerical modelling approach may predict a more extensive fracture growth in the vertical plane. The numerical model may suggest a more conservative way to address environmental concerns. The resulting cumulative distribution of probabilities suggests the CDFs of the analytical model as the lower band for fracture length, whereas the numerical CDFs presents the upper band.

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Uncertainty analysis: influence of hydraulic fracturing on overlying aquifers in the presence of leaky abandoned wells

Cited by 2 publications

References 69 publications

Modeling Gas Migration, Sustained Casing Pressure, and Surface Casing Vent Flow in Onshore Oil and Gas Wells

Modeling Gas Migration, Sustained Casing Pressure, and Surface Casing Vent Flow in Onshore Oil and Gas Wells

Uncertainty analysis on environmental impacts of hydraulic fracturing

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