Wellbore Permeability Estimates from Vertical Interference Testing of Existing Wells

Gasda, Sarah E.; Celia, Michael A.; Wang, James; Duguid, Andrew

doi:10.1016/j.egypro.2013.06.489

Cited by 42 publications

(31 citation statements)

References 12 publications

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“…However, gaps along the cement/casing interface and/or fractures in the cement matrix can significantly increase the equivalent permeability (which can reach 10 21 to 1 mD). Crow et al [2010] and Gasda et al [2013] studied the casing integrity of several wells using a Vertical Interference Test (VIT), which is a downhole test designed to measure hydraulic connection of the casing annulus over a selected well section. Their results indicate that the equivalent permeability of a casing annulus can range from 1 mD to more than 100 mD.…”

Section: 1002/2014wr016146mentioning

confidence: 99%

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Numerical investigation of methane and formation fluid leakage along the casing of a decommissioned shale gas well

Nowamooz

Lemieux

Molson

et al. 2015

Water Resources Research

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Methane and brine leakage rates and associated time scales along the cemented casing of a hypothetical decommissioned shale gas well have been assessed with a multiphase flow and multicomponent numerical model. The conceptual model used for the simulations assumes that the target shale formation is 200 m thick, overlain by a 750 m thick caprock, which is in turn overlain by a 50 m thick surficial sand aquifer, the 1000 m geological sequence being intersected by a fully penetrating borehole. This succession of geological units is representative of the region targeted for shale gas exploration in the St. Lawrence Lowlands (Qu ebec, Canada). The simulations aimed at assessing the impact of well casing cementation quality on methane and brine leakage at the base of a surficial aquifer. The leakage of fluids can subsequently lead to the contamination of groundwater resources and/or, in the case of methane migration to ground surface, to an increase in greenhouse gas emissions. The minimum reported surface casing vent flow (measured at ground level) for shale gas wells in Quebec (0.01 m 3 /d) is used as a reference to evaluate the impact of well casing cementation quality on methane and brine migration. The simulations suggest that an adequately cemented borehole (with a casing annulus permeability k c 1 mD) can prevent methane and brine leakage over a time scale of up to 100 years. However, a poorly cemented borehole (k c ! 10 mD) could yield methane leakage rates at the base of an aquifer ranging from 0.04 m 3 /d to more than 100 m 3 /d, depending on the permeability of the target shale gas formation after abandonment and on the quantity of mobile gas in the formation. These values are compatible with surface casing vent flows reported for shale gas wells in the St. Lawrence Lowlands (Quebec, Canada). The simulated travel time of methane from the target shale formation to the surficial aquifer is between a few months and 30 years, depending on cementation quality and hydrodynamic properties of the casing annulus. Simulated longterm brine leakage rates after 100 years for poorly cemented boreholes are on the order of 10 25 m 3 /d (10 mL/d) to 10 23 m 3 /d (1 L/d). Based on scoping calculations with a well-mixed aquifer model, these rates are unlikely to have a major impact on groundwater quality in a confined aquifer since they would only increase the chloride concentration in a pristine aquifer to 1 mg/L, which is significantly below the commonly recommended aesthetic objective of 250 mg/L for chloride.

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Section: 1002/2014wr016146mentioning

confidence: 99%

“…The effective permeabilities and porosities were selected in order to cover the range of values presented by Bachu and Bennion [2009], Gasda et al [2013], and Tao and Bryant [2014]. The minimum and maximum considered values are 20% and 45% for the porosity e and 10 23 to 10 3 mD for the equivalent permeability k (Table 4).…”

Section: Materials Propertiesmentioning

confidence: 99%

Numerical investigation of methane and formation fluid leakage along the casing of a decommissioned shale gas well

Nowamooz

Lemieux

Molson

et al. 2015

Water Resources Research

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“…This is achieved using an MCMC stochastic simulation method that successively samples the parameter space with stable frequencies from a fixed probability distribution. It then tunes the proposal distribution during the evolution to the posterior target distribution using information inferred from the sampling history induced by the transitions of the Markov Chain . Data selected for the VIT analysis begins when rapid pressurization starts outside the packers on the MDT string and ends immediately if any of the following four criteria are met: Dual packer assembly (MRPA) pressure in between the packers is greater than the single‐probe assembly (MRPS) pressure outside the packers. dMRPA/dt is less than zero: MRPA is not monotonically increasing. d 2 MRPA/dt 2 greater than zero: MRPA function is not concave down. A change of more than 10% occurs in either the MRPS or MRPA gauge within a very short time. …”

Section: Methodsmentioning

confidence: 99%

Baseline integrity property measurement of legacy oil and gas wells for carbon storage projects

et al. 2017

Self Cite

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An import factor for long‐term storage is the integrity of wells penetrating the carbon storage reservoir. Well integrity will play a crucial role in establishing leakage risk in areas where there is a high density of existing (legacy) wells that could intersect operations including depleted petroleum fields where enhanced oil recovery or carbon storage will occur. The objective of this study was to develop methods that establish the baseline flow parameters from individual measurements in five wells in Wyoming. This paper describes the methods used to collect and analyze the data. The methods included isolation logging tools, in situ point and average permeability measurements, and laboratory tests on samples collected in the wells. The log results collected in the wells, considered in conjunction with the core measurements, indicate that interfaces and/or problems with cement placement related to eccentering provide preferential pathways for fluids, which increase the effective permeability of the barrier several orders of magnitude above that of intact cement. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

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“…Eff ective well permeabilities have been characterized on the basis of fi eld or laboratory measurements, and also on the basis of 'soft ' information on various well characteristics such as well type, depth, age, and regulatory requirements at the time of drilling. More recent VIT measurements from nine data sets described in Gasda et al 35 and Duguid et al 36 found eff ective permeability estimates of the well barrier system to be highly variable and ranging from approximately 1 mD to over 1000 mD. VITs measure pressure drops along the outside of the well casing over intervals of several meters, which allows calculating the eff ective permeability of potential pathways along the rock-cement interface, along the casing-cement interface, and through fractures or cracks within the cement or the surrounding rock.…”

Section: Alternative Well Leakage Scenariomentioning

confidence: 99%

A tiered area‐of‐review framework for geologic carbon sequestration

2013

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This paper discusses the current guidance given by the United States Environmental Protection Agency (EPA) on delineating the so‐called Area of Review (AoR) for the permitting of geologic carbon sequestration (GCS) projects. According to the EPA's regulatory framework for GCS, the AoR refers to the region surrounding the CO2 injection well(s) wherein leakage of CO2 and/or the migration of formation fluids could possibly endanger overlying groundwater resources. Our evaluation of the current framework for delineating the size of this area finds unnecessary conservatism in the definition of the critical pressure, which could lead to a heavy burden on permit applicants that seek to get regulatory compliance, in particular for very large GCS projects. We propose a risk‐based re‐interpretation of this framework, separating the total Area of Review into different sub‐areas with different regulatory requirements depending on whether the concern is about free‐phase CO2 or pressure‐driven brine migration. This leads to a tiered AoR definition in which the projected region of CO2 plume extent would have the highest regulatory standards regarding site characterization, monitoring, and corrective action. The requirements in the AoR outside this central region would be less burdensome because of a narrower focus on major pathways for brine leakage such as unplugged wellbores and large faults. We expect that this revised framework would allow for a reduction in the cost of regulatory compliance for projects with very large injection volumes, while ensuring that the objective of protecting valuable groundwater resources is preserved.

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Wellbore Permeability Estimates from Vertical Interference Testing of Existing Wells

Cited by 42 publications

References 12 publications

Numerical investigation of methane and formation fluid leakage along the casing of a decommissioned shale gas well

Numerical investigation of methane and formation fluid leakage along the casing of a decommissioned shale gas well

Baseline integrity property measurement of legacy oil and gas wells for carbon storage projects

A tiered area‐of‐review framework for geologic carbon sequestration

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