Critical Conditions for Coal Wellbore Failure During Primary Coalbed Methane Recovery: A Case Study from the San Juan Basin

Fang, Huang; Kang, Yili; Liu, Hongyuan; You, Lijun; Li, Xiangchen

doi:10.1007/s00603-019-01825-5

Cited by 7 publications

(6 citation statements)

References 68 publications

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“…Additionally, an appropriate shear failure criterion for wellbore stability should be applied for coal failure evaluation. The Mogi-Coulomb failure criterion, considering the effect of intermediate principal stress, can match well with field data [14,16,29]. In this study, the Mogi-Coulomb failure criterion is used to forecast coal failure during CO 2 -ECBM [14].…”

Section: Failure Criterionmentioning

confidence: 86%

“…(2) A steady reservoir pressure profile changing logarithmically from a constant borehole pressure at the wellbore (r w ) to a reservoir pressure p res at the outer boundary (r b ); (3) Gas injection can occur after depletion, in which case the reservoir pressure is unequal to the initial value before depletion (p res = p 0 ); (4) A zero displacement at the outer boundary rather than each point (common uni-axial strain model) in the reservoir [15]; (5) A plane strain condition near the wellbore and a constant overburden σ zz far from the wellbore [14]; (6) At the final steady state, uniform gas composition of the injected gas is achieved.…”

Section: Simplifications and Assumptionsmentioning

confidence: 99%

“…According to the classical Kirsch solution, the stress distribution around the wellbore for a vertical wellbore is given as [14,24,25]…”

Section: Mode 1: Stresses Induced By the Initial In-situ Stress And B...mentioning

confidence: 99%

“…Furthermore, shear failure in the reservoir formation is promoted by near-wellbore stress concentration [13]. In addition, local wellbore failure occurred before reservoir-scale coal failure [14]. So, a basis for the safe CO 2 -ECBM or sequestration is wellbore stability rather than coal stability, and it can provide an upper limit for CO 2 storage capacity.…”

Section: Introductionmentioning

confidence: 99%

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Critical Conditions for Wellbore Failure during CO2-ECBM Considering Sorption Stress

Xiao

Wang

et al. 2023

Sustainability

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Significant stress changes caused by sorption-induced swelling raise the coal wellbore failure potential, which directly impacts the safety and sustainability of CO2 enhanced coalbed methane (CO2-ECBM). Additionally, a mixture gas (CO2/N2) injection is recommended due to the sharp decline of permeability with pure CO2 injection. In this study, incorporating the impacts of mixture gas adsorption and poroelastic effects, a semi-analytical model of coal wellbore stability during mixture gas injection is proposed. Model results indicate that the stress field is significantly influenced by the boundary condition and sorption effect. In addition, parametric studies are performed to determine the influence of adsorption parameters, mechanical properties, and gas composition on the stress distribution and then on the wellbore failure index. Furthermore, mixture gas injection with a large proportion of CO2 or N2 both cause wellbore instability. Significant compressive hoop stress and shear failure are caused by the mixture gas injection with a large proportion of CO2. In contrast, the displacement of CH4 with weakly adsorptive N2 will result in less compressive and shear or tensile failure, which occurs near the wellbore. Thus, mixture gas (including pure CO2/N2) injection must be controlled by coal wellbore failure, providing an accurate estimation of in-situ coal seams’ CO2 storage capacity from the perspective of wellbore stability.

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Section: Failure Criterionmentioning

confidence: 86%

Section: Simplifications and Assumptionsmentioning

confidence: 99%

“…According to the classical Kirsch solution, the stress distribution around the wellbore for a vertical wellbore is given as [14,24,25]…”

Section: Mode 1: Stresses Induced By the Initial In-situ Stress And B...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Critical Conditions for Wellbore Failure during CO2-ECBM Considering Sorption Stress

Xiao

Wang

et al. 2023

Sustainability

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“…CBM reservoirs consist of relatively low-strength, weakly cemented, and fragile rocks . Under the effects of tectonic events, drilling, fracturing, and production, coal rock is susceptible to failure, resulting in the formation of a massive amount of coal fines. − During the process of CBM recovery, hydrodynamic and/or capillary forces are exerted on in situ coal fines. , When the incipient motion condition of coal fines is satisfied, coal fines get detached from the channel surface and are entrained by the fluid. − The transport channels in CBM reservoirs can be divided into the following three types: natural cleats/fractures, propped fractures, and boreholes. Transport and retention of coal fines in natural and propped fractures can block flow paths, reduce the fracture conductivity, and therefore lead to a decline in CBM productivity (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Effects of Proppant Wettability and Size on Transport and Retention of Coal Fines in Saturated Proppant Packs: Experimental and Theoretical Studies

et al. 2021

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Hydraulic fracturing is the main stimulation technique that enables the economic production of coalbed methane reservoirs. However, massive invasion and retention of coal fines in proppant packs can clog the pore spaces and lead to an impairment of fracture conductivity. In this study, the effects of proppant wettability and size on retention of coal fines in proppant packs during the dewatering stage were investigated, for their optimization to achieve a long-term and effective control of fines retention. First, a series of transport and retention experiments of coal fines were performed on saturated proppant packs with different proppant sizes and wettabilities. Herein, standard quartz sand was used as the proppant carrier, and its surface wettability was modified to either hydrophobicity or stronger hydrophilicity by treatment with fluorocarbon resin and piranha solution, respectively. The experimental results indicated that both the retained amount and the deposition rate coefficient of coal fines decreased with increasing proppant hydrophilicity (or decreasing proppant hydrophobicity) and size. For the proppants treated with piranha solution, almost no coal fines were retained in proppant packs. Second, the forces/torques acting on coal fines in the vicinity of proppants were analyzed to elucidate the underlying mechanisms responsible for the influence of proppant wettability and size on fines retention. The effective filter surface (EFS) parameter was estimated by analyzing forces/torques to evaluate the filtration performance of proppant packs. Theoretical results illustrated that the EFS value decreased with increasing proppant hydrophilicity and size. The EFS value for proppants treated with piranha solution was near zero, which was due to the chemically "unfavorable" retention condition induced by piranha solution treatment. The EFS exhibited a similar tendency to the retention of coal fines observed in experiments, which validated the model. Finally, the recommendations on fines retention control in proppant packs were provided.

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Short- and Long-term Wellbore Stability Analysis for a Horizontal Well in a Transversely Isotropic Poroelastic Formation

Lu,

Li,

Jin

et al. 2024

Rock Mech Rock Eng

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Critical Conditions for Coal Wellbore Failure During Primary Coalbed Methane Recovery: A Case Study from the San Juan Basin

Cited by 7 publications

References 68 publications

Critical Conditions for Wellbore Failure during CO2-ECBM Considering Sorption Stress

Critical Conditions for Wellbore Failure during CO2-ECBM Considering Sorption Stress

Effects of Proppant Wettability and Size on Transport and Retention of Coal Fines in Saturated Proppant Packs: Experimental and Theoretical Studies

Short- and Long-term Wellbore Stability Analysis for a Horizontal Well in a Transversely Isotropic Poroelastic Formation

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