Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds

Zhang, Yanhua; Underschultz, Jim; Langhi, Laurent; Mallants, Dirk; Strand, Julian

doi:10.1016/j.coal.2018.05.008

Cited by 14 publications

(7 citation statements)

References 43 publications

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“…The loss of signal in the center of these subsidence areas is probably due to the displacement, being too large to be detected by MT-InSAR with the C-band Sentinel-1 data. This conforms to the mining-induced displacement field which presents a bowlshaped subsidence pattern, as observed in other studies (He et al, 1994;Litwiniszyn, 1956;Zhu et al, 2020). The dense fringes, i.e., strong deformation, suggests active underground mining just below this subsidence basin (referred to as primary subsidence basin and denoted by ellipses in Fig.…”

Section: Correlation Between Ground Deformation and Groundwater Withdrawsupporting

confidence: 90%

Assessments of land subsidence along the Rizhao–Lankao high-speed railway at Heze, China, between 2015 and 2019 with Sentinel-1 data

Zhu

Motagh

et al. 2020

Nat. Hazards Earth Syst. Sci.

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Abstract. The Heze section of Rizhao–Lankao high-speed railway (RLHR-HZ) has been under construction since 2018 and will be in operation by the end of 2021. However, there is a concern that land subsidence in the Heze region may affect the regular operation of RLHR-HZ. In this study, we investigate the contemporary ground deformation in the region between 2015 and 2019 by using more than 350 C-band interferograms constructed from two tracks of Sentinel-1 data over the region. The small baseline subset (SBAS) technique is adopted to compile the time-series displacement. We find that the RLHR-HZ runs through two main subsidence areas: one is located east of the Heze region with rates ranging from −4 to −1 cm yr−1, and another one is located in the coalfield with rates ranging from −8 to −2 cm yr−1. A total length of 35 km of RLHR-HZ is affected by the two subsidence basins. Considering the previous investigation and the monthly precipitation, we infer that the subsidence bowl east of the Heze region is due to massive extraction of deep groundwater. Close inspections of the relative locations between the second subsidence area and the underground mining reveals that the subsidence there is probably caused by the groundwater outflow and fault instability due to mining, rather than being directly caused by mining. The InSAR-derived ground subsidence implies that it is necessary to continue monitoring the ground deformation along RLHR-HZ.

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Section: Correlation Between Ground Deformation and Groundwater Withdrawsupporting

confidence: 90%

Assessments of land subsidence along the Rizhao–Lankao high-speed railway at Heze, China, between 2015 and 2019 with Sentinel-1 data

Zhu

Motagh

et al. 2020

Nat. Hazards Earth Syst. Sci.

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“…The deformation of the surrounding rock of the roadway https://doi.org/10.56578/gsi010102 shows asymmetric characteristics such as time non-uniformity and spatial asymmetry. Especially after entering the deep mining, the deep nonlinear mechanical system [4] and surrounding rock stability are related to the dip angle of the coal seam, the length of the shear plane and the physical and mechanical parameters of the coal and rock mass [5]. Zhou et al [6] established the instability model of the upper coal mass by using the Bishop algorithm, and deduced the calculation formula of the stability safety factor of the upper coal mass.…”

Section: Introductionmentioning

confidence: 99%

Asymmetrical Deformation Mechanisms in Layered Inclined Surrounding Rock of Roadways

Tan,

Zhan,

Zhen

et al. 2023

GSI

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In the context of layered inclined surrounding rock in roadways, this study presents a comprehensive analysis focusing on the asymmetrical deformation characteristics inherent to such geological structures. The intersection of layered surrounding rock with roadways forms the basis for constructing a deformation partition model, encompassing distinct sub-regions around the roadway. This model facilitates a detailed mechanical analysis, wherein the stress exerted on rock formations within each sub-region is meticulously examined. Consequently, specific mechanical formulas correlating to the stress in different sub-regions are established. This approach yields insights into the failure modes of the layered surrounding rock across various sub-regions. Notably, the roadway's high side predominantly exhibits tensile failure, whereas the low side is characterized by shear failure. The application of the Goodman model enables a simulation of interlayer slip occurring between the surrounding rock of the roadway, distributed across different partitions. This study delineates the deformation of the layered inclined surrounding rock road-way as a process with pronounced temporal characteristics. The progression of deformation and failure in the surrounding rock typically initiates at the tangent point between the roadway roof and the rock layer, extending to the roadway floor, the high-top bottom angle, and subsequently the low-top bottom angle. This sequence culminates in the development toward the high-top shoulder angle. The research further establishes a direct correlation between the onset of asymmetrical deformation and the angle of shear stress on the roadway surface relative to the inclination of the rock formation; a smaller angle precipitates an earlier onset of this deformation.

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“…Currently, a multibranch horizontal well has been applied to coal-bed methane mining in Guizhou. Multibranch horizontal well mining technology integrates drilling, completion, and stimulation and is suitable for low permeability CBM mining. − This mining technology can reduce the pressure of the coal reservoir, promote the change of the in situ stress field and fracture field of the coal seam, , and form a favorable channel for desorption and seepage of CBM to improve gas production. It is suitable for thick coal seams with simple structural and hydrogeological conditions.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Porosity and Permeability Change of High-Rank Coal under Cyclic Loading and Unloading

Yang

Liu

et al. 2022

ACS Omega

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It is of great significance to study the evolution law and change characteristics of the porosity and permeability of coal under cyclic disturbance to efficiently exploit coal-bed methane (CBM). In this paper, the GCTS rock mechanics experimental system is applied, the unsteady gas seepage test under cyclic loading and unloading is carried out with high-grade coal samples from Zhijin County, Guizhou Province, as the research object, and the mathematical formula of the dynamic change of porosity during loading and unloading is established. The results show that (1) the porosity and permeability parameters of coal are negatively correlated with confining pressure, and all decrease with the increase in confining pressure; (2) the change rate of the porosity and permeability of bedding coal decreases gradually with the increase in stress, and the porosity and permeability under high stress decrease gradually with the increase in cycle times; (3) during cyclic loading and unloading, the permeability loss ( D k ) of coal mainly occurs in the first loading (>90%), and D k gradually decreases with the increase in cyclic times; (4) under the same test conditions, the evolution law of the porosity and permeability of parallel bedding coal and vertical bedding coal is similar but the stress sensitivity of vertical bedding coal is higher; (5) the circumferential strain of parallel bedding coal is higher than that of vertical bedding coal, and the porosity change and permeability loss show a specific bedding effect; and (6) under the action of cyclic stress, the change of strain–permeability of coal is abnormal after it is destroyed. With the increase in strain before the sample is destroyed, the permeability drops sharply, and after the sample is destroyed, the strain decreases and the permeability never recovers. The research results can provide favorable theoretical guidance and technical support for pressure relief exploitation of coal-bed methane, such as multibranch horizontal wells.

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Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds

Abstract: Strand , Numerical modelling of coal seam depressurization during coal seam gas production and its effect on the geomechanical stability of faults and coal beds.

Cited by 14 publications

References 43 publications

Assessments of land subsidence along the Rizhao–Lankao high-speed railway at Heze, China, between 2015 and 2019 with Sentinel-1 data

Assessments of land subsidence along the Rizhao–Lankao high-speed railway at Heze, China, between 2015 and 2019 with Sentinel-1 data

Asymmetrical Deformation Mechanisms in Layered Inclined Surrounding Rock of Roadways

Experimental Study on the Porosity and Permeability Change of High-Rank Coal under Cyclic Loading and Unloading

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