Discrete Fracture Modeling of 3D Heterogeneous Enhanced Coalbed Methane Recovery with Prismatic Meshing

Zhang, Yongbin; Gong, Bin; Li, Junchao; Li, Hangyu

doi:10.3390/en8066153

Cited by 24 publications

(14 citation statements)

References 41 publications

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“…However, according to previous studies [1][2][3]6,[8][9][10][11][12], this CO 2 -ECBM process leads to CO 2 adsorption-induced coal matrix alterations, which in turn affect its hydro-mechanical properties. Particularly in the geomechanical respect, the coal mass becomes weaker with the substitution of existing adsorbate CH 4 with the highly chemically potential CO 2 [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…The process of enhanced coal bed methane (ECBM) recovery is being implemented and tested as a viable option to store and reduce the amount of anthropogenic carbon dioxide (CO 2 ) in the Earth's atmosphere, as well as for the recovery of useful coal bed methane (CH 4 ) gas [1][2][3][4][5][6][7]. Overall, the ECBM process involves introducing CO 2 through injecting wells into deep coal seams and this CO 2 then acts as a displacing gas, which allows the already adsorbed CH 4 to be desorbed from the coal matrix.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

2016

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During CO 2 sequestration in deep coal seams, the coal mass may be subjected to various fluid (CO 2 , N 2 , etc.) saturations. Therefore, in order to maintain the long-term integrity of the process, it is necessary to identify the mechanical responses of preferable coal seams for various fluid saturations. To date, many studies have focused on the CO 2 saturation effect on coal mass strength and less consideration has been given to the influence of other saturation mediums. Hence, this study aims to investigate coal's mechanical responses to water and N 2 saturations compared to CO 2 saturation and to determine the effect of coal-rank. A series of unconfined compressive strength (UCS) tests was conducted on Australian brown and black coal samples saturated with water and N 2 at various saturation pressures. An advanced acoustic emission (AE) system was utilized to identify the changes in crack propagation behaviors under each condition. According to the results, both CO 2 and water act similarly with coal by enhancing the ductile properties of the coal mass and this mechanical weakening is greater for high-rank coal. Conversely, N 2 saturation slightly enhances coal strength and delays crack propagation in coal and this strength enhancement can be improved by increasing the N 2 saturation pressure.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

2016

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“…CBM production and CO 2 sequestration is very difficult for the reservoir with less understanding of gas transport phenomena (Swami and Settari, 2012). Importance of fluid transport and its impact on mechanical properties of coal bed have been studied elsewhere (Xiao et Zhang et al, 2015). Diffusion of methane from the matrix and flow through the natural cracks (fractures and cleats) leads deformation in coal bed (Zhao and Jin, 1994;Wang et al, 2013;.…”

Section: Introductionmentioning

confidence: 99%

“…It comprises 95% pure methane with calorific value 8500 Kcal/g (Zhang et al, 2015;Ojha et al, 2011). It is one of the promising technologies to fulfil the rapid increasing demand of energy.…”

Section: Introductionmentioning

confidence: 99%

3D Modelling of Coal Deformation under Fluid Pressure using COMSOL Multiphysics

Kumar¹,

Mishra²,

Mishra³

2017

JESTR

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Gas transportation in coal bed is a complex physical process. The Adsorption/desorption process is associated with migration of gas in coal. Adsorption/desorption of CO 2 /CH 4 in coal bed includes diffusion of gas from coal matrix and its flow through natural fractures. Therefore, it is necessary to have a clear concept of the flow behavior of gas in coal bed for successful coal bed methane (CBM) production and carbon dioxide sequestration. Flow of gas through natural cracks results in deformation of coal bed. Injection of CO2 in enhanced coal bed methane (ECBM) depends on the permeability and fluid flow behavior.Deformation in solid coal induced by fluid pressure during CBM and ECBM process is still not clearly understood. Numerical models and Multiphysics are dominant in modelling of complex study of flow induced deformation. Such modelling is required for detailed understanding of deformation as well as flow parameters. In this study 3D model of fractured coal core was developed. The deformation in coal core at multiple injected fluid pressures was analysed. Geo-mechanical parameters (Stress, Strain, Deformation, Pore pressure and Darcy's Velocity etc.) were determined at varying injection pressures. The relations between different Geo-mechanical parameters were established using a statistical approach.

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“…The surface well drilling method has been widely used in many developed countries, such as the USA, Canada, and Australia. However, the main method in China is underground gas drainage in order to recover gas and coal simultaneously [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Research on and Design of a Self-Propelled Nozzle for the Tree-Type Drilling Technique in Underground Coal Mines

Zhou

et al. 2015

Energies

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Due to the increasing depths of coal mines and the low permeability of some coal seams, conventional methods of gas drainage in underground mines are facing many problems. To improve gas extraction, a new technique using water jets to drill tree-type boreholes in coal seams is proposed. A self-propelled water-jet drilling nozzle was designed to drill these boreholes. The configuration of the self-propelled nozzle was optimized by conducting drilling experiments and self-propelling force measurements. Experimental results show that the optimal self-propelled nozzle has a forward orifice axial angle at 25˝, a radial angle at 90˝, a center distance of 1.5 mm, and backward pointing orifices with an axial angle of 25˝. The self-propelling force generated by the jets of the nozzle with 30 MPa pump pressure can reach 29.8 N, enough to pull the hose and the nozzle forward without any external forces. The nozzle can drill at speeds up to 41.5 m/h with pump pressures at 30 MPa. The radial angles of the forward orifices improve the rock breaking performance of the nozzle and, with the correct angle, the rock breaking area of the orifices overlap to produce a connecting hole. The diameter of boreholes drilled by this nozzle can reach 35.2 mm. The nozzle design can be used as the basis for designing other self-propelled nozzles. The drilling experiments demonstrate the feasibility of using the tree-type drilling technique in underground mines.

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Discrete Fracture Modeling of 3D Heterogeneous Enhanced Coalbed Methane Recovery with Prismatic Meshing

Cited by 24 publications

References 41 publications

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

3D Modelling of Coal Deformation under Fluid Pressure using COMSOL Multiphysics

Research on and Design of a Self-Propelled Nozzle for the Tree-Type Drilling Technique in Underground Coal Mines

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