Study of the effects of hydraulic fracturing at different dip angles for the development of coalbed methane: a case study in the southeast part of Qinshui Basin, China

Zhang, Qian; Huang, Wenhui; Hu, Zhazha; Zhou, Hongpu; Lu, Xiaofan; Lin, Kunqi; Xia, odong

doi:10.1504/ijogct.2017.081101

Cited by 6 publications

(4 citation statements)

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“…Hydraulic fracturing not only has a role in the exploitation of coalbed methane but also has been more widely utilized to improve permeability and eliminate coal and methane outbursts in gassy coal seams (Lu et al., 2015; Ma et al., 2016; Wang et al., 2017; Xu et al., 2017; Zhai et al., 2015; Zhang et al., 2017). When water injection or hydraulic fracturing is conducted in high gassy coal seams, methane concentration of the air current in the air-return roadway will rise.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Huang

Chen

et al. 2020

Adsorption Science & Technology

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During hydraulic fracturing in a high-methane coal seam, there is a water-displacing-methane effect. A pseudo triaxle experimental system, which is opposite to the name of true triaxial system, for the water-displacing-methane effect was created. First, cylindrical coal samples in a methane adsorption equilibrium state, spontaneously desorbed. And then water was injected into the coal samples. The following was shown: (1) The displacement methane volume gradually rises with an increase of injected water, while the displacement methane rate tends to rise at first before declining later. Simultaneously, the water-displacing-methane process is characterised by a time effect. The methane displacement lags behind water injection. (2) Competitive adsorption and displacement desorption between the water and methane will promote adsorption methane into free methane, while the pore pressure increase caused by water injection will turn free methane into adsorption methane. The net free methane of the combination action provides a methane source for the water-displacing-methane effect. (3) A pore pressure gradient, which provides a power source for the water-displacing-methane effect, is formed and reduces gradually at the front of the water seepage along the seepage direction. The increase in water pressure can rapidly improve the pore pressure gradient and boost the displacement methane volume as well as improve displacement methane efficiency. (4) A starting porosity pressure gradient and limit pore pressure exist in the process of water-displacing-methane. When the pore pressure gradient is less than the starting pore pressure gradient, there is free methane in the coal rock, but it cannot be displaced. When the pore pressure is between the starting pore pressure and the limit pore pressure, the free methane can be displaced. When the pore pressure is greater than the limit pore pressure, the methane is almost completely adsorption methane, and water cannot be used to displace the free methane.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Huang

Chen

et al. 2020

Adsorption Science & Technology

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“…Then another improved measuring method using a cubic shale sample in a triaxial cell was implemented in the research of shale . Simultaneously, some anisotropic permeability models of coal considering the adsorption-induced swelling effects were established; − moreover, the roles of effective stress variation, thermal swelling, and water saturation on coal were also elaborated. , And practical significance of anisotropic permeability on the optimal design of a multilateral well for coal bed methane production was emphasized. , …”

Section: Introductionmentioning

confidence: 99%

“…43,44 And practical significance of anisotropic permeability on the optimal design of a multilateral well for coal bed methane production was emphasized. 45,46 Apparently, the anisotropic characteristics of coal seams increase enormous challenges for primary and enhanced methane recovery. Though the anisotropic swelling and permeability have received due attention to a certain extent, studies of three-dimensional swelling (face cleat, butt cleat, and bedding plane) and interrelated permeability are lacking, especially for physical simulation research, because it is challenging to design such experiments.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO₂ in Coal

et al. 2018

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The changes of anisotropic adsorption–swelling and permeability with injecting CO2 in coal influence the CO2 injectivity during CO2-ECBM or CGS (ECBM = enhancing coal bed methane; CGS = CO2 geological sequestration). To strengthen the understanding of this issue, two special-made cubic coal samples were adopted to test the porosity, swelling, and permeability in parallel face cleat and bedding plane direction, parallel butt cleat and bedding plane direction, and vertical bedding plane direction. To quantitatively characterize the anisotropic porosity, anisotropic swelling, and anisotropic permeability, an anisotropy index was introduced in this work. The results show that porosity anisotropy reflects the pore connectivity in different directions, which fall in the order of parallel face cleat and bedding plane direction > parallel butt cleat and bedding plane direction > vertical bedding plane direction. The porosity varieties can be owed to the compaction effect, thermal evolution effect, banded structure, and cleat distribution in coal seams. The maximum swelling ratios of the vertical bedding plane direction to the parallel bedding plane direction are 2.30 in sample 1 and 1.89 in sample 2. However, the ratios of parallel face cleat to parallel butt cleat are 1.28 in sample 1 and 1.30 in sample 2. The inhomogeneity of matter composition in the vertical bedding direction and the difference of cleat distribution in various coal bands mainly cause the anisotropic swelling. Both injecting CO2 in coal and raising its temperature increase the anisotropy swelling index, but the effect of thermal swelling is quite weak. Adsorbing CO2 especially for supercritical CO2 will enhance the permeability anisotropy of coal. This is because the low-permeability cleat possesses higher permeability adsorption sensitivity and the bedding plane fracture with higher permeability instead does not produce a pronounced permeability drop because of its lower permeability adsorption sensitivity. Cleats that are easily affected by adsorption–swelling always serve as throats between fractures and the coal matrix in a high-anisotropic coal, which will restrain CO2 flow in coal pores. Accordingly, cleat seepage and corresponding potential enhanced permeability measures deserve being paid enough attention to in future research. This work clarifies the understanding and offers some implications for CO2 injecting into coal seams from the perspective of anistropic properties of coal.

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“…Several factors altered the importance of this technology which the affordability and the ubiquity use of recent innovation in the technological tools in the drilling and exploration industries especially in the well construction processes and the recovery of gas regarding the massive volume of natural gas sources worldwide. Thereby, this recent and harnessing technologies revolutionize the way petroleum industries drill oil and gas reservoirs along the coming decades [1][2][3][4][5][6]. However, reservoir characteristics and the wrong orientation in the design of the hydraulic fracturing operations make the fractures inefficient and they squander vast sums of money for operating the procedures.…”

Section: Introductionmentioning

confidence: 99%

Application of Fuzzy Analytical Hierarchy Process (FAHP) for Selecting the Suitable Hydraulic Fracturing Method in Oil Recovery Enhancement

2018

International Journal of Petroleum and Petrochemical Engineerin

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Study of the effects of hydraulic fracturing at different dip angles for the development of coalbed methane: a case study in the southeast part of Qinshui Basin, China

Cited by 6 publications

References 0 publications

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO₂ in Coal

Application of Fuzzy Analytical Hierarchy Process (FAHP) for Selecting the Suitable Hydraulic Fracturing Method in Oil Recovery Enhancement

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Study of the effects of hydraulic fracturing at different dip angles for the development of coalbed methane: a case study in the southeast part of Qinshui Basin, China

Cited by 6 publications

References 0 publications

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO2 in Coal

Application of Fuzzy Analytical Hierarchy Process (FAHP) for Selecting the Suitable Hydraulic Fracturing Method in Oil Recovery Enhancement

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Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO₂ in Coal