Coal and Coalbed Methane Co-Extraction Technology Based on the Ground Movement in the Yangquan Coalfield, China

Hu, Guozhong; Xu, Jialin; Fu-xi, Zhang; Zhao, Changsui; Qin, Wei; Zhu, Yun

doi:10.3390/en8076881

Cited by 24 publications

(17 citation statements)

References 16 publications

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“…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%

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%

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

2016

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“…[36][37][38] Section 2.3 refers to the theoretically determined approximate scope of km borehole layout. Therefore, to promote the gas drainage, it is necessary to put up a fine division of the strata above the gob.…”

Section: Strata Division and Layout Parameters Of The Layoutmentioning

confidence: 99%

A new pattern of underground space‐time tridimensional gas drainage: A case study in Yuwu coal mine, China

Nie

et al. 2019

Energy Science & Engineering

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With the increase of mining depth, the high gassy coal mine confronts with a variety of gas problems, such as gas concentration exceeding the limit in the working face, gas outburst and gas explosion. According to the situation of gas drainage in Qinshui Basin (South of Shanxi Province, China) and enlightened by horizontal directional drillings (HDD) and multi‐branched horizontal wells, a new gas drainage pattern that inverted π‐shape km borehole layout was proposed. Verified in Yuwu Coal Mine, the gas drainage data were standardized via the unified theory of standardization. It could dropped the coal seam gas content to 7.71 m3/t, and increased the gas drainage rate to 34.2%, which conformed to the Chinese regulation (<8 m3/t, >30%, respectively). This pattern has a significant effect on coal mines with a single seam, where protective seam mining technology was unsuitable to prevent gas outburst and gas explosion.

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“…In 2015, underground CBM production was 13.6 billion cubic meters, accounting for 76% of the total CBM recovered in China [1]. The CBM reservoirs in Chinese mines are characterized by low saturation, low permeability, low reservoir pressure, and relatively high metamorphic grade [2]. The production of CBM from this kind of reservoir is a worldwide problem, and it is also the main difficulty in the development of Chinese CBM extraction.…”

Section: Introductionmentioning

confidence: 99%

A New Tree-Type Fracturing Method for Stimulating Coal Seam Gas Reservoirs

et al. 2017

Energies

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Hydraulic fracturing is used widely to stimulate coalbed methane production in coal mines. However, some factors associated with conventional hydraulic fracturing, such as the simple morphology of the fractures it generates and inhomogeneous stress relief, limit its scope of application in coal mines. These problems mean that gas extraction efficiency is low. Conventional fracturing may leave hidden pockets of gas, which will be safety hazards for subsequent coal mining operations. Based on a new drilling technique applicable to drilling boreholes in coal seams, this paper proposes a tree-type fracturing technique for stimulating reservoir volumes. Tree-type fracturing simulation experiments using a large-scale triaxial testing apparatus were conducted in the laboratory. In contrast to the single hole drilled for conventional hydraulic fracturing, the tree-type sub-boreholes induce radial and tangential fractures that form complex fracture networks. These fracture networks can eliminate the "blank area" that may host dangerous gas pockets. Gas seepage in tree-type fractures was analyzed, and gas seepage tests after tree-type fracturing showed that permeability was greatly enhanced. The equipment developed for tree-type fracturing was tested in the Fengchun underground coal mine in China. After implementing tree-type fracturing, the gas extraction rate was around 2.3 times greater than that for traditional fracturing, and the extraction rate remained high for a long time during a 30-day test. This shortened the gas drainage time and improved gas extraction efficiency.

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Coal and Coalbed Methane Co-Extraction Technology Based on the Ground Movement in the Yangquan Coalfield, China

Cited by 24 publications

References 16 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

A new pattern of underground space‐time tridimensional gas drainage: A case study in Yuwu coal mine, China

A New Tree-Type Fracturing Method for Stimulating Coal Seam Gas Reservoirs

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