Features of Coal Pore & Fracture in Chuandong and their Relationship with Extra-Low Permeability

Abstract:

The comparative datas from home and abroad indicate that extra-low permeability of coal seam is the basic reason why the gas outbursts obviously demonstrate three features in Chuandong. Further analysis on the microstructure of coal pore and fracture show that, firstly，the quantity of micro pores is much more than that of macro pores; the total volume of the pores is large while the volume of interconnected pores is small. This is helpful to gas storage but going against gas flow. Secondly, fracture density varys with magnification; there are many short fractures but only a few long fractures; all of the fractures are similar in width and in the form of zigzag; the directivity of fracture extension is irregular. Thirdly, fracture fillings are mainly hard inorganic matters. It is put forward that both pressure sensitive effect and water sensitivity effect exist in the coal seam and they are "double-edged swords" to permeability. In order to increase the permeability, it is necessary to change passive exhausting into active driving, remove gas reservoir and provide the passageway for gas dissipation.

• Periodical: Advanced Materials Research (Volumes 594-597)
• Pages: 2636-2639
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.594-597.2636
• Online since: November 2012
• Authors: Fei Mao, Jian Xin Tang, Jiao Jiao Peng, Zhi Qiang Li
• Keywords: Coal Gas, Extra-Low Permeability, Fracture, Pore, Pressure Sensitive Effect, Water Sensitivity Effect

References

[1] Qianting Hu. Devoting to safety science and technology and promoting life guarantee[C].Chongqing: Prevention and control technology of gas disaster in coal mine, 2009, 3-10.

[2] Díaz Aguado María B., González Nicieza C. Control and prevention of gas outbursts in coal mines, Riosa-Olloniego coalfield, Spain[J]. International Journal of Coal Geology, 2007,69(4): 253-266.

DOI: 10.1016/j.coal.2006.05.004

[3] Guan Ping, Wang Haoyue, Zhang Youxue. Mechanism of instantaneous coal outbursts [J]. Geology, 2009, 37(10):915-918.

DOI: 10.1130/g25470a.1

[4] Panova O.A. Pryvalov V.A. Izart A., et al. Geodynamical events (coal-and-gas outbursts) in the Donets Basin, Ukraine[J].Society of Petroleum Engineers-71st European Association of Geoscientists and Engineers Conference and Exhibition , 2009,2: 753-757.

DOI: 10.3997/2214-4609.201400154

[5] FedorovA.V., FedorchenkoI.A. Mathematical modeling of methane flow in coal beds [J]. Journal of Mining Science, 2009, 45(1): 9-21.