Structure and coalbed methane occurrence in tectonically deformed coals

Research on structure of tectonically deformed coals (TDC) is a key issue in coal and gas outburst prevention and coalbed methane (CBM) exploitation. This paper presents a summary on the research progress in TDC’s structural-genetic classification, tectonic strain influence on coal microstructure, coal porosity system, coal chemical structure and constituents, and their relationship with the excess coalbed methane. Previous studies suggested that tectonic deformation had significant influence on coal microstructure, coal super microstructure, and even chemical macromolecular structure. The main mechanisms of coal deformation are the tectonic stress degradation and polycondensation metamorphism (dynamical metamorphism). Besides, under different deformation mechanisms, the ultra- and micro-structure and chemical constituents of TDC presented distinct characteristics. Based on these achievements, we propose one possible evolutionary trend of TDC with different deformation mechanisms, and suggest that the coal and gas outburst in the TDC, especially in the mylonitic coals, may be not only controlled by geological structure, but also influenced by the tectonic stress degradation of ductile deformation. Therefore, further study on TDC should be focused on the controlling mechanism of deformation on structure and composition of coal, generation conditions and occurrence state of excess coalbed methane from deformation mechanism of coal.

[1]  Y. Gensterblum,et al.  High-pressure methane and carbon dioxide adsorption on dry and moisture-equilibrated Pennsylvanian coals , 2002 .

[2]  D. White.  Metamorphism of Organic Sediments and Derived Oils , 1935 .

[3]  P. Hatcher,et al.  On the porous structure of coals: Evidence for an interconnected but constricted micropore system and implications for coalbed methane recovery , 1997 .

[4]  G. Wolff,et al.  Influence of temperature and pressure on maturation processes—I. Preliminary report , 1986 .

[5]  H. Kanoh,et al.  Cluster structures of supercritical CH4 confined in carbon nanospaces with in situ high-pressure small-angle X-ray scattering and grand canonical Monte Carlo simulation , 2004 .

[6]  R. Bustin,et al.  Vitrinite anisotropy under differential stress and high confining pressure and temperature: preliminary observations , 1986 .

[7]  B. Beamish,et al.  Coal microstructure and secondary mineralization: their effect on methane recovery , 1996, Geological Society, London, Special Publications.

[8]  Jiang Bo,et al.  13 C NMR spectra of tectonic coals and the effects of stress on structural components , 2005 .

[9]  Cheol-Min Yang,et al.  Highly Ultramicroporous Single‐Walled Carbon Nanohorn Assemblies , 2005 .

[10]  Yujiro Ogawa,et al.  Mechanism of methane flow through sheared coals and its role on methane recovery , 2003 .

[11]  Zhang Yu-gui,et al.  Investigation into coal-gas outburst occurred in Daping Coalmine, by using theories of gas-geology , 2005 .

[12]  Zhang Shouren,et al.  Influence of tectonic stress on coalification: Stress degradation mechanism and stress polycondensation mechanism , 2007 .

[13]  Yiwen Ju,et al.  New research progress on the ultrastructure of tectonically deformed coals , 2009 .

[14]  Y. Ogawa,et al.  Pore structure of sheared coals and related coalbed methane , 2001 .

[15]  Coal Microstructure and Micropermeability and Their Effects on Natural Gas Recovery , 1992 .

[16]  Jiang Bo,et al.  The new structure-genetic classification system in tectonically deformed coals and its geological significance , 2004 .

[17]  J. Rouzaud,et al.  Mechanisms of graphite formation from kerogen: experimental evidence , 1995 .

[18]  Zhang Wen-feng.  Elements distribution and effecting factors of high rank coals of different deformational-metamorphic types in Beihuaiyang area , 2006 .

[19]  L. K. Rixon,et al.  Outbursts and geological structures in coal mines: A review , 1981 .

[20]  Bo Jiang,et al.  Behavior and mechanism of the adsorption/desorption of tectonically deformed coals , 2009 .

[21]  A. Alexeev,et al.  Phase states of methane in fossil coals , 2004 .

[22]  Y. Ju,et al.  Relationship between nanoscale deformation of coal structure and metamorphic-deformed environments , 2005 .

[23]  Zhang Lin.  A New Kind of Mechanism for Hydrocarbon Generated ——Mechanochemistral function and experimental prove , 2000 .

[24]  A. Alexeev,et al.  Latent methane in fossil coals , 2004 .

[25]  J. Jian.  Study on XRD and dynamometamorphism of fault coal , 2001 .

[26]  Y. Ju,et al.  [FTIR spectroscopic study on the stress effect of compositions of macromolecular structure in tectonically deformed coals]. , 2005, Guang pu xue yu guang pu fen xi = Guang pu.

[27]  Wei Jian-ping,et al.  New genetic-texture-structure classification system of tectonic coal , 2009 .

[28]  M. Mastalerz,et al.  The effect of temperature, pressure and strain on carbonization in high-volatile bituminous and anthracitic coals , 1993 .

[29]  Yugui Zhang,et al.  The influence of tectonic deformation on some geochemical properties of coals—a possible indicator of outburst potential , 2003 .

[30]  Y. Ju,et al.  Comparison of coalbed gas generation between Huaibei-Huainan coalfields and Qinshui coal basin based on the tectono-thermal modeling , 2011 .

[31]  Wang Gui-liang.  Rheology of Coal Seams and Their Relation with Gas Outbursts:a Case Study of the Haizi Coal Mine, Huaibei Coalfield , 2002 .

[32]  R. Bustin,et al.  Vitrinite anisotropy resulting from simple shear experiments at high temperature and high confining pressure , 1997 .

[33]  W. Kneller,et al.  The use of dyes as an aid to coal petrography , 1984 .

[34]  M. Monthioux,et al.  Comparison between natural and artificial maturation series of humic coals from the Mahakam delta, Indonesia , 1985 .

[35]  Zhang Shou-ren.  Study on pyrogenation hydrocarbon generation character of deformed coal and undeformed coal , 2005 .

[36]  M. Mastalerz,et al.  The role of shear strain in the graphitization of a high-volatile bituminous and an anthracitic coal , 1993 .

[37]  Cao Yun-xing.  Deformed-coal structure and control to coal-gas outburst , 2007 .

[38]  Daming Wang,et al.  Deformation metamorphism of bituminous and anthracite coals from China , 2000 .