Excess Coalbed Methane Production Mechanism in the Process of Coal Tectonic Deformation

摘要

Source and occurrence of Excess Coalbed Methane is a long-term concernresearch topic in Coal Geology and Structural Geology. Since it is essential tounderstand the outburst mechanism of coal gas, and to support the coalbedmethane development projects as the theoretical basis. We found in the studythat, huge imparity is behind the evolutionary trend on molecular structure andthe mechanism of influence from different deformation. The thesis demonstratesits probable routes of gas evolution according to distinct deformationmechanisms of coal. In the role of brittle deformation mechanism, a rapidlyformed advantage rupture surface along with sliding motion from which hasworked on coal. As another result, mechanical energy has transformed intofriction and kinetic energy during the process. Kinetic energy increasessimultaneously, which brings some results, that the new generated gas molecule.While the chemical structure of coal remains in a steady-state and do not reacteasily an outburst with gas. Mechanical energy turns into strain energy throughits ductile deformation mechanism. The dislocation or lamellar slip madedisordered between the constitutional units of aromatic rings and aromaticlamellas, as soon as secondary structural defects created. On another hand,molecular motion accelerates and splits off the small molecular on the sidechain, due to the dissociation of aromatic nucleus; CH4? gas molecular was generated and placedin the secondary structural defect of coal, along with a great deal of strainenergy in non-steady-state. By breaking away the balance maintaining terms,huge strain energy releases suddenly, small moleculars are free from thesecondary structure defect, react outburst with gas. Furthermore to extend thediscussion of the conventional physical ideas on coal absorb gas, according tothe phenomenon of exceeded CBM, the gas molecular has a significant chance existingin a low bond energy of chemical bonds of coal structure.