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Li M.,China University of Mining and Technology | Li M.,Key Laboratory of Coalbed Methane Resources and Reservoir Forming | Li M.,University of Waterloo | Jiang B.,China University of Mining and Technology | And 8 more authors.
Mining Science and Technology | Year: 2011

To evaluate the effect of tectonic deformation on coal reservoir properties, we provide an analysis of the types of tectonically deformed coal, macro- and microscopic deformation and discuss pore structural characteristics and connectivity based on samples from the Puhe and Shanchahe coal mines. Our research shows that the tectonically deformed coal mostly includes cataclastic structural coal, mortar structural coal and schistose structural coal of a brittle deformation series. The major pore structures of different types of tectonically deformed coal are transitional pores and micropores. The pore volumes of macropores and visible fracture pores produced by structural deformations vary over a large range and increase with the intensity of tectonic deformation. Mesopores as connecting passages develop well in schistose structural coal. According to the shapes of intrusive mercury curves, tectonically deformed coal can be divided into parallel, open and occluded types. The parallel type has poor connectivity and is relatively closed; the open type reflects uniformly developed open pores with good connectivity while the occluded type is good for coalbed methane enrichment, but has poor connectivity between pores. © 2011 Published by Elsevier B.V. on behalf of China University of Mining & Technology.

Li Y.B.,China University of Mining and Technology | Li Y.B.,Key Laboratory of Coalbed Methane Resources and Reservoir Forming | Jiang B.,China University of Mining and Technology | Jiang B.,Key Laboratory of Coalbed Methane Resources and Reservoir Forming | And 2 more authors.
Science China Earth Sciences | Year: 2014

Tectonically deformed coal (TDC) develops because of the superimposed deformation and metamorphism of a coal seam by tectonic movements. The migration and accumulation of trace elements in TDC is largely in response to stress-strain conditions. To develop a law governing the migration and aggregation of sensitive elements and investigate the geological controls on TDC, coal samples from different deformation sequences were collected from the Haizi mine, in the Huaibei coalfield in Anhui Province, China, and the concentrations of 49 elements were determined by XRF and ICP-MS, and then microscopically analyzed. The results show that the distribution and morphology of minerals in coal is related to the deformation degree of TDC. The evolutionary process runs from orderly distribution of minerals in a weak brittle deformed coal to disordered distributions in ductile deformed coal. According to the elemental distribution characteristics in TDC, four types of element migration can be identified: stable, aggregate, declining, and undulate types, which are closely related to the deformation degree of TDC. Present data indicate that the overall distribution of rare earth elements (REE) does not change with metamorphism and deformation, but it shows obvious dynamic differentiation phenomena along with the deformation of TDC. Tectonic action after coal-formation, brittle or ductile deformation, and the metamorphic mechanism and its accompanying dynamic thermal effects are the main factors that influence the redistribution of elements in TDC. We conclude that tectonic movements provide the motivation and basis for the redistribution of elements and the paths and modes of element migration are controlled by brittle and ductile deformation metamorphic processes. The dynamic thermal effect has the most significant effect on coal metamorphism and tectonic-stress-accelerated element migration and accumulation. These factors then induce the tectonic-dynamic differentiation phenomenon of element migration. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg.

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