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Xu H.,Anhui University of Science and Technology | Sang S.,China University of Mining and Technology | Yi T.,Guizhou Bureau of Coal Geological Exploration | Zhao X.,Guizhou Bureau of Coal Geological Exploration | And 4 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2014

The distribution of mainable coal seams of NO.36 in Western Guizhou was obtained by hydraulic fracturing method to measure in-situ stress. The result shows that Liupanshui and Zhina coal field respectively belong to the high-middle stress area and middle stress area. The horizontal tectonic stress dominates absolutely, and the primary horizontal stress mainly aligns with north-west. It is also noticed that principal stresses all increase following a linear relationship as coal seam burial depth increases. The type of stress field transforms with 600, 750 and 1000 m in depth, and it manifests as dynamic stress field, quasi static stress field, geostatic stress field and quasi static stress field with the increase of depth. The studied area is in high stress background of extrusion influenced by collision of North India plate and Eurasia. The structure of sedimentary cover is controlled by fracture of "X" type, and some secondary fault block is formed, such as echelon structure and triangle structure. So, different combining forms of stress in fault block emerge, and the regional difference of the stress field distribution is displayed. Source

Wang H.,China University of Mining and Technology | Wang H.,University of Leeds | Shao L.,China University of Mining and Technology | Hao L.,China University of Mining and Technology | And 7 more authors.
International Journal of Coal Geology | Year: 2011

The Lopingian coal measures of southwestern China were deposited within a range of facies associations spanning a spectrum of settings from fluvial to marine carbonate platform. The transitional to terrestrial coal measures are dominated by siliciclastics, but they also contain fifteen laterally extensive marine bands (limestone beds and mudstone). These bands act as marker horizons that enable correlation between fully marine and terrestrial facies. Examination of this range of facies and their sedimentology has enabled the development of a high-resolution sequence stratigraphic framework. Set against the established backdrop of second-order Lopingian transgression, sixteen fourth-order sequences and three composite sequences (third-order) are recognized. Results show that, in the composite sequences, peat accumulation in the seaward parts of the study area predominantly correlates with early transgressive sequence sets (TSS), while in more landward areas it correlates with the middle TSS to late highstand sequence sets (HSS). Differences in peat-accumulation regimes within the sequence stratigraphic framework are attributed to variations in subsidence and background siliciclastic input rates in different depositional settings, with these combining to produce differences in the rate of accommodation change. The preservation of coal resources in the middle to late HSS in this area was most likely related to the rise of the regional base level throughout the Lopingian. © 2010 Elsevier B.V. Source

Chen Y.-L.,China University of Mining and Technology | Qin Y.,China University of Mining and Technology | Yi T.-S.,Guizhou Bureau of Coal Geological Exploration
Meitan Xuebao/Journal of the China Coal Society | Year: 2013

In order to study the compositional change of residual gas during different desorption stages, refined desorption experiments of nine freshly anthracite samples, collected from the drilling wells and coal mines in Zhina, Guizhou, were carried out, and the gas compositions were determined by gas chromatography (model SP-3400). It was found that the desorbed gas volume is largest at crushed desorption stages, indicating that most of the residual gas is trapped in closed coal pores. Methane, carbon monoxide, carbon dioxide and ethane concentrations show a V-type change and are lowest at crushed desorption stage, whereas nitrogen concentration gives anti-V type trend and is highest. A remarkable compositional fractionation of each component occurs during heated desorption after crushing, showing the progressive enrichment of carbon monoxide, carbon dioxide and ethane, and relatively depletion of methane and nitrogen. It was suggested that the fractionation effect is derived from the differences of adsorption temperature and adsorption capacity, resulting in more retention of the gas components with higher adsorption capacity in micropores after desorption at the room temperature, and then desorption at the higer temperature 90-95°C of water bath heating. Source

Guo C.,China University of Mining and Technology | Qin Y.,China University of Mining and Technology | Yi T.-S.,Guizhou Bureau of Coal Geological Exploration | Gao D.,Guizhou Bureau of Coal Geological Exploration | And 2 more authors.
Meitan Xuebao/Journal of the China Coal Society | Year: 2014

Western Guizhou has the most abundant coalbed methane resources in South China. In order to efficiently exploit the coalbed methane in this area, it is important to understand the drainage decompression and orderly development methods of coal seam groups under the control of Unattached multiple superposed CBM-bearing system. This paper took Feitian Block of Zhina coal field in Western Guizhou as the researching area, analyzing the meticulous hydrogeological condition of coal-bearing strata and the difference of development condition of different coal seam groups in vertical. Based on pumping test data from previous coal exploration, useful information was generated, including the apparent reservoir pressure, pressure gradient, unit water inflow, permeability coefficient and radius of influence. The difference of hydrogeological condition in different parts of coal-bearing strata in three-dimensional space was compared. Eventually, the factor of evaluating CBM development priority was established through fuzzy mathematics synthetical judgement. Accordingly, the developing potential and development order of different coal seam groups in vertical of the three coal mine areas was discussed. It is concluded that the Feitian 2 and Feitian 3 mine areas have a better CBM development condition than Feitian 1, among which Feitian 2 medium part, Feitian 3 upper part and medium part are prior for CBM development. Generally, The development order of each part of coal-bearing strata of each coal mine area is: Feitian 3 upper part→Feitian 2 medium part→Feitian 3 medium part→Feitian 3 lower part→Feitian 2 lower part→Feitian 2 upper part→Feitian 1 upper part /Feitian 1 medium part→Feitian 1 lower part. Source

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