Coalbed methane(CBM) resources in No.15 coal seam of Taiyuan Formation account for 55% of the total CBM resources in southern Qinshui Basin(SQB), and have a great production potential. This study aims at investigating...Coalbed methane(CBM) resources in No.15 coal seam of Taiyuan Formation account for 55% of the total CBM resources in southern Qinshui Basin(SQB), and have a great production potential. This study aims at investigating the CBM production in No.15 coal seam and its influence factors. Based on a series of laboratory experiments and latest exploration and development data from local coal mines and CBM companies, the spatial characteristics of gas production of No.15 coal seam were analyzed and then the influences of seven factors on the gas productivity of this coal seam were discussed, including coal thickness, burial depth, gas content, ratio of critical desorption pressure to original coal reservoir pressure(RCPOP), porosity, permeability, and hydrogeological condition. The influences of hydrological condition on CBM production were analyzed based on the discussions of four aspects: hydrogeochemistry, roof lithology and its distribution, hydrodynamic field of groundwater, and recharge rate of groundwater. Finally, a three-level analytic hierarchy process(AHP) evaluation model was proposed for predicting the CBM potentials of the No.15 coal seam in the SQB. The best prospective target area for CBM production of the No.15 coal seam is predicted to be in the districts of Panzhuang, Chengzhuang and south of Hudi.展开更多
During the Late Paleozoic,West Junggar(Xinjiang,NW China)experienced a shift in tectonic setting from compression to extension.Ha'erjiao is an important area for investigating collisional structures,post–collisio...During the Late Paleozoic,West Junggar(Xinjiang,NW China)experienced a shift in tectonic setting from compression to extension.Ha'erjiao is an important area for investigating collisional structures,post–collisional structures,and magmatic activities.Based on the petrological and geochemical characteristics of pyroclastic and other volcanic rocks in the Permian Kalagang Formation from the borehole ZKH1205 in the Jimunai Basin,the main types of source rock for the pyroclastic rocks deposited in the basin are identified and their implications for the Early Permian tectonic setting examined.The abundance of basalt and andesite lithic fragments in the pyroclastic rocks,together with the REE characteristics and the contents of transition and high field strength elements show that the source rocks were chiefly intermediate–basic volcanic rocks.High ICV values,low CIA values,low Rb/Sr ratios,low Th/U ratios and the mineralogical features suggest weak chemical weathering of the source rocks;the geochemical patterns of the pyroclastic rocks might not only have been impacted by crustal contamination but also might be related to the nature of the magma from the source area.The geochemical properties of the pyroclastic rocks distinguish them from arc-related ones,and such samples plot in the within-plate basalt(WPB)field in some diagrams.This is consistent with the formation background of the Early Permian volcanic rocks in this region.展开更多
基金financially supported by the Natural Science Foundation of China (No.41802192)the National Science and Technology Key Special Project of China (No.2016ZX05044-002 and No.2016ZX05043)+2 种基金the Shanxi Provincial Basic Research Program-Coal Bed Methane Joint Research Foundation (No.2012012001 and No.2015012014)Open Fund of State Key Laboratory of Water Resource Protection and Utilization in Coal Mining (No.SHJT-17-42.18)the Fundamental Research Funds for the Central Universities (No.CUGL170811)
文摘Coalbed methane(CBM) resources in No.15 coal seam of Taiyuan Formation account for 55% of the total CBM resources in southern Qinshui Basin(SQB), and have a great production potential. This study aims at investigating the CBM production in No.15 coal seam and its influence factors. Based on a series of laboratory experiments and latest exploration and development data from local coal mines and CBM companies, the spatial characteristics of gas production of No.15 coal seam were analyzed and then the influences of seven factors on the gas productivity of this coal seam were discussed, including coal thickness, burial depth, gas content, ratio of critical desorption pressure to original coal reservoir pressure(RCPOP), porosity, permeability, and hydrogeological condition. The influences of hydrological condition on CBM production were analyzed based on the discussions of four aspects: hydrogeochemistry, roof lithology and its distribution, hydrodynamic field of groundwater, and recharge rate of groundwater. Finally, a three-level analytic hierarchy process(AHP) evaluation model was proposed for predicting the CBM potentials of the No.15 coal seam in the SQB. The best prospective target area for CBM production of the No.15 coal seam is predicted to be in the districts of Panzhuang, Chengzhuang and south of Hudi.
基金This research was funded by the National Science Foundation for Young Scientists of China(No.41602176)Key Laboratory of Tectonics and Petroleum Resources(TPR–2018–16).
文摘During the Late Paleozoic,West Junggar(Xinjiang,NW China)experienced a shift in tectonic setting from compression to extension.Ha'erjiao is an important area for investigating collisional structures,post–collisional structures,and magmatic activities.Based on the petrological and geochemical characteristics of pyroclastic and other volcanic rocks in the Permian Kalagang Formation from the borehole ZKH1205 in the Jimunai Basin,the main types of source rock for the pyroclastic rocks deposited in the basin are identified and their implications for the Early Permian tectonic setting examined.The abundance of basalt and andesite lithic fragments in the pyroclastic rocks,together with the REE characteristics and the contents of transition and high field strength elements show that the source rocks were chiefly intermediate–basic volcanic rocks.High ICV values,low CIA values,low Rb/Sr ratios,low Th/U ratios and the mineralogical features suggest weak chemical weathering of the source rocks;the geochemical patterns of the pyroclastic rocks might not only have been impacted by crustal contamination but also might be related to the nature of the magma from the source area.The geochemical properties of the pyroclastic rocks distinguish them from arc-related ones,and such samples plot in the within-plate basalt(WPB)field in some diagrams.This is consistent with the formation background of the Early Permian volcanic rocks in this region.
