--> Coalbed Methane Geology of the Jurassic Middle-Lower Series, Southern Junggar Basin, China: Low-Rank Coalbed Methane Enrichment Characteristics, Accumulation Model, and Resource Evaluation

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Coalbed Methane Geology of the Jurassic Middle-Lower Series, Southern Junggar Basin, China: Low-Rank Coalbed Methane Enrichment Characteristics, Accumulation Model, and Resource Evaluation

Abstract

Up to now no exploitation breakthrough of coalbed methane (CBM) from low-rank coal in China has been achieved yet. However, a large number of low-rank coals have been continuously found in the formation of Jurassic middle-lower series, southern Junggar basin, China. How about coalbed methane in this area? This paper is to answer this question by means of researching low-rank coalbed methane (LRCBM) enrichment characteristics, establishing LRCBM accumulation model, and accomplishing LRCBM resource evaluation. Firstly, based on the analyses of the coal measure strata sedimentary sequence, sedimentary environment and its evolutionary process, the LRCBM enrichment characteristics of Jurassic middle-lower series southern Junggar basin is illustrated. Then, relying on a large number of data from laboratory tests and field tests, comprehensive analyses have been carried out, presenting the basic geological characteristics of this area, such as the coal seam distribution, petrology, reservoir property, coal rock thermal evolution, coal rock quality of 6 sections, as well as the CBM generating and bearing characteristics, the sealing properties of the CBM reservoir's top and bottom rocks, the hydrogeological characteristics preserved by the CBM reservoir; Combining with the tectonic burial history, geothermal history, hydrocarbon evolution and CBM gas saturation changes, the LRCBM accumulation model of this area has been established. Finally, the LRCBM resources calculation and comprehensive evaluation of the 6 sections divided in this area points out the relatively favorable sections for further exploration in this area. The results show that the LRCBM resources of this area above 2000m amount to 3054.7×108m3, with the resource abundance between (0.42–11.65)×108m3/km2, and the resource abundance of Section 4 and Section 5 of this area is even higher than that of the CBM fields in the middle and east China, demonstrating very favorable exploitation prospect.