Himalayan Geology, Vol. 40 (1), 2019, pp. 1-15, Printed in India
Geological characteristics of the Carboniferous-Permian coal-measures superimposed reservoir and its favourable zones in the Jiyang Sub-basin
HAN SIJIE1,2, SANG SHUXUN1,2*, ZHOU PEIMING3, LIANG JINGJING1,2
1Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process of the Ministry of Education,
China University of Mining and Technology, Xuzhou, 221116, China
2School of Resources and Earth Sciences, China University of Mining & Technology, Xuzhou, 221116, China
3Guizhou Provincial Engineering & Technology Research Center of Coalbed Methane & Shale gas, Guiyang, 550081, China
*Email (Corresponding author) shxsang@cumt.edu.cn
Abstract: For this study, a coal-measure superimposed reservoir (CMSR) within the Shanxi Formation in the Jiyang Sub-basin of the Bohai Bay Basin has been proposed and the CMSR characteristics in sedimentary setting, source rocks and reservoirs are analyzed. Accordingly we construct a reservoirs model for the CMSR and predict its favourable zones. The CMSR occurs in coal-sandstone superimposed paragenetic assemblages derived from a large-scale shallow water delta environment in the Jiyang Sub-basin. Carboniferous-Permian (C-P) coal-measure source rocks, mainly composed of type III kerogen, have considerable hydrocarbon potential during the Cenozoic time. Deep coals with high rank have a significant adsorption capacity. In the superimposed sandstones secondary dissolved pores are developed that account for more than 50% of the total porosity and permeability in localized regions. The CMSR are characteristic of a “self-source and self-reservoir” type gas reservoir wherein, gas migrates and exchanges through weak layers between the coal and lenticular sandstone, and thus the gases in coal and its superimposed sandstone form a coal-bearing gas reservoir system. Based on multi-factor geological analysis and gradational parameter evaluation, seven measurable parameters are selected to predict five primary favourable zones and ten secondary favourable zones of the CMSR in the Jiyang Sub-basin.
Key words: Coal-measures superimposed reservoir (CMSR); Deep coalbed methane; Reservoirs model; Geological process; Favorable zones; Jiyang Sub-basin.
