Structure and production fluid flow pattern of post-fracturing high-rank coal reservoir in Southern Qinshui Basin

LIU Shi-qi(刘世奇)¹, SANG Shu-xun(桑树勋)², ZHU Qi-peng(朱启朋)², LIU Hui-hu(刘会虎)³, GAO He-feng(高贺凤)²

(1. School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China;
2. School of Mineral Resource and Earth Science, Key Laboratory of CBM Resources and Reservoir Formation
Process of Ministry of Education, China University of Mining and Technology, Xuzhou 221116, China;
3. School of Geoscience and Environment, Anhui University of Science and Technology, Huainan 232001, China)

Abstract:Field geological work, field engineering monitoring, laboratory experiments and numerical simulation were used to study the development characteristics of pore-fracture system and hydraulic fracture of No.3 coal reservoir in Southern Qinshui Basin. Flow patterns of methane and water in pore-fracture system and hydraulic fracture were discussed by using limit method and average method. Based on the structure model and flow pattern of post-fracturing high-rank coal reservoir, flow patterns of methane and water were established. Results show that seepage pattern of methane in pore-fracture system is linked with pore diameter, fracture width, coal bed pressure and flow velocity. While in hydraulic fracture, it is controlled by fracture height, pressure and flow velocity. Seepage pattern of water in pore-fracture system is linked with pore diameter, fracture width and flow velocity. While in hydraulic fracture, it is controlled by fracture height and flow velocity. Pores and fractures in different sizes are linked up by ultramicroscopic fissures, micro-fissures and hydraulic fracture. In post-fracturing high-rank coal reservoir, methane has level-three flow and gets through triple medium to the wellbore; and water passes mainly through double medium to the wellbore which is level-two flow.

Key words:flow pattern; structure model; high-rank coal reservoir; hydraulic fracture; Southern Qinshui Basin