Triple Medium Physical Model of Post Fracturing High-Rank Coal Reservoir in Southern Qinshui Basin  

作　　者：Shiqi Liu Shuxun Sang Qipeng Zhu Jiefang Zhang Hefeng Gao Huihu Liu Lixing Lin 

机构地区：[1]School of Safety Engineering, China University of Mining and Technology [2]Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education, School of Mineral Resource and Geoscience, China University of Mining and Technology [3]School of Geoscience and Environment, Anhui University of Science and Technology [4]Faculty of Engineering and Applied Science, University of Regina

出　　处：《Journal of Earth Science》2015年第3期407-415,共9页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos. 41330638, 41272154, 51325403, 51104148, and 51204162);the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD);Jiangsu Planned Projects for Postdoctoral Research Funds (No. 1302049B)

摘　　要：In this paper, influences on the reservoir permeability, the reservoir architecture and the fluid flow pattern caused by hydraulic fracturing are analyzed. Based on the structure and production fluid flow model of post fracturing high-rank coal reservoir, Warren-Root Model is improved. A new physical model that is more suitable for post fracturing high-rank coal reservoir is established. The results show that the width, the flow conductivity and the permeability of hydraulic fractures are much larger than natural fractures in coal bed reservoir. Hydraulic fracture changes the flow pattern of gas and flow channel to wellbore, thus should be treated as an independent medium. Warrant-Root Model has some limitations and can’t give a comprehensive interpretation of seepage mechanism in post fracturing high-rank coal reservoir. Modified Warrant-Root Model simplifies coal bed reservoir to an ideal system with hydraulic fracture, orthogonal macroscopic fracture and cuboid matrix. Hydraulic fracture is double wing, vertical and symmetric to wellbore. Coal bed reservoir is divided into cuboids by hydraulic fracture and further by macroscopic fractures. Flow behaviors in coal bed reservoir are simplified to three step flows of gas and two step flows of water. The swap mode of methane between coal matrix and macroscopic fractures is pseudo steady fluid channeling. The flow behaviors of methane to wellbore no longer follow Darcy’s Law and are mainly affected by inertia force. The flow pattern of water follows Darcy’s Law. The new physical model is more suitable for post fracturing high-rank coal reservoir.In this paper, influences on the reservoir permeability, the reservoir architecture and the fluid flow pattern caused by hydraulic fracturing are analyzed. Based on the structure and production fluid flow model of post fracturing high-rank coal reservoir, Warren-Root Model is improved. A new physical model that is more suitable for post fracturing high-rank coal reservoir is established. The results show that the width, the flow conductivity and the permeability of hydraulic fractures are much larger than natural fractures in coal bed reservoir. Hydraulic fracture changes the flow pattern of gas and flow channel to wellbore, thus should be treated as an independent medium. Warrant-Root Model has some limitations and can’t give a comprehensive interpretation of seepage mechanism in post fracturing high-rank coal reservoir. Modified Warrant-Root Model simplifies coal bed reservoir to an ideal system with hydraulic fracture, orthogonal macroscopic fracture and cuboid matrix. Hydraulic fracture is double wing, vertical and symmetric to wellbore. Coal bed reservoir is divided into cuboids by hydraulic fracture and further by macroscopic fractures. Flow behaviors in coal bed reservoir are simplified to three step flows of gas and two step flows of water. The swap mode of methane between coal matrix and macroscopic fractures is pseudo steady fluid channeling. The flow behaviors of methane to wellbore no longer follow Darcy’s Law and are mainly affected by inertia force. The flow pattern of water follows Darcy’s Law. The new physical model is more suitable for post fracturing high-rank coal reservoir.

关 键 词：triple medium physical model high-rank coal reservoir hydraulic fracture SEEPAGE southern Qinshui Basin 

分 类 号：TE357[石油与天然气工程—油气田开发工程]