Characteristics and control mechanisms of coalbed permeability change in various gas production stages  

作　　者：Da-Zhen Tang Chun-Miao Deng Yan-Jun Meng Zhi-Ping Li Hao Xu Shu Tao Song Li 

机构地区：[1]School of Energy Resources, China University of Geosciences [2]Coal Reservoir Laboratory of National Engineering Research Center of Coalbed Methane Development & Utilization

出　　处：《Petroleum Science》2015年第4期684-691,共8页石油科学（英文版）

基　　金：financial support from the various funding agencies including the Major State Basic Research Development Program of China (973 Program, 2009CB219604);the National Natural Science Foundation of China (41272175);the Key Project of the National Science & Technology (2011ZX05034-001);the China Scholarship Council

摘　　要：According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.

关 键 词：Production stage - Coalbed methane PERMEABILITY Dynamic change - Control mechanism 

分 类 号：TE312[石油与天然气工程—油气田开发工程]