煤层气井排采动态主控地质因素分析

沁水盆地寿阳区块和柿庄区块煤层气(CBM)井的排采动态在整体上表现出明显差异,而单一区块内部煤层气井的排采动态也存在较大差异。本文就两个区块的煤系地层沉积相、煤层渗透率、断裂构造、地应力类型和构造应力强度以及顶底板岩性组合类型等因素对排采动态的影响开展对比分析。基于静态地质条件和排采动态资料的综合研究表明:煤系地层沉积相、煤层渗透率、地应力类型和构造应力强度的差异是两个区块煤层气井排采动态差异的主要原因;单一区块内煤层气井的排采动态差异受控于局部断裂构造、地应力类型以及煤层顶底板岩性组合类型等局部因素;在煤层气开发选区和开发井位部署时,应综合考虑资源量、渗透率和多种局部地质因素的共同影响。

Analysis on Controlling Geological Factors Influencing Drainage Performances of Coalbed Methane Wells

Objectives: Shouyang block and Shizhuang block are the main coalbed methane (CBM) exploration and development blocks in China. There is an obvious integral difference of drainage dynamic of CBM wells between two blocks. Moreover, that difference is also observed in a single block. This paper is focused on analysis of controlling geological factors drainage dynamic of CBM wells. Methods:Based on geological data from two blocks, this paper carries out a comparison analysis on the sedimentary facies, coal seam permeability, characteristics of faults, in situ stress types and tectonic stress amplitude, as well as lithological assemblages for understanding the controlling factors causing the integral difference of drainage dynamic of CBM wells between two blocks and that in a single block. Results:The study shows that the distinction of sedimentary facies, coal seam permeability, in situ stress types and tectonic stress amplitude are main factors causing the difference of drainage dynamic of CBM wells between two blocks, while the faults, in situ stress types and lithological association types at specific well locations interpret the difference of drainage dynamic of CBM wells within a block. Conclusions:Selections of favorable area and well site/coal target for CBM development should be based not only on the resources evaluation, but also and especially essential, on sedimentary facies, coal seam permeability, structure and lithological association types.