低渗煤储层背景下高渗带主控地质因素及模式

沁水盆地南部郑庄区块相邻煤层气井地质条件和开发工艺基本相同，但产气量却有巨大差异。针对这一现象，利用构造裂隙填图、煤体结构测井解释、裂隙特征压裂曲线反演、构造曲率分析等技术，分析了煤储层裂隙系统的发育特征；从古地应力场演化、原地应力测试入手，讨论了煤储层裂隙优势方向上有效应力对渗透率的控制作用。研究认为，煤储层裂隙系统的发育特征和优势裂隙方向的有效应力，是低渗背景下高渗带的主控地质因素。建立了3种渗透率发育地质模式：一是裂隙系统发育适中与有效应力匹配型，煤储层渗透率高，煤层气井产量高；二是煤储层裂隙系统过度发育型，无论有效应力适中或者过高，两者条件均不匹配，储层渗透率较低，产气量低；三是有效应力过高型，无论裂隙发育程度如何，均会导致煤储层渗透率较低，产气量低。研究成果对于相似地质条件的煤层气区块内高渗带预测具有借鉴意义。

Main geological factors and models of high permeability zone under the background of low permeability coal reservoir

The geological conditions and development technology of adjacent coalbed methane wells in Zhengzhuang block of southern Qinshui Basin are basically the same，but the gas production varies greatly.In view of this phenomenon，the development characteristics of fracture system in coal reservoir are analyzed by means of structural fracture mapping，logging interpretation of coal body structure，inversion of fracture characteristic fracturing curve and structural curvature analysis.It is considered that the development characteristics of the fracture system and the effective stress in the dominant fracture direction are the main geological factors controlling the high permeability zone under the low permeability background.Three kinds of permeability development geological models are established：Firstly，the fracture system is moderately developed and the effective stress matches，the permeability of coal reservoir is high，and the production of coalbed methane wells is high;Secondly，the fracture system of coal reservoir is over-developed，whether the effective stress is moderate or high，the two conditions are not matched，the reservoir permeability is low，and the gas production is low;Thirdly，the high effective stress type，regardless of the degree of fracture development，will lead to low permeability of coal reservoirs，low gas production.The research results can be used for reference in the prediction of high permeability zones in CBM blocks with similar geological conditions.