沁南郑庄区块煤层气直井产能控制因素精细解析

Analysis of Main Controlling Factors of Gas Productivity of CBM Vertical Wells in Zhengzhuang Block of Southern Qinshui Basin

通过对郑庄区块相邻6口煤层气直井在地质因素和工程因素基本相同的条件下,产能却有巨大差异的现象展开研究,精细解析煤层气井的埋深、含气量、煤层厚度、地质构造、压裂工程和排采工程等影响因素,认为郑庄区块煤层气直井产量偏低的控制性因素是煤储层的低渗透性,其产生的机理是由于古地应力场控制的煤储层构造裂隙的发育产状和发育密度,与现今地应力场控制着煤储层裂隙的开合程度二者不相互匹配,决定了郑庄区块煤储层低渗透性的非均质性。

This paper studies the phenomenon of huge difference in production capacity of six adjacent CBM vertical wells in Zhengzhuang block under the condition that the geological factors and engineering factors are basically the same. Affecting factors of CBM wells, such as burial depth, gas content, coal seam thickness, geological structure, fracturing engineering and drainage engineering, are analyzed in detail. It is believed that low permeability of coal reservoir is the controlling factor of low production of CBM vertical wells in Zhengzhuang area. The mechanism of formation is due to the formation and density of structural fissures in coal reservoirs controlled by paleogeostress field, they do not match with the degree of fracture opening in coal reservoirs controlled by present geostress field, which determines the heterogeneity of low permeability of coal reservoirs in Zhengzhuang block.