沁水盆地柿庄区块煤层气井排采动态诊断方法

摘要

受多因素影响,煤层气井的排采动态具有复杂多变的特点,对煤层气井的排采动态进行诊断,有助于煤层气开发井层优选和压裂方案制定.以均匀分布在柿庄区块的单采3号煤层的30口煤层气井的静态地质资料和排采动态资料为基础,通过单井典型日产水量和典型日产气量指标提取和气水产出关系分析,从井筒和压裂煤层系统封闭性的角度,讨论高产水的外源成因,进而提出单井排采动态层次诊断方法,并通过实例分析进行验证.研究表明,柿庄区块煤层气井产气与产水之间存在负向包络而非简单的相关关系,高产水对产气有明显的抑制作用;断裂和压裂缝沟通含水层是造成柿庄区块部分煤层气井高产水及井间排采动态差异的重要原因;“一看断裂,二看压裂缝类型,三看岩性组合”的单井排采动态层次诊断方法,在柿庄区块单井实例分析中得到验证,该方法具有一定的普适性,可推广应用到其他煤层气区块的单井排采动态诊断分析中.%The characteristics of a CBM well performance is complex due to multiple influencing factors.It is beneficial for well site/layer selection and fracturing design to diagnose the performance of single CBM well.Based on the geological conditions and well performance data of 30 CBM wells producing from No.3 coal seam of Permian Shanxi formation in Shizhuang block,this paper studies the characteristics of CBM Wells performances and the relationship between gas production and water production.A negative enveloping relationship between gas production and water production is revealed,with high water production generally inhibiting high gas production.From a point of view of closeness of system borehole-stimulated coal interval,the mechanism of high water production due to outside water supply from sandstone aquifers is discussed and a hierarchical performance diagnostic method for single CBM well is proposed.The performance of some typical well are diagnosed using this hierarchical method,showing the method provides a tool for understanding the performance of single CBM well in Shizhuang CBM block and the application of this method can be extended to other CBM blocks.