临兴区块深部煤层气井生产特征及影响因素

Production characteristics of deep coalbed methane wells in the Linxing block and associated their influencing factors

【目的】深部煤层气生产特征与中浅部煤层气生产特征具有明显区别,且同一区块内深部煤层气排采井也存在差异性。相关研究尚处于探索阶段,深入分析深部煤层气生产特征差异的影响因素对后续大规模开发阶段的产能预测与生产管理具有重要意义。【方法】为明确临兴区块深部煤层气生产特征及其影响因素,基于含气性、煤厚、埋深、水化学特征及压裂工艺等地质工程因素开展研究。【结果和结论】结果表明:(1)临兴区块深部煤层气井分为过饱和气藏自喷井、过饱和气藏排采井和欠饱和气藏排采井3类。(2)含气性是3种生产特征的主控因素,工区内1800~2000 m埋深的煤层气井含气量与稳产气量均相对较高。(3)欠饱和气藏排采井储层保存条件较差,水化学特征与其他两类井存在明显差异,导致其生产效果相对较差,且由于高矿化度和高碳酸氢根离子产生的管柱结垢与腐蚀导致排采不连续。(4)大规模压裂是提高气井产量的有效储层改造措施,压裂砂对裂缝的有效支撑是保障深部煤层气井高气量稳产的关键因素。上述成果明确了临兴区块深部煤层气生产特征差异影响因素,对研究区和邻近地区深部煤层气生产具有参考意义。

[Objective]The production characteristics of deep coalbed methane(CBM)are significantly distinguished from those of middle-shallow CBM,and even the production wells of deep CBM within the same block exhibit different characteristics.Given that relevant research remains in its exploratory stage,gaining a deeper understanding of the factors influencing the differences in production characteristics of deep CBM is significant for the production capacity prediction and production management of the subsequent large-scale production stage.[Methods]To determine the production characteristics of deep CBM in the Linxing block and their influencing factors,this study examined geological engineering factors including gas content,coal thickness,burial depth,hydrochemical characteristics,and fracturing technology.[Results and Conclusions]The results are as follows:(1)Deep CBM wells in the Linxing block can be categorized into three types:flowing wells of supersaturated CBM reservoirs,production wells of supersaturated CBM reservoirs,and production wells of undersaturated CBM reservoirs.(2)Gas-bearing properties are identified as a dominant factor controlling the production characteristics of three types of wells.CBM wells in coal seams with burial depths ranging from 1800 to 2000 m exhibit relatively high gas content and stable gas production.(3)Production wells of undersaturated CBM reservoirs reveal inferior preservation conditions and hydrochemical characteristics that are significantly different from those of the other two types of wells,resulting in relatively poor production performance.Addition-ally,the fouling and corrosion of strings,caused by high total dissolved solids(TDS)HCO3-and concentration,lead to discontinuous production.(4)Large-scale fracturing serves as an effective reservoir stimulation measure to increase the production of gas wells,and the effective propping of proppants for fractures proves critical in guaranteeing high and stable gas production of deep CBM wells.The results of this study present the factors influencing the differences in the production characteristics of deep CBM in the Linxing block,acting as a reference for the production of deep CBM in the Linxing block and its adjacent areas.