沁水盆地南部高煤阶煤储层敏感性

Sensitivity of high-rank coal-bed methane reservoir in the Southern Qinshui Basin

为实现沁水盆地南部煤层气的高效开采,对该区主力煤储层3号煤进行了流速敏感性、水敏感性、碱敏感性和应力敏感性实验分析。实验结果表明:3号煤速敏损害程度为中等偏弱,在实际煤层气开发过程中要重视含砂压裂液对煤层冲刷产生的煤粉运移造成的速敏损害;3号煤为中等偏弱水敏储层,向工作液中添加少量KCl可以起到降低水敏的效果;3号煤为弱碱敏储层,但高pH值工作液会使压裂用的石英砂受碱液溶解而降低支撑效果;3号煤为强应力敏储层,根据升压和降压阶段渗透率变化对比,不可逆损害率达55.88%。在煤层气藏的开发过程中,通过加强储层保护理论上可以提升煤层气产量。

In order to achieve a high-efficient exploitation of CBM in the southern Qinshui Basin,the velocity sensitivity,water sensitivity,alkaline sensitivity and stress sensitivity of the main coalbed 3 were investigated and analysed. The results show that:the degree of velocity sensitivity damage at the coalbed 3 varies from medium to weak. In the actual CBM development process,the velocity sensitivity damage is due to the transportation of coal powder produced by the coalbed washout of the fracturing fluid containing sand. The degree of water sensitivity damage at the coalbed 3 varies from medium to weak. Adding a small amount of KCl to the working fluid can reduce the water sensitivity effect. The coalbed 3 is a weak alkaline sensitive reservoir,however,the high pH fluids will dissolve quartz sand and reduce the support effect. The coalbed 3 is a strong stress sensitivity reservoir. According to the comparison of permeability change in the step-up and step-down phases,the irreversible damage rate is 55. 88%. In the coalbed methane development process,in theory,strengthening reservoir protection can increase the coalbed methane production.