煤层气水平井钻井过程储层损害机理

摘要

Taking No.3 coal in Qinshui Basin as research object,factors such as solid phase of drilling fluid,water sensitivity,stress sensitivity,scaling,capillarity and polymer plugging which maybe damage coal reservoir were researched during coalbed methane drilling.Sample results analyzed show that No.3 coal reservoir has low porosity and low permeability,high content of clay mineral.Lab evaluation results show water sensitivity,scaling,solid phase invasion of drilling fluid and polymer plugging are factors which induce the coal reservoir damage.Drilling fluid which has suitable salinity,suitable density,anti-scaling,and removable drilling fluid agents can protect coal reservoir from damage during drilling for pinnate horizontal wells.%以山西沁水盆地山西组3号煤层为研究对象,对羽状水平井钻井过程可能发生损害煤储层因素如钻井液固相、水敏损害、应力敏感性、毛细现象、结垢和聚合物堵塞等进行了实验研究。结果表明,山西沁水盆地3号煤层孔隙度和渗透率均较低,煤层黏土矿物含量较高,水敏损害、结垢、钻井液固相侵入和聚合物堵塞是水平井钻井过程中造成煤储层损害的主要因素。使用合适矿化度、密度和具有防垢功能的钻井液以及可解除的钻井液处理剂是煤层气水平井钻井过程保护煤储层的有效措施。