无固相活性盐水钻井液在柳林地区煤层气水平井中的应用

Research and Application of Solid-free Active Brine Drilling Fluid for CBM Horizontal Well Drilling in Liulin Area

柳林区块3#煤层含有少量黏土矿物,孔隙不发育、比较致密,煤岩表面呈弱亲水性。针对清水在煤层保护方面存在水敏性和水锁损害的不足,提出无固相活性盐水作为该地区煤层气水平井钻井液,其配方为:清水+2%KCl+0.1%防水锁剂+1%水基润滑剂。相对于清水,无固相活性盐水钻井液具有更强的抑制能力、更低的表面张力和更优的润滑能力,防止煤层中的黏土矿物水化膨胀,有利于钻井液返排,降低摩阻有利于水平井钻井作业;煤心污染后的渗透率恢复值接近100%,储层保护效果优异。该钻井液在CLU-07H多分支水平井中成功应用,表现出良好的应用前景。

The 3# coal seam in Liulin Area contains less clay minerals,where porosity is undeveloped and compacted,the coal petrography surface is weak hydrophilic.In allusion to the shortcomings of the existence of damages of water sensitivity and water locking induced by fresh water,it is proposed that solid-free active brine is used as a drilling fluid for CBM horizontal well drilling in the area,its formula includes clear water+2%KCl+0.1%pre-water blocking agent+1%water based lubricant.Compared with clear water,the solid-free active brine drilling fluid has better inhibition ability,lubrication and reservoir protection for preventing the swelling of clay minerals,it is beneficial for flowback of drilling fluid,friction reduction and beneficial for the operation of horizontal wells.The permeability recovery value is 100%after the pollution of coal cores,it obtains better effect of formation protection.It is applied successfully in CLU-07 H Multilateral Horizontal Well.It obtains good prospects of application.