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吐哈盆地沙尔湖区块的储层是煤层气地层,井深在600～900m之间,煤层面积大,煤层厚,具有良好的开发前景。该区块煤层的压力系数低,裂缝发育,易垮塌,因此防漏防塌是钻井液技术的重点。沙试1井采用聚合物钻井液钻井,发生恶性漏失,严重破坏了煤层。经过调研,决定在沙试3井采用可循环微泡钻井液体系,并在室内对可循环微泡钻井液的配方进行了优选。在沙试3井二开井段的现场应用中,将微泡钻井液密度降低到0.70～0.80g/cm3,同时提高微泡堵漏浆中的堵漏剂浓度,有效地封堵了漏层。煤层平均取心收获率达到80%以上,取得了良好的效果,为煤层气井的钻探提供了可借鉴的经验。
The reservoir of the Shahehu block in Turpan-Hami Basin is a CBM formation with a well depth of 600-900 m. The coal seam has a large area and a thick seam with good development prospect. The pressure coefficient of the coal seam in this block is low, and the fractures develop and collapse easily. Therefore, the leak prevention and collapse prevention is the key point of the drilling fluid technology. Sha test 1 drilling wells using polymer drilling fluid, a vicious loss occurred, severely damaged the coal seam. After investigation, it was decided to adopt a circulating microbubble drilling fluid system in Shaxi test well 3 and optimize the recirculating microbubble drilling fluid formulation indoors. In the field application of the second well section of Shaxi test 3, the density of micro-bubble drilling fluid is reduced to 0.70 ~ 0.80g / cm3, meanwhile, the concentration of plugging agent in the microbubble plugging slurry is increased, effectively blocking the leakage layer . The average coring rate of coal seams reaches more than 80%, and good results have been obtained, which can provide reference for the drilling of coalbed methane wells.