YM21C井盐膏层小间隙水平井尾管固井技术

Narrow Annular Liner Cementing Technology in Gypsum Bed of Horizontal Well TM21C

YM21C井是一口老井开窗侧钻水平井,地层复杂,裸眼段存在盐层、盐膏层及膏泥岩、泥膏岩、泥岩互层,井壁脱落、掉块、缩径严重;由于调整靶标和盐膏层长期划眼,出现了3个不同B点的井眼叠加现象;井斜变化率大,大狗腿及键槽井段多,井眼质量差,起下钻阻卡严重,多次处理卡钻事故;为了平衡支撑盐膏层,钻井液采用饱和盐水钻井液体系,密度由1.45提至1.60 g/cm3,划眼过程中,井下发生失返性漏失;因井下复杂,未完井电测,下入φ127 mm尾管至目的层顶部,套管卡死。为了完成复杂井下条件下的尾管固井,依据固井液密度差的浮力效应,液体胶凝强度差的拖曳和黏性推移作用及有效接触时间的作用原理,采用欠饱和盐水水泥浆和黏性隔离液体系,完成了小井眼尾管固井作业。

The well of YM21C is a side tracking horizontal well,salt gypsum and mud stone formations are drilled through,so as the caving and tight-hole are encountered while drilling.Because of reaming,three different target B points are drilled out,as well as the hard tripping and pipe-stuck difficulties are forced to deal with in this well.A saturated salt drilling fluid system is applied in the open hole,the density is improved from 1.45 g/cm3 to 1.60 g/cm3 to balance the formation pressure,however,while reaming a severe lost circulation happens,and the 127 mm liner is stuck on the top of target zone without electric logging.Based on the buoyancy effect of cement slurry density difference,drift effect of gel strength difference and contact time effect theory,under-saturated salt water cement slurry system and gel spacer fluid are used to finish the liner cementing job successfully.