适用于连续管钻井的无固相卤水钻井液体系

A solids-free brine drilling fluid system for coiled tubing drilling

针对连续管钻井管内循环压耗大、钻压传递困难及黏卡几率高等难题,以卤水为基液进行室内实验,通过核心处理剂的优选,研发了无固相卤水钻井液体系,评价其性能并进行现场应用。通过对流型调节剂、抗盐降滤失剂、高效润滑剂、钻头清洁剂的优选,形成了无固相卤水钻井液体系的基本配方:卤水+(0.1%~0.2%)Na OH+(0.2%~0.4%)HT-XC+(2.0%~3.0%)YLJ-1+(0.5%~2.0%)SDNR+(1.0%~2.5%)FT-1A+(1.0%~5.0%)SD-505+复合盐密度调节剂。室内性能评价表明,该钻井液抗温150℃,抗钻屑污染性能较好,岩屑滚动回收率92.7%,润滑性能与全油基钻井液相近,只需在环空返速不低于0.8 m/s的前提下保证动塑比在0.5以上,就能达到井眼净化要求。将无固相卤水钻井液应用于辽河油田3口连续管侧钻井施工,其性能稳定易调整,井眼净化能力强,井径规则,机械钻速高且无任何事故。无固相卤水钻井液满足连续管钻井工艺的技术需求。

There are many problems associated with coiled tubing drilling operations,such as great circulation pressure loss inside pipe,difficulties in weight on bit（WOB） transferring,and high probability of differential sticking.Aiming at these problems,solids-free brine drilling fluid system was developed on the basis of formulation optimization with brine base fluid experiment,which was evaluated and applied to field drilling.Based on the optimization of flow pattern regulator,salt-resisting filtrate reducer,high performance lubricant and bit cleaner,the basic formula of the solids-free brine drilling fluid system was formed：brine ＋（0.1%-0.2%） Na OH ＋（0.2%-0.4%） HT-XC ＋（2.0%-3.0%） YLJ-1 ＋（0.5%-2.0%） SDNR ＋（1.0%-2.5%） FT-1 A ＋（1.0%-5.0%） SD-505 ＋ compound salt density regulator.Lab evaluation showed that the fluid had satisfactory temperature resistance（up to 150 ℃）,excellent cuttings tolerance（up to 25%）,and strong inhibition（92.7% cuttings recovery）; Moreover,its lubrication performance was similar to that of all oil-based drilling fluid.The wellbore could be fairly cleaned at annular up-flow velocity of more than 0.8 m/s if the ratio of yield point to plastic viscosity was kept above 0.5.This fluid system has been applied in the drilling of three coiled tubing sidetracking wells in the Liaohe Oilfield,during which the system was stable and easy to adjust,resulting in excellent cuttings transportation,high ROP,regular hole size,and no down hole accidents.In summary,the solids-free brine drilling fluid system can meet the technical requirements of coiled tubing drilling.