超深井连续管短半径侧钻工艺研究与现场试验

Research and Field Testing of CT Short-Radius Sidetracking Technology for Ultra-deep Wells

采用连续管经过油管柱对现有储层进行加深或对未开发层段进行开窗侧钻,不仅可以省去起出油管的费用,也可以避开复杂盖层快速进入目标储层。为了验证连续管过油管侧钻技术的优势,以TH区块深井A井三开井身为例,分析了连续管侧钻面临的技术难点,通过井眼轨迹优化形成了全增并造斜率逐渐增加的方案,依据短半径工程实施中工具柔性弯曲的附加轴向力要求,通过工具优化,形成了?114.3 mm扶正管柱配套侧钻?88.9 mm井眼的设计方案。现场应用结果表明:在2.5°单弯螺杆定向造斜的配合下,连续管钻井平均机械钻速达1.06 m/h,最大机械钻速10.8 m/h,经济效益显著,也证实了连续管钻井的技术优势;连续管钻井管柱组合中,中间部分可以依靠钛合金的柔性特点,尽量缩短两端的工具串长度,以满足短半径侧钻要求。所得结论可为连续管在老油区实施钻侧提供应用参考。

Deepening existing wellbores or sidetracking to drill non-produced intervals by means of coiled tubing drilling(CTD) through tubing string can eliminate the cost of tripping out the tubing string and facilitate rapid access to target reservoirs while avoiding complex overlying layers.In this paper, Well A with the casing program of three casing sections was taken as an example to discuss the challenges for CT sidetracking through tubing string.Optimized wellbore trajectories featuring full build-up trajectory and gradual growth of build-up rates were developed.Moreover, according to the extra axial force required by the drilling tool flexible bending during the practice of short-radius drilling, the wellbore plan of sidetracking a ?88.9 mm wellbore assisted by the ?114.3 mm centralizing string was developed.Field application reveals that in the case of directional drilling with the 2.5° single-bend positive displacement motor(PDM),the rate of penetration(ROP) reaches an average of 1.06 m/h, with a maximum of 10.8 m/h during CTD,indicating remarkable economic benefits.The tool string lengths at both ends of the CTD string can be minimized using flexible titanium alloys for the middle part, so as to enable short-radius sidetracking.The results provide references for applications of CT sidetracking in mature oilfields and confirm the advantages of CTD.