偏心扩眼器在中石油尼日尔项目首次应用

中石油尼日尔项目是西非“一带一路”建设的重点地区，Sokor泥岩地层、低速泥岩地层泥页岩发育，蒙脱石含量为11.24％，易水化膨胀导致井壁稳定性差（以缩径为主）、套管遇阻严重、电测工具下放不畅、事故复杂处理时间长，截止2020年底，遇阻遇卡共计73口井（占 29.4％），平均单井损失时间67.5 ｈ，严重影响钻井周期。针对尼日尔项目缩径难题，优选微扩眼器形成随钻扩眼钻具组合，分别在尼日尔Gololo, Dibeilla 和Koulele三个区块的4 口定向井进行偏心扩眼器随钻扩眼技术先导性试验。现场试验效果表明，试验井测井作业时在定向段没有遇阻遇卡点，偏心扩眼器可有效提高井眼扩大率 （平均井径扩大率由6.13 ％ ～10.43％ 提 高 至 12.35％ ～14.82％），同时可以破坏定向井段微狗腿和微台阶，从而减小测井及完井下套管作业阻卡风险。

First Application of Eccentric Reamer in CNPC Niger Project

Petrochina Niger project is a key construction area of the Belt and Road Construction in West Africa, which has been well developed with Sokor mudstone, low velocity mudstone and shale formation. The content of montmorillonite is 11.24%, which is prone to swelling and hydration leading to poor stability of the borehole, serious casing stuck accident, logging tools blocking and long processing time, and the drilling cycle is thus extended ( by the end of 2020, 73 wells had been encountered with logging obstruction which is accounting for 29.4% , and the average time lost per well was 67.5 hours). In order to solve the problem of wellbore shrinkage in Niger project, the eccentric reamer is applied to be the bottom hole assembly to realize reaming while drilling, and the pilot test of eccentric reamer reaming while drilling technology was carried out in 4 directional wells in Gololo, Dibeilla and Koulele blocks in Niger. The field test results show that there is no blocking point in the directional section during the logging operation of the test well. The eccentric reamer can effectively improve the wellbore diameter with average hole diameter expansion rate increased from 6.13%～10. 43% to 12.35%～14.82% , and can destroy the micro dog legs and micro steps in the directional section, so as to reduce the blocking risk of logging and casing running after completion.