北堡西3×1大位移井钻井液技术

Drilling fluid technology for the extended reach Well Beipuxi 3×1

北堡西3×1井上部地层成岩性差,造浆严重,井眼斜度大,裸眼井段长,井壁容易垮塌失稳,钻井过程中极易在井眼下井壁形成钻屑的沉积层,导致钻柱扭矩增大,摩阻升高,造成卡钻。上部地层采用聚合物钻井液;钻开储层时采用聚合物硅基钻井液。现场应用表明,该套钻井液体系使北堡西3×1井固相含量为5％～17％,保证了钻井液性能的稳定;抑制防塌效果好,在聚合物钻井液中加入复合两性金属离子包被剂、无荧光防塌剂和聚合醇,提高了钻井液的抑制防塌能力,井径扩大率较小;润滑防卡效果强,二开定向前在钻井液中加入白油、磺化沥青,钻进过程中保持润滑剂含量不低于3％,三开施工中加入聚合醇、磺化沥青、白油,四开加入极压润滑剂、聚合醇并保持其含量为2％,以减轻旋转钻进时的扭矩、起下钻和下套管时的负荷,减少了复杂事故的发生;携岩净化效果强,95％以上的井段3都为2～10,6为3～12,满足了大位移井对井眼净化的要求,保证了钻井作业的顺利进行。

In Beipuxi area of Dagang Oilfield, the upper formation has the problems of serious dispersion and mud making. Because of high inclined directional hole, long open section and hole collapsing, cutting settling frequently takes place in low-side well bore during the drilling which cause the increasing of torque and frictional drag and leads to pipe sticking. Polymer drilling fluid was used in the upper formation and silicon base polymer drilling fluid was used in reservoir layer. Field using shows the drilling system keeps the solid content at 5%-17% in Well Beipuxi 3×1 and has such properties as stability, anti-collapse, lubricating, carrying and cleaning, e. g. , with the adding of complex metalloid ion encapsulating agents, non-fluorescence sloughing control agent and polyol, inhibiting and anti-collapse ability of the drilling fluid were improved and the borehole diameter enlargement ratio was minimized; before orienting in the second section, adding white oil, sulfonated asphalt to keep the content of lubricant above 3% , adding polyol, sulfonated asphalt and white oil in the third section and EP lubricant, polyol in the fourth section to keep the content of lubricant at 2%, thus, the rotary torque and load tripping could be reduced, downhole failure could be avoided; in great mass of well section (over 95%),3 is 2-10 and 6 is 3-12,that means the drilling system satisfies the requirements of cleaning the extended reach well and ensures the success of drilling engineering.