长庆致密气田超长水平段钻井降摩减阻技术

Drag reduction technology for ultra-long horizontal drilling in the Changqing tight gas reservoir

为了保护生态环境,提高单井产量,长庆气田部署了多口水平段超过3 000 m的井。针对超长水平段井裸眼段长,存在井下摩阻大、扭矩大的问题,选取了S135钢级钻柱和清砂钻杆减阻工具,采用旋转导向井眼轨迹控制技术,优化了钻进参数:最佳钻井液环空返速为1.20~1.30 m/s、最低钻柱转速为60 r/min,选用氯化钾、石灰石和高性能润滑剂提高钻井液及其所形成滤饼的润滑性,控制钻井液有害固相含量,其动塑比提高至0.5 Pa/(mPa·s),最终形成了一套长庆致密气田超长水平段降摩减阻技术。将该技术应用于水平段长度为5 256 m的靖51-X井,其水平段平均全角变化率为0.74 (°)/30 m,钻井液固相含量最高为16%,完钻后最大起钻摩阻为380 kN,下钻最大摩阻为280 kN。实践表明在超长水平段应用该技术具有良好的降摩减阻效果。

For the purposes of protecting the ecological environment and increasing single-well production,the Changqing gas field deploys multiple wells with horizontal wells exceeding 3000 m.Given the ultra-long horizontal openhole well and the excessive drag and torque,the S135-steel grade drill string and the cutting-removal drillpipe drag reduction tool were adopted;the rotary steerable system was used for trajectory control;the drilling parameters were optimized.Specifically,the optimal annular circulation rate of drilling fluids is 1.20–1.30 m/s;the minimum drill string rotation speed is 60 r/min;the potassium chlorite,limestone and highperformance lubricant are used to improve the lubricant performance of drilling fluids and formed mud cake,control the content of unwanted solids in drilling fluids,and raise the ratio of yield point to plastic viscosity to 0.5Pa/(mPa·s).The above measures jointly form the drag reduction technology for ultra-long horizontal wells in the Changqing tight gas field.It has been applied to Well Jing 51-X with a 5256 m long horizontal well.The average dogleg severity of the horizontal well was 0.74(°)/30 m;the maximum solid content of drilling fluids was 16%;the maximum drag of tripping out after completion of drilling is 380 kN;the maximum drag of tripping in was 280 kN.Such an application to ultra-long horizontal drilling demonstrates the excellent drag reduction performance of the presented technology.