开窗侧钻井小井眼小间隙固井技术

Study and Application of Small Clearance Cementing Technique for Casing Sidetracking Slime Hole

油层套管开窗侧钻是老油田盘活报废井、提高采收率的重要手段。然而侧钻井固井时由于环空间隙小,固井过程中水泥浆上返摩阻大,环空当量密度大大增加,经常压漏地层,导致水泥浆漏失低返;另外受井眼尺寸的限制,套管居中度差,水泥浆易窜槽,其固井质量严重制约了侧钻井技术的应用前景。从水泥浆密度和性能上考虑,研制了低密度低摩阻水泥浆,通过降低水泥浆密度来减小固井时的液柱压力,同时配套采用综合技术措施,在现场多口井进行应用,固井质量显著提高。探索出一套适合华北油田特点的提高侧钻井固井质量技术,实践证明该技术是切实可行的。

Casing sidetracking of production casing string is an important means of bringing back to life abandoned oil wells and enhancing oil recovery.Casing sidetracking has the advantage of cost efficient and time saving,but small annular space clearance increases the friction of cement slurries flowing upward,thus fracturing the formation and resulting in losses of cementing slurry.Another disadvantage of cementing the sidetracking well is the big eccentricity of casing string,which will result in channeling of cement slurry.To solve these problems,a low friction coefficient low density cement slurry was developed.By reducing the density of the cement slurry,the hydrostatic pressure exerted by cement slurry column was reduced.In field operations,cement job quality was remarkably improved.It is proven to be a feasible cementing technology for use in Huabei Oilfield.