塔里木油田深层寒武系白云岩钻井提速技术研究与应用

Research and Application of Drilling Speed Increasing Technology for Cambrian Dolomite in Tarim Oilfield

塔里木油田寒武系油气藏埋藏深,可钻性差,部分层段含燧石或硅质,常规钻头磨损严重,机械钻速低,严重影响寒武系盐下油气藏的勘探进程。基于白云岩岩石力学实验及钻头磨损、钻井参数分析,得出白云岩高抗压强度、地层不均质以及井底振动是白云岩地层钻头磨损严重的主因,提出了以非平面齿解决钻头冲击破坏、以“预破碎”解决破岩效率低、以螺杆和扭冲等提速工具解决稳定切削等难题。基于优选原则的复合钻头、尖圆混合齿钻头和扭冲、螺杆等提速工具较常规钻头提速30%以上,进尺提高80%以上。

Cambrian oil and gas reservoirs in Tarim Oilfield are deeply buried and have poor drillability.Some intervals contain chert or siliceous rock.Conventional bits are seriously worn and themechanical penetration rate is low,which seriously affects the exploration process of Cambrian undersalt oil and gas reservoirs.Based on the dolomite rock mechanics test and the analysis of bit wear and drill⁃ing parameters,it is concluded that the high compressive strength of dolomite,formation heterogeneity and bottom hole vibration are the main causes of serious bit wear in dolomite formation.It is proposed to solve the problem of bit impact failure by non-planar teeth,the problem of low rock breaking efficiency by"pre-breaking",and the problem of stable cutting by screw,torsional punching and other speed increasing tools.The application of the speed raising tools such as composite bit,sharp-circular mixed tooth bit,torsional punch and screw based on the principle of optimization can increase drilling speed by more than 30%and the footage by more than 80%com⁃pared with conventional bit.