连续管套管内开窗钻压预测研究

WOB Prediction for CT Casing Window Milling

针对目前连续管套管内开窗钻压不易控制,极易造成马达失速损坏,以及窗口质量不理想的现状,以造斜器开窗为对象,采用"纵横弯曲法"对一定结构的连续管开窗钻具组合,在一维井身内的受力变形进行计算机编程计算,结合一些贴近实际工况的切削条件,通过设定马达不失速、钻具按照设定轨迹钻进以及开出高质量窗口3个限制条件,对整个开窗过程中的合理钻压范围进行预测研究。研究结果表明,连续管开窗钻压预测有利于保护钻具以及开出高质量窗口,对现场施工具有很好的指导意义。初始开窗阶段马达易发生失速,应施加较小钻压。

The WOB during window milling in coil tubing( CT) casing is hardly controlled,so motors might be damaged,and undesirable quality of the window might be caused. With the window milling of whipstock as object,the 'vertical and horizontal bending method 'was used for programming of computer software to calculate forces and deformation of drilling assemblies with specific structures for windowing in coil tubing in the one-dimensional wellbore. With consideration to cutting conditions similar with those encountered in field,three limiting conditions have been clarified,namely,proper functioning of the motor,drilling in accordance with pre-determined trajectory and generation of high-quality window, to predict range of acceptable WOBs during window milling. Research results show that proper prediction of WOB during window milling in coil tubing may be favorable for protection of drilling tools and generation of high-quality window. Such results may provide necessary guidance for on-site application. Since the motor may stall at the stage of initial window milling,minor drilling pressures shall be deployed.