用可控偏心器控制井眼轨迹的方法研究

井控轨迹自动控制技术是钻井行业急待解决的最前沿课题，用可控偏心器可以实现井眼轨迹自动控制，提高井眼轨迹控制精度，降低钻井成本。可控偏心器是一种井下可调的、可采用转盘钻进方式的井下寻向工具，它由翼片体转轴、翼片体、翼片和测控总成组成，在钻井过程中，通过随时调节可控偏心器翼片对井壁的作用力或伸缩来实现对井眼轨迹的控制。在使用可控偏心器进行钻井作业时，不需要频繁起下钻就可以在井下实现对井眼轨迹的控制，这对高难度密集丛式井、各种曲率斜井、水平井、加密井和抢险井等在完成各自的钻井目的方面有重大意义和极其宽广的应用前景。

A Study of the Method of Controlling Borehole Trajectory with Controllable Eccentric

Automatic control of borehole trajectory is one of the most frontier research areas in drilling engineering. This paper presents the results of a study on the realization of automatic trajectory control with controllable eccentric to improve the precision of control and reduce drilling cost. The controllable eccentric is a kind of downhole guided drilling tool consisting of a central axle, measuring and controlling system units, eccentric blades and eccentric shell, which can be controlled within the wellbore and can be used with rotary drilling. Automatic trajectory control is realized during drilling by way of adjusting the force of eccentric blades against wellwall and the length of the blades at all time. When controllable eccentric is used in drilling practice, trajectory control can be performed without tripping frequently. This feature of the method has great significance and prospects in accomplishing the goal of highly-dense cluster drilling, all kinds of directional drilling, horizontal drilling and emergency drilling.