ANALYSIS OF MECHNICAL FEATURES FOR LOW DRILL ASSEMBLY WITH CONTROLLABLE ECCENTRIC STABILIZER

It’s extremely important to control automatically the well bore path of large displacement wells. Auto-controlled downhole guide tools, such as controllable eccentric stabilizers, are being developed underway both inside and outside China. This paper studies the mechanical features for lower drill assembly with controllable eccentric stabilizer, based on the relative theory. The study indicates that the deviating force on bit is increased along with increment of the eccentric distance; and the force is reduced along with the upward movement of the eccentric stabilizer. when expansion block movement of the eccentric stabilizer is controlled, but the azimuthal force is opposite from the deviating force. The variation law of deviating force along with the eccentric azimuth is similarly a half sine function, whereas the variation law of the azimuthal force is similarly a sine function.