Displacement vectors control method for orienter ribs during path correction in coiled tubing drilling

摘要

The well path easily deviates from the original design trajectory during coiled tubing drilling, which needs to be corrected with an orienter. A three-segment correction trajectory with two arc segments and a line segment is constructed based on the differential geometry principle, and the direction at the target is consistent with the direction of the original borehole. Based on the parameters of the design correction trajectory, a mathematical relationship between trajectory parameters and the displacement vectors of orienter ribs is established by using the vector analysis method. According to the principle of minimum energy, the problem of multisolvability in mathematics is avoided. Then, the control model of the displacement vectors of orienter ribs with the parameters' variation of the designed correction trajectory is established. The similarly periodic variation rule of displacements of orienter ribs with the variation of tool face angle is obtained, and the closed-loop control scheme for correction trajectory while drilling is made. The results of field test show that by using coiled tubing drilling, during the circular arc section of the designed three-segment correction trajectory, the displacement vectors of orienter ribs vary similarly periodically, which is called the directional drilling mode. During drilling in the slanted segment, the displacements of each rib are equal, which is called the keeping drilling mode. The design method of correction trajectory and the displacement vector control method of the orienter ribs are practicable during path correction in coiled tubing drilling, which is helpful to improve the efficiency of coiled tubing drilling.