Directional Drilling Bha Mechanical Analysis And Deviation Control Technology

According to the work state of bottom hole assembly (BHA) in the directional well, the nonlinear mechanics model of BHA is presented in the paper. In the model, it is considered that the BHA structure, hole trajectory, various loads, the initial gap and contact friction between BHA and hole wall, and also the vertical bending to be caused by the BHA weight and drill pressure. In order to solve the model, the beam element and multi-directional contact gap element are adopted, which present a method so as to analyze the force and deformation of BHA. Through the inclined capacity analysis of BHA to be affected by various parameters, it is shown that the distance between drill bit and the first stabilizer to be changed a little, the inclined capacity of BHA can be changed, which provide the theory for the various distance stabilizer (VDS) to be designed and applied in drill engineer. The VDS has been used in 5 inclined straight wells. The test results show that the VDS work principle is reliable and the structure is reasonable, the distance between drill bit and the stabilizer can be changed by adjusting the drill pressure and pump pressure at the well head, which make the inclined capacity of BHA change, thus the continuous control of well bore inclination during rotary directional drilling was achieved.