Study On Optimization Methods Of Directional Well Trajectory

With the advancement of drilling engineering technology and the improvement of drilling equipment, drilling technology develops rapidly. Directional Well, as a very important drilling method, has gained great attention. Currently, there have been many articles and monographs about design and calculation methods of directional well trajectory, both planar and three-dimensional. But they have a common point, that is, the trajectory designed can satisfy in-situ demand, but can't be proved as an optimal trajectory. The optimal trajectory is designed under in-situ tool capacity, which has the minimum rate of inclination, the minimum rate of azimuth, the minimum length of measured depth, and the minimum torque and friction.The author has done the following work based on the experiences of former experts. One is summing up several calculation methods of directional well trajectory and working out useful software which can be used easily and calculated quickly and precisely. Another is introducing nonlinear mathematical programming into directional well trajectory design and putting forward a quantitative design method and establishing several optimized mathematical models of directional well trajectory.Aimed at different mathematical models, the paper gives several application examples, analyses calculation process, and solves the models. Also the author writes calculation software which can design directional well trajectory with conventional methods. The software can also be an assistant tool for studying optimization methods of directional well trajectory.By comparing the results of conventional design methods and optimized design methods, the length of well trajectory designed by optimized design methods is shorter than that designed by conventional design methods. Therefore, the optimized design trajectory can largely reduce the rate of under well accidents, shorten penetration period and decrease drilling cost.