NEW METHOD FOR HOLE TRAJECTORY DESIGN WITH A REQUIRED DIRECTION AT TARGET

Design of hole trajectory being restricted to the required direction at its target is very important for well trajectory control in directional and horizontal well.It can be used to improve the ability of well trajectory control and target hitting.According to the principle that the number of constraints and unknowns of well trajectory should be equal,the paper provides all the possible profiles and demonstrates that a three-section profile with two planar circular arcs and one straight line is the simplest and right profile for correctional well-path with a required direction at target.On the basis of it,a new method called Path-Seeking One-by-One is presented to avoid solving the nonlinear constraint equation set.To reduce the computing time used on Path-Seeking One-by-One to reasonable range,the function with two independent variables for path-correction planning is abandoned and a new function with one independent variable is constructed.The method based on the new function is called modified Path-Seeking One-by-One.The steps of the method is described and a planning example is solved and analyzed.The result shows that the method of modified Path-Seeking One-by-One neednt solve the nonlinear constraint equation set and is an efficient and reliable method.