| 摘要 |
A method is provided for generating an improved torque-drag model for at least the collar portion of the drill string in a directional oil or gas well. The techniques of the present invention determine the stiffness of incremental portions of the drill string, and uses this information, the borehole clearance, and the borehole trajectory to determine the contact locations between the drill string and the sidewalls of the well. The contact force at these determined locations can be calculated, taking into consideration all significant kinemataic, esternal, and internal forces acting on that incremental portion of the drill string. More acurate torque-drag analysis provided by the improved model of the present invention assists in well planning, prediction, and control, assists in avoiding drilling problems, and reduces total costs for the well.
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