Method of suspender line trajectory design

Abstract

Based on the mechanical model of an elastic rod, a new trajectory design method was established. The advantages of the suspender line trajectory in reducing drag and torsion were compared, and the main controlling factors of drag and torque and their influence rules were analyzed. Research shows that the suspender line trajectory reduces drag and torque more effectively than the conventional trajectory in a certain parameter interval and has more controllable parameters than that of the catenary trajectory. The main factors affecting the drag reduction and torque reduction of the suspender line trajectory include the friction coefficient, vertical distance, horizontal distance, and deviation angle at the initial point in the suspended section. The larger the friction coefficient and deviation angle, the less the drag reduction and torque reduction. The suspender line trajectory has the best drag reduction effect when the horizontal and vertical distances are more than 3000 m and the ratio is close to 1.5. The drag in sliding drilling can be reduced up to 60%, and the torque in rotary drilling can be reduced by a maximum of 40%. Therefore, the trajectory design of the suspender line has unique application prospects in deep extended-reach wells.

Keywords

• wellbore trajectory design
• suspender line trajectory
• mechanics of drill string
• drag and torque reduction
• drilling