The Practice and Evolution of Torque and Drag Reduction: Theory and Field Results

Abstract

Abstract With the global trend moving toward drilling deep water wells, ultra-extended reach wells (u-ERW) and complex geometry wells, we can no longer ignore the drilling limitations caused by high torque and drag forces. Extreme torque and drag, especially unplanned, can be detrimental to drilling operations. Over the years, engineers have developed numerous ways to challenge the drilling limitations by reducing torque and drag forces in order to drill further and deeper. This paper attempts to describe the practices and the evolution of torque and drag reduction methods. The different torque and drag reduction methods that this paper focuses on are listed below. Wellpath design Light weight string components Lubricants Hole cleaning Co-polymer beads Mechanical friction reduction tools Increased drill string and rig capability In highly inclined wells, solutions to problematic torque and drag are essential in order to complete the drilling and completion operations. Because many restrictions are imposed by the drilling rig, top drive, wellpath and drilling components, engineers have came up with ways to reduce torque and drag while drilling. There are weight limitations that a rig can provide, especially in non-rotating operations such as slide drilling. If the compressive forces in the drill string are too high, bucking will occur. In an extended reach well (ERW), two common problems with torque are the friction resistance to drill string rotation and the make-up torque limitations. If the rotary torque is too high, torsional failure would result. Therefore, it is essential for engineers to accurately account for the torque and drag forces and attempt to reduce them in order to prohibit these scenarios from occurring. At the same time, it is the engineer's responsibility to ensure that we do not over-design to accommodate unnecessary needs.