Advanced Torque and Drag Considerations in Extended-Reach Wells

Excessive torque and drag can be critical limitations in extended-reach drilling (ERD). This paper details issues related to torque-and-drag prediction, monitoring, and management in ERD wells. Results are presented from sensitivity analyses of extreme ERD trajectories such as 7- to 8-km departures at 1,600 m true vertical depth (TVD). Several such wells have now been successfully drilled at the Wytch Farm oilfield using results from these studies. In such high-angle ERD wells, compression generated in the drillpipe during tripping and sliding operations can exceed the critical buckling load and cause the drillpipe to buckle. As a result, buckling initiation and post-buckling analyses are used to quantify the extent and severity of buckling and the associated increases in drag forces and pipe stresses. The paper addresses the importance of drilling data in calibrating torque, drag models to capture the continual changes in drilling parameters and operating conditions. The paper presents a number of field case studies where analyses have been conducted to directly assist drilling operations. This paper should be of high interest to engineers executing, planning, or evaluating ERD operations.