One of the major challenges the Oil and Gas Industry faces nowadays during drilling operations is the twist-offs on Bottom Hole Assembly (BHA) components such as Drilling Jars, Shock Tools, Mud Motors, Roller Reamers, Stabilizers, Drill Collars, PBLs, Heavy Weight Drill Pipe (HWDP), Drill Pipe (DP), etc. To overcome this challenge, an initiative was proposed by performing a study based on twist-offs experienced on BHA components while drilling operations and recommendations are provided to reduce and eliminate twist-offs related to drilling with suboptimal drilling parameters.
The statistical data for the twist-off events was collected coming from Daily Drilling Reports, and the analysis was limited to all wells which presented twist-offs on the drillstring and BHA components. Three examples of twist-offs due to drilling with erratic torque are discussed as well as a successful example of drilling parameters optimization.
The three examples which presented drillstring and BHA twist-offs were analyzed using available BHA Dynamics and vibrations software and it was discovered that the parameters utilized (operational RPM) fell within the critical zone shearing force peaks (resonance vibrations). The components with the most twist-offs were identified. The hole size where we have the most twist-offs were also identified, which will help in focusing on these areas for the recommendations provided.
This analysis will help Drilling Engineers and Foremen to foresee vibration dysfunctions and act accordingly by the use of available BHA Dynamics software in order to optimize drilling parameters before and during drilling. By drilling within a safe operating RPM window (away from resonant RPM), there will be reduction in the number of twist-offs and associated lost time.