Case Study of BHA Damages Caused by Sudden Release of Trapped Torque During Drill Pipe Connection Process
Authors: Simon Aaron , Li Denis 
Published: February 2025

This paper presents a study of three cases in which release of trapped torque occurs during the drill pipe connection process, leading to bottomhole assembly (BHA) damages. It highlights the contributing factors and root causes of the trapped torque release events, and it proposes prevention and mitigation measures to prevent these transient events.

In recent years, the industry has sought to reduce connection times to reduce overall well construction cycle time. Over the same period, the industry has upgraded to high-performance motors and aggressive bits which are more capable of trapping torque in the drillstring and BHA. This study highlights three cases which demonstrate how evolution of connection procedures has led to sudden releases of trapped torque, ultimately causing BHA damages, including backed-off connections and twisted-off tubulars.

This study came about through repeated investigation of bit/BHA damages, back-off events and twist-off events. Review of downhole conditions leading up to these incidents showed catastrophic overspeed events from the rotary steerable system (RSS) rotational speed (RPM) channel either just before or just after the connection. Correlation of downhole data with surface activities confirms that these overspeed events correlate with specific sequences performed as part of the pre- and post-connection procedures. In these cases, symptoms of BHA damages become evident shortly after the overspeed events.

The overspeed events are primarily caused by two high-risk activities during the connection process: picking up off bottom without drilling off and leaving the bit on bottom during the connection.

Pre-connection overspeed events are related to the sudden release of trapped torque while picking up off bottom. Torque is inherently trapped in the BHA and drillstring during normal on-bottom drilling activities. If picking up off bottom without drilling off, that trapped torque is released suddenly, resulting in a potentially-catastrophic overspeed event.

Post-connection overspeed events are associated with the bit being left on bottom or too close to bottom during the connection. When the bit is left engaged on bottom, excessive torque is required to break that static friction after making the connection. The overspeed event occurs due to the sudden release of the torque that became trapped during the time required to break the friction.

Analysis suggests that there is not one universal connection procedure which works perfectly for all applications. Ultimately, the risk of the overspeed event versus the time and steps required to prevent/minimize the consequences must be considered to optimize the procedure.

Dysfunctions occurring during connections are often overlooked since traditional BHA specifications do not capture these transient overspeed events. The emphasis on faster connection times in recent years has led to increased occurrences of sudden overspeed events at the bit/BHA, resulting in damages, backed-off connections and twisted-off tubulars. One operator was successful in achieving a 17% year-over-year improvement in single run curve-lateral production sections by implementing fit-for-purpose connection practices as part of their performance improvement strategy.