A Guide to Successful Backreaming: Real-Time Case Histories

Abstract

Summary Backreaming is the practice of pumping and rotating the drillstring while simultaneously pulling out of the hole. When reliable topdrive drilling systems (TDSs) on conventional drilling rigs were introduced more than 25 years ago, the practice of backreaming became a popular technique in the driller's toolbox for tripping out of hole initially in deviated wells. In general, backreaming operations have become a popular solution to poor hole conditions while pulling out of hole, but they are also notorious for causing the very same problems they are supposed to prevent, such as stuck pipe. If backreaming is not performed properly, it may complicate the operations, cause wellbore-stability issues, cause higher equivalent circulating densities (ECDs), and cause stuck-pipe incidents caused by packoffs. As part of the company's stuck-pipe prevention initiative, it became clear that when backreaming is carried out in a wellbore that has a large amount of cuttings and/or cavings, it can cause problems rather than solve them if it is not done with sufficient care. Also, backreaming and tripping operations were usually occasions when the rig-based team went to a "low-vigilance" level. On the basis of historical cases, it was concluded that in the majority of instances, there were no clear guidelines on when to start, how to do it, when to slow down, and when to stop backreaming operations. A review of industry literature also indicated a lack of procedures generally for backreaming. As a result of the analysis of the real-time data from several case histories, a plan was put in place to improve backreaming operations, define the situations that require backreaming, and focus on tripping practices to prevent stuck-pipe incidents and tool failures. This paper focuses on one of the industry's most controversial subjects, reviews the implications of backreaming by using real-time data and case histories, and suggests proven procedures to trouble-free backreaming. It recommends the conditions that require backreaming and also suggests wellbore conditions that are not recommended for backreaming. More importantly, it proposes key drilling parameters that need to be monitored when backreaming. These include pump pressure, torque, hookload, cuttings rate, and downhole measurements (if available) to detect and prevent backreaming-induced operational problems. In addition, this paper provides guidelines for successful backreaming operations and defines conditions that may be resolved without needing to backream. Backreaming guidelines have been developed on the basis of the company's worldwide operations, supported by real-time case histories and an extensive stuck-pipe prevention program.