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.
© 2010. Society of Petroleum Engineers
View full textPDF
(
1,814 KB
)
History
- Original manuscript received:
6 July 2008
- Meeting paper published:
21 September 2008
- Revised manuscript received:
27 March 2009
- Manuscript approved:
26 May 2009
- Published online:
21 January 2010
- Version of record:
11 March 2010
View Cart
