Summary
In late July 2003, for the first time since rotary drilling was introduced,
a section of hole was drilled without interrupting circulation while new joints
of drillpipe were added to the drillstring. This was made possible by the use
of the continuous-circulation system (CCS), developed over the previous 3 years
by a joint industry project (JIP) that was managed by Maris Intl. and funded by
six major oil companies (Shell U.K., BP, Statoil, BG, Total, and Eni),
Coupler Development Ltd., and Varco, and supported by the U.K.’s Industry
Technology Facilitator. The field trial of the CCS was carried out on a land
well being drilled in Oklahoma, U.S.A. Its success marked the end of the JIP
and the commencement of commercial development of the system.
The CCS is a new and enabling technology; the potential benefits of which
include the following:
• Elimination of negative and positive pressure surges when stopping and
starting circulation to make a connection.
• No rig downtime to circulate out cuttings to clear the bottomhole assembly
before making a connection.
• Improved drilling-fluid management.
• Elimination of kicks on connections.
• Improved control of equivalent circulation density (ECD).
• Reduced total connection time (TCT).
• Reduced chance of stuck pipe during a connection.
• No downtime in high-pressure/high-temperature (HP/HT) wells to circulate
out connection gas.
• Reduced wellbore “breathing” or “ballooning.”
• Improved safety around the rig floor.
Potential applications of the system include the following:
• Extended-reach drilling (ERD) and horizontal wells.
• HP/HT wells.
• Near or underbalance wells.
• Deepwater wells.
The CCS is also a potential-enabling technology in achieving the “one-trip
well.” The concept was presented in a paper by inventor L. Ayling at the
Offshore Technology Conference, May 2002.
© 2005. Society of Petroleum Engineers
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History
- Original manuscript received:
5 May 2004
- Revised manuscript received:
29 June 2005
- Manuscript approved:
17 July 2005
- Version of record:
15 September 2005
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