Abstract
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 drill pipe were added to the drill string. This was made possible by the use of the Continuous Circulation System (CCS), developed over the previous three years by a Joint Industry Project (JIP) managed by Maris International, funded by six major oil companies (Shell UK, BP, Statoil, BG, Total and ENI), Coupler Development Ltd (CDL) and Varco and supported by the UK's Industry Technology Facilitator (ITF). The field trial of the CCS was carried out on a land well being drilled in Oklahoma, USA. 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 are:
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 bottom hole assembly before making a connection
Improved drilling fluid management
Elimination of kicks on connections
Improved control of Equivilent Circulation Density (ECD)
Reduced Total Connection Time (TCT)
Reduced chance of stuck pipe during a connection
No downtime in HPHT wells to circulate out connection gas
Reduced wellbore "breathing" or "ballooning"
Overall improvement in hole condition
Improved safety around the rig floor
Potential applications of the system are in drilling:
Extended reach (ERD) and horizontal wells
High Pressure/High Temperature (HPHT) wells
Near or underbalance (UBD) wells
Deepwater wells
The CCS is also a potential contributor in achieving the "One Trip Well", Journal of Petroleum Technology (JPT) May 2004. The concept was presented in the paper "Continuous Circulation Drilling" by L. Ayling at the Offshore Technology Conference in May 2002.
