【文章內(nèi)容簡介】 the ball posed no issue with being transferred using almost no pressure differential. Another area of interest was the clearance between the internals of the continuous circulation sub and the associated plumbing with respect to the ball. This ball must be transported efficiently within these pipes for a short distance, so the leakage cannot be excessive. The clearance didn’t prove to be as much concern as expected, even when using low viscosity fluids and much larger than practical clearances. The system is also very intuitive。 first impressions have been positive from people familiar with the drill floor and connection processes. The Market Managed Pressure Drilling has gained a lot of momentum in the last six years since the mercial introduction of a continuous circulation chamber in 2022. The 5 demand for these chambers is growing, from its initial applications in the North Sea and the Mediterranean Sea, to offshore Gulf of Mexico and Brazil. A 2022 survey published in the Journal of Petroleum Technology reached an industry consensus that 40% of offshore wells would be using MPD within five is a large demand onshore also that is not able to be accessed by the continuous circulation chambers. This is primarily due to restricted rig space and configuration. This potentially opens up a market for very pact continuous circulation subs which have minimal footprint on the rig floor with MPDReady land rigs also being more mon. 6 The Continuous Circulation System: An Advance in Constant Pressure Drilling Abstract In late July 2022, 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 panies (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 mencement of mercial development of the system. The CCS is a new and enabling technology, the potentialbenefits of which are: ?Elimination of negative and positive pressure urges 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 2022. The concept was presented in the paper “Continuous Circulation Drilling” by L. Ayling at the Offshore Technology Conference in May 2022. Introduction The CCS relies on advancements made over recent decades in Top Drives, drill pipe handling equipment, BOP ram seals, Iron 7 Roughnecks and puterized drilling control heart of the CCS is the Continuous Circulation Coupler(Coupler) which evolved from earlier work by L. Ayling on aseabed located drilling rig. A Coupler was required to separate the drilling fluid from the seawater while adding or removing drill pipe from the drillstring. The significance of such a device and its potential impact on improving drilling efficiency was realized and lead to the establishment of the JIP to develop the system, starting in October 2022. The Concept The Coupler (Fig 1) is effectively a pressure chamber located on the rig floor over the rotary table, through which the drill string passes and which seals around the drill pipe pin and box during the connection make a connection, drilling fluid at circulating pressure is introduced into the pressure chamber, (Fig 2) equalizing the pressure inside and outside the drill string, the connection is broken and the tool joint pin backed out and raised clear of the box. The pressure chamber is divided into two sections by a sealing device and pressure is bled off in the upper chamber allowing the pin connection to be removed. Meanwhile circulation is maintained without interruption to the drill string through the lower chamber. The new joint of drill pipe, connected to the Top Drive, is run into the upper chamber,which is sealed and repressured with drilling fluid from the circulating system. With pressure equalized the dividing seal is opened, the new drill pipe joint lowered and the connection made up with circulation continuing through the drill string. The pressure in the chamber is bled off, the seals opened and drilling is restarted. The Project The project to develop the CCS was set up in four phases: Phase 1 Preliminary Engineering to develop the concept into a basic design, identifying any challenges to be investigated during the next phase of detailed engineering and to eliminate any “showstoppers”.Phase 2 – Detailed Engineering to prepare the engineering desi