When drilling conventionally, upon indication of an influx, the drill string is lifted off bottom, circulation is stopped, a flow check is performed, and if the well is flowing, the well is shut in. The influx is then circulated out through rig choke using a reduced circulating rate.
With Managed Pressure Drilling (MPD), when kicks occur, they are typically smaller, contained more quickly, and, in some cases, they may be circulated out through MPD equipment without drilling or circulation interruption. The IADC MPD sub-committee has drafted a Well Control Matrix (WCM) in an effort to offer guidelines on when it is acceptable to kill the well dynamically when practicing CBHP MPD.
Rotating Control Devices (RCD) are commonly used on conventional overbalanced mud programs. To many in the industry, no specific distinction is made or special name is given to this type of operation. Confidence acquired over time has encouraged the common practice of drilling ahead while kicks are being circulated out, in appropriate circumstances. An influx, with only a very basic equipment configuration and whether it's called MPD or not, has often been handled in the industry as a routine operation without any special preparation or a formal WCM.
If a WCM is to be required to be in place, it should be engineered properly. A methodology for developing a WCM will be discussed in this paper. Procedures to control influxes as well as how to determine when to revert to secondary well control equipment under these operating conditions and examples of practical applications will be discussed.