A simplified and highly effective method to identify influx and losses during Managed Pressure Drilling without the use of a Coriolis flow meter

Abstract

AbstractConventional methods of identifying a kick as well as the shut-in procedure can take a significant amount of time and therefore result in additional influx volumes. Coriolis flow meters have been used for more than 15 years for delta flow kick detection and have been very effective in most cases in identifying or confirming kicks much faster than conventional means. In Managed Pressure Drilling operations, Coriolis meters are frequently used for delta flow kick detection purposes since the system is in a closed loop and it is not possible to perform a conventional flow check. Unfortunately, Coriolis flow meters are sensitive to gas entrainment and also need to be properly maintained to ensure they are always in good working order. The constant bottomhole pressure (BHP) calculation and control system of the Dynamic Annular Pressure Control (DAPC) system has been modified to provide an effective means of accurately detecting an influx without a Coriolis flow meter and then controlling the unplanned event, which significantly reduces influx volume and shut-in time, as well as eliminating the cost and complexity of using a Coriolis flow meter. Mud losses during drilling can also be confirmed. The modified DAPC system has been adapted to shut-in the well whenever the rig pumps are turned off. By observing the choke position it is possible to determine if the well is unexpectedly flowing and at what rate. If the well is shut-in, the system can monitor the choke position and identify additional flow out. In addition, the system can be configured to account for normal back flow to reduce the occurrence of false alarms and, in the event the well is flowing and the system’s warning is overlooked, the system can be programmed to automatically increase shut-in pressure to stop the influx. Recent tests performed at the Louisiana State University PERTT facility proved the system’s ability to reliably identify unplanned flow events. The system has also been field tested. Test results will be shown and ways in which the system can easily be installed on a rig will be discussed.