Using MPD and Conventional Methods to Address a Well Control Event in aDeepwater Exploration Well

摘要

This paper presents a case where Managed Pressure Drilling (MPD) was used to drill a challengingexploration well through a pore pressure ramp and to address a well control event in conjunction withconventional methods when an influx was encountered The MPD system was used to drill using primary and secondary indicators, such as background gas,cuttings shape, and changes in ROP to determine if onset of the pore pressure ramp was imminent. TheMPD system provided a means to measure the flow in versus the flow out of the well and chokes to addsurface back-pressure (SBP) to adjust the bottomhole pressure. The MPD operators monitored the trends asdrilling continued and reacted if any indications of a pore pressure ramp were experienced. The pressure ramp was encountered, and the flow out exceeded the flow in. The driller applied moresurface back pressure to control the influx and reduce the influx size. The well could not be controlled withinthe allowable back pressure limitations as outlined by the MPD Operations Matrix, so the well was shutin on the Subsea Blow-Out Preventer (SSBOP). The well was controlled with conventional well controlmethods, using the Driller's Method. The mud weight was increased to the extent that it was not enoughto hydrostatically kill the well, but sufficient to allow operations to resume within a new MPD OperationalMatrix adding back pressure to keep BHP overbalanced to the formation. This application of MPD reducedthe impact of the influx event and allowed the rig to safely continue drilling and meet the well objectiveswithout losing the hole section.