Adaptive Backstepping Based Control of Heave-Induced Pressure Deviations In Managed Pressure Drilling (MPD)

Abstract

Managed pressure drilling (MPD) is a controlled process of o shore hydrocarbons' exploration. It is not only capable to handle weather's severe e ects on drilling process but it also improves the e ciency of o shore drilling operations. In drilling operation, circulating drilling uid (with particular density to maintain desired pressure in the well) is pumped in drill-string through choke valve, and it leaves through the drill bit, cools and lubricates the bit and the drill-string, and shifts the drilled cuttings to the surface. Besides this normal operation, heave motions force drill-string to move it vertically which introduce pressure deviations in mud pressure. These pressure

uctuation may damage the well. To vanish the e ect of heave motion, a controller is required to control choke valve in such a way which regulate desired mud pressure in the well, throughout the operation. In this thesis, two nonlinear controllers have been presented for veri ed two volumes model of well pressure dynamics. Backstepping controller controls the choke valve to suppress pressure uctuation e ectively, in the well. On the other hand, Adaptive backstepping controller guarantee to regulate pressure close to desired level irrespective of variation in one of system parameter. In the last, a table for performance analysis of proposed controllers has been presented.