Back-stepping based Pressure Controller for Managed Pressure Drilling

Managed pressure drilling (MPD) is a controlled process of offshore hydrocarbons' exploration. It is not only capable of handling severe effects of weather on drilling process but it also improves the efficiency of offshore drilling operations. In drilling operation, circulating drilling fluid (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 of earth. Besides this normal operation, heave motion force drill-string to move it vertically up and down which introduces pressure deviations in mud pressure. These pressure fluctuations may damage the well. To mitigate the effect of heave motion, a controller is required to control choke valve in such a way that it regulates the desired mud pressure in the well, throughout the operation. In this research work, a backstepping based nonlinear controller has been presented for verified two volumes model of well pressure dynamics. It controls the choke valve to suppress pressure fluctuation effectively in the well. Finally, a table along with simulation results comparing different controllers given in the literature has been presented using MATLAB/SIMULINK.