Observer-based control of a managed pressure drilling system

During well drilling, the annular downhole pressure should be precisely controlled throughout the well bore continuously while drilling. A choke valve and a back pressure pump are used to control the annular pressure. This paper presents a nonlinear observer-based control scheme to stabilize the annular pressure profile. A simple mechanistic model is developed to capture the dominant phenomena of the drilling system and for the observer and model-based control design. A new nonlinear adaptive observer is developed for state estimations. The developed nonlinear controller is designed to stabilize the annular pressure and achieve asymptotic tracking.