A H-infinity control approach for oil drilling processes

Abstract

This paper presents a robust optimization framework to improve the Managed Pressure Drilling (MPD) process for safer and superior economical and environmental operations while removing risk-prone conventional drilling limitations such as a need for constant monitoring of the system parameters. The nonlinear MPD process considers the mud pump flow rate and the differential flow rate of the backpressure pump and the choke as the two inputs while the process downhole pressure rate as the output. The MPD process unmodeled disturbances, uncertain geological parameters and related model nonlinearities are considered to be the corresponding system uncertainties in a closed loop robust control and optimization framework for real-time operations. Moreover, the MPD process inputs are formulated to remain within practical bounds by introducing performance weighting functions. The proposed framework numerical results demonstrate the efficiency of the closed loop robust control implementations for efficient drilling operations in operator guidance systems and provide a low-computational complexity design algorithm for safer drilling operations in regions with a-priori unknown geological properties. © 2013 The Authors. Published by Elsevier B.V.