Using MPC for Managed Pressure Drilling

Abstract

As production on the Norwegian shelf enters tail production, drilling wells with vanishing pressure windows become more attractive. This motivates use of automatic control systems for improved control of downhole pressure using Managed Pressure Drilling (MPD) techniques. PID SISO control solutions for MPD are by now relatively standard, and well understood. This article explores the potential benefits of using linear Model Predictive Control (MPC) for MPD. It is shown that in combination with wired drill pipe, the downhole pressure can be controlled at multiple locations in the open wellbore, by using both pumps and choke in applied backpressure MPD. Also, downhole pressure constraints (pore and fracture pressures) fit naturally in MPC. Illustrative simulations are presented from using a high fidelity well simulator called WeMod, and Statoil's MPC software SEPTIC.