Infinite-Dimensional Observer for Process Monitoring in Managed Pressure Drilling∗

Utilizing flow rate and pressure data in and out of the mud circulation loop provides a driller with real-time trends for the early detection of well-control problems that impact the drilling efficiency. This paper presents state estimation for infinite-dimensional systems used in the process monitoring of oil well drilling. The objective is to monitor the key process variables associated with process safety by designing a model-based nonlinear observer that directly utilizes the available information coming from the continuous-time online process output measurements at the topside of the well. The observer consists of a copy of the plant plus output injection terms where the gain is computed analytically in terms of the Bessel function of the first kind. The design is tested using data from a real-field drilling commissioning test in the North Sea by Statoil Oil Company. The results show that the design estimates the flow and pressure accurately.