Boundary Control and Estimation for Underbalanced Drilling With Uncertain Reservoir Parameters
Boundary Control and Estimation for Underbalanced Drilling With Uncertain Reservoir Parameters
In underbalanced drilling (UBD), the bottom hole pressure is kept below pore pressure, causing pressure-dependent influx of reservoir gas into the wellbore that makes the system unstable at low drawdowns. In this article, we propose a feedback controller which stabilizes the system, represented by the "reduced drift flux model (DFM)," …