Espen Hauge

Model based pipeline monitoring with leak detection

We design a leak detection system consisting of an adaptive Luenberger- type observer based on a set of two coupled one dimensional first order nonlinear hyperbolic partial differential equations governing the flow dynamics. It is assumed that measurements are only available at the inlet and outlet of the pipe, and output injection is applied in the form of boundary conditions. Heuristic update laws for adaptation of the friction coefficient and leak parameters are given, and simulations demonstrate their ability to detect, quantify and locate leaks. Particular attention is given to time-varying boundary conditions, such as during pipeline shut-down. A scenario consisting of leak detection followed by pipeline shut-down during which the leak is accurately quantified and located is successfully simulated for both liquid and gas systems.

Model-based estimation and control of in/out-flux during drilling

A model-based in-/out-flux detection scheme for managed pressure drilling is presented. We design a globally exponentially stable adaptive observer which estimates the unknown states and parameters of the hydraulic system and in particular quantifies the magnitude of the in-/out-flux and its location in the well. While the observer can be used purely as an in-/out-flux detection system, the paper also presents a simple controller that automatically and effectively stops an in-/out-flux. This novel control scheme departs from common practice for automatic managed pressure drilling, which is to regulate down-hole pressure to some predetermined set point. Simulations are provided to show the effectiveness of the method.

A Dynamic Model of Percolating Gas in a Wellbore

The two-phase dynamics of gas percolating up a vertical well filled with water is described by two ordinary-differential equations and algebraic relations. We model the gas as bubbles distributed with a distribution function along the well. The model is based on first principles and accommodates tracking of the front of the gas. An unscented Kalman filter (UKF) is used together with the model and wired-drillpipe (WDP) pressure measurements to estimate the liquid-holdup profile as the gas is circulated out of the well. The performance of the model and the method of estimation are compared with results from a state-of-the-art simulator.

A Dynamic Model of Percolating Gas in an Open Well-Bore

Abstract The two-phase dynamics of a gas-kick percolating up a vertical well, drilled using a partly evacuated riser, is described by two ordinary differential equations and algebraic relations. We model the gas as bubbles distributed with a distribution function along the well. The simplicity of the model makes it well suited for estimation purposes and controller design. We present simulation results where an unscented Kalman filter is used to estimate the current location of the gas, distribution of the gas, and rise-velocity. These estimates can be used to predict when the gas will pass the blowout preventer and reach the drilling rig.