Steinar Elgsæter

Modelling and control of growing slugs in horizontal multiphase pipe flows

In this paper, a method to detect slugs with typical sparse and local measurements in eld lines is developed.It is also shown how active control can be used to restrict slug growth. Simulations in OLGA2000show that a feedback controller can use measurements or estimates of slug length to control the growth of aslug in a horizontal pipeline by partially closing inlet or outlet chokes. A control-volume approach is used to develop a low-order model of inlet choke-slug growth dynamics based on mass- and impulse balances. The resulting model is a system of nonlinear differential algebraic equations, which is suitable for estimator design. The tuned model is found to be in good agreement with experiments and OLGA2000-simulations. Linearizations of the model are found to be observable around realistic trajectories when rates and pressures at the inlet and outlet are measured. An extended Luenberger-observer is shown to give good estimates of slug length and -position in simulations.