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Anti-slug control of multiphase risers involves stabilizing an open-loop unstable operating point. PID control is the preferred choice in the industry, but appropriate tuning is required for robustness. In this paper, we define PIDF as a PID with a low-pass filter on its derivative action where the low-pass filter is crucial for the dynamics. We compared a(More)
— Instability and inverse response behaviour make anti-slug control at offshore oilfields an interesting control problem where a robust solution considering the nonlinearity of the system is required. We tested three control solutions by experiments in this paper. First, we used state-feedback with state estimation by a nonlinear high-gain observer.(More)
Active control of the production choke valve is the recommended solution to prevent severe slugging flow conditions at offshore oilfields. The focus of this work is to find the structure of a simple, yet robust anti-slug control system. In order to find suitable control variables for stabilization, a controllability analysis of the system with different(More)
— To prevent slug-flow on offshore oil production units, controlling a subsea pressure is the recommended solution. However, the subsea pressure is not often available as a measurement. The top-side pressure is usually measured but it is difficult to use for stabilizing control, because of its Right Half-Plane zero dynamics combined with nonlinearity. We(More)
Active control of the production choke valve is the recommended solution to prevent severe slugging flow conditions at offshore oilfields. The slugging flow constitutes an unstable and highly nonlinear system; the gain of the system changes drastically for different operating points. Although PI and PID controllers are the most widely used controllers in(More)
Oil well instabilities cause production losses. One of these instabilities, referred to as the "void-wave" is an oscillatory phenomenon occurring in gas-lift oil wells. A modified distributed delay model for this dynamic is presented in this paper. Then, the proposed model is used for stability analysis of a hypothetic gas-lift oil well undergoing this type(More)
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