FlowManagerœ Dynamic is a transient multiphase flow simulator for online surveillance, optimization and prediction of subsea oil and gas production. The simulator covers all operational scenarios (e.g. production, shut-in, restart) for a complete subsea field layout (reservoir, wells, pipelines, subsea process equipment). This paper focuses on prediction of multiphase flow in wells and pipelines.

The simulator is based on models that are fast, robust, simplified and highly tuneable, but valid for all operational conditions. The model for wells and pipelines is a 1-D drift flux model with algebraic slip and friction relations for all flow regimes. All friction and slip relations, and the transition between flow regimes, are continuous and smooth for robustness, easy tuning and optimization. The equations are solved numerically using the Strongly Implicit Mixture Flux (SIMF) method developed by Evje and Flåtten (1). SIMF is a fast and robust numerical method that ensures accurate resolution of liquid slugs and surges.

Network calculations, rate allocation and tuning are performed using multivariable optimization, ensuring consistency between all variables (flow rates, pressures, temperatures, tuning factors). The unique combination of multivariable optimization and fast, smooth and robust models enables simple and fast tuning and adjustment to measurements. This unique feature strongly reduces the configuration complexity compared to other simulators where controllers in combination with artificial pressure drop and temperature sources (e.g. valves, heat exchangers or tuning factors) are used to adjust the model to measurements.

FlowManagerœ Dynamic agrees well with experimental data and data from the FlowManagerœ field database. In this paper, the strengths of the simulator are demonstrated on an existing field application. It is shown that the simulator is easy to tune and gives accurate predictions of flow rates, pressure drop and liquid surges.

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