A simple approximate density-based phase envelope construction method

Summary Two-phase and three-phase equilibria are frequently encountered in a variety of industrial processes, such as carbon dioxide (CO2) injection for enhanced oil recovery in oil reservoirs, multiphase separation in surface separators, and multiphase flow in wellbores and pipelines. Simulation and engineering design of these processes using isothermal/isochoric (VT) multiphase equilibrium algorithms are sometimes more convenient than that using the conventional isothermal/isobaric (PT) algorithms. This work develops a robust algorithm for VT multiphase equilibrium calculations using a nested approach. The proposed algorithm is simple because a robust PT multiphase equilibrium algorithm is used in the inner loop without any further modifications, while an effective equation-solving method (i.e., Brent’s method; Brent 1971) is applied in the outer loop to solve the pressure corresponding to a given volume/temperature specification. The robustness of the VT algorithm is safeguarded by using a highly efficient trust-region-method-based PT algorithm. We demonstrate the good performance of the newly developed algorithm by applying it to calculate the isochores of fluid mixtures that exhibit both two-phase and three-phaseequilibria.

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Development of Robust Equilibrium Calculation Algorithms for Reservoir Fluids at Given Volume, Temperature and Composition

Lu¹

2020

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A simple approximate density-based phase envelope construction method

Cited by 3 publications

References 45 publications

Saturation point and phase envelope calculation for reactive systems based on the RAND formulation

Saturation point and phase envelope calculation for reactive systems based on the RAND formulation

Simple and Robust Algorithm for Multiphase Equilibrium Computations at Temperature and Volume Specifications

Development of Robust Equilibrium Calculation Algorithms for Reservoir Fluids at Given Volume, Temperature and Composition

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