May 22 – 25, 2023
Europe/London timezone

Four-phase equilibrium calculation algorithm for water/hydrocarbon mixtures

May 24, 2023, 3:15 PM
Oral Presentation (MS07) Mathematical and numerical methods for multi-scale multi-physics, nonlinear coupled processes MS07


Martin Jex (ctu fnspe)


Successful large-scale compositional reservoir simulation requires robust and efficient equilibrium calculations. In recent years a large number of papers have been published on the topic of three-phase vapor-liquid-aqueous (VLA) equilibria
which frequently appear in hydrocarbon reservoirs. The presence of the aqueous phase increases the probability of equilibrium calculations to have issues. One may experience convergence problems or even not being able to distinguish a fourth phase altogether. This is generally due to the lack of good initial guesses, which is usually solved by proposing supplementary inital guesses which are designed to deal with a particular mixture. The commonly used approach is to perfrom a stability test, before the equilibrium calculation,
which determines whether it is needed to add an additional phase. Another
benefit of this approach is that the result from the stability testing provides a good initial guess for the phase equilibrium calculation. In this contribution we derive a robust algorithm which can deal with up to four phase equilibrium
calculation. We demonstrate the algorithm and its robustness and efficiency
in several examples from literature (mainly computing the phase envelopes of
water/hydrocarbon mixtures).

Participation In-Person
Country Czech Republic
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Primary authors

Martin Jex (ctu fnspe) Prof. Abbas Firoozabadi (Rice University; Reservoir Engineering Research Institute) Dr Mikyška Jiří (ctu fnspe)

Presentation materials