Three-phase flash in compositional simulation using a reduced method

R. Okuno, R. T. Johns, K. Sepehrnoori

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


CO2 flooding at low temperatures often results in three or more hydrocarbon-phases. Multiphase compositional simulation must accurately simulate such gas floods. Drawbacks of modeling three hydrocarbon-phases are the increased computational time and convergence problems associated with flash calculations. Use of a reduced method is a potential solution. We first demonstrate the importance of using three-phase flash calculations in compositional simulation by investigating difficulties with two-phase equilibrium approximations proposed in the literature. We then extend an algorithm for reduced two-phase flash calculations to three-phase calculations and show the efficiency and robustness of our algorithm. The reduced three-phase flash algorithm is implemented in a multiphase compositional simulator to demonstrate the speed-up and increased robustness of simulations in various case studies. Results show that use of a two-phase equilibrium approximation in reservoir simulation can result in a complete failure or erroneous simulation results. Simulation case studies show that our reduced method can significantly decrease computational time without loss of accuracy. Computational time is reduced because of the smaller number of equations to be solved and increased time-step sizes. We show that phase behavior convergence problems lead directly to reduced time-step sizes.

Original languageEnglish (US)
Title of host publication15th European Symposium on Improved Oil Recovery 2009
Number of pages22
StatePublished - Dec 1 2009
Event15th European Symposium on Improved Oil Recovery 2009 - Paris, France
Duration: Apr 27 2009Apr 29 2009

Publication series

Name15th European Symposium on Improved Oil Recovery 2009


Other15th European Symposium on Improved Oil Recovery 2009

All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology


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