An improved methodology for estimation of two-phase relative permeability functions for heavy oil displacement involving compositional effects and instability

Pedram Mahzari, Usman Taura, Mehran Sohrabi

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In heavy oil recovery by immiscible gas injection, adverse mobility ratio and gravity segregation along with influential mass transfer are the most crucial factors controlling displacement efficiencies. Obtaining relative permeability functions using conventional techniques that are based on a stable displacement front could be highly misleading. In this work, an improved methodology was proposed for estimating relative permeability curves under simultaneous effects of frontal instability and mass transfer using history-matching techniques. The compositional analysis of produced oil from a coreflood experiment was employed, which represents dynamic interactions more realistically. For the history matching, an optimum, high-resolution, two-dimensional core model was used, as opposed to the industry standard use of a one-dimensional model. The results of the simulation were then verified by a semi-empirical approach using the Koval model, which was then used to predict a similar experiment but in a vertical orientation. A good match was obtained between the forward simulation and the experiment. To highlight the effect of mass transfer on the shape of relative permeabilities, the simulation results from two immiscible gas injection corefloods were compared: CO2 injection with mass transfer and N2 injection without mass transfer. The results showed that the two estimated functions were quite similar, indicating that instability levels would determine the displacement pattern rather than local mass transfer. This integrated approach, therefore, highlights the importance of employing the right fluid model and an appropriate 2D-grid model in estimating relative permeabilities in displacement with instability and mass transfer against the current industry practice.

Original languageEnglish
Pages (from-to)975–991
Number of pages17
JournalComputational Geosciences
Volume22
Issue number4
Early online date16 Jan 2018
DOIs
Publication statusPublished - Aug 2018

Keywords

  • CO injection
  • Compositional simulation
  • Heavy oil
  • History matching
  • Relative permeability
  • Unstable displacement

ASJC Scopus subject areas

  • Computer Science Applications
  • Computers in Earth Sciences
  • Computational Theory and Mathematics
  • Computational Mathematics

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