Formulations for a three-phase, fully implicit, parallel, EOS compositional surfactant–polymer flooding simulator

Abstract

As chemical flooding becomes more attractive due to increased oil prices and advances in chemical production, the need for a powerful and comprehensive chemical flood simulator increases. A key requirement of success in chemical flooding is optimization of the design in field scale using appropriate resolution which may be significantly more than the resolution adequate for waterflood modeling. This requires immense computation power and parallelization of the simulation. Another key requirement is comprehensive oil/brine/surfactant phase behavior modeling for exploring the performance of any attractive design in field scale. The simulator described by Han et al. (2007) was limited to only two-phases and under optimum Type I phase behavior.This paper describes the formulations for a three-phase, fully implicit, parallel, EOS compositional chemical flooding simulator with comprehensive compositional phase behavior model as a function of salinity. Presented formulation assumes that the reservoir is isothermal and no free gas or alkali is present. The improved simulator can handle the full transition from Type I to Type III to Type II microemulsion phase behavior. The parallel processing capability combined with fully implicit time stepping allows high-resolution full field scale chemical flooding simulations. The fully implicit simulation results are validated against an IMPEC chemical flooding simulator. This generalization required a substantial reformulation of the equations and extending the three phase water/oil/gas to up to four phases of water/oil/gas/microemulstion with corresponding physical property models. The full coupling of chemical with EOS model will provide a general framework to model the effect of live oil and pressure on surfactant phase behavior.This paper presents a fully implicit, chemical-EOS compositional simulator with a comprehensive surfactant phase behavior that can take into account the effect of salinity and the resulting two- or three-phase flow with efficient parallel scalability.