Daqing Oilfield has conducted various complex chemical improved oil recovery methods in both pilot tests and field applications such as alkali-surfactant-polymer (ASP) flooding, ASP+Foam flooding and multi-polymer flooding, in the meantime, some new process mechanism for various chemical flooding techniques has been rediscovered, for example, polymer elasticity could increase micro-scale oil displacement efficiency, making the existing chemical flooding simulators insufficient to handle these complex chemical flooding process mechanism. In this paper we develop an applied chemical flooding simulator to have capability to simulate various complex chemical flooding processes in Daqing Oilfield. In comparison with existing chemical simulators, the newly incorporated features include the chemical synergistic effect among surfactant, alkali and oil in ASP flooding with ultra-low surfactant concentration, increasing micro-scale oil displacement efficiency by polymer elasticity, multi-polymer commixing flooding process, foam behavior dependent on the reservoir pore structure and the ratio of gas to liquid in foam system, relative permeability that is a function of polymer elasticity and capillary number. The simulator models the other main physicochemical phenomena in chemical flooding process such as convection, dispersion, diffusion, adsorption, aqueous reactions, in-situ generation of surfactant from acidic crude oil, etc. The solving scheme for the simulator is sequential solution method, deriving pressure equation, saturation equation and concentration equation from mass conservation equation, and then solving the pressure equation implicitly, followed by obtaining the implicit solution of the saturation equation through Newtonian method. For concentration equation, an operator splitting method is employed to split it into a diffusion equation and convection equation, obtaining implicit solution by alternately solving the diffusion and convection equation. The solution procedure for diffusion equation is ADI. The convection equation is discretized using an implicit single point upstream method, by taking advantage of the reservoir flow potential field, to obtain an implicit non-iteration solution algorithm. The developed model is a 3-D 3-phase (oil, water and gas) and multi-component chemical flooding simulator, having ability to simulate single polymer flooding, multi-polymer flooding, ASP flooding, and ASP+Foam flooding. It has been successfully applied in various chemical flooding simulations. This paper also presents some cases for its application in Daqing Oilfield.
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