Modeling Chemical EOR Processes: Some Illustrations from Lab to Reservoir Scale Modélisation des procédés EOR chimiques : du laboratoire au réservoir

Chemical flooding, SP (Surfactant Polymer) or ASP (Alkali-Surfactant-Polymer), are of increasing interest due to the need to increase oil production. Design of chemical processes is very project specific and requires case by case studies including various steps among which reservoir data analysis, chemical formulations, coreflood validations and reservoir simulation. Every step is dependent on the preceding ones and the last reservoir simulation step gathers all the information collected during the project. In this paper, we present a chemical simulator describing two phase flow with chemical transport of alkali, surfactant, polymer and salinity. Two phase flow is related to capillary desaturation curve through the decrease of oil-water interfacial tension. Physical chemistry reactions are described either with a thermodynamic approach or a simplified one using tables or simplified physics to be compatible with large scale reservoir simulations. In this paper, we describe the simulator and present results of numerous experiments specially designed to validate the model: alkaline injections of carbonates and borates, surfactant adsorption experiments at different salinities and pH, systematic effect of salinity on interfacial tension and oil recovery with/without salinity gradient. The good agreement between the experimental and numerical oil recoveries and chemical compositions is very encouraging and supports the validity of the physics implemented in the simulator. In particular, the dominant effect of pH on adsorption and the importance of a salinity gradient on oil recovery is highlighted by numerical simulation. Finally, a sensitivity study at the reservoir scale is presented to illustrate relevant factors for the implementation of an economic surfactant-based process. Les procédés de récupération tertiaire par voie chimique, SP (Surfactant Polymer) ou ASP (Alkali-Surfactant-Polymer), sont en plein essor du fait d’une demande croissante en produits pétroliers. La mise en uvre des méthodes de récupération d’huile par voie chimique sont très spécifiques et demandent des études intégrées allant de l’étude du réservoir à la simulation du procédé à l’échelle du réservoir, sans oublier les études de laboratoire. Cet article présente le simulateur chimique SARIPCH développé pour les évaluations à l’échelle du réservoir. Il s’agit d’un simulateur de type ‘‘black oil’’ incorporant des équations de transport pour les produits chimiques : alcalin, tensio-actif et polymère. Le processus de récupération d’huile est introduit par la courbe de désaturation capill