Pore scale modelling of Linked Polymer Solution (LPS): a new EOR process

The paper describe the concept of developing a modeling tool for pore scale modeling of Linked Polymer Solution (LPS) or Colloid dispersion gels (CDG). The linked polymer solutions consist of low concentration of partially hydrolyzed Polyacrylamide polymer cross linked with alumina citrate which may be used as EOR method after water or polymer flooding. Although the results from field trials are very promising, the mechanism and the physics of LPS arc not still well understood. We believe increasing oil recovery after LPS implementation is attributed to the mobilization of capillary trapped oil by flow diversion in pore scale. To bring this conceptual idea into the reality, we modeled linked polymer solution process by creating a two-phase pore scale network model. A new approach of combining semi-static invasion percolation models with dynamic network modeling of enhanced oil recovery methods has been developed. The purpose is to model injection of colloidal dispersion gels (CDG). This model allows us to study the mechanisms involved in LPS injection like polymer viscosity effects, adsorption and blocking processes. The combination of both network types was considered here; two phase invasion percolation semi-static network which used for the primary drainage and imbibition until residual oil saturation obtained and dynamic model which applied to capture the blocking of bonds that occurs due to LPS blocking mechanisms. Communication between semi-static and dynamic networks to calculate the proper injection pressure was found to be crucial here. Results demonstrate that blocking of bonds after injecting LPS reduces the residual oil saturation because of log-jamming process. In this process, small polymer particles accumulate in the bond and prevent fluid flow through the bond. Therefore flow is diverted towards the oil bonds leading higher oil displacement. Sensitivity tests of a conceptual network model for pore blocking by polymer gels have been successfully completed.