Branched polymers and nanoparticles flooding as separate processes for enhanced oil recovery

Since it was first theorized more than half-century ago, nanotechnology has proven to be the perfect boost for existing technologies and the oil industry has made use of this avant-garde discipline to upsurge the productivity of mature oilfields. With respect to polymer flooding, recent research has stressed the importance of the (macro) molecules' architecture on the physical properties. This paper presents the numerical simulation of these two agents in standard, not combined, oil recovery processes. The polymer solution viscosity is calculated considering the polymer's architecture, its degradation and the salinity. The nanoparticles affect the carrier-phase viscosity and the rock formation wettability, which modifies the oil mobility. Results evidenced the improved capabilities of branched (i.e. star/comb) polymers with respect to traditional linear ones. The modified architecture improves not only the rheological but also the viscoelastic properties, which ultimately increases the microscopic sweeping efficiency. Nanoparticles increase slightly the carrier phase viscosity, but their main recovery mechanism is their adsorption onto the rock and subsequent wettability modification, reducing the residual oil saturation. Furthermore, it is also important to properly characterize both the particles' average size and also their aggregation rate, since these affect the recovery efficiency. Simulations show the importance of a good characterization of oil recovery agents and their effect on the phases' physical properties as well as the potential of nanoparticles to act as a boost of traditional enhanced recovery processes.