Oil Recovery Improvement in Heterogeneous Layered Reservoirs Using Polymer Nanohybrids: A Numerical Approach

In this study, the efficiency of clay nanoparticles-assisted polymer (CNAP) flooding in enhancing oil recovery was numerically scrutinized and compared with the conventional polymer flooding. Thus, using a three-dimensional chemical flood simulator, comprehensive numerical simulations were carried out to find out the most suitable scenario for ameliorating oil production from a stratified reservoir with a high permeability contrast. Therefore, the effects of reservoir heterogeneity, well arrangement, and salinity on the simultaneous flow of crude oil and the nanofluid in the layered reservoir were explored. The results disclosed that, by increasing the rock heterogeneity index, the ultimate oil recovery during water flooding was reduced from 41 to 34% of original oil-in-place (OOIP). However, for the case of polymer flooding and CNAP flooding, the ultimate oil recovery was reduced by a factor of 3% and 1%, respectively. In addition, for the cases studied here, the inverted-two-5-spot pattern was proposed as the best well-placement strategy to boost oil recovery from layered formations. Due to the greater degree of salt tolerance of the clay nanoparticles dispersed in polymer (CNDP) solution, compared with polymer flooding, the CNAP flooding in the reservoir with the highest formation salinity showed a better macroscopic sweep efficiency and improved oil recovery by a factor of 15% of OOIP. Interestingly, the output of numerical simulations proved that the amount of required polymer to gain an ultimate oil recovery of more than 60% of OOIP can be reduced by half when the injectant has clay nanoparticles (NPs).