Adsorption of silica nanoparticles and its synergistic effect on fluid/rock interactions during low salinity flooding in sandstones

摘要

Several research works have shown the potential of incremental oil recovery by low salinity water (LSW) injection. The research in this area has also shown that LSW interaction with rock's mineral (sandstone and chalk) raises the potential for formation damage by produced fines. The objectives of this work are to address the adsorption of silica nanoparticles (NPs) on sandstone and their effect on fluid/rock interaction during LSW flooding. Isothermal static adsorption of NPs on sandstone minerals surfaces showed a higher adsorption affinity on quartz surface compared to kaolinite. This was also shown by scanning electron microscope images. The adsorption of NPs was enhanced by increasing salinity. To investigate the dynamic adsorption, a co-injection of about 0.033 g NPs slug with tracer (about 0.13 g of LiCl2) as a reference. The estimated irreversible adsorption of NPs in the berea flooding of core was about 35%. While estimated desorption of the flooded core was about 21.2%. Detailed mass balance analysis is included. It was observed that the adsorption/desorption processes of silica NPs are influenced by the pH wherein increased alkalinity favors NP desorption. NP adsorption on the mineral surface during combined LSW and NP flooding was shown to reduce mineral dissolution, ion exchange, loss of cementing mineral and reduced resistance to flow compared to LSW alone. Surface forces estimation showed that combining LSW with NPs reduced the repulsion between fines and berea. The work here demonstrated the synergistic effect of combining the two technologies of LSW and nanoparticles where the probability of formation damage in sandstone reservoirs is reduced.