RESUMO
Surfactant-polymer (SP) flooding is considered an efficient technique to increase the recovery of oil, especially from carbonates reservoirs, because of their complex nature. The objective of this study is to analyze the effect of polymer drive composition on surfactant retention. We developed a geochemical model that uses various surface complexation reactions at the mineral/brine interface, oil/brine interface, surfactant/brine interface, and oil/surfactant interface. We also incorporated four new surface complexation reactions that honor oil/surfactant geochemical interaction to determine the influence of polymer composition on surface retention for the first time. Then we validated the developed geochemical model against coreflooding experimental data. Additionally, we investigated the influence of various parameters of polymer drive on surface retention under high temperature and salinity using the suggested surface complexation model. The findings showed that our surface complexation model can estimate surfactant retention and its concentration in the effluent with a certain accuracy during polymer drive. The developed geochemical model is validated against single-phase and two-phase coreflooding experimental data. The findings revealed that for a more representative and accurate estimation of surfactant retention in chemical flooding, it is important to consider the oil/surfactant surface complexation reactions. Moreover, the detailed and comprehensive analysis showed that with the increase in temperature of the polymer drive, the retention of surfactant increases, and its concentration in the effluent decreases. The latter shows that surfactant retention is a more chemical process as opposed to physio-retention. It is also shown that the injection of a specific composition of polymer drive after a surfactant slug could decrease the surfactant retention, which is related to the force of repulsion between the ionic species and the rock surface. Moreover, the effect of hard ions (calcium and magnesium) in polymer drive is significant where the increase in the concentration of hard ions increases the retention of surfactant. Furthermore, it is important to mention that the lowest level of surfactant retention was achieved through a certain composition of polymer drive, thus the polymer solution dilution is not an effective approach. This is the first study to test a novel formulation of surface complexation modeling that considers the oil/surfactant effect on surfactant retention corresponding to the composition of polymer drive. The suggested framework to determine surfactant retention is conducted for harsh reservoir conditions of temperature and salinity and suggests that the surface complexation reactions for all rock-forming minerals must be considered.
RESUMO
In this study, we numerically investigated the effect of swirl inserts with and without nanofluids over a range of Reynolds numbers for parabolic trough collectors with non-uniform heating. Three approaches were utilized to enhance the thermal-hydraulic performance-the variation of geometrical properties of a single canonical insert to find the optimized shape; the use of nanofluids and analysis of the effect of both the aforementioned approaches; the use of swirl generators and nanofluids together. Results revealed that using the straight conical strips alone enhanced the Nusselt number by 47.13%. However, the use of nanofluids along with the swirl generators increased the Nusselt number by 57.48%. These improvements reduced the thermal losses by 22.3% for swirl generators with nanofluids, as opposed to a reduction of only 15.7% with nanofluids alone. The investigation of different swirl generator designs showed various levels of improvements in terms of the overall thermal efficiency and thermal exergy efficiency. The larger swirl generator (H30mm-θ30°-N4) with 6% SiO2 nanofluids was found to be the optimum configuration, which improved the overall collector efficiency and thermal exergy by 14.62% and 14.47%, respectively.
