Dear Muhammad Ali, I worked during my Master thesis on the synthesis of partially hydrolyzed polyacrylamides for polymer flooding. I think both are used depending mainly on salinity and the reservoir rock physicochemical nature. It is worth to tell extensive work was done on the field Daqing west in china for decades, you may search for such a long lasting experimental work. Also most promising approches are based on using nanofluids. Please check the following documents. My Regards

https://doi.org/10.1016/j.molliq.2019.04.146

https://www.researchgate.net/publication/263142953_Comparison_of_the_effects_of_wettability_alteration_and_IFT_reduction_on_oil_recovery_in_carbonate_reservoirs

https://link.springer.com/article/10.1007/s13202-019-00789-0

https://doi.org/10.1016/j.molliq.2020.114943

https://www.nature.com/articles/s41598-020-74450-w

Thanks