Preparation and oil displacement evaluation of amphiphilic carbon quantum dots
A stable amphiphilic carbon quantum dots(CQDs)oil displacement agent(CQDs-S)was rapidly syn-thesized by one-step hydrothermal method with glucose as carbon source and dodecyl hydroxypropyl sulfobe-taine(DHSB)as surface modifier.FTIR,TEM and DLS were used to characterize the structure,morphology and stability of CQDs-S.Interface performance test,contact angle measurement and static oil washing experi-ment were carried out to study the performance advantages of CQDs-S,compare with DHSB and CQDs in oil recovery,and analyze the mechanism of enhanced oil recovery.The results show that CQDs-S is a spherical par-ticle with an average particle size of 7.8 nm,and its surface is modified with alkyl,which has amphiphilic prop-erties and good stability.With a mass concentration of 0.1％CQDs-S,the oil-water interfacial tension is reduced to 0.96 mN/m,the contact angle is reduced to 48.5°,the static oil washing efficiency is as high as 86.8％,and the oil recovery rate in the core with a permeability of 50×10-3 μm2 is increased by 16.74％,which is signifi-cantly higher than that of CQDs and DHSB.The EOR mechanism of CQDs-S is mainly to reduce interfacial ten-sion,change wettability and realize profile control.CQDs-S is an efficient nano oil displacement agent,which can reduce the oil-water interfacial tension,change the rock wettability,and realize profile control.
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