Recent developments, challenges, and prospects of carbon dots (CDs) for fluid flow investigation in porous media

Carbon nanostructures exhibit unique physicochemical properties and play a significant role in modern and advanced technologies. Carbon dots (CDs) are a subset of carbon-based particles less than 20 nm in size. In this study, a comprehensive review was performed on the applications of CDs for fluid flow investigations in porous media. CD technology provides precious information about the heterogeneity and permeability of the rock and the existence of a sealed part between the wells in the hydrocarbon reservoir. Studying the volume and flow potential of aquifers is another application of CD in fluid flow study. CDs can be used as an additive in the fluid to modify the chemical or physical properties. Adding CD to injected fluid in the reservoir can change the rheological properties of the fluid and reduce its viscosity. CD injection as a nanofluid in the reservoir rock increases the oil recovery factor and decreases injection pressure due to the change in the wettability of rock from oil-wet to water-wet and the reduction of interfacial tension between the fluids. The mobility and performance of CDs in pore scale are related to some parameters including ionic strength, pH, pore size distribution, and type of fluids in porous media.