Interaction of Clay–Crude Oil–Injection Brine: An Experimental Approach for Understanding the Effectiveness of Low Saline Water (LSW) During Enhanced Oil Recovery (EOR)

Abstract

Low saline water flooding (LSWF) in sandstone is an emerging technique for enhanced oil recovery (EOR). However, understanding the nature of the process is still limited and debated. Hence, there is a need to better understand the molecular level insights into the interactions between the rock–oil–water. This study elucidates the interaction phenomenon occurred between different reservoirs components considering smectite-rich clay, dead crude oil and different concentrations of brine (1500–50,000 ppm) for designing customized flooding fluid for specific reservoir type. The interaction study has been done using different analytical methods including X-ray diffraction patterns, Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), UV–visible spectroscopy, fluorescence spectroscopy, powder wettability and contact angle measurements. The results reveal that 1500–3000 ppm range of salinity is working better during EOR. However, the composition of smectite and crude oil present in the reservoir is the key factor on which the oil recovery also depends. The saline water extracts different polycyclic aromatic structures from the oil sample. The study proves that the monovalent cation like Na+ is more compatible to exploit oil as compared to divalent cations like Ca2+ and Mg2+.KeywordsSmectiteLow saline water flooding (LSWF)AsphaltenesPolycyclic aromatic hydrocarbon (PAH)WettabilitySpectroscopy