title: Sodium Dodecyl Sulfate-combined Cellulose Nanocrystals for Enhanced Heavy Oil Recovery from Berea Sandstone Reservoirs
Creators: name: Ullah, Aqrab
Publisher: name: Graduate Studies
Year: 2025
Subjects: subject: Enhanced Oil Recovery Nanomaterials Surfactants
subject: Engineering--Chemical
subject: Engineering--Petroleum

description: For heavy oil recovery, thermal and gas injection techniques have recently shown substantial difficulties associated with heat loss, inefficient oil recovery, and large greenhouse gas footprints. Alternatively, chemical assisted heavy oil recovery techniques can enhance the micro- (displacement) and/or macroscopic (sweeping) efficiencies with employment of long-chained polymers or surfactants. However, most of recently implemented polymers tend to be structurally changed or degraded at the steam chamber temperature or under saline conditions, which significantly limits their oil recovery effectiveness. Thus, the surfactant injection has been successfully remained as the most effective chemical enhancing the oil recovery technique, which typically work through a combination of mechanisms, including interfacial tension (IFT) reduction, wettability alteration, foam generation and emulsification. Through these mechanisms, the use of vast groups of anionic, cationic, and amphoteric surfactants have been widely investigated to enhance the volume of the recovered oil. Compared with cationic and amphoteric surfactants, the anionic surfactants, such as sodium dodecyl sulfate (SDS), has been extensively utilized at high dosages in sandstone reservoirs, due to less chances of SDS adsorption on the rock surface. Herein, a stable nanofluid is produced using biodegradable and organic-based nanomaterials that consists of cellulose nanocrystals combined with SDS at room conditions to enhance the residual oil recovery in the sandstone reservoirs. This production method for the nanofluid systems was done by directly dispersing diverse concentrations of SDS (0.01-0.5%) with certain amount of CNC (0.01-0.5%) under acidic conditions at room temperature. After that, the generated systems were examined in reducing the IFT with spinning drop tensiometer (SDT), and the optimized one was well characterized using fourier transform infrared spectroscopy (FTIR) to confirm the surface functionality change after combining the CNC with the dissociated and acid treated SDS. Then, the combined SDS-CNC systems were used to generate diverse nanofluids that their stabilities were indicated by conducting zeta potential measurements and dynamic light scattering (DLS). At last, the capability of the combined CNC-SDS nanofluids to enhance the residual oil recovery performance were examined, compared with the surfactant and low salinity fluids, by spontaneous imbibition experiments and oil displacement tests under confining pressure of 1500 psi. The results revealed that the interfacial tension (IFT) between aqueous phase and crude oil was reduced considerably by 91.2%, using 0.1 wt. % SDS and 0.05 wt.% CNC as the organic based nanomaterials can mitigate the desorption of surfactant at the interface. Besides, the SDS-CNC nanofluids were able to displace 11% more oil during imbibition as compared to SDS alone, indicating that the nanofluids generated with our nanofluids had strong capabilities to alter wettability of the cores from oil wet to water wet due to arise of structural disjoining pressure. From the core flood testing, it was also confirmed that the oil recovery was increased from 57.5% (by 0.1 wt. % SDS) to 74.4% (0.1 wt. % SDS and 0.05 wt. % CNC) which unveils the competency of SDS-CNC nanofluids for cEOR applications.