title: Surfactant-Modified Nanoparticles for Enhanced Oil Recovery in Sandstone and Carbonate Reservoirs
Creators: name: Aboabdulla, Jomaa Ahmed Melad
Publisher: name: Schulich School of Engineering
Year: 2025
Subjects: subject: Engineering--Petroleum

description: This work delves into the realm of enhanced oil recovery (EOR) from carbonate and sandstone reservoirs by using cetyltrimethylammonium and alpha-olefin sulphonate (AOS) grafted on silica nanoparticles with low salinity water (LSW). The research investigates the mechanisms underlying the grafting of surfactants onto silica nanoparticles for carbonates and sandstone core applications, forming surfactant nano-based nanofluids. When coupled with LSW, these nanofluids offer a transformative strategy for chemical EOR. Rigorous experiments were conducted, ranging from material and fluid characterization, interfacial tension (IFT) measurements, wettability assessment using contact angle, spontaneous imbibition, and nuclear magnetic resonance (NMR) measurements and followed with core flooding experiments on different core plug samples both for carbonates and sandstones. For carbonate core plugs, limestone cores consisting of low (50 mD) and higher permeability (200 mD) scenarios were used. For sandstone core plugs, Brea sandstone of permeability in the range of 60-100 mD was used. The outcomes of these experiments clarified key insights into oil recovery. The reduction in IFT, particularly at elevated pH levels, emerged as a critical mechanism. For the case of carbonate reservoirs, while contact angle measurements indicated a significant shift from oil-wet to water-wet conditions, NMR and Amott index measurements indicated no wettability change upon the application of nanofluids. In the core flood experiments, the effectiveness of hexadecyltrimethylammonium bromide (CTAB) alone was contrasted with that of CTAB-grafted silica nanoparticles. For 200 mD cores, CTAB alone had an additional recovery of 22.4% over 6 pore volumes (PV), whereas CTAB-grafted silica nanoparticles at higher pH levels (SE) showed a higher recovery of 34.7%. In the case of 50 mD cores, CTAB alone yielded a recovery of 15%, while SE resulted in 20% of the oil originally in place (OOIP). These findings underscore the unparalleled potential of CTAB-grafted silica nanoparticles at elevated pH levels as a pioneering method, offering an economically viable, efficient, and highly effective approach for implementing surfactant-nanoparticle solutions in carbonate reservoirs, covering both low and high-permeability reservoirs. For the sandstone application, AOS surfactants and silica nanoparticles were tested for EOR applications via a series of tests, facilitating the mobilization of trapped oil. The study presented a new approach to the integration of silica-grafted AOS when dispersed in LSW for EOR applications in sandstone reservoirs. The formulated fluids comprised formation water (FW), LSW, silica nanofluids, AOS surfactant, and AOS+ silica (pH 9). Recovery at the tertiary stage was as follows: FW (0.00%), LSW (1.43%), silica nanofluids (2.85%), AOS (5.71%), and AOS+Silica (pH 9) (15.71%). The significant additional recovery observed in AOS and AOS-assisted nanofluids was attributed mainly to the ultra-low interfacial tension, which resulted in a change in capillary number magnitude (10-5 to 10-3) that facilitated the displacement of trapped oil since the wettability change was not significant. This study demonstrated the potential of integrating AOS-silica nanofluids with low-salinity water for enhanced oil recovery, providing valuable insights for optimizing EOR strategies in sandstone reservoirs. This research contributes significantly to the academic discourse surrounding EOR and holds immense promise for the petroleum industry, heralding a new era of enhanced recovery techniques in challenging reservoirs.