Emerging applications of TiO₂/SiO₂/poly(acrylamide) nanocomposites within the engineered water EOR in carbonate reservoirs

In this study, TiO₂/SiO₂/poly(acrylamide) nanocomposites (NCs) as a newly-developed-nano enhanced oil recovery (EOR) agent is proposed using a simple, green and economic method from the extract of pomegranate seeds. The ultraviolet–visible spectroscopy (UV–Vis), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) are applied to analyze the characterization of NCs. Nano-smart solutions are prepared from the dispersion of NCs within the smart water at three different concentrations (500, 1000 and 1500 ppm). The used smart water solutions are formulated from mixing the single and binary systems of the monovalent and divalent salts (NaCl, KCl, MgCl₂, CaCl₂, Na₂SO₄, MgSO₄, K₂SO₄ and CaSO₄) at different concentrations of 2500, 5000 and 10,000 ppm within the distilled water. In order to identify the effect of the prepared NCs in smart EOR applications, the interfacial tension (IFT) of crude-oil/smart-water and crude-oil/smart-nanofluid systems is measured using the pendant drop technique, the wettability behavior of carbonate rock is studied using the contact angle (CA) measurement, and recovery efficiency is determined by preforming the coreflooding test for eight core plugs. According to the obtained experimental results of IFT and CA, KCl-5000, K2SO4-5000, CaSO₄ + CaCl₂ (5000 + 5000) and K₂SO₄+ CaCL₂ (2500 + 2500) are selected as the optimal smart solutions. Furthermore, the performance of the selected smart water solutions is influenced by 65% in IFT reduction, 32% in wettability alteration and 10.5% in oil recovery when the prepared NCs is added to the solutions. Nano-OSS3-5000 smart-nanofluid developed from mixing 1500 ppm of TiO₂/SiO₂/poly(acrylamide) NCs with 5000 ppm of CaSO₄ and CaCl₂ ions demonstrated the highest performance in increasing oil recovery from 36.0 to 46.53% original oil in place (OOIP).