Synthesis, Characterization, And Application Of Flaxseed Nanoparticles And Hybrid System As Eco‑Friendly Agents For Improving Oil Recovery

Abstract

This thesis investigates a green and locally accessible chemical EOR approach by developing flaxseed‑derived polymer nanoparticles (PNP) and a nanoparticle-surfactant hybrid system (PNP and SDS). The experimental workflow involves the synthesis of PNP, which begins with the extraction of flaxseed mucilage and gentle ultrasonic treatment with acid. A hybrid dispersion with SDS near its effective interfacial range is then prepared. Systematic testing is then conducted using characterization, rheology, interfacial tension (IFT), and core displacement modeling. Once the nanoparticles and hybrid system are ready, they are sent for characterization. The characterization results show that the resulting particles are organic and largely amorphous. As shown in the example, the X-ray diffraction pattern exhibits a structureless pattern without sharp Bragg peaks. This does not correspond to a crystalline material, but rather to a polysaccharide-rich matrix. IR spectroscopy results indicate the carbohydrate nature of the PNP and confirm the presence of SDS in the hybrid by the presence of sulfate group bands in the "fingerprint" region. Another characterization method using colloidal measurements (ZetaView, at pH 7, 25°C) revealed that PNP has a median hydrodynamic size of 331 nm with a negative zeta potential (-26 mV). Two experiments were performed, and the results were not significantly different. However, the hybrid's results are slightly shifted toward a larger median size (378-391 nm) with a much weaker surface charge (-8.4 mV). This can be explained by the fact that the lower the charge, the lower the repulsion, which leads to easier aggregation and a larger median size. Thus, under the same measurement conditions, this means that the hybrid exhibits a less stable state, indicating lower electrostatic stabilization than PNP. Discussing the rheological test results, we note a pronounced decrease in viscosity with increasing shear rate in all the cases studied. From an injection perspective, this is favorable, as apparent viscosity decreases with increasing shear rate. Generally, the effects of temperature, salinity, and concentration are strongest at lower shear rates, where the curves are most widely spaced. Therefore, they become less pronounced at higher shear rates, as the internal structure is disrupted by the flow. In performance tests, PNP itself exhibits a salinity-dependent interfacial tension: that is, at 1000 ppm, the change with concentration is minimal (17.0 → 16.7 mN/m), while at 10,000-35,000 ppm, a more pronounced decrease is observed, reaching 14.1 mN/m at 1 wt% in 10,000 ppm brine and 13.7 mN/m at 2 wt% in 35,000 ppm brine....