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Abstract
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The major challenges in using nanoparticles in oil and gas industry projects are high investment costs and environmental problems. Bio-nanoparticles provide a solution to environmental and economic challenges in the nano-assisted EOR processes. In this work, the potential of natural calcium carbonate nanoparticles containing chitin for wettability alteration in enhanced oil recovery was studied. The adsorption behavior of bio-nanoparticles onto calcite-dolomite rock surface was distinguished through kinetics, equilibrium, and thermodynamics assessments. Besides, oil recovery is measured through forced imbibition experiments. The Taguchi experimental design was conducted to optimize the parameters influencing oil recovery factor in forced imbibition experiments, including nanofluid concentration, temperature, and oil type. Results of the adsorption experiment showed that adsorption kinetics of bio-Ca nanoparticles onto calcite-dolomite surface follows the pseudo-second-order model and monolayer, Langmuir adsorption of bio-nanoparticles. The endothermic heat of physical adsorption (physisorption) was found 3.32 kJ/mol. Based on the experimental design, the optimum parameters that can rise to additional oil displacement are a nanofluid concentration of 0.05wt.%, normal heptane as liquid phase, minimum salinity (Milli-Q-water), and ambient temperature. The oil recovery factor increased by 17.52% at an optimum nanofluid concentration of 0.05wt.% in comparison to a base fluid without nanoparticle. The results indicate that synthesized bio-Ca nanoparticles have proper EOR potential in both light oil and heavy oil reservoirs at certain conditions.
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