Improving heavy oil oxidation performance by oil-dispersed CoFe_2O_4 nanoparticles in In-situ combustion process for enhanced oil recovery

摘要

In this work, bimetallic oxide CoFe2O4 nanoparticles were synthesized by the hydrothermal method. CoFe2O4 nanoparticles were coated by oleic acid (CoFe2O4@oleic acid) to provide the oil-dispersed catalyst for accelerating heavy oil oxidation in in-situ combustion (ISC) process for enhanced oil recovery (EOR). The synthesized CoFe2O4 and CoFe2O4@oleic acid nanoparticles were characterized by XRD, Mossbauer spectroscopy, and highresolution field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray (EDX) analysis system, etc. The catalytic performance of CoFe2O4 and CoFe2O4@oleic acid nanoparticles in heavy oil oxidation process was studied by TG-FTIR and high-pressure differential scanning calorimetry (HP-DSC) as well as kinetics calculation using isoconversional methods (KAS, OFW, and Friedman). The results showed that CoFe2O4@oleic acid nanoparticles were gradually decomposed during the oxidation process and formed CoFe2O4 nanoparticles that have most likely cationic distribution Co0.1Fe0.9[Fe1.1Co0.9]O-4. CoFe2O4@oleic acid nanoparticles showed a much higher catalytic activity than CoFe2O4, which benefits from the uniform dispersion and distribution of CoFe2O4@oleic acid and its decomposed products (CoFe2O4) in the entire oxidation process of the heavy oil. It significantly shifted the FD and HTO reaction into lower temperatures, enhanced the heat release, and reduced the energy barriers of FD, thus promoting the formation of coke and its combustion with high efficiency. The high catalytic activity together with its low cost make this catalyst a good candidate for its wide use in the ISC process for improving its combustion efficiency and success rate for heavy oil production.