In-situ Synthesis of Nanoparticles in Reservoir Model Oils and Their Effects on Asphaltene Adsorption, Pyrolysis, and Oxidation during In-situ Combustion Enhanced Oil Recovery

A proper method for uniform distribution of the nanoparticles in the reservoir fluids is in-situ synthesis of the nanomaterials. In in-situ combustion EOR process, precursor metal ionic solutions and heavy oil form water/oil emulsions downstream of the combustion front by the aid of asphaltenes as surfactant. The droplet size and stability of the emulsions were monitored at different temperature and pressure. The in-situ prepared coked nanoparticles were characterized by XRD, FESEM, and BET techniques and compared with ex-situ prepared NiO nanoparticles. The pyrolysis and post-pyrolysis oxidation of the coke residue were investigated by temperature-programmed pyrolysis and oxidation methods, respectively. Compared to the ex-situ synthesized nanoparticles, the in-situ prepared NiO nanoparticles shift the coke combustion temperature by about 100-130℃ downward. Higher amount of coke is formed onto the in-sitiu prepared nanoparticles rather than the ex-situ NiO. This may indicate that the in-situ combustion front temperature is decreased and the front stability is improved, leading to the succeful sweeping of the reservoir oil by the advanced in-situ combustion EOR method