Hydroxyl-Functionalized Carbon Nanoparticles Alter the Asphaltene Aggregate Structure and Reduce the Viscosity of Heavy Oil

A nanoparticle viscosity reducer has been shown to reduce the viscosity of heavy oil effectively. Carbon nanoparticles (CNPs) are environmentally friendly materials with good application prospects and biocompatibility. In this research, hydroxyl CNPs with phenyl groups on their surface were synthesized and used to reduce viscosity and improve fluidity in heavy oil. The effects of the CNPs on the rheological properties of heavy oil and their ability to reduce viscosity were measured using a rheometer and a rotational viscometer. The CNP viscosity reducer decreased the viscosity of Tahe heavy oil by up to 65.89%, with the introduction of long-chain alkyl groups affecting the viscosity reduction performance. The asphaltene structure was studied using X-ray diffraction and Raman spectroscopy, which showed that the microcrystalline structural parameters of asphaltene changed after the interaction with the CNP viscosity reducer. The effect of the viscosity reducer on the intermolecular hydrogen bonds of asphaltene was studied using Fourier-transform infrared and proton nuclear magnetic resonance spectroscopies, which showed that the interaction with the viscosity reducer destroyed the original hydrogen bonds within the asphaltene. The CNP viscosity reducer decreases the accumulation height of asphaltene aggregates by changing the microcrystalline structural parameters of asphaltenes and dispersing asphaltene aggregation structures, thereby reducing the viscosity of heavy oil.