Study on the micro-mechanism of annealing treatment on the intermolecular action of waxy crude oil

Abstract

To investigate the influence mechanism of the annealing treatment on the intermolecular action of waxy crude oil, this study selected the molecular models of oil, wax, resin and asphaltene, and constructed the model system to imitate instead of the waxy crude oils by using the Materials Studio software, and revealed the influence mechanism of annealing treatment. Three main findings were made: 1) The basic molecular unit structure is the premise of phase transformation, and the different annealing times are the main factors affecting the phase transformation. 2) After annealing treatment, the conformation of molecular chain gradually changes from the initial straight chain to the curly state, and the change is most obvious at the lowest energy; in terms of system energy, the changes of E_val, E_non-bond and E_total of the three oil samples all increase in different extent during the whole thermal process. 3) In terms of the radial distribution function (RDF) between the identical types of molecules and heterogeneous molecules of waxy crude oil, the accumulation of asphaltenes plays a leading role in the annealing process of waxy crude oil system, and the van der Waals force is the main force.