Oil Deposits in Highly Paraffinic Crude Oils and in Model System

Abstract

The effects of temperature gradient on the formation, composition, and strength of oil deposits were investigated. As the crude oil temperature and the wall surface temperature were lowered, the concentrations of the oil fraction and low-molecular-weight paraffins in the deposits increased; simultaneously, the amounts of resins and asphaltenes declined. In the asphalt–resin–paraffin deposits formed in an asphaltene-free oil sample, cooling led to a rise in the content of resins and a decline in the content of the oil fraction. Model experiments demonstrated that the highest inhibitory capacity with respect to paraffin wax deposition was achieved in the case of 0.5–1.0 wt % asphaltenes being added. This can be attributed to the steric effect of aromatic rings manifested in their ability to disrupt the nucleation of paraffin networks. Therefore, the model wax deposits formed after adding asphaltenes exhibited a lower strength than the samples obtained with the addition of benzene resins and alcohol–benzene resins.