Effect of Solvent on Rheological Behavior of Iranian Waxy Crude Oil

Flow improvers are used extensively to increase the mobility of crude oil. This article deals with the relation between the rheological properties and solubility parameter of flow improvers in different solvents. Two types of Iranian waxy crude oils with different pour points were selected. The rheological behavior of this crude oil in the presence and absence of flow improvers in different solvents was measured. The rheological data cover the temperature range of 5 degrees C to 40 degrees C. Results show that the shear rate has an appreciable effect in decreasing viscosity, particularly at temperatures below the pour point. Poly ethylene-vinyl acetate copolymer (EVA) as flow improver with different range of molecular weights was used for the treatment of waxy crude oil. The results indicated that the performance of flow improvers was dependent on the molecular weight, type of solvent, and the type of crude oil. The phase behavior of EVA copolymers was investigated in various solvents. The flow improver in the poor solvent (cyclohexane) gave better results in improving the flowability of the crude oil, compared with the other solvent.