Abstract

The rheological properties of heavy crude oil have been investigated using RheoStress RS100 from Haake. The effects of shear rate, temperature and oil concentration on the viscosity have been determined. From the rheological data, it was observed that blending the heavy crude oil with a limited amount of lighter crude oil worked better than using the other alternatives and was considered as the proposed method of reducing the viscosity. Therefore, the theological behavior of heavy crude oil and heavy crude oil-light crude oil (O-light) mixtures has been studied and a series of experiments was conducted. The experiments were performed in terms of studying the effect of shear stress x, shear rate Þ, yield stress x 0 , thixotropic behavior, the storage modulus G' , the loss modulus G" , the complex modulus G* , and the complex viscosity j*. The results showed a significant viscosity reduction of 0.375 Pa.s at room temperature 298 K through which it complies with the desired value required for pumping the heavy crude oil through the pipelines. Moreover, the heavy crude oil showed a thixotropic behavior with hysteresis area of 321.65 KPa.s -1 which decreases with temperature. It was clear that the heavy crude oil required a yield stress of 0.7 Pa, whereas it did not require any yield stress to pump the heavy crude oil-light crude oil mixture. In addition, it was noted that the complex modulus, the storage modulus and the loss modulus showed a direct proportional with frequency and inverse proportional with temperature. The complex viscosity of the heavy crude oil decreased with temperature and fraction of water added, and it reached 225 Pa.s at 338 K.