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Abstract
For the transportation of larege quantities of crude oils, pipelines are the only possible and the most economic means.
High wax content and low API gravity crude oils cause a variety of problems during pipeline transportation.
Three types of problems faced during waxy crude oil transportation are: pressure losses dye to high pour point, high yield stress for restarting the flow and deposition of wax crystals on pipe surfaces.
The large viscosity of asphaltic-base crude oils is the main source of problems through pipeline transportation.
Before the transportation of suh problematic crude oils via pipelines, their flow properties should firstly be improved by a suitable technique.
To study the effect of the improvement techniques on highly asphaltene and highly paraffin crude oils, five Egyption crude oils were tested; namely Agiba, Waha, Zeit Bay, Belayim Land and Asran crude oils.
These crude oils were selected according to their content of the paraffin (wax) and the asphaltene. The wax content of these crudes is ranged between 1.5 & 12.1 Wt %, and the asphaltene content is ranged between 0 & 16 Wt %.
Three different techniques were investigated in this study for improving the flow properties of such crude oils. These techniques are: dilution with natural solvents (straight run gasoline (SRG), Kerosene and condnsate), chemical additives (FI, PD and AD) and heating.
The evaluation of the flow properties before and after treatment was carried out using both the rheological measurements and the pour point determination.
The rheological measurements were conducted using a Haake rotational viscometer at three different temperatures which are: 10C below pour point, at pour point and 10C above the pour point of each crude oil.
The shear stress-shear rate data before and after treatment were first fitted to the most crude oil models. The Bingham plastic model was found the best one, so the effect of the forementioned techniques on the Bingham yield stress and the Bingham plastic viscosity was discussed.
A comparison among the forementioned techniques was carried out on the basis of pressure loss and hence the precent reduction in pressure loss achieved by each technique.