The Research On Rheology Of Waxy Crude Oil

The crude oils exploited in our country's oilfields are mainly waxy crude oil, which have high solidification point and abnormal point and shows most complex rheology. When the temperature drops and approaches the solidification point, it will has the thioxtropy. Traditionally the pipeline transportation of crude oil is done in the calefaction technique. To decrease the cost of transportation and make its more economical, the pipeline transportation at the normal temperature will be developed. So the throughout research to the flow behavior of crude oil at low temperature and its characteristic in the pipeline is most necessary.The deposition of wax often appears in the storage, transportation and production, which can result in the increase of apparent viscosity of oils, and this may cause much severe problems and dangers in the pipeline transportation. Hence, the throughout research to the rheological behavior of wax crude oil, especially at the low temperature, is very important to oil industries.hi this paper, Daqing forth transportation wax crude oil is use as an experimental sample, and a series of experiment have been designed and finished to study the rehology of waxy crude oil. More important, some experimental research has been performed to find out the thixotropy of Daqing crude oil under the solidification point. Based on the experimental data, we have gotten all the parameters in the R-G equation, used to characterize the curve of firstly breaking up and decaying stress of the waxy crude oil at different temperatures. We have also studied and acquired the relationship between these parameters and temperature. The calculation results agree with the experimental data well. It has been find out that cooling rate has great influence on thixotropy in the experiments and as cooling rate getting higher yield stress and equilibrium stress will both be larger.We has also done the experiment research on the rheology of waxy crude oil with depressant and discuss the mechanism of depressant. The morphology of paraffin crystals in crude oils and crude oils with depressant has been observe by the polarized microscopy. We have gotten many photos and acquired some quantitative parameters to characterization the paraffin crystals by some software, and discussed the relationship between the morphology and configuration of paraffin crystals and rheology of crude oil. We have used fractal theory to characterize the morphology and configuration of paraffin crystals quantitatively. This point out a new way to further make the quantitative mechanism model of rheology of crude oil and relationship between rheology and morphology or configuration of paraffin crystals of crude oil.