Study On The Effect Of PMSQ/EVA Composite Pour Point Depressant On Qinghai Waxy Crude Oil

Adding polymer-type pour point depressant(PPD)to waxy crude oil can effectively improve the economy and safety of pipe transportation.However,people’s understanding of the traditional PPD has not been comprehensive enough and the traditional PPD itself has some shortcomings.The main manifestations are as follows: the traditional PPD is not satisfactory to waxy crude oil.Its thermal stability and shear resistance are relatively poor.In this paper,waxy crude oil in Qinghai is selected as the research object,and choose different types of EVA PPDs.Through the condensation point measurement and rheological test,screen out the best PPD EVA2806.EVA2806 and different size PMSQ microspheres are melt blended to prepare a composite PPD.Using DSC,TGA,SEM and polarized light microscope to study the crystallinity,thermal stability and dispersivity of the composites.The results show that PMSQ microspheres have good dispersibility in EVA.Adding PMSQ microspheres to EVA can improve the crystallinity and thermal stability of PPD.The optimum heat treatment temperature is 60℃ and the optimal dosage is 50 ppm.The condensation point can be reduced to 21℃ and the viscosity reduction rate is 90.10%.Subsequently,the paper investigates the effects of adding 10 ppm PMSQ microspheres with different particle sizes on the rheology of crude oil.The results shows that adding PMSQ microspheres alone,the condensation point of the crude oil is unchanged still at 31℃,viscosity slightly increased.Finally,choosing EVA2806 and PMSQ microspheres with different particle sizes(500 nm,2 μm,5 μm,7 μm and 10 μm)to compound at different compositeing ratios(1%,2%,5%,10% and 20%).Through the condensation point measurement,rheological experiment,DSC and polarizing microscope,study the effects of complex PPD on the crystallization characteristics and rheology of crude oil.The experimental results show that particle size 2 μm PMSQ with EVA2806 are composited in a 5% ratio,and the prepared composite PPD has the best effect,which can reduce the condensation point to 19℃ and the average rate of 93.73%.Finally,the paper evaluates the effect of pipeline transport conditions on the effect of composite PPD by simulating tube shear,pump shear,repeated heating and timeliness.The results show that: after tube shear,adding PPD oil samples still has good results,the effect of the composite is still better than EVA;The oil samples are cut at a high speed for a short time,the viscosity of oil samples increased at different degrees at 20℃,but the PPD did not fail.The effect of the composite is still better than EVA;Repeat heating makes the rheological properties of the additive oil deteriorate to a certain degree.When the repeated heating temperature is 45℃,the viscosity increase is the largest.The pour point depressant has a certain timeliness,but compared with crude oil without additives,the rheology is still significantly improved.