Stratification Phenomenon And Development Laws Of Wax Deposits Formed By Asphaltenes-containing Waxy Oil

Based on a newly developed Couette device,stratification phenomenon and development laws of the wax deposit formed by Jienuo crude oil and 11 kinds of synthetic waxy oils which have different composition was studied.In the study of stratification phenomenon of wax deposits,the macroscopic morphology,DSC curves of wax deposits were analyzed.it was found that the change of wax content and carbon number distribution couldn't lead to stratification phenomenon,but asphaltene addition leads to the generating of outer wax deposit and inner wax deposit which have different composition and structural property.And then,the rheological property,HTGC,wax crystals microcosmic morphology and SARA of pure waxy oil,wax deposit of pure waxy oil,asphaltenes-containing waxy oil and outer and inner wax deposit of asphaltenes-containing waxy oil were analyzed.The result shows that?a?the equilibrium viscosity and yield stress of outer wax deposit less than the wax deposit of pure waxy oil,and the equilibrium viscosity and yield stress of inner wax deposit more than outer wax deposit and the wax deposit of pure waxy oil.?b?the CCN of the wax deposit of pure waxy oil and outer wax deposit are C₂₄,but the CCN of inner wax deposit rises to C₂₆.?c?pure waxy oil and its wax deposit is filled with needle-like wax crystals;outer wax deposit is filled with needle-like wax crystals,branch-like wax crystals and small spherical-like wax crystals;inner wax deposit is filled with big spherical-like or sheet-like wax crystals.?d?the amount of wax crystals increase when the asphaltene content increases,but the size of wax crystals decrease with the asphaltene content increment for bulk oil.?e?the asphaltene content of outer and inner wax deposit more than bulk oil,and the growth of inner wax deposit more than outer wax deposit.In the study of development laws of the wax deposit formed by synthetic waxy oils,the deposition rate and aging rate of wax deposits with different experimental condition and different composition of synthetic waxy oils was measured.It was found that the deposition rate of outer wax deposit increases with the increase of wax content and decreases with the increase of the temperature of wax deposition barrel,the temperature difference of oil and wax deposition barrel,rotate speed of oil sample barrel,carbon number and asphaltene content;the aging rate of outer wax deposit increases with the increase of the temperature of wax deposition barrel,the temperature difference of oil and wax deposition barrel,rotate speed of oil sample barrel,wax content and asphaltene content and decreases with the increase of carbon number,but the extent of variation is small.The deposition rate of inner wax deposit increases with the increase of the temperature difference of oil and wax deposition barrel,rotate speed of oil sample barrel,carbon number and wax content and decreases with the increase of the temperature of wax deposition barrel and asphaltene content;the aging rate of inner wax deposit increases with the increase of the temperature of wax deposition barrel,the temperature difference of oil and wax deposition barrel,rotate speed of oil sample barrel,wax content and asphaltene content and decreases with the increase of carbon number,and the extent of variation is big.And then,the development of the composition of wax deposit and wax crystal microcosmic morphology with time using HTGC,SARA and polarizing microscope were analyzed.The result shows that?a?the phenomenon that the CCN of the inner wax deposit more than the outer wax deposit and the wax deposit of the oil sample without asphaltene is further proved.?b?the asphaltene content of the outer deposit increases with the increase of time,but the asphaltene content of the inner deposit reach saturation quickly.?c?the wax crystals of the oil sample without asphaltene is needle-like,the wax crystals of the outer wax deposit of the oil sample with asphaltene is branch-like,the wax crystals of the inner wax deposit of the oil sample with asphaltene is sheet-like,their size increases with the increase of time.