Study On The Wax Crystal Morphology Structure And Rheology Of Waxy Crude Oil

Waxy crude oil is the mixture hydrocarbons and non-hydrocarbons, its characteristics arehigh pour point, poor flow ability and complicated rheology. With temperature dropping,waxy crude oil will be deformed from the sol state to gelld state, during which wax wouldprecipitate and grow larger, making the rheology of the crude oil change greatly. Most workdone on the structure of the wax crystal and rheology of the waxy crude oil is under thecondition of temperature dropping, rather than the condition of keeping the temperatureconstant. This article will mainly focus on isothermal incubation stage crystallizationprocess research, respectively in three different experimental methods to study the process ofwax crystal micro parameters, vacuum degree and variation rules of rheological parameters.Microscope and graphic analysis software are used to study the micro-change of the waxcrystal structure at a constant temperature. This article mainly analyzes the waxy area, grainnumber, equal-area circle diameter, fractal dimension along with the time of incubationtemperature and static, and fitting the waxy area formula along with the change of incubationtime. Summarized predecessors’ describe the microscopic parameters used in the wax crystalmorphology, and the Clustering statistics method was applied to analyze the microscopicparameters such as waxy area, perimeter, aspect ratio, number of paticles, characteristic length,diameter, particle size distribution dimension and box dimension, elliptical axis length ratio.The results show that the nine parameters can be divided into4categories, respectively,represent different aspects of wax crystal; Vacuum was used to evaluate the structure variationof gelled crude oil and the wax crystal in the experimental loop, which was used to simulatethe practical working condition of shutdown at constant temperature. The variation of crudeoil structure was studied under small amplitude oscillatory shear and constant temperature byusing rheometer. Dynamic and static temperature experiment of crude oil was made, and thevariation of Energy storage modulus and loss Angle with time aging was studied underdifferent temperature, temperature dropping rate and shear rate. Relative crystallinity was defined by using Energy storage modulus and the characteristic of crystallization at constanttemperature is analyzed through crystallization kinetics theory. Through the study ofisothermal crystallization process, further enrich the microscopic mechanism of waxy crudeoil crystal.