Effect Of Emulsified Water On Gelling Characteristic For Waxy Crude Oil

The appearance,aggregation and precipitation of paraffins will be caused with the temperature reduction in the process of extraction,storage and transportation for the waxy crude oil,which will significantly affect the rheological properties of crude oil,and then the gelling issue will be caused.With the water phase existing in the waxy crude oil,the gelling characteristic of non-Newtonian oil-water two-phase system is not identical with the crude oil.A series of challenges are proposed for the optimization design and flow assurance of oil/water two phase transportation in the petroleum production because of the special gelling characteristic for emulsion system.Therefore,the water-in-oil(W/O)waxy crude oil emulsion was studied according to the actual engineering of oil/water two-phase low-temperature gathering and transportation under the background of energy saving and consumption reduction.The characteristic parameter and boundary of waxy crude oil gelling were both recognized with the effect of emulsified water.The gelling process and aggregation structure were both described by the particle video microscope and fractal geometry.Based on the gelling nucleation mechanism and thermal analysis theory,the nucleation rate model of emulsification gelling was established,and then the gelling characteristic and dynamics were both analyzed depending on the experiment data of differential scanning calorimetry(DSC).The rheological properties test results indicated that the gelling temperature boundary of W/O waxy crude oil emulsion increased and the structure strength of the gels also improved in the gelation process with the emulsified water fraction enhancing.The increase of gelling temperature boundary and the decrease of gelling structure strength were both caused with the cooling rate rising under the constant stress.As the emulsified water fraction enhanced,the fractal dimension of gelling aggregation structure for paraffins with emulsified water was up and the co-existence morphology of paraffins with emulsified water was changed from dispersed granular into aggregation micelle.The gelling aggregation of W/O waxy crude oil emulsion was facilitated and the high-strength gelling structure was easier to form with the emulsified water fraction enhancing.The nucleation rate of W/O waxy crude oil emulsion going through the same shear action was promoted with the emulsified water fraction being up at the range of gelling characteristic temperature.For the identical water-cut W/O waxy crude oil emulsion,the nucleation was accelerated by improving the shearing strength and reducing the emulsified water drop radius.The study is of great significance for enriching the waxy crude oil gelling theory,and it is of value to form a series of regular understanding for the optimization design and flow assurance parameters formulation of oil/water two phase transportation in the petroleum production.