关键词: 乳状液, 粒径, 稳定性, 剪切作用, 含水率, 方差分析, 回归分析

Abstract:

The properties of an emulsion are affected by several factors including emulsifier type, emulsifier concentration, water content （oil-water volume ratio） and stirring speed （shear rate）. In this work, the effects of stirring speed, water content and their combined action on the droplet size and stability of the emulsion were investigated by using the water separation percent and the Sauter mean diameter of the emulsion as the evaluation indexes. The results showed that, for the YMX-1 emulsion system of a water content of 50% at 50 ℃, when the stirring speed was increased from 7 000 r/min to 15 000 r/min, the Sauter mean diameter would decrease from 18.83 μm to 14.54 μm, and the water separation percent decreased from 72.00% to 50.80%. It suggested that with the increase of stirring speed, the droplet size of emulsion decreased and the stability increased. In the case of a stirring speed at 7 000 r/min, when the water content was increased from 40% to 70%, the Sauter mean diameter would increase from 17.11 μm to 27.65 μm, and the water separation percent increased from 58.50% to 86.29%. It suggested that with the increase of water content, the droplet size of the emulsion increased and the stability decreased. The results of variance analysis and regression analysis showed that, the water content had greater influence on the droplet size and stability of the emulsion than the stirring speed did. The prediction equations of Sauter mean diameter （D） and stability score （VF） for water content （X） and stirring speed （Y） were obtained: D = 16.55+2.85X-2.94Y -1.5XY+1.35X²+1.73Y² and VF = 9.0-3.54X+1.55Y, and the fitting degree reached 0.837 1 and 0.947 9, respectively, which could provide a theoretical basis for subsequent emulsion flooding to improve oil recovery in Y oilfield.

Key words: emulsion, particle size, stability, shearing, water content, variance analysis, regression analysis