Huntington Beach equilibrated samples

Figure 7. Kinetics of coalescence for equilibrated samples of Huntington Beach crude oil-caustic systems...

Figures 10 and 11 display both the interfacial tension and electrophoretic mobility data for Huntington Beach crude as a function of NaOH concentration in aqueous solutions containing 1% NaCl. It is to be noted that as in the case of the Long Beach crude, the minimum in interfacial tension corresponds to the maximum in electrophoretic mobility and hence interfacial charge. It should be further stated that this behavior is the same for both the equilibrated system (Figure 10) and for the non-equilibrated system (Figure 11). In the latter case, the interfacial tension reported here is the initial value at a given NaOH concentration. It is observed that the minimum interfacial tension for the pre-equilibrated system lies at about 0.06% NaOH whereas the minimum for the non-equilibrated sample is between 0.003% and 0.005% NaOH concentration. Furthermore, the minimum interfacial tension in this case is below 0.001 dynes/cm.

Figure 13 exhibits both interfacial tension and electrophoretic mobility for the Huntington Beach Field crude oil against sodium orthosilicate containing no sodium chloride. The interfacial tension values are observed to be higher for the non-equilibrated sample in this case than for the caustic system reported in Figure 12. The minimum interfacial tension of 0.01 dynes/cm occurs at about 0.2% sodium silicate as opposed to a value of less than 0.002 dyne/cm at about 0.06% NaOH. It is interesting to note, however, that the maximum electrophoretic mobility is the same for the two systems. Once again, it should be noted that a maximum in electrophoretic mobility does not correspond to a minimum in interfacial tension for those samples which contained no sodium chloride.

Figure 11. Effect of caustic concentration on electrophoretic mobility and inter-facial tension of equilibrated sample of Huntington Beach crude...

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