The name is absent

Chapter 4

Prior to sample preparation, 100 ppm (based on the total volume of the
sample) sodium naphthenate and other additives were added to the synthetic
brine. The equivalent naphthenic acid concentration is 2.25×10^⁵ M based on
soap titration ^[7]. All samples of 1.0 w.% kaolinite in brine-toluene (1:1, v∕v) were
prepared by mixing 25 ml synthetic brine, 25 ml toluene and 0.50 g kaolinite in a
flat-bottom glass bottle with a six-blade turbine, as shown in Figure 3.8. Stirring
speed of turbine was 2000 rpm, and the mixing time was 5 minutes. After
preparation, all the samples were left at ambient temperature for 24 hours to allow
separation. After removing the top toluene layer, kaolinite in aqueous phase was
collected by centrifugation at 5000 g for 30 minutes. This part of kaolinite is
considered water-wet. Water-wet fraction of kaolinite is used to express the
wettability of kaolinite.

4.2.2. Effect of naphthenate

Figure 4.2 shows the separation results of the samples with and without
naphthenate. The first bottle is the sample without sodium naphthenate. This
sample has almost complete separation of toluene, brine and kaolinite. Nearly all
the kaolinite settles to the bottom of the aqueous phase. The second bottle is the
sample with 100 ppm sodium naphthenate. The upper layer of the sample is
oil-in-water emulsion with kaolinite. The lower layer is the aqueous phase with

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