Chapter 6
distinguishable, which suggests drop size distribution of the emulsion can not
obtained from CPMG measurement.
In this case, NMR restricted diffusion experiment (PGSE) can be used for the
measurement of emulsion drop size distribution. In absence of demulsifier,
experimental data from PGSE measurements shows the emulsion drop size does
not change much during 11.2 hours. This is consistent with the observation that
water in diluted bitumen emulsion is very stable without demulsifier.
NMR 1-D Ti weighted profile measurement can distinguish the composition
difference of the sample in vertical direction. Sedimentation rate of front position
and water droplet sedimentation velocity can be obtained from profile results.
Emulsion flocculation can be deduced by comparing the sedimentation velocity
from experimental data and the calculated value from Stokes Law prediction.
Coalescence can be detected from the time evolution of signal amplitude using
pure oil and water as the references. Water fraction profile can be also calculated
from the profile results.
6.1.2. Wettability test and zeta potential
Emulsion separation experiments show that clay wettability is important to
emulsion stability. Emulsion separation is incomplete and a rag layer consisting of
skins of solids, oil and emulsion forms near the interface between oil and water
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