Steam-assisted
gravity drainage (SAGD) produced water (PW) consists
of oil, solids, clays, petroleum-derived compounds, and other dissolved
organic matters (DOMs), which make the SAGD PW highly stable and,
therefore, very hard to treat. Developing a correlation between SAGD
PW properties and dynamics of interfacial tension (IFT) between dispersed
and continuous phases is important to understand the coalescence of
dispersed phase droplets, which, in turn, leads to demulsifications
of these difficult emulsions produced during SAGD operations. This
work sheds light on the interfacial activity of SAGD PW endogenous
surfactants, humic acids (HAs), as well as the interaction dynamics
of these compounds with naphtha-diluted Alberta oil sand bitumen (AOSB)
present in a model SAGD PW. We quantify the dynamics of the IFT of
a naphtha-diluted AOSB oil drop in pure water as well as SAGD synthetic
brine. Our results pinpoint the distinctive influence of the percentage
weight composition of the naphtha-diluted AOSB and the surrounding
model SAGD PW pH on the dynamics of this oil–water IFT. We
anticipate that the results of this study will bring about a better
understanding of interfacial film properties, leading to a predictable
coalescence mechanism in SAGD PW emulsions, facilitating the design
of next-generation SAGD deoiling unit operations.