Page 43 - Formation Damage during Improved Oil Recovery Fundamentals and Applications

Low-Salinity Water Flooding: from Novel to Mature Technology 25

improved the accuracy of predictions of potential incremental produc-
tion achievable with LSWF. Vledder et al. (2010) claimed from core
experiments and field production results that LSWF causes desorption
of petroleum heavy ends from the clays present on the pore wall, result-
ing in a more water-wet rock surface, a lower remaining oil saturation,
and higher oil recovery. A reservoir simulation sensitivity study
(Al-adasani et al., 2014) suggested that it is the initial and final wetting
states of an oil reservoir which control oil recovery through an increase
in the relative permeability oil. That study concluded that a decrease in
IFT was shown to be the primary recovery effect in reservoirs which
were strongly water-wet, but other factors dominated in other types of
reservoir (i.e., lowering of capillary pressure in weak water-wet reservoirs;
change of nonwetting phase to oil in weak oil-wet conditions).
The significance of polar bonding of crude oil to saline-water film
covering the clay minerals of the rock matrix (Fig. 2.2), and the ability of
LSWF to break those bonds to form mixed-wet fines that mobilize to
the oil-water interface flowing through the pore space of a reservoir, was
recognized by Tang and Morrow (1999).

Figure 2.2 Polar components from crude play an important role in binding some oil
to the pore walls and in the formation of wet-mixed fines some of which can be
mobilized by changing flow conditions and fluid chemistry. Modified after Tang &
Morrow (1999).