Page 65 - Hybrid Enhanced Oil Recovery Using Smart Waterflooding

CHAPTER 3 Modeling of Low-Salinity and Smart Waterflood 57

the anhydrite mineral, but the chalk does not. The PHREEQC software to calculate the two surface
simulations of LSWF result in the increasing or constant complexation models on the oil-water and water-rock
adsorption of carboxylic group on the surface for chalk, interfaces. The surface complexation models determine
but decreasing adsorption on the surface for limestone the z-potentials at both oil and rock surfaces, which will
(Fig. 3.11A). Because the desorption of carboxylic group be used in the calculation of EDL term in the disjoining
from the surface improves the wetness toward water- pressure based on the extended DLVO theory. The
wet, the limestone, not chalk, shows the increase EDL model via Gouy-Chapmann calculates the EDL po-
of oil recovery (Fig. 3.11B). It is explained that the tential at any point in the system. Secondly, the
anhydrite dissolution generates the sulfate ion in water extended DLVO theory is applied to calculate the inter-
and the increasing sulfate ion leads to the desorption of action potentials and forces across a water film between
carboxylic group on the surface due to the reactions of oil and rock surfaces. With the extended DLVO, the total
Eqs. (3.73) and (3.78). In addition, the numerical disjoining pressure is the combination of van der
study hypothetically investigates the effects of calcite Waal’s, EDL, and the structural forces as shown in
dissolution on the concentration of adsorbed carboxylic Eq. (3.79). The negative disjoining pressure indicates
material for the chalk (Fig. 3.12). Despite the equivalent the attractive force between the oil and rock surfaces,
LSWF model, neglecting the calcite dissolution reaction and the positive disjoining pressure represents the
decreases the adsorption of carboxylic material. Howev- repulsive force between the surfaces.
er, it quantitatively captures the trend of adsorption Y Y Y Y
of carboxylic material as ionic composition of brine t ðhÞ¼ VDW ðhÞþ EDL ðhÞþ s ðhÞ (3.79)
changes. Although this study proposed the multiple where h is the distance between the oil and rock
interactions between crude oil, brine, and solid surface, surfaces, i.e., a water film thickness, Q t (h) indicates
it neglected the ion bridging interaction owing to lack of the total disjoining pressure, Q VDW (h) is the term of
experimental and thermodynamic data. van der Waal’s force in the disjoining pressure, Q EDL (h)
Sanaei, Tavassoli, and Sepehrnoori (2018) from the is the term of EDL force in the disjoining pressure, and
University of Texas at Austin proposed the application Q s (h) is the term of structural force in the disjoining
of disjoining pressure based on extended DLVO theory pressure.
as well as comprehensive geochemical reactions, Incorporating the augmented Young-Laplace
including the surface complexation reactions to model equation, the disjoining pressure is used to model the
the LSWF process for both sandstone and carbonate wettability modification of LSWF process. At the
reservoirs (Fig. 3.13). The study upgraded the equilibrium condition, the augmented Young-Laplace
UTCOMP-IPhreeqc software after the study by Kazemi equation describes the relationship between disjoining
Nia Korrani et al. (2016). Firstly, the study used the pressure and capillary pressure, i.e., Laplace pressure,
as shown in Eq. (3.80). For an infinite thickness of water
0.70 film, the disjoining pressure is zero and the augmented
Previous Model
Young-Laplace equation appears to the conventional
0.60 Current Model Young-Laplace equation. Using the augmented Young-
Laplace equation, the contact angle can be derived
Current Model without calcite dissolution
0.50
Surface Fraction of Adsorbed Carboxylic Material 0.40 from the disjoining pressure following Eq. (3.81). The
calculated contact angle is used for the wettability
modification of LSWF process. The linear modification
0.30
of relative permeability and capillary pressure uses the
interpolation factor as a function of the contact angle.
0.20
0.10 p c ¼ Y t ðhÞþ 2C m s (3.80)
0 1
Q Z
Z
0.00 1 ðh 0 Þ Y 1 B h N Y C
1 cos q ¼ hd ¼ @p c h 0 þ dhA
FW SW SW0NaCl SW0NaCl4SO4 s 0 s h 0
FIG. 3.12 Comparison of the calculated surface fraction of
(3.81)
adsorbed carboxylic material for chalk from various models
with and without calcite dissolution. (From Qiao, C., Johns, where C m is the mean curvature, h 0 is the minimum
R., & Li, L. (2016). Modeling low-salinity waterflooding in thickness of water film, and h N is the infinite thickness
chalk and limestone reservoirs. Energy and Fuels, 30(2), of water film.
884e895. https://doi.org/10.1021/acs.energyfuels.5b02456.)