SUPPORTING INFORMATION FOR
Role of Particle Size and Surface Acidity of Silica Gel Nanoparticles in Inhibition
of Formation Damage by Asphaltene in Oil Reservoirs
Stefanía Betancur,† Juan C. Carmona,† Nashaat N. Nassar,§* Camilo A. Franco, †, ‡*
Farid B. Cortés †, ‡*
†Grupo
de Investigación en Fenómenos de Superficie – Michael Polanyi, Facultad de
Minas, Universidad Nacional de Colombia Sede Medellín, Kra 80 No. 65–223,
Medellín, Colombia.
‡Grupo
de Investigación en Yacimientos de Hidrocarburos, Facultad de Minas,
Universidad Nacional de Colombia Sede Medellín, Kra 80 No. 65–223, Medellín,
Colombia.
§Department
of Chemical and Petroleum Engineering, University of Calgary, 2500
University Drive NW, Calgary, Alberta, Canada.
* Corresponding authors
E–mails: caafrancoar@unal.edu.co, fbcortes@unal.edu.co, nassar@ucalgary.ca
Recently, our research group1 proposed a three-parameter model to describe the
adsorption isotherms of n-C7 asphaltenes onto solid surfaces. The model is based on a
theoretical framework of adsorption of self-associated n-C7 asphaltenes over solid
surfaces. The SLE model equation is expressed as follows:
CE =
ψ 
ψH
exp 

1 + Kψ
 qm 
(2)
with
ψ=
−1+ 1+ 4K ⋅ξ
2K
(3)
and
 qm ⋅ q 

 qm − q 
ξ =
where q (g/g) is the amount of n-C7 asphaltenes adsorbed,
capacity,
(4)
qm (mg/g) is the saturation
CE (mg/g) is the equilibrium concentration of n-C7 asphaltenes in the solution,
K (g/g) is the reaction constant related to the degree of association of the n-C7
asphaltenes in the nanoparticles surface and H (mg/g) is the Henry’s law constant
linked to the preference of the n-C7 asphaltenes for being in the liquid phase or in the
adsorbed phase.1 Higher values of K indicate that the degree of n-C7 asphaltenes
association is higher. Additionally, if the value of H decreases, it means a higher
affinity of n-C7 asphaltenes for the adsorbed phase than for the liquid phase.
The Table S1 shows the model parameters obtained from SLE model for different
conditions. The first section includes the parameters for n-C7 asphaltenes adsorption on
S11, S58 and S240 nanoparticles in Heptol 60. The second section, shows parameters
estimated from the SLE model for S11 nanoparticles for different Heptol ratios. The last
section, presents parameters for S11A, S11B, S11N and S11 nanoparticles from Heptol
60 at 298 K.
In addition, the Table S1 shows H increases (i.e., adsorption affinity decreases) in the
order of S11 < S58 < S240, while K (degree of self-association of n-C7 asphaltenes)
tends to increase in the order of S240 < S58 < S11. That is, that the preference of the nC7 asphaltenes for being adsorbed on S11 nanoparticle surfaces rather than being in the
bulk phase is higher than that for the other evaluated nanoparticles.
In the Table S1 is observed the degree of self-association of n-C7 asphaltenes and qmax
tend to increase with increasing heptol ratio. On the other hand, H, which is related to
the Henry's law constant, decreases as the heptol ratio increases. That is, as the heptol
ratio increases, the affinity between the n-C7 asphaltenes and the nanoparticles
increases.
The Table S1 also shows the H parameter is lowest for the S11A nanoparticles.
Additionally, these nanoparticles show that the K parameter is highest. The S11A
nanoparticles presented the most adsorbed n-C7 asphaltenes compared with the other
studied nanoparticles. In addition, the similarities in the H parameter for S11B, S11N
and S11 nanoparticles corroborate the idea that the basic and neutral treatments do not
affect the adsorptive behavior.
Table S1. Parameters estimated from the SLE model for n-C7 asphaltene adsorption on
s
Sample
Solvent
S11
S58
S240
Heptol 60
S11
Toluene
Heptol 70
S11A
S11B
S11N
Heptol 60
H (mg/g)
K (g/g)
qmax (mg/g)
R2
χ²
1579.6
1749.2
1814.1
1682.0
1486.6
1120.1
1510.0
1500.0
2227.4
2023.6
1993.1
2122.0
2284.1
2340.2
2230.1
2250.0
1680.2
1345.1
1289.7
1570.0
1747.6
1792.1
1710.2
1730.0
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.11
0.05
0.13
0.07
0.04
0.65
0.23
0.41
References:
1.
Montoya, T.; Coral, D.; Franco, C. A.; Nassar, N. N.; Cortés, F. B., A novel
solid–liquid equilibrium model for describing the adsorption of associating asphaltene
molecules onto solid surfaces based on the “Chemical Theory”. Energy & Fuels 2014,
28, (8), 4963-4975.