7 research outputs found
Importance of the Nanofluid Preparation for Ultra-Low Interfacial Tension in Enhanced Oil Recovery Based on Surfactantā NanoparticleāBrine System Interaction
The main objective of this study is to evaluate the effect of the preparation of the nanofluids based on the interactions between the surfactants, nanoparticles, and brine for being applied in ultra-low interfacial tension (IFT) for an enhanced oil recovery process. Three methodologies for the addition of the saltāsurfactantānanoparticle components for the formulation of an efficient injection fluid were evaluated: order of addition (i) salts, nanoparticles, and surfactants, (ii) salts, surfactants, and then nanoparticles, (iii) surfactants, nanoparticles, and then salts. Also, the effects of the total dissolved solids and the surfactant concentration were evaluated in the interfacial tension for selecting the better formulation of the surfactant solution. Three nanoparticles of different chemical natures were studied: silica gel (SiO2), alumina (Ī³-Al2O3), and magnetic iron coreācarbon shell nanoparticles. The nanoparticles were characterized using dynamic light scattering, zeta-potential, N2 physisorption at ā196 Ā°C, and Fourier transform infrared spectroscopy. In addition, the interactions between the surfactant, different types of nanoparticles, and brine were investigated through adsorption isotherms for the three methodologies. The nanofluids based on the different nanoparticles were evaluated through IFT measurements using the spinning drop method. The adsorbed amount of surfactant mixture on nanoparticles decreased in the order of alumina > silica gel > magnetic iron coreācarbon shell nanoparticles. The minimum IFT achieved was 1 Ć 10ā4 mN mā1 following the methodology II at a coreāshell nanoparticle dosage of 100 mg Lā1.StefaniĢa
Betancur wants to acknowledge the Departamento
Administrativo de Ciencia, TecnologiĢa
e InnovacioĢn de
Colombia (COLCIENCIAS) for the scholarship received
from call 727ā2015. The authors also acknowledge Universidad
Nacional de Colombia, Universidad de Granada,
agreement 3010388 of 2017 with Ecopetrol S.A., agreement
064 of 2018 with COLCIENCIAS and Agencia Nacional de
Hidrocarburos (ANH), Spanish Ministry of Science, Innovation
and Universities, FEDER, contract number RTI2018-
099224-B-I00 and Junta de AndaluciĢa
ref RNM-172 for the
support provide
Effect of Sodium Oleate Surfactant Concentration Grafted onto SiO2 Nanoparticles in Polymer Flooding Processes
Chemical Alteration of Wettability of Sandstones with Polysorbate 80. Experimental and Molecular Dynamics Study
In this work experimental
and theoretical evaluations of the wettability
alteration of sandstones, using the commercial surfactant polysorbate
80 (P80), are presented. The experimental evaluation started from
a virgin sandstone core (water-wet); damage was then induced to modify
the wettability of the rock from water-wet to oil-wet, with the purpose
of evaluating the surfactantās ability to restore the wettability
of the core to the water phase. The contact angles of water and <i>n</i>-decane droplets were used to evaluate the wettability
alteration of the surface. The theoretical evaluation was made using
molecular dynamics to determine the configuration of the surfactant
adsorbed on the surface and to calculate the surfactantāliquid
interaction energy. Experimental results showed that a concentration
of 100 ppm P80 in the impregnation solution generated the greatest
contact angle for <i>n</i>-decane droplets and a small contact
angle for water droplets using the least amount of surfactant, restoring
the water-wet state of the solid and generating a lipophobic surface.
The molecular dynamics results showed that adsorption of the surfactant
on the surface is associated mainly with interactions between the
chains of the surfactant that contain the ester group and the surface,
whereas the chains containing ethylene oxides are exposed toward the
liquid phase. By evaluating the interaction energy between the P80
coating and the liquid phases, it was established that the chains
containing the ethylene oxides were key to restoring the water-wet
state of the surface since they exerted an attractive interaction
over water and a slightly repulsive interaction over <i>n</i>-decane, generating the lipophobic surface. The molecular model developed
in this work allows the performance of predictive calculations of
the contact angle of liquid droplets, with deviations, in most cases,
of less than 5% compared to the experimental value
Development of a Population Balance Model to Describe the Influence of Shear and Nanoparticles on the Aggregation and Fragmentation of Asphaltene Aggregates
The
precipitation and deposition of asphaltenes is a primary problem
related to the processing, transportation, and production of oil.
Flocculation of asphaltene aggregates is likely to occur during the
production and processing of crude oil. Recently, it has been shown
that nanotechnology in the form of nanoparticles is useful for the
inhibition or prevention of asphaltene formation damage. Although
it is well-known that the adsorption of asphaltenes on the nanoparticle
surface would reduce the capacity of these asphaltic compounds to
interact with each other, limited studies have been performed regarding
the processes and the mechanisms associated with the effect of nanoparticles
on the inhibition of the formation damage due to asphaltenes. To better
understand this phenomenon from a mathematical approach, a population
balance model (PBM) is proposed to describe the kinetics of asphaltene
flocculation-fragmentation in the presence of nanoparticles. The model
assumes that asphaltenes in the presence of a shear rate are related
to the aggregation and fragmentation phenomena and includes a term
related to the asphaltene adsorption on nanoparticles. An adsorption
kinetic term was introduced into the model using the double exponential
model. Experimental data of the kinetics of asphaltene aggregation
were obtained by dynamic light scattering (DLS) measurements at a
fixed initial asphaltene concentration of 1000 mg/L and with different
Heptol mixtures. In this study, commercial silica, Ī³-alumina,
and magnetite nanoparticles were used as adsorbents to study the effect
of the chemical nature of the nanoparticles on the inhibition of the
asphaltene growth and for model validation. Additionally, to demonstrate
the versatility of the proposed model, the effect of asphaltene was
also evaluated. The obtained results from the proposed population
balance model agree well with the experimental data, within an RSME
% < 9%
Influence of Asphaltene Aggregation on the Adsorption and Catalytic Behavior of Nanoparticles
This study is a continuation of our
previous works on the use of
metal-based nanoparticles for the adsorption of asphaltenes and its
subsequent catalytic thermal decomposition. In this study, we evaluated
the effects of asphaltene aggregation on the adsorption process and
the subsequent catalytic oxidation using fumed silica and nanoparticles
of NiO and/or PdO supported on fumed silica. Adsorption isotherms
were constructed through batch adsorption experiments at 25 Ā°C
by using mixtures of <i>n-</i>heptane and toluene in amounts
of 0, 20% v/v <i>n-</i>heptane (Heptol 20), and 40% v/v <i>n-</i>heptane (Heptol 40) to obtain different aggregate sizes
of asphaltenes. Subsequently, asphaltene oxidation in the presence
and absence of the nanoparticles was carried out in a TGA/FTIR system
to investigate the impact of adsorbed asphaltene aggregates on the
catalytic activity of the selected nanoparticles. The adsorption isotherms
were described by the solidāliquid equilibrium (SLE) model,
and the catalytic behavior of the nanoparticles was compared based
upon the trend of effective activation energies using the isoconversional
method of Ozawa, Flynn, and Wall (OFW method). The results showed
that the <i>K</i> parameter of the SLE model for both nanoparticles
followed the trend of Heptol 40 > Heptol 20 > toluene, indicating
that, as the amount of precipitant in the solution increases, a higher
degree of asphaltene self-association on the active site of the catalysts
is found. On the other hand, the <i>H</i> parameter revealed
higher adsorption affinities as the <i>n-</i>heptane in
the solution increased. However, when different adsorbents were compared
at a fixed asphaltene concentration from the same solution, it was
found that the use of functionalized nanoparticles led to a lower
degree of asphaltene self-association and a higher affinity. A correlation
between the effective activation energies from the OFW model and the
SLE parameters was developed, finding that, for a fixed adsorbent, <i>E</i><sub>Ī±</sub> increases as the affinity and the degree
of self-association of asphaltenes increases. However, when the same
asphaltenes were compared using different adsorbents, it was observed
that <i>E</i><sub>Ī±</sub> increases as the affinity
decreases and the degree of asphaltene self-association increases.
Consequently, this work shows the effect of the adsorption process
on the catalytic activity of the nanoparticles. The reported results
should give a better context for the use of such nanoparticles for
the upgrading of heavy and extra-heavy oil
Role of Particle Size and Surface Acidity of Silica Gel Nanoparticles in Inhibition of Formation Damage by Asphaltene in Oil Reservoirs
The
main objective of this study is to evaluate the effect of particle
size and surface acidity of synthesized silica gel nanoparticles on
the inhibition of formation damage caused by asphaltene precipitation/deposition.
Silica gel nanoparticles were synthesized through the solāgel
method, and their characterization was performed via N<sub>2</sub> physisorption at ā196 Ā°C, field emission scanning electron
microscopy (FESEM), dynamic light scattering (DLS) measurements, and
NH<sub>3</sub> temperature-programmed desorption (TPD). The size of
the synthesized nanoparticles ranged from 11 to 240 nm. The ability
of the nanoparticles to adsorb asphaltenes and to reduce asphaltene
self-association was evaluated using batch-mode experiments. The kinetics
of asphaltene aggregate growth in the presence and absence of nanoparticles
were evaluated using DLS measurements in different Heptol solutions.
The smallest nanoparticles (11 nm) had the highest adsorptive capacity
for <i>n</i>-C<sub>7</sub> asphaltenes among the nanoparticles
studied. Therefore, these nanoparticles were modified using acid,
base, and neutral treatments, which showed the following order S11A
ā« S11B ā S11N ā S11 according to the <i>n</i>-C<sub>7</sub> asphaltene affinity and the reduction of
its mean aggregate size in the bulk phase. The surface acidity values
obtained through of temperature-programmed desorption test ranged
from 1.07 and 1.32 mmol/g. In general, the asphaltene self-association
was reduced to a higher degree as the amount of adsorbed asphaltene
increased. Additionally, in this study, the performance of a nanofluid
treatment was tested under flow conditions in porous media under typical
reservoir conditions using the nanoparticles with the best performance
in batch-mode experiments. Indeed, nanofluid treatment with silica
nanoparticles increased the effective permeability to oil and enhanced
the oil recovery with an increase in the recovery factor of 11% under
the conditions reported here. This approach has the major benefit
of being scalable to a producing field, and the study provides an
understanding of the roles of size and surface acidity of silica nanoparticles
in the wettability alteration and inhibition of formation damage caused
by asphaltenes and their influences on asphaltene aggregate size in
the oil matrix and the adsorbed phases