The primary objective of this study is the synthesis of nanocapsules (NC) that allow the reduction of the adsorption process of surfactant over the porous media in enhanced oil recovery processes. Nanocapsules were synthesized through the nanoprecipitation method by encapsulating commercial surfactants Span 20 and Petro 50, and using type II resins isolated from vacuum residue as a shell. The NC were characterized using dynamic light scattering, transmission electron microscopy, Fourier transform infrared, solvency tests, softening point measurements and entrapment efficiency. The obtained NC showed spherical geometry with sizes of 71 and 120 nm for encapsulated Span 20 (NCS20), and Petro 50 surfactant (NCP50), respectively. Also, the NCS20 is composed of 90% of surfactant and 10% of type II resins, while the NCP50 material is 94% of surfactant and 6% of the shell. Nanofluids of nanocapsules dispersed in deionized water were prepared for evaluating the nanofluid—sandstone interaction from adsorption phenomena using a batch-mode method, contact angle measurements, and FTIR analysis. The results showed that NC adsorption was null at the different conditions of temperatures evaluated of 25, 50, and 70 °C, and stirring velocities up to 10,000 rpm. IFT measurements showed a reduction from 18 to 1.62 and 0.15 mN/m for the nanofluids with 10 mg/L of NCS20, and NCP50 materials, respectively. Displacements tests were conducted using a 20 °API crude oil in a quarter five-spot pattern micromodel and showed an additional oil recovery of 23% in comparison with that of waterflooding, with fewer pore volumes injected than when using a dissolved surfactant.
The nanotechnology has been applied
recently to increase the efficiency of enhanced oil recovery methods.
The main objective of this study is to evaluate the effect of SiO
2
nanoparticle functionalization with different loadings of
sodium oleate surfactant for polymer flooding processes. The sodium
oleate surfactant was synthesized using oleic acid and NaCl. The SiO
2
nanoparticles were functionalized by physical adsorption
using different surfactant loadings of 2.45, 4.08, and 8.31 wt % and
were characterized by thermogravimetric analyses, Fourier-transform
infrared spectroscopy, dynamic light scattering, and zeta potential.
Adsorption and desorption experiments of partially hydrolyzed polyacrylamide
(HPAM) polymer solutions over the unmodified and surface-modified
nanoparticles were performed, with higher adsorption capacity as the
surfactant loading increases. The adsorption isotherms have a type
III behavior, and polymer desorption from the nanoparticle surface
was considered null. The effect of nanoparticles in the polymer solutions
was evaluated through rheological measurements, interfacial tension
(IFT) tests, contact angle measurements, capillary number, and displacement
tests in a micromodel. The surface-modified SiO
2
nanoparticles
showed a slight effect on the viscosity of the polymer solution and
high influence on the IFT reduction and wettability alteration of
the porous medium leading to an increase of the capillary number.
Displacement tests showed that the oil recovery could increase up
to 23 and 77% regarding polymer flooding and water flooding, respectively,
by including the surface-functionalized materials.
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