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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 salt–surfactant–nanoparticle 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 (γ-Al2O3), and magnetic iron core–carbon shell nanoparticles. The nanoparticles were characterized using dynamic light scattering, zeta-potential, N2 physisorption at −196 °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 core–carbon shell nanoparticles. The minimum IFT achieved was 1 × 10–4 mN m–1 following the methodology II at a core–shell nanoparticle dosage of 100 mg L–1., Stefanía Betancur wants to acknowledge the Departamento Administrativo de Ciencia, Tecnología e Innovación de Colombia (COLCIENCIAS) for the scholarship received from call 727−2015. 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 Andalucía ref RNM-172 for the support provided

The presence of water in coal presents a technological challenge for its industrial use in energetic processes. Water tends to negatively affect the coal quality and its net heating value (NHV), in addition to affecting its transportation costs. Therefore, this study aims to investigate the effects of glycerol and temperature on water adsorption onto systematically modified coals. A Colombian bituminous coal sample was used as support for being modified with glycerol. The virgin coal and modified coal were characterized by nitrogen adsorption at 77 K (SBET), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, elemental analysis (C–H–N elemental), and thermogravimetric analysis (TGA). The results showed that the water uptake decreased as the amount of glycerol on the coal surface increased. The optimum concentration of 8 wt% of glycerol impregnated on the coal minimized water adsorption. Over a range of water activity evaluations, this amount of glycerol (C8) reduced water adsorption by approximately 60% compared with nonimpregnated coal (C0). As expected, water uptake decreased with increasing temperature. These results are reflected in the NHV with an increase of 17% for the C8 sample compared with the other samples evaluated. The Talu and Meunier model was used to fit the experimental adsorption isotherms, and the mean square root error (MSRE%) was lower than 10%. The isosteric heat of sorption (IHS) for coal tends to decrease as the amount of adsorbed water increases. In addition, the value of IHS decreases as the concentration of glycerol increases due to the blocking of polar adsorption sites present on the coal surface, which are the main regions of low uptake of adsorbed water. Additionally, the Gibbs free energy was found to have negative values, which corroborates the spontaneous adsorption process.

Las partículas finas débilmente cementadas a la matriz porosa pueden ser liberadas y movilizadas, causando reducciones en la porosidad y permeabilidad de un yacimiento y disminuyendo el recobro de petróleo. Con el fin de determinar el daño de formación por migración de finos y dar una posible solución a este problema, se desarrolló un sistema de adsorción en lechos empacados en los cuales se simuló experimentalmente la estabilización de los finos mediante el uso de nanopartículas. Los lechos adsorbentes usados fueron preparados con arena Ottawa y esferas de vidrio (radio promedio de 0,53 mm). Se usaron tres lechos de arena: uno sometido a un proceso de lavado (lecho humectable al agua), otro sometido a un proceso de daño usando un crudo colombiano extrapesado (lecho humectable al aceite) y un último compuesto de arena tratada con nanopartículas de sílice (5-15 nm). Con las esferas de vidrio se prepararon dos lechos: uno con las esferas lavadas y otro con las esferas impregnadas con nanopartículas. La suspensión de finos se preparó con nanopartículas de alúmina (50 nm) y agua destilada. Se observó que los lechos tratados con nanopartículas seguían los patrones idealizados de las curvas de ruptura, indicando que las nanopartículas de sílice inhiben la migración de finos debido a su alta capacidad adsortiva.

Uno de los impactos de la producción de petróleo es el aumento de la contaminación debido a la descarga de aguas de formación. Este documento presenta el estudio de la adsorción de crudo en nanopartículas de sílice funcionalizada con residuos de refinería (VR) al 2 y al 4 %wt. Además de zeolita y zeolita modificada (2 y 4%wt de VR) para reducir la cantidad de crudo en las emulsiones crudo/agua (W/O). Los modelos de Langmuir y Freundlich se usaron para ajustar las isotermas de adsorción a los datos experimentales. El rango de la concentración de crudo inicial fue desde 200 hasta 2000 mg/l. El cambio en la concentración después de la adsorción se determinó utilizando un espectrofotómetro UV visible. La cantidad máxima de adsorción se obtuvo con nanopartículas de sílice modificada al 4% para una concentración inicial de 200 mg/g con una eliminación de crudo del 100%, 9 mg/g más que la obtenida con zeolita modificada de 191 mg/g a la misma concentración. Los modelos de pseudo primer y pseudo segundo orden se usaron para ajustar los datos experimentales de la cinética de adsorción obtenidos a diferentes concentraciones de crudo, con mejores resultados para el modelo de pseudo segundo orden.