Chemical Alteration of Wettability of Sandstones with Polysorbate 80. Experimental and Molecular Dynamics Study

Abstract

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 surfactant’s ability to restore the wettability of the core to the water phase. The contact angles of water and n-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 surfactant–liquid interaction energy. Experimental results showed that a concentration of 100 ppm P80 in the impregnation solution generated the greatest contact angle for n-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 n-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.

The effect of nanoparticles on reservoir wettability alteration: a critical review

“…Therefore, recently nanoparticles have played a vital role in increasing oil production by changing the wetting system from oil wet to a strongly water wet. It is well known that there are some active agents and techniques which can be applied to alter the wettability of rock surface (Cheraghian 2016;Moncayo-Riascos et al 2017;RezaeiDoust et al 2009), but the economic and environmental factors should be considered. Recently, many researchers recognised that nanoparticles had a clear impact on the wettability alteration and would increase the rate of oil production.…”

Investigating the Applicability of Molecular Dynamics Simulation for Estimating the Wettability of Sandstone Hydrocarbon Formations

“…In this matter, the interaction energy calculations by MDS were used, and obtained contact angles displayed less than 5% deviation with laboratory measurements. 13 …”

Dynamic Molecular Modeling and Experimental Approach of Fluorocarbon Surfactant-Functionalized SiO2 Nanoparticles for Gas-Wettability Alteration on Sandstones

“…In this sense, molecular dynamics (MD) simulations contribute to obtaining valuable physical insights from an atomistic description of the heterogeneous system, describing how the interaction energies change due to the proposed treatment (wettability modifiers such as nanoparticles or surfactants). Hence, the molecular simulations have become a powerful tool to understand the interfacial phenomena based on the study of the atomistic interactions by in silico experiments. − Molecular dynamics models have widely been used to understand the interfacial phenomena in the IOR/EOR process, ,, wettability alteration, − and interfacial tension reduction, − among others. In the specific case of the fluorocarbon surfactant applications, molecular dynamics studies are focused on the wettability alteration ,, and ultralow interfacial tension. − The results reported show a suitable representation by molecular dynamics simulations of the contact angles of water and oil droplets measured experimentally.…”

“…In the specific case of the fluorocarbon surfactant applications, molecular dynamics studies are focused on the wettability alteration ,, and ultralow interfacial tension. − The results reported show a suitable representation by molecular dynamics simulations of the contact angles of water and oil droplets measured experimentally. Also, in wettability alteration evaluations from an initial water-wetting state to a gas-wetting state, the calculation of the interaction energies shows an important reduction of the solid–liquid interaction promoted by the fluorocarbon surfactant, at least of 49 and 37% for water and n- decane, respectively. , Sepehrinia and Mohammadi studied through molecular dynamics simulations the wettability alteration using fluorinated SiO 2 nanoparticles. Results obtained by the authors showed that the nanoparticle–mineral surface interaction is greater than the nanoparticle–nanoparticle interaction in both n- decane and water-filled pores, indicating that the spatial distribution of the nanofluid coating leads to the removal of the liquid blockage.…”