Adsorção de tensoativos iônicos e não iônicos em rochas reservatórios via solução micelar: avaliação do planejamento experimental e efetivação dos parâmetros

Abstract

The adsorption of surfactants on rock surfaces can modify their hydrophobicity, surface charge, and other important properties that govern enhanced oil recovery (EOR) processes, such as reducing the interfacial tension between water and oil and increasing permeability. In general, the need to control and/or reduce the adsorption of surfactants on reservoir rock surfaces has been a challenging task in EOR methods, as it directly impacts the project's economy. This requires a comprehensive study and understanding of the adsorption mechanism on rocks. The main functions of this method are to reduce the interfacial tension between water and oil and alter the wettability of the reservoir rock, which is often oil-wet, making it water-wet. This property of surfactants is due to their amphiphilic nature. In this study, the adsorption behavior was investigated using micellar solutions of ionic surfactants (OCS, OCBS, OMS, and SDS) and non-ionic surfactants (NP 9.5EO, NP 11EO, and NP 15EO) with carbonate and arenite rocks as adsorbents, respectively. Mineralogy and morphology analyses of reservoir rocks were conducted, along with studies on the thermal stability of adsorbed surfactants. The finite bath method was employed to assess adsorption in all systems. For anionic surfactants, an experimental factorial design was applied to optimize the adsorption process. It was observed that OCS, OCBS, and OMS adsorption was effective in limestone and insignificant for OCBS and OMS in sandstone, while SDS showed low adsorption efficiency in both rocks. The adsorption efficiency in limestone was 85.74% for OCS, followed by 82.52% for OCBS and 45.30% for OMS. The adsorption study revealed that the equilibrium data of anionic surfactants fitted the Sips isotherm model. The results also indicated that adsorption conformed to the pseudo-second-order kinetic model. OCS adsorption isotherms better matched the Langmuir isotherm model at three different temperatures (298, 313, and 333K). Thermodynamic parameters (ΔH, ΔS, and ΔG) suggested that the OCS adsorption process was spontaneous and endothermic. For the non-ionic surfactants, experiments were conducted using only sandstone as the adsorbent, following the Scheffé network. The results showed an adsorption efficiency of 66.89% for NP-15EO, 67.15% for NP-11EO, and 70.60% for NP-9.5EO. Point F was chosen as the optimal point, as it remained constant during the experiments, being a water-rich region with low butanol content. The sandstone exhibited oil-favorable wettability, which underwent wettability inversion after treatment. Among the studied isotherm models, the Redlich-Peterson model provided the best fit, indicating that the adsorption process of non-ionic surfactants on sandstone occurs in monolayers and multilayers.