Análises da molhabilidade e da adsorção de tensoativos em diferentes tipos de calcários para aplicação na recuperação avançada de petróleo

Abstract

The oil industry and pre-salt production are considered among the greatest global technological advancements. This field, rich in large accumulations of high-market-value oil, has posed and continues to pose immense technological challenges in both research and development (R&D) and exploration and production (E&P) of its reserves. One crucial aspect in this context is the type of reservoir rocks predominant in the formation of oil reserves, which are carbonates, particularly limestones. These rocks typically exhibit oil-wet characteristics, reducing the recovery factor. Therefore, research is being conducted to alter the wettability of these rocks to improve production factors. One strategy to optimize reservoir conditions involves the use of chemical methods with surfactants. Due to their amphiphilic structure, surfactants can adsorb at interfaces and surfaces based on their affinity, reducing interfacial free energy and potentially reversing rock wettability. This, in turn, increases oil mobility in the porous medium and enhances the recovery factor. The study aimed to analyze the adsorption of different surfactants on limestone rocks and their effectiveness in altering wettability. Three types of surfactants were investigated—cationic (CTAB), nonionic (UTM150), and anionic (Sodium Myristate - MS) —all in a 2% KCl solution to prevent clay swelling in the rock. Different adsorption models were applied using the batch method. The limestones analyzed, including calcitic, dolomitic, and magnesian types, were collected from the Mossoró/RN microregion. The anionic surfactant MS did not adsorb on any of the three types of rocks studied. The nonionic surfactant UTM150 adsorbed on dolomitic and magnesian limestones but not on calcitic limestone. The cationic surfactant CTAB adsorbed on all three types of limestone. Post-treatment with UTM150 and CTAB surfactants showed an increase in water wettability of the limestone rocks, with CTAB being more effective than UTM150.