Experimental study of the effects of acid microemulsion flooding to enhancement of oil recovery in carbonate reservoirs

Abstract

Enhanced oil recovery (EOR) techniques play an essential role in the maintenance of petroleum production worldwide. These techniques are receiving special attention due to the continuous decline in availability of oil resources. The study of surfactants and correlated systems have been considered due to their capacity to alter the wettability and interfacial proprieties, consequently reducing residual oil saturation and increasing oil production. In this context, heterogeneity becomes one of the main challenges to overcome, for it makes the fluid flow preferably thought the highest permeability regions, affecting sweep efficiency. It is also known that acids react with carbonate formations promoting matrix dissolution. However, few works in the literature report the use of reactive fluids in EOR. Therefore, this work analyzes the effects of reactive acid flow on porous carbonate media and its impact on advanced oil recovery operations. It presents an experimental study of the effects of acid microemulsion flooding in the enhancement of oil recovery in carbonate reservoirs. Acid microemulsions studied were characterized by surface tension, droplet diameter, viscosity, and corrosiveness. Flooding experiments demonstrated that the reactive flow of acid microemulsions in porous media increases oil recovery, achieving up to 30% additional recovery of the total oil in place. However, by increasing the reactivity of the systems, severe dissolution of the porous matrix can occur. The results presented open a new path on the use of low reactive fluids in enhanced oil recovery.

Experimental Microemulsion Flooding Study to Increase Low Viscosity Oil Recovery Using Glass Micromodel

“…e maximum attained recovery in this system was 49% [48]. Castro Dantas et al examined the effect of acid microemulsion on EOR in carbonate reservoirs, and the maximum reported recovery was 30% [49].…”

Review on Oil Displacement Technologies of Enhanced Oil Recovery: State-of-the-Art and Outlook

“…There have been many advances in researching microemulsion formulations in the laboratory. Dantas et al 176 investigated the effect of acidic microemulsions on oil recovery from carbonate reservoirs. The results showed that acidic microemulsions could increase the total crude oil recovery by 30%.…”

Microemulsions Based on Diverse Surfactant Molecular Structure: Comparative Analysis and Mechanistic Study

“…This theory describes an equilibrium process. According to Equation (1) and grounded on the Gibbs equation, the introduction of surfactant molecules to an oil-water blend can drastically diminish the oil-water interfacial tension. Furthermore, the inclusion of a co-surfactant (another active agent) leads to mixed adsorption, amplifying the reduction in oilwater interfacial tension.…”

“…−𝑑𝛾 = ∑Γ 𝑖 𝑑𝜇 𝑖 = ∑Γ 𝑖 𝑅𝑇𝑑ln 𝑐 𝑖 (1) where γ is the interfacial tension between oil and water; Γ 𝑖 is the adsorption amount of component 𝑖; 𝜇 𝑖 is the chemical potential of component 𝑖; and 𝑐 𝑖 is the concentration of the bulk phase. The theory explains the mechanism of microemulsion formation, but it has many shortcomings.…”

“…The oil recovery rate in this stage is only 15%. As the inherent energy diminishes, secondary oil extraction is facilitated in the second phase by the injection of gas or water to replenish the elastic energy of the reservoir rocks and fluids [1]. Due to the heterogeneity of geological formations, the injected fluids often exhibit a 'fingering effect', meaning they tend to move along the path of least resistance.…”