Cationic/Nonionic Mixed Surfactants as Enhanced Oil Recovery Fluids: Influence of Mixed Micellization and Polymer Association on Interfacial, Rheological, and Rock-Wetting Characteristics

Abstract

In this study, the efficacy of ionic/nonionic mixed surfactant systems as a promising chemical route toward enhanced oil recovery applications is investigated. The critical micelle concentration of the (CTAB + Tween 60) surfactant system was confirmed using conductivity studies and surface tensiometry. Thermodynamic analyses revealed that both adsorption and micellization processes in mixed surfactant compositions are more pronounced/effective as compared to pure surfactant solutions. Addition of polymer resulted in improved micellar stability in mixed surfactant systems by steric interactions. Ultralow interfacial tension values were obtained for mixed surfactant systems using a spinning drop technique. In the presence of carboxymethylcellulose (polymer), the viscosity of surfactant slugs are improved, leading to sweep efficiency during oil displacement process. Viscoelasticity investigations reveal that elastic modulus (G′) dominate over viscous modulus (G″) at an angular frequency of >1 rad/s, showing their capability to displace trapped oil through low permeability regions. Mixed surfactant solutions exhibit favorable sessile drop spreading onto oil-saturated rock surfaces and alter wetting characteristics to the water-wet state. Surfactant adsorption onto sand reduced significantly in mixed surfactant systems. Flooding studies revealed that nearly 20% of the original oil in place was recovered by (mixed surfactant/polymer) chemical fluid injection after a conventional secondary recovery process. In summary, mixed surfactant + polymer fluids constitute an effective driving fluid for the extraction of crude oil previously trapped within mature petroleum reservoirs.

Studying the effect of acidic and basic species on the physiochemical properties of polymer and biopolymer at different operational conditions

“…The interfacial activities of produced molecules (carboxylic and amino acids) and ionic species (carboxylate and amino) show that the added natural surfactant (stearic acid) or in situ formation of surfactant from PAM/XG solution in water dominating the IFT reduction. In general, surfactants are amphiphilic molecules containing both hydrophobic chain and hydrophilic head that have the ability to adsorb to the oil and water interface[30]. Depending on the length of hydrophobic chain the concentration of surfactant at interface changes where the longer length results in higher adsorption hence higher reduction in IFT.…”

Enhanced Oil Recovery from the Methyl Ester Sulfonate Derived from Flaxseed Oil: Interfacial, Adsorption and Rock Wetting Characteristics

“…Thus, the micellization of the surfactant occurred at higher concentrations. Earlier studies performed on the effect of temperature on the CMC value of the surfactant support these findings [47,51] …”

“…Hence, it is important to look at surfactant CMC. The conductivity of the surfactant solution was measured to determine the CMC of the Flaxseed surfactant [47,48] . The conductivity of the surfactant solution of varying concentrations from 1000 ppm to 10000 ppm was studied.…”

Interfacial Tension Measured at Nitrogen–Liquid and Liquid–Liquid Interfaces Using Model Microemulsions at High-Pressure and High-Temperature Conditions

“…Wettability alteration has been assessed by measurements of contact angle, capillary number, and IFT, over a limited range of temperatures and pressures. − Imbibition studies on water-wet hydrophilic surfaces suggest lower surfactant concentration requirements for efficient IFT reduction, which appears to be contradictory to observations of surfactant bilayers formed on water-wet hydrophilic surfaces as compared to monolayer formation on oil-wet hydrophobic surfaces . These apparent discrepancies are related to different mechanisms.…”