Wettability Alteration on Carbonate Rock by the Mixture of the Gemini Surfactant and Chelating Agent

Abstract

Gemini surfactants are novel surfactants that show unique properties, including low critical micelle concentrations, good water solubility, and outstanding performance in interfacial tension reduction. A previous study focusing on a group of locally synthesized cationic gemini surfactants found promising wettability alteration performance, which indicates the possible application in carbonate reservoirs that are naturally fractured and oil-wet. However, the tested surfactants seemed not to be efficient in high-salinity conditions. Chelating agents are used to reduce salinity by capturing the metal ions, helping maintain the performance of the selected enhanced oil recovery materials. In this study, wettability alteration by the locally synthesized ethoxylated quaternary ammonium gemini surfactant (GS8, with eight carbon atoms in the spacer group) alone and by the mixture between GS8 and a commonly used chelating agent [diethylenetriaminepentaacetic acid (DTPA)] was assessed by contact angle measurements. Results show that GS8 can modify strongly oil-wet Indiana limestone to intermediate-wet when dissolved in deionized water. Adding salts impairs the ability of the surfactant in altering wettability. The negative effect decreases in the sequence: CaCl2 > Na2SO4 > NaCl ≈ NaHCO3 ≈ MgCl2. The addition of DTPA improved the ability of the surfactant to alter the wettability in the presence of salts. A mixture of DTPA and GS8 showed better performance compared to GS8 and DTPA alone. These results suggested that, for high-salinity reservoirs, adding a chelating agent in combination with a cationic gemini surfactant could improve the wettability alteration.

Enhanced Oil Recovery in Carbonate Reservoirs Using Single Component Synthesized Surfactants under Harsh Reservoir Conditions

“…These surfactants showed strong compatibility with both FW and SW with no precipitations after aging for a long period at elevated temperatures. The interested reader may refer to the previously published articles for more details. ,− Although these surfactants have shown low CMC values of less than 100 ppm, low concentrations in the flooding process may lead to ineffective performance, while high concentrations may result in higher costs. The concentration of 2500 ppm was selected based on the initial screening experiments.…”

“…A thorough evaluation of the wettability alteration capability and the IFT measurements of the inhouse synthesized cationic Gemini and zwitterionic surfactants have been presented in the literature. 48 Hastelloy core holder, a dual injection pump, confining and backpressure pumps, a back-pressure regulator, a heating bath, and fluid accumulators. More details on the flooding setup can be found elsewhere.…”

“…The IFT measurements were also conducted between the crude oil and each surfactant solution utilizing a spinning drop tensiometer made by Krüss (Germany). A thorough evaluation of the wettability alteration capability and the IFT measurements of the in-house synthesized cationic Gemini and zwitterionic surfactants have been presented in the literature. − …”

Novel Anionic–Nonionic Surfactant Based on Water–Solid Interfacial Wettability Control for Residual Oil Development

“…Wetting control chemical agents for reservoirs are realized by constructing new hydrophilic surfaces to replace the original lipophilic surfaces. The main mechanism is adsorption, including ion-pairing adsorption, hydrogen adsorption, and hydrophobic adsorption. , Ion-pairing wetting control agents construct local hydrophilic active sites through electrostatic attraction between the positively charged surfactant molecules and negatively charged formation rock surfaces to modify the surface hydrophilicity. , However, this wetting modification is not selective, and the adsorption losses are high. The hydrogen adsorption wetting control agent gradually covers the lipophilic surface to form a new hydrophilic surface by forming hydrogen bonds between the molecules and the polar components on the lipophilic rock surface. , Hydrophobic wetting regulators, due to their strong lipophilicities, rely on hydrophobic interaction forces with the surface lipophilic components to expose hydrophilic groups and construct new hydrophilic surfaces. , When wetting regulator molecules achieve wetting regulation primarily through hydrophobic forces, they act selectively on lipophilic surfaces, which results in efficient reagent utilization. , Achieving hydrophilic modifications of rock surfaces through surfactant design and screening is the key to improving residual oil recovery.…”

Wettability Alteration of Berea Sandstone for Gas Condensate Applications

“…A few studies have been conducted using chelating agents, viscoelastic, and Gemini surfactants to alter the wettability of carbonate formations. , Jafarbeigi et al investigated the effect of reducing the interfacial tension on altering the wettability of carbonate formations. The use of nanofluids increased the hydrocarbon recovery by 26%.…”