Researchers have developed a new class of surfactants that can effectively tackle the challenges faced in traditional enhanced oil recovery (EOR) techniques. These CO2-philic surfactants exhibit remarkable properties, such as lowered critical micelle concentration, improved interfacial tension reduction, and reduced adsorption on rock surfaces. By understanding the adsorption behavior of these surfactants, researchers aim to optimize their use in CO2-EOR and carbon capture and storage (CCS) applications, paving the way for more sustainable oil and gas operations.
Tackling the Challenges of Conventional Foaming Agents
Conventional foaming agents used in EOR often face issues such as premature rupture of lamellae when in contact with oil, surfactant loss due to adsorption on rock surfaces or partitioning between oil and water, and limited tolerance to high salinity and temperature conditions. To address these drawbacks, researchers have developed a new class of CO2-philic surfactants that exhibit enhanced activity at the gas-water interface and reduced adsorption on rock surfaces, leading to improved foam durability in the presence of oil.
Unraveling the Adsorption Behavior of CO2-Philic Surfactants
The focus of the current research was to understand and predict the adsorption mechanism of newly developed anionic CO2-philic surfactants through experimental and modeling approaches. The researchers investigated the adsorption of three types of surfactants, named S, D, and T, which differ in their chain lengths, branching, and sulfonate head group.
Experimental Insights and Adsorption Modeling
The researchers performed a comprehensive study on the adsorption of these surfactants onto a Berea sandstone rock surface. They observed several key findings:
– The critical micelle concentration (CMC) of the surfactants decreased from 750 ppm for S to 480 ppm for D and 40 ppm for T, indicating enhanced surfactant activity at the CO2-water interface.
– The adsorption values of the surfactants were found to be 0.65, 0.94, and 1.65 mg/g for S, D, and T, respectively, with T showing the highest adsorption due to its bulkier structure.
– The adsorption decreased significantly when the solution pH was increased from 6.2 to 9.8, as the adsorbent surface became predominantly negatively charged at higher pH, leading to repulsion with the anionic surfactants.
– The adsorption increased with higher salinity, as the electrical double layer at the interface was compressed, enhancing the chemical adsorption process.
– The adsorption data was best fitted to the Langmuir isotherm model, indicating a monolayer adsorption process, and followed a pseudo-second-order kinetic model.
Implications for CO2-EOR and CCUS
The insights gained from this study on the adsorption behavior of CO2-philic surfactants are crucial for optimizing their use in CO2-EOR and carbon capture, utilization, and storage (CCUS) applications. By understanding the factors influencing surfactant adsorption, researchers can design more effective foaming agents that minimize surfactant loss and enhance the efficiency of CO2-based EOR and CCS processes. This knowledge paves the way for more sustainable oil and gas operations, contributing to the industry’s efforts to reduce its environmental impact.
Author credit: This article is based on research by SeyedehHosna Talebian, Muhammad Sagir.
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