Performance Evaluation of Green Surfactants for Enhanced Oil Recovery in Carbonate Reservoirs: A Microfluidic Approach

Surfactant flooding is a well-established technique for enhanced oil recovery. Many studies have been carried out on a core scale to examine the mechanisms of surfactant flooding. This study presents a new approach employing microfluidics technology to visually analyze the performance of environmentally friendly 'green' surfactants in a carbonate reservoir model. The results from this research provide useful information to optimize surfactant flooding techniques in carbonate reservoirs, leading to more effective and sustainable oil recovery. A Glass-Silicon-Glass chip was used to mimic carbonate reservoirs and experiments were performed using an advanced microfluidics platform that can handle high temperature and pressure. All tests were done at 50°C and a radial confining pressure of 20 bars. First, the glass chip was thoroughly cleaned with toluene, and then crude oil was injected to 100% saturate the micromodel. Three eco-friendly surfactants were tested-Coco Betaine, Capryl Glucoside, and Bio-Terge AS40K. The amount of oil recovered from the original oil in place (OOIP) was calculated by analyzing the images taken during the flooding process. Each surfactant was mixed at a 1 wt% concentration with synthetic seawater (35,000 ppm) and injected into the chip 100% saturated with crude oil at 1 ft/day. The micro model high-resolution images provided insights into how the remaining oil was distributed within the pore structure of the carbonate rock. After Bio-Terge AS40K injection, most of the residual oil became trapped in narrow channels as isolated droplets. Image analysis quantified the oil recovery performance of the three surfactants. Coco Betaine, a surfactant that can effectively reduce the interfacial tension (IFT) between oil and water and change wettability, had the highest oil recovery at 80% of the OOIP. In comparison, Capryl Glucoside, which is a nonionic surfactant, resulted in a 68% oil recovery due to its stability in high salinity. Bio-Terge AS40K, an anionic surfactant, performed the least, recovering 62% of the oil because it had a limited effect on reducing the oil-water tension and altering surface characteristics. The results of this microfluidics study showed how oil is displaced when green surfactants are used in carbonate reservoirs. Green surfactants are eco-friendly and break down naturally, making them a sustainable alternative to traditional surfactants. By exploring these new surfactants and using a microfluidics approach, the aim is to not only boost oil recovery rates but also lessen the impact on the environment. This research is distinct because it focuses on being both efficient and sustainable, addressing the needs of the industry while also considering ecological issues with the help of advanced microfluidics technology.