LABORATORY STUDY: SURFACTANT COMPOSITION AND CONCENTRATION OPTIMIZATION FOR IMPROVING HEAVY OIL RECOVERY FACTOR ON SANDSTONE RESERVOIR

摘要

Heavy oil and Sandstone reservoir (oil wet) are challenges in the oil and gas industry. This would cause problems of oil production by conventional water-flooding. Oil wet parameter shows that oil is difficult to be pushed by water. Therefore, one of the proper EOR (Enhanced Oil Recovery) studies is using a chemical surfactant. Surfactant can reduce surface tension that can change wettability from oil wet to water wet or oil-water wet. Thus, the incremental recovery factor will be higher. The study was conducted by varying the composition ratio of surfactant and co-surfactant and its concentration. Spontaneous imbibition would be tested as a method in proving the recovery factor. Varying surfactant composition is the fundamental process which makes recovery different between surfactant itself. The concentration of the correct surfactant component would optimize surfactant performance in the reservoir. The parameters used as reference in the determination of the best surfactant are maximum oil recovery, contact angle and 1FT (Interfacial Tension). Spontaneous imbibition test was performed using artificial core sandstone (oil wet) with a porosity about 26%, heavy oil with API gravity about 20.088 API and viscosity about 176.625 cp at standard temperature and pressure. The type of surfactant tested was non-ionic which has a compatibility with sandstone reservoir. The optimized surfactant composition and concentration obtained the result that non-ionic surfactant NR-03 (3%) yields the highest oil recovery of about 98% with composition surfactant: co-surfactant is 4:1. Contact angle and IFT are the parameters to clarify the result. High recovery factor is caused by reduced contact angle between oil and sandstone reservoir and having the lowest surfactant IFT. Wettability alteration in sandstone from oil-wet to water-wet and CMC (Critical Micelle Concentration) as surfactant concentration to become emulsifying agent are factors of contact angle and IFT reduction in this study.