ADDITION OF POLYMER IN MICROEMULSION: CHARACTERIZATION EFFECT IN THE EOR TEST
Surfactant; Polymer; Microemulsion; Oil recovery factor; Enhanced recovery
After exhaustion of its natural energy, the reservoirs retain high amounts of hydrocarbons. The application of advanced oil recovery methods is a way of increasing the oil recovery factor resulting from the use of conventional recovery methods, which are capable of shifting only about 30% of the oil and this is due to the high viscosity of the oil and the elevated interfacial tensions between the injection fluid and the fluid to be displaced. Among the advanced recovery methods, there are thermal, miscible and chemical methods. The application of the chemical methods is done when a certain chemical interaction between the injection fluids and the fluid to be displaced is desired. This work aims to study microemulsion systems (with and without polymer in its composition) for the advanced recovery of oil, determining the phenomena of interface and viscosity, and evaluating their recovery efficiencies. For this, these systems were characterized by measurements of aggregate size, viscosity, surface tension, contact angle and oil recovery. The microemulsion systems were obtained by choosing points in the Pseudoternary diagram, of the following composition: Ultranex Np 120 (Surfactant - T), secondary butanol (Co-surfactant - C), heptane (oil phase - FO), distilled water (aqueous phase - FA) and polyacrylic acid (polymer), in a fixed ratio of C/T = 1. The chosen systems have a fixed quantity of 5% m/m FO, while the quantities of C/T and FA vary between 35 and 60%. The systems with polymer in its formulation were obtained with the addition of 0.2% m/m of the polymer. A comparison made between the surface tension results and the viscosity measurements showed that the oil displacement, for the systems without polymer, is mainly due to interfacial action, while for the systems with polymer, the recovery obtained is mainly due to mechanical displacement. In addition, all the systems under study presented positive results for tertiary recovery, increasing the wettability of sandstone, reaching 41% of original oil in place recovery (% OOIP).