Microemulsions and nanoemulsions with alkali-surfactant-polymer applied in advanced oil recovery
Surfactant. Polymer. Microemulsion. Nanoemulsion. Wettability reversal. Enhanced oil recovery
The combination of polymer, surfactant and alkali in a same slug, known as alkali-surfactant-polymer method (ASP) presents favorable characteristics for use in advanced oil recovery (EOR). In this work, multi-component microemulsion and nanoemulsion systems with ASP were developed for application on reservoir rock wettability reversal and EOR. Pseudoternary diagrams in region rich of aqueous phase were obtained and some points were selected for application. The sodium carbonate was selected as alkalinizing agent and subsequently 0.6% of three commercial polymers of polyacrylamide in aqueous phase were used to formulate new Microemulsion systems. With ASP MicroEmulsion points, by dilution method, systems were formulated nanoemulsions containing 1.5% of Na2CO3 and 0.06% of polymer. The microemulsions and nanoemulsions were characterized according to the average droplet diameter, maximum size and format of micelar aggregates, hydrogen ionic potential, surface tension, viscosity and rheological behavior through mathematical models, and finally applied on wettability reversal through contact angle and EOR through oil Simulator using sandstone rock Botucatu. The sizes of Microemulsion droplets are characteristic values, the maximum size of micelar aggregates was 4.2 nm and the formats of the micelles were Oblate ellipse type, ball and hollow sphere. PH confirmed an alkaline value (average pH equal to 10.0) and surface tension has been reduced, with values below 35.0 mN/m at 24° C ± 1. For microemulsions without polymer and the nanoemulsions rheological behavior was Newtonian-type, the other microemulsions rheological mathematical model of non-Newtonian fluids was appropriate, being the model of Ostwald of Waale, characteristic of fluids Polymeric. The viscosity of Microemulsion with polymers, with values of the cP 41 19, 24° C ± 1, were all larger than the average oil (29.3° API) present in the reservoir rock Botucatu, was 14.5 cP . All systems formulated left the wettable rock water, being efficient in the wettability reversal, favoring the the oil production. The results proved the efficiency of recovery and displacement of Microemulsion and nanoemulsions, once the total oil in place recovery were high, ranging from 65% to 97%.