Organization
College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China
Abstract
Polymer is used as a foam stabilizer to further enhance the CO2 foam stability, which could reduce the CO2 mobility efficiently, and the higher swept volume and recovery efficiency are obtained. By evaluating the stability of CO2 foams generated by stirring method and in porous media, the performance of enhancing CO2 foam stability was analyzed thoroughly after adding the polymer, hydroxyl-propyl methyl cellulose(HPMC). Furthermore, the influence of surfactant concentrations, injection methods, foam qualities and injection velocities was also considered. The results show that when the concentration of dodecylamine polyoxyethylene-2 was higher than 0.2%, the surfactant concentration had little effect on the foam stability. The polymer HPMC could further enhance the foam half-life about 115% efficiently with low concentration 0.1% at 60 ℃ and 12 MPa due to the higher solution viscosity, where the foam volume remained similar value. The foam resistance factor in sand-pack reached up to about 200, when the injecting CO2-solution ratio was 8∶2. Moreover, comparing with gas-alternative-liquid injection method, the CO2 foam in sand-pack could reach equilibrium state with fewer injecting pore volume when injecting CO2 and solution simultaneously. With increasing the injection velocity, the foam resistance factor increased first and then decreased, while the foam stabilized with single surfactant solution system was more sensitive with the injection velocity.
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