Preparation And Performance Evaluation Of Modified Nano Silica Stabilized Foam System

In view of the temperature tolerance of the foam system,the laboratory synthetized C12 AEC,which is used as the aerating powder and combined with other aerating powder to improve its temperature resistance and foaming ability.The nano silica was modified as a stabilizer in order to obtain the temperature resistant stable foam system.The foaming performance,stability,temperature resistance and oil displacement properties of the foam system were tested in laboratory.The synthesis conditions of the foaming agent C12 AEC is that the optimum reaction molar ratio ofdodecanol polyoxyethylene ether and sodium chloroacetate was 1:2,the optimum reaction temperature is 60℃ and the optimum reaction time is 6-7h.The synthetic foaming agent C12 AEC was analyzed by IR and the foaming performance of C12 AEC was evaluated by Warning-Blender method.The amphoteric ionic foaming agent DAHSB with good temperature resistance and the anionic foaming agent AOS with good foaming properties were screened to mix with C12 AEC.The optimum compound ratio was 1:1:1 and the optimum mass fraction was 0.7%.Nano silica was generated by ethyl orthosilicate through hydrolysis in alkaline conditions and and the silica were adsorbed by lauric acid betaine(LAB-30)in order to make the nano silica was modified,so the betaine modified nano silica was obtained.The stabilized performance of the foam was compared between unmodified nano silica and modified nano silica under the static and dynamic tensile conditions.The stability of the modified nano silica foam system was better than the unmodified nano silica foam system and the optimum amount of nano silica was 0.3%.The adsorption amount of unmodified and modifiednano silica on the foam liquid membrane were compared and the relationship between the amount of adsorption and the half-life was reviewed.We can work out that under the same mass fraction,the adsorption amount of modified nano silica on foam liquid membrane is better than the unmodified nano silica.And the half-life of modified nano silica stabilized foam system is proportional to the adsorption amount of modified nano silica on the foam liquid membrane.The temperature resistance,oil resistance and salt tolerance of the modified silica stabilized foam system were evaluated.So it is concluded that the modified silica foam system can be applied to reservoirs,which its temperatureunder 200 degrees,oil saturation below to 40% and salinity up to 12×104ppm.In the laboratory,the Qi 40 Lianhua block reservoir was stimulated to carry on core displacement experiment in order to make sure that the modified nano silica foam system has more obvious effect of increasing oil recovery in steam flooding reservoirs than other foam system.The modified nano silica foam system has a certain value of application.