Optimization And Performance Evaluation Of Foam Assisted Gas Flooding Foam System In Fractured Vuggy Reservoirs

The porosity and permeability of the fractured vuggy reservoir are very low,the height of fracture cavity is high,and the reservoir heterogeneity is strong.In gas flooding,gas injection flow easily along high permeability channels,the response time becomes shorter,the ultimate recovery rate is not high.Foam,because of its own characteristics,has the function of regulating mobility.It is often used in foam assisted gas flooding to ease gas channeling and improve gas efficiency time.However,due to the high temperature and high salt environment of the fractured vuggy reservoir,the foam system is very demanding,and there is no suitable stable foam system to provide technical support.Therefore,this paper mainly studies the formulation and performance evaluation of foam system which can meet the severe conditions of fractured vuggy reservoir.Using Waring Blender stirring method as the main means of the evaluation,selection of new anionic nonionic surfactant SS-163 and anionic surfactants commonly used α-AOS,the proportional mixture of compound foaming agent system with foaming volume,resistance to temperature and salt resistant characteristics;at the same time selected increase the viscosity of foam stabilizing agent starch gel as the foam stabilizing agent,foam stabilizing agent has stable performance,but also by viscosity,improve foam stability,the high temperature of 120 ℃,up to the high salinity of 22×104mg/L,and the compatibility of SS-163 foaming agent and α-AOS has very good the.Therefore,under the condition of salinity 22×104 mg/L and temperature 120 ℃,the optimum formulation of foam system is 0.15% SS-163+0.15% α-AOS+0.3% starch gel.It is found by optical microscope that the thickness of the foam liquid film is suitable,the moisture content is adequate,and the particle size distribution is uniform.Performance evaluation experiments show that the foam has not only good temperature resistance and salt resistance,but also excellent oil resistance.In the fractured vuggy reservoir gas foam assisted experiments that physical drive,with the increase of gas bubble and slug injection PV,oil recovery degree also increased;water flooding after foam assisted gas flooding after water flooding and gas drive are simple compared to the former mining degree is higher,the bubble gas effectively slow down effect of gas channeling,prolong period,expand the sweep efficiency,so that the final recovery efficiency.The results show that the foam system in this paper can not only adapt to high temperature and high salinity conditions of fractured vuggy reservoir,also suitable for driving to ease the gas channeling foam assisted gas technology has the reference value and practical significance in the application of fractured vuggy reservoirs on foam assisted gas flooding.