Research On Foam Flooding System For Reducing Viscosity Of Heavy Oil

China's oil and gas resources are very rich,and 20%of petroleum resources are heavy oil resources.Heavy oil reservoir is characterized by serious heterogeneity and deep burial,so water flooding development is difficult to achieve results and cannot achieve ideal recovery.Taking the research area as an example,waterflood development started in May 1997.As of April 2012,it has been developed for 15years and has a water content of up to 85%.The current recovery rate is low,only5.16%.Foam flooding is a excellent tertiary oil recovery technology.Foam flooding has good plugging performance and selectivity for oil and water,and has great potential for development.In view of the characteristics of high viscosity of crude oil in the research area,on the basis of foam flooding to improve the spreading efficiency,the foam can be used to reduce the viscosity of the crude oil to improve the fluidity ratio to further improve the flooding efficiency,thereby increasing the final recovery rate,which is important for heavy oil development.So it is necessary to study the foam flooding system that can reduce viscosity.This article first conducted a foam viscosity reduction experiment,It is determined that the foam system can achieve the optimal viscosity reduction effect when the effective concentration is 0.1%and the temperature is above 70?.Then,under the condition of reservoir in the study area,several kinds of foaming agents were screened and evaluated by agitation method,and KX-048 foaming agent with good foaming performance and strong stability was obtained.The adaptability of the foaming agent was analyzed.The results showed that the performance of the foaming agent decreased with the increase of the salinity.Because of the defoaming effect of crude oil,the increase of oil content will reduce the plugging capacity of foam,but when the oil content is 10%,the foam can still meet the performance requirements of foam flooding.The pressure test of foam shows that the higher the pressure,the stronger the foaming ability and stability.Foam plugging ability test shows that when the effective concentration is 0.1%,the resistance factor of the foam reaches the peak value of 58.9;when the gas-liquid ratio is 1.0:1.0,the foam has an ideal plugging effect,and when the permeability is high,especially higher than 485×10~3?m~2,the resistance factor of the foam is relatively stable,about 65.At this time,the foam system has strong plugging performance.Finally,two experiments were carried out,including foam improving mobility experiment and enhanced oil recovery experiment.KX-048 foaming agent significantly reduced the water-oil fluidity ratio by reducing the viscosity of crude oil by 70%.At the same time,it enhanced the foam oil fluidity ratio and controlled the oil displacement system.And foam prevents channeling and fingering.Compared with KX-048 and XHY-4,KX-048 foaming agent has better control of convection,and the minimum moisture content can be reduced to 68.32%,which is 6.46%lower than XHY-4 foaming agent,and XHY-4 is improved the recovery factor is 11.57%,and KX-048 increases the recovery factor is 19.96%,which shows that after reducing the viscosity of heavy oil,foam flooding can increase the recovery factor more significantly.