Study On Improving CO₂ Flooding Effect In Strong Bottom Water Reservoir

A number of blocks in Shengli Oilfield have active bottom water with sufficient natural energy,which belong to strong bottom water reservoirs.However,the horizontal wells have high fluid content and high water content,the development effect is poor,and the remaining oil is more difficult to be used.In this paper,carbon dioxide injected to control water yield in horizontal well is studied,aiming at strong water reservoir in the Zhuangxi block.This subject studied the main mechanism of carbon dioxide recovery,including the mechanism of increasing formation energy,gas injection to reduce oil resistance and increase water flow resistance.Visualization experiment proved that the carbon dioxide throughput can improve the recovery rate of the near well area.Due to the problems of carbon dioxide overburden and sticky fingering,the volume and the half-life of foam are taken as the main indexes to evaluate the performance of foaming agents in this paper.By comparing the different surfactants and high-molecular polymer,0.1%partially hydrolyzed polyacrylamide（HPAM）is taken as the thickener of foaming agent sodium dodecyl sulfate（SDS）.The foam half-life can be extended on the basis of maintaining the volume of foam.The effect of sodium carbonate（Na₂CO₃）was also tesed in this experiment.The experiments showed that the viscous foaming agent system with low interfacial tension can improve the recovery rate by 30%compared to water flooding.During the implementation of the project,a total of 7wells have been developed with the average water content decreasing by 23.7%.The cumulative oil production has reached 2103 tons which is a considerable economic benefits.