Experimental Study on the Mechanism of Nitrogen Foam to Improve the Recovery of Bottom-Water Heavy Oil Reservoir

During the late stage of water flooding, most reservoirs will enter the high water cut stage. The remaining oil is mainly concentrated in the high structural part. At this time, the water flooding effect is no longer ideal. Based on this problem, nitrogen foam-enhanced FOR research is carried out. Through two-dimensional visualization experiments, we observed the migration and diffusion of nitrogen foam and summarized the mechanism of nitrogen foam flooding system in enhancing oil recovery in heavy oil reservoirs with bottom water. The physical displacement experiment of core tube is carried out under simulated reservoir conditions, the gas-liquid ratio parameters of nitrogen foam are optimized, and the influence of injection and production methods on recovery factor is studied. The results show that nitrogen foam flooding has certain washing ability and can increase the sweep efficiency. The plugging effect of foam can effectively improve the oil displacement effect. Foam foaming is used to form frothing solution with emulsifying and viscosity-reducing function. The crude oil is produced in the form of foam oil and emulsion under the action of emulsification and viscosity reduction, and the recovery factor is increased. In visual experiments and core tube experiments, the recovery rates of foam flooding stage are 22.4 and 34.9%, respectively. The gas-liquid ratio of 3:1 is the best proportion, and the injection method is the best effect of nitrogen foam flooding and foam huff and puff. The recovery rate of nitrogen foam flooding-foam injection method is 40.7%, which is 5.8% higher than that of nitrogen foam flooding injection mode.

Automated summary

This study investigates the nitrogen foam-enhanced oil recovery in heavy oil reservoirs with bottom water through experimental observations and physical displacement experiments under simulated reservoir conditions. The results show that nitrogen foam flooding has the ability to improve oil recovery by increasing the sweep efficiency and enhancing the oil displacement effect. The optimal gas-liquid ratio and injection method have significant effects on the nitrogen foam flooding process.