裂缝性油藏微乳液配方优选及驱油效果

为筛选出最优微乳液驱油体系，以微乳液性能对孔隙剩余油的影响为指标进行优选，通过分析裂缝性岩心驱油实验和孔隙剩余油分布规律，从宏观和微观两方面证明微乳液驱提高采收率的显著效果。结果表明，最佳微乳液体系：正辛烷8 mL，水8 mL，质量分数为4.5%的羧基甜菜碱、6%的正丁醇、5%的NaCl的微乳液体系的粒径分布范围较小，具有较高的黏度，较强的稳定性和较小的含孔隙剩余油比例。与水驱相比，微乳液驱采收率增幅可达10.8%，最终采收率高达49.7%，说明微乳液驱油体系采收率提高效果显著。含剩余油孔隙比例随孔隙半径的减小而减小，表明孔隙半径对剩余油分布有显著影响；与基质岩心相比，裂缝性岩心的含剩余油孔隙比例较大，驱油效率相对较低。

Optimization of Microemulsion Formulation of Fractured Reservoirs and Oil Displacement Effect

In order to screen out the best microemulsion flooding system, the influence of microemulsion performance on the remaining oil of the pores is selected as an index. Through the core oil?displacement test and pores of remaining oil experiment, we have proved the remarkable effect of the microemulsion flooding in enhancing the recovery factor from two aspects, macroscopic and microscopic. The results show that the particle size of the best microemulsion for 8 mL n?octane, 8 mL water,4.5 mass fraction of Carboxyl betaine,6 mass fraction of N?Butyl alcohol,5 mass fraction of NaCl has smaller particle size distribution, higher viscosity, stronger stability and smaller proportion of residual oil containing pores. To compare with the water flooding, the amplification of microemulsion flooding can achieve 10.8% and the final recovery is up to 49.7%.This result proves that microemulsion can remarkably improve recovery efficiency. The ratio of residual oil to pore decreases with the decrease of pore radius, which indicates that pore radius has a significant effect on remaining oil distribution. Compared with matrix core, the ratio of residual oil pore to fractured core is larger and oil displacement efficiency is relatively low.