致密砂岩油藏注热水降压增注实验研究

为探索致密砂岩油藏注热水降压增注技术，通过室内物理模拟研究了注热水对目标区块黏土矿物水化膨胀、岩石孔隙结构、油水黏度、原油热膨胀性、油水界面张力、油水相启动压力和油水相对渗透率曲线的影响，分析了致密油藏注热水降压增注机理，并评价了不同注热水温度下的降压增注效果。实验结果表明，注热水具有较好的降压增注效果，且注入水的温度越高，注水启动压力越低、峰值效应越弱，降压增注效果越明显；不同渗透率岩芯注热水降压增注效果不同，渗透率越低效果越好；该致密油藏区块最合理的注热水温度为100℃左右。

Experimental Study on Hot Water Flooding in Tight Sandstone Reservoir to Reduce Water Injection Pressure and Increase Injection Capacity

To investigate the use of hot water flooding to reduce water injection pressure and increase injection capacity in tight sandstone reservoirs, laboratory-based physical models were used to study the effects of hot water flooding on clay minerals from the target block in terms of hydration-induced expansion, rock pore structure, oil-water viscosity, crude oil thermal expansion, oil-water interfacial tension, oil and water phase starting pressures, and oil-water relative permeability curve. The mechanisms by which hot water flooding reduced water injection pressure and increased injection capacity in tight sandstone reservoirs were analyzed, and the effectiveness of hot water flooding at achieving these processes was assessed for a range of hot-water temperatures. Our experimental results showed that hot water flooding was highly effective at reducing water injection pressure and increasing injection capacity. Increase in the temperature of the water flood decreased the starting pressure of water injection and weakened the impact of the peak effect, thus improving the ability of the water flood at reducing water injection pressure and increasing injection capacity. The effectiveness of hot water flooding differed with the permeabilities of the rock cores and generally improved with decreases in the permeability coefficients of the rock cores. Finally, it was found that the optimal temperature for hot water flooding in the targeted tight sandstone reservoir block was approximately 100℃.