胜坨油田二区沙二段3砂组高温高盐油藏低张力氮气泡沫驱单井试验

A single-well test with low-interfacial tension nitrogen foam flooding in high-temperature and high-salinity reservoir, No.3 sand group, Shengtuo2 area, Shengtuo oilfield.

针对高温高盐油藏的特点,采用分子模拟和室内实验等手段,研制了低张力氮气泡沫体系。室内评价结果表明,当温度为80℃时,不同质量分数的氮气泡沫体系在吸附前后发泡体积均保持在200 mL左右,半衰期大于5 000s,表明其具有良好的起泡性能和泡沫稳定性能。为了验证该体系在高温高盐油藏中的起泡性能、泡沫稳定性能及对高渗透条带的封堵性能,优选合理的注入方式和气液比,于2011年8月30日在胜坨油田二区沙二段3砂组高温高盐油藏开展了为期1个月的低张力氮气泡沫驱单井试验,30 d累积注入泡沫剂溶液2 087 m3,3口受效油井平均综合含水率由试验前的98.5%降至试验结束后的97.8%,平均单井产液量保持稳定,产油量由6.3 t/d上升到9.2 t/d。油水井动态变化及吸水剖面变化结果表明:低张力氮气泡沫体系在高温高盐油藏条件下能够形成稳定的泡沫,且封堵高渗透条带性能好;气液混合注入渗流阻力大,封堵效果好;试验条件下最佳气液比为1∶1。

A new low-tension foam flooding system is developed for high-temperature and high-salinity reservoir using molecular sim-ulation and in-home experiments. Under the conditions of 80 °C, the foam volume maintained at 200 mL and half-life >5 000 s, imply-ing that the foam system has great foaming capability and foam stability. A one-month single-well test with low-tension nitrogen foamflooding is carried out at Shengtuo field on August 30, 2011. The foaming capability and foam stability of foam system under differentconditions are investigated. The plugging ability for high-permeability streaks is examined as well. The injection mode and gas/liquidratio are optimized. The cumulative injection of foaming agent is 2 087 m3. The average water cut of 3 influential producers decreasedfrom 98.5% to 97.8%. The average fluid production is stable and oil production increases from 6.3 to 9.2 t/d. According to the perfor-mance of injectors and producers and the variation of injection profile, the low-tension foam system can form stable foam and exhibitgood blocking efficiency for high-permeability streaks. The gas-liquid mixed injection can improve percolating resistance and pluggingability. The optimal gas/liquid ratio under test condition is 1∶1.