特低渗透油藏水驱、CO_2驱和水/CO_2交替驱效果对比

Water Flooding, CO_2 Flooding and Water-alternating-CO_2 Flooding Effect Contrast in Extra-low Permeability Reservoir

针对特低渗透油藏,在模拟实际油藏条件下开展水驱、CO2驱和水/CO2交替驱室内实验研究。结果表明:在相同条件下,水/CO2交替驱的采收率比CO2驱高22.63%,比水驱采收率高27.22%。水驱见水早,含水率上升快,注入压力高;CO2驱虽然注入压力低,但CO2气窜非常严重;水/CO2交替驱注入压力比CO2驱高,但远远低于水驱压力。水/CO2交替驱见气和见水时间较CO2驱和水驱晚,而且气油比和含水率上升速度慢。因此利用CO2驱油时,应首先选择水/CO2交替驱。

To extra-low permeability reservoirs, we simulate the practical reservoir conditions and carry out water flooding, CO2 flooding and water-alternating-CO2 flooding in laboeatory. The results show that under the same conditions the recovery of water- alternating-CO2 flooding is 22.63 percent higher than that of CO2 flooding, and 27.22 percent higher than that of water flooding. For water flooding, the water breakthrough time is early, moisture content rises fast, and injection pressure is high. Although CO2 flooding injection pressure is low, CO2 gas channeling is very serious. The injection pressure of water-alternating-CO2 flooding is higher than CO2 flooding, but far lower than the water flooding pressure. The gas breakthrough time and water breakthrough time of water-alternating-CO2 flooding is separately later than CO2 flooding and water flooding, but gas-oil ratio and moisture content rise slowly. Therefore, when using CO2 flooding we should first choose water-ahemating-CO2 flooding.