CO2注入方式对芳48油藏开发效果的影响

大庆油田芳48断块为特低渗透油藏,对该油藏进行了水驱、CO₂驱、CO₂吞吐、CO₂转水驱、水驱转CO₂驱等开采方式室内物理模拟研究。实验结果表明,该区块水驱见水早、含水率上升快、注水能力低。在上述5种气驱方式中,CO₂吞吐后气驱的累积采收率最高,然后依次为水驱转CO₂驱、气驱、CO₂驱转水驱,CO₂吞吐的累积采收率最低。从累积气油比来看,CO₂吞吐累积气油比最高,其次为CO₂驱,而水驱转气驱、气驱转水驱、吞吐转气驱的累积气油比较低。从气体注入能力来看,气驱的注入能力最高,而水驱转气驱、气驱转水驱的注入能力比较低。考虑开采效果和气体注入能力,芳48特低渗透油藏开采应优先选择CO₂吞吐后气驱,其次为水驱转CO₂驱。

The Effect of CO2 Injection Process on Production Response of Fang-48 Reservoir in Daqing Oilfield

Fang-48 fault block in Daqing oilfield is a super low permeability oil reservoir. The physical modeling studies are conducted by processes of water flooding, CO2 flooding, CO2 stimulation, CO2-water alternate flooding, water-CO2 alternate flooding. The experimental results indicate that the water breakthrough is early, water cut rises rapidly and water injectivity is low. Among the processes of CO2 flooding, CO2 stimulation followed by CO2 drive allows the highest cumulative oil recovery factor, in turn declining for water-CO2 alternate flooding, CO2 drive, CO2-water alternate flooding, CO2 stimulation. In view of the cumulative gas-oil ratio, it is the highest for CO2 stimulation, in turn declining for CO2 drive, water-CO2 alternate flooding, CO2-water alternate flooding, CO2 stimulation followed by CO2 drive. In light of the CO2 injectivity, it is the highest for CO2 drive, in turn declining for water-CO2 alternate flooding, CO2-water alternate flooding. Considering the production response and the CO2 injectivity, the development scheme of Fang-48 fault block should be firstly the CO2 stimulation followed by CO2 drive, secondly by water-CO2 alternate flooding.