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把特低渗透油藏岩心根据渗透率划分为不同等级,分别对不同等级岩心进行注水、注氮气和注二氧化碳室内实验。测得了不同开发方式条件下注采压差梯度和洗油效率,回归出不同开发方式下洗油效率随渗透率变化关系式,并对不同开发方式效果进行对比分析。研究结果表明:特低渗油藏在不同方式开发过程中,注入压力都表现为先上升后下降,最后趋于稳定值;由于启动压力的存在,洗油效率在注入开发初期都为零;注氮气开发注采压差大于注二氧化碳开发注采,小于注水开发注采压差;在渗透率较高情况下,注氮气和二氧化碳注采压差相差不大;二氧化碳驱油效果最好,氮气次之,水驱最差。
According to the permeability, the cores of ultra-low permeability reservoirs are divided into different grades, and the experiments of water injection, nitrogen injection and carbon dioxide injection for different grades of cores are carried out respectively. The pressure drop gradient and wash efficiency under different development modes were measured, and the relationship between wash efficiency and permeability under different development modes was regressed. The effects of different development modes were compared and analyzed. The results show that during the development of UHVDC reservoirs, the injection pressure increases firstly and then decreases and finally stabilizes. Because of the start-up pressure, the oil scrubbing efficiency is zero at the initial stage of injection development. Note The pressure difference between injection and withdrawal for nitrogen development is larger than that for carbon dioxide injection and is less than that for injection and injection. In the case of higher permeability, the pressure difference between nitrogen injection and carbon dioxide injection and injection is similar, and that of carbon dioxide displacement is the best, The worst water flooding.