低渗透油藏二氧化碳混相驱超前注气实验研究——以吉林油田黑79区块为例

Experimental research on CO_2 miscible flooding by advanced gas injection in low permeability reservoir-case of H79 block,Jilin oilfield

为了进一步提高低渗透油藏采收率,进行了二氧化碳混相驱超前注气可行性实验研究。以吉林油田黑79区块为例,利用细管实验确定二氧化碳驱的最小混相压力,通过长岩心物理模拟实验研究低渗透油藏超前注气室内驱油效果,并与相同地层条件下水驱和同步注气的驱油效果进行了对比分析。结果表明,二氧化碳混相驱超前注气、同步注气和水驱的最终采收率分别为77.03%,73.09%和56.47%。二氧化碳混相驱超前注气最终采收率最高,原因是超前注气能够在开采前就使地层压力升高、地层能量增加,并且提前注入的气体与原油接触混相,可降低原油粘度、增加原油流度。

In order to enhance the oil recovery in low permeability reservoir by CO2 miscible flooding through advanced gas injection, its feasibility is tested in laboratory. The minimum miscible pressure is determined by micro-tubes tests;the laboratory result of CO2 miscible flooding by advanced gas injection with long core physical simulation device is researched and the result is compared with that of synchronous gas injection and water flooding. The ultimate recovery of CO2 miscible flooding by advanced gas injection is 77. 03 %,synchronous gas injection is 73. 09% and water flooding is 56. 47%. Results show that, since the advanced gas injection can in- crease the formation pressure and energy, the oil's viscosity is reduced and its mobility is increased because gas injected in advance is contacted with oil, recovery of advanced gas flooding is higher than that of synchronous gas injection and water flooding.