不同注入气对裂缝性油藏原油高压物性的影响

Effect of Different Injected Gases on High Pressure Physical Property of Crude Oil in Fractured Reservoir

裂缝性油藏的原油储量非常丰富,但由于其非均质性严重,如何有效开发该类油藏成为亟待解决的问题之一。注气是现今比较受关注的一种有效开发方式。为了解裂缝性油藏注入不同气体后原油物性变化,采用数值模拟方法对该类油藏分别注CO2及伴生气之后的原油高压物性进行分析。结果表明,相对于注CO2,注伴生气的饱和压力上升速度更快,即随着注气比例的增加,注伴生气越来越难达到混相。CO2对原油物性的影响更明显,如界面张力在注气比例为77.94%时已经消失,理论上已经达到混相,即注CO2的驱油效果要好于注伴生气。研究表明,注气能使裂缝性油藏中的原油黏度降低,界面张力下降,饱和压力升高;但不同注入气对原油高压物性的影响存在差异。

Fractured reserovoir has rich oil reserves,but because of its severe heterogeneity,its effective development remains to be solved.Gas injection is one of effective ways to develop fractured reservoir.In order to understand crude oil property change after different gases are injected into fractured reservoir,analyzed are high-pressure physical properties of crude oil in fractured reservoir after injection with numerical simulation method.The results show that compared with saturation pressure increass faster with associated gas injection than CO2 injection,which means that when ratio increased,injected associated gas became more difficult to form miscible.CO2 has more significant effect on crude oil physical properties:interfacial tension disappears when gas injection proportion goes up to 77.9%,which means that it already formed miscible theoretically and CO2 injection's oil displacement efficiency is better.Research results show that gas injection can decrease the fractured reservoir oil viscosity and interfacial tension and increase saturation pressure.But injection of different gases has different effects on high-pressure physical properties of crude oil.