封闭油藏注气增能降粘提高采收率研究

Enhancing Bounded Reservoir Oil Recovery by Injecting Gas to Increase Energy and Decrease Viscosity

封闭油藏主要靠油藏自身的弹性能开采,能量衰竭很快。向地层注入CO2或烟道气,可以增加封闭油藏的压力,补充地层弹性能。利用高温高压PVT设备,把注入烟道气或者CO2和稠油充分混合,测得1MPa到7MPa条件下的烟道气或者CO2稠油的粘度和体积系数。并用岩心实验模拟注入烟道气或者CO2的稠油压力衰竭开采过程。实验表明,CO2和烟道气在原油中有很好的降粘能力,40℃、7MPa条件下分别饱和CO2和烟道气,饱和CO2原油的粘度降低幅度超过95%,体积膨胀15%;饱和烟道气的原油粘度降低38.1%,体积膨胀4.9%。压力衰竭实验表明,注入段塞的大小0.4PV为宜;三轮次注气增能降粘CO2能采出57.84%的原油;烟道气能采出43.99%原油;水驱后注气增能分别能提高采收率17.31%、13.29%。

Bounded reservoir produced oil mainly by self-expanding energy,and pressure decreases rapidly.It can increase bounded reservoir pressure and formation expansion ability by injecting CO2 or flue gas.Injected flue gas,CO2 and heavy oil into a HTHP PVT equipment,and measured it＇s viscosity and volume factors in the condition 1 MPa to 7 MPa.Simulating heavy oil,after injected flue gas or CO2,pressure depleted recovery process by using core huff and puff experiment.Experimental results show the CO2 and flue gas dissolved in oil can greatly decrease oil viscosity.Oil viscosity,saturated CO2,decreased more than 95%,and volume expansion increased 15% in 40 ℃,7 MPa condition;but in the same condition oil viscosity,saturated flue gas,decreased 38.1%,and volume expansion increased 4.9%.Pressure depletion experiments show the injecting 0.4 PV gas is optimum.It can displace out 57.84% oil by injecting three runs o.4 PV CO2;and get 43.99% by injecting three runs 0.4 PV flue gas.Oil recovery increases separately 17.31%,13.29% by injecting 0.4 PV CO2 or flue gas after water flooding.