纳米驱油剂提高原油采收率效果及作用机理分析

Effect and Mechanism of Nano Oil Displacement Agent on Enhancing Oil Recovery

李鸿儒 卢祥国 王晓燕 殷庆国 李毓 曹豹

LI Hongru LU Xiangguo WANG Xiaoyan YIN Qingguo LI Yu CAO Bao

为高效开发大港油田低渗致密储层，通过纳米驱油剂CN-1 的粒径分布、界面张力、润湿性和乳化性测试研 究了纳米驱油剂CN-1 的物化性质，针对大港致密油田开展静态渗吸实验和常规驱替实验，并对CN-1 的作用机 理进行分析。结果表明，CN-1 是一种非均相驱油剂，它由纳米颗粒与携带液组成，颗粒粒径分布10～100 nm。 驱油剂CN-1 和携带液与原油间界面张力均高于3.69 mN/m，它们浸泡岩心后致使油水接触角升高，岩石表面亲 水性减弱。与注入水相比较，CN-1 驱油剂渗吸采收率增幅较高，说明纳米驱油剂具有提高洗油效率的作用。与 CN-1 驱油剂相比较，尽管表面活性剂BHS溶液洗油效率较高，同时乳化作用引起“贾敏效应”也产生了扩大波及 体积效果，但其注入压力明显低于CN-1 驱油剂的水平，扩大波及体积效果较差，最终采收率增幅较低。纳米颗 粒在岩石孔隙内滞留引起渗流阻力和注入压力升高，进而造成中低渗透部位（孔隙）吸液压差和吸液量增大，因 而扩大波及体积是CN-1驱油剂提高采收率的主要机理。纳米驱油剂注入时机愈早，采收率增幅愈大。

In order to efficiently develop low permeability and tight reservoirs in Dagang Oilfield，the physicochemical properties of nano oil displacement agent CN-1 were studied through the measurement of particle size distribution，interfacial tension， wettability，and emulsification. Static permeability and conventional displacement experiments were conducted for Dagang tight oilfield，and the mechanism of action of CN-1 was analyzed. The results showed that CN-1 was a heterogeneous oil displacement agent，composed of nano particles and carrier fluid，and the particle size distribution was 10—100 nm. The interfacial tension between CN-1 oil displacement agent（or carrier fluid）and crude oil was higher than 3.69 mN/m，the oil-water contact angle was increased and the hydrophilicity of rock surface was weakened after soaking the core into the CN-1 oil displacement agent or carrier fluid. Compared with injected water，CN-1 oil displacement agent had a higher increase in imbibition recovery rate，indicating that nano oil displacement agent could improve oil washing efficiency. Compared with CN-1 oil displacement agent，although the oil washing efficiency of surfactant BHS solution was higher，and the "Jamin effect" caused by emulsification also had the effect of expanding the swept volume，its injection pressure was significantly lower than that of CN-1 oil displacement agent，the effect of expanding the swept volume was poor，and the enhanced oil recovery was low. The retention of nano particles in the pores of rocks caused the increase of seepage resistance and injection pressure，which in turn caused the increase of liquid suction pressure difference and liquid suction volume in the middle and low permeability parts（pores）. Therefore，expanding the swept volume was the main mechanism of CN-1 oil displacement agent to enhance oil recovery. The earlier the injection time of nano oil displacement agent was，the greater the increase of oil recovery would be.

10.19346/j.cnki.1000-4092.2023.02.018