水气交替注入过程纳米颗粒对CO_2运移特征的影响

Influence of nanoparticles on CO_2 transport characteristics in water alternating gas injection process

为了有效控制CO_2提高采收率和CO_2埋存过程中CO_2流体的流动性,在储层或砂岩含水层中注入纳米颗粒。室内实验采用CT扫描仪观察和测量CO_2驱替盐水/纳米颗粒溶液以及盐水/纳米颗粒溶液驱替CO_2的流动形态和流体饱和度。研究结果表明,纳米颗粒溶液实验中CO_2驱替前缘比较一致并且流体流动较慢,其初始CO_2饱和度和剩余CO_2饱和度要大于盐水实验中的初始CO_2饱和度和剩余CO_2饱和度。纳米颗粒使得CO_2与盐水产生稳定的乳状液,减小流体流动性,增加流体有效黏度。根据Land方程,盐水实验中C常量为2.45,纳米颗粒实验中C为2.25,因此CO_2注入方案的制定应尽量选取小的C常量,以减缓气水交替注入过程中CO_2的黏性指进,将更多的CO_2滞留或保存在地层中。

In order to effectively control CO2 EOR and the lfuidity of CO2 lfuid in CO2 storage process, the nanoparticles are injected into reservoir or sandstone aquifer. In the indoor test, a CT scanner is used to observe and measure the lfow pattern and saturation of lfuid in the displacement of brine/nanoparticle solution by CO2 as well as in the displacement of CO2 by brine/nanoparticle solution. The research indicates that, in the nanoparticle solution test, the CO2 displacement fronts are relatively consistent, the lfow velocity of lfuid is relatively low, and the initial CO2 saturation and residual CO2 saturation are higher than those in brine test. The nanoparticles drive CO2 and brine to form the stable emulsion, reduce the lfuidity of lfuid, and increase the effective viscosity of lfuid. According to the Land Equation, the constant C is 2.45 in brine test and is 2.25 in nanoparticle test. Therefore the constant C should be as less as possible during the formulation of the plan of CO2 injection, so as to slow down the viscosity ifngering during the alternate injection of gas and water, and retain or store more CO2 in stratum.