纳米颗粒吸附后强界面效应量化表征及多尺度流固耦合模拟理论研究

The adsorbed nanoparticle has intense interfacial effect in porous media, whose migration and retention behave notable fluid-solid interaction characteristics. The current chemical flooding seepage theory is unable to effectively simulate the nanoparticle flooding process. It is very important to develop a set of simulation theory to quantitatively depict the intense interfacial effect and multiscale fluid-solid interaction. This study aims at the problem that it is difficult to quantitatively evaluate the intense interfacial effect after adsorption and migration retention characteristics of nanoparticles. The study thinking is to combine the microscope method and macroscopic method, meanwhile to combine the experiments analysis and simulation computation. Multidisciplinary theories such as reservoir physics, microscope porous flow mechanics, and reservoir numerical simulation are integrated. Several lab experiments are conducted such as interfacial tension test, static contact angle test and core flooding test to clarify the intense interfacial effect for nanoparticles after adsorption. A fluid-solid coupling microscopic migration simulation method is developed to reveal the adsorption retention and Enhanced Oil Recovery mechanisms for nanoparticles. A nanoparticle macroscopic migration multiphase multicomponent fluid-solid coupling mathematics model is built on the dynamic reservoir parameters varying model. The multiscale fluid-solid interaction numerical simulaiton theory system is formed for nanoparticle Enhanced Oil Recovery. This study lays theoretical foundation for reasonably developing mature oil field and hard-to-recover oil field by using nanoparticle enhanced chemical flooding methods.

纳米颗粒在多孔介质中吸附会产生强界面效应，运移滞留存在显著流固耦合特征，现有化学驱渗流理论无法有效模拟其驱油过程，建立一套纳米颗粒吸附后强界面效应量化表征及多尺度流固耦合模拟理论对于纳米颗粒提高采收率技术应用具有重要作用。本课题针对纳米颗粒吸附后强界面效应和运移滞留特征难以定量评价的问题，采用微观和宏观相结合、实验研究和模拟计算相结合的思路，综合运用油层物理学、微观渗流力学、油藏数值模拟等多学科理论，开展界面张力、静态接触角以及岩心驱替等实验，阐明纳米颗粒吸附后强界面效应的作用机制，研发纳米颗粒微观运移流固耦合数值模拟方法，揭示纳米颗粒吸附滞留特征及提高采收率机理，在储层参数动态变化模型基础上建立纳米颗粒宏观运移多相多组分流固耦合数学模型，形成纳米颗粒提高采收率多尺度流固耦合数值模拟理论体系。本研究为纳米颗粒强化化学驱老油田和难动用油藏高效开发奠定了理论基础。

纳米流体在水驱降压增注中具有很好应用效果，纳米颗粒吸附后通过改变润湿性、防止黏土膨胀，增大孔道半径大幅度降低注入流体在多孔介质的流动阻力。然而现有化学驱渗流理论无法有效模拟其渗流过程，建立一套纳米颗粒吸附后强界面效应量化表征及多尺度流固耦合模拟理论对于纳米颗粒降压增注技术应用具有重要作用。本项目针对纳米颗粒吸附后强界面效应及流固耦合渗流表征的科学问题，采用微观和宏观相结合综合运用油层物理学、微观渗流力学、油藏数值模拟等多学科理论，从纳米颗粒吸附后强界面效应、微观宏观渗流特征及流固耦合数值模拟三个方面开展研究工作。首先开展了纳米颗粒吸附后界面张力及润湿角的测量，分析了生物纳米材料与油藏岩石孔喉结构配伍性，利用驱替实验研究生物纳米吸附后渗透率改变；然后开展了物纳米材料降压增注机理微观模拟，建立了生物纳米储层径向复合渗流数学模型，并在此基础上分析了储层物性及流体物性对生物纳米作用效果的影响；最后在实验和渗流表征模型基础上建立了生物纳米材料降压增注多相多组分数值模拟模型并建立了数值求解方法，结合实际井组实例开展了生物纳米材料降压增注施工关键注入参数优化，并对生物纳米试验井组降压增注效果进行定量预测与评价。本项目阐明纳米颗粒吸附后强界面效应的作用机制，依据其渗流特征建立了纳米颗粒多尺度流固耦合数值模拟理论体系，这为纳米颗粒改善老油田水驱效果及化学驱难动用油藏高效开发奠定了理论基础。