含油多孔介质中超磁性纳米颗粒的传递机理研究

Exciting new applications are being continually developed in the medical and biological sciences on the use of paramagnetic nanoparticles as enhanced imaging and biosensing agents; as agents that facilitate sorting of biological molecules and cells; as delivery vehicles of drugs to target human organs; and numerous other applications, due to its big specific surface, tracer, and sensing. To the upstream oil industry, the novel use of paramagnetic nanoparticles as nanosensors that have the capability to detect certain reservoir properties, and as agents to improve oil recovery offers intriguing and exciting opportunity. The good transportability of paramagnetic nanoparticles is pre-requisite for these applications, however, its major pore-level physics has not been incorporated into the numerical modeling. In this project, theroies of Langmuir and interfacial phenomena, together with pore-scale coreflood experiments and numerical analysis, will be applied to study the adsorption/desorption equations under different working conditions. Based on these equations, the transport model will be proposed by combining current DLVO theory and Clean-bed Filtration theory. The adsorption of nanoparticles at water/oil interface and surface tension will be further investigated to explore the feasibility of enhanced oil recovery. Our study will provide a more accurate prediction for transport of paramagnetic nanoparticles in reservoir rocks, moreover, it will provide scientific evidence for further application of paramagnetic nanoparticles in upstream oil industry.

超磁性纳米颗粒具有比表面积大、示踪性好、传感型好等特性，但目前仅局限应用于生物医学领域。我们希望将其应用于石油工程领域，目前理论上已经证实超磁性纳米颗粒可以作为注入剂以提高采收率，也可以作为探测地层油藏参数的传感器。但是这些应用的前提是颗粒在油藏岩石中要有较好的传递性，但纳米颗粒在油藏中传递的本质特征还没有真正具体的体现在目前的各种数值模型中。本项目应用多孔介质中的界面现象理论和Langmuir理论，结合岩心驱替实验和数值分析方法，建立不同工况下超磁性纳米颗粒的吸附-解吸方程；在此基础上，综合现有的DLVO理论和Clean-bed Filtration理论，构建油藏中超磁性纳米颗粒的传递模型；并进一步研究超磁性纳米颗粒在油水界面的吸附，以及对油水界面张力的影响，探索其对于提高采收率的可行性。本课题的研究将为超磁性纳米颗粒在油藏中的传递提供准确的预测方法，对其应用于石油领域提供科学依据。

超磁性纳米流体应用在石油工程领域的前提是颗粒在油藏岩石中要有较好的传递性。本项目通过调研总结前人对超磁性纳米颗粒的传递机理研究进展，在前人的一些理论指导下，使用清华大学合成的、以及其他商业超磁性纳米材料作为研究对象，在大量实验的基础上得到了纳米颗粒在岩石表面的传递和解吸规律。通过向含油水得岩心中注入纳米流体及再次进行水洗，模拟得出影响纳米颗粒在油水界面的传递因素，分析各类因素对纳米流体在油水界面传递影响的大小，进而指导出纳米流体在实际生产中对于提高原有采收率有着一定的作用，但约束条件很多。在DLVO理论和胶体过滤理论的基础上进行改进，建立了超磁性纳米颗粒在油藏中的传递-解吸的表征方程及传递模型，得并通过实验论证了模型的可靠性。本课题的研究将为超磁性纳米颗粒在油藏中的传递提供准确的预测方法，对其应用于石油领域提供科学依据。