Singh Rajveer, Sivaguru Mayandi, Fried Glenn A, Fouke Bruce W, Sanford Robert A, Carrera Martin, Werth Charles J
Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801, USA; Energy Bioscience Institute, University of Illinois Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801, USA; Department of Civil and Environmental Engineering, University of Illinois, Urbana-Champaign, 205 N. Mathews Avenue, Urbana, IL 61801, USA.
Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801, USA.
J Contam Hydrol. 2017 Sep;204:28-39. doi: 10.1016/j.jconhyd.2017.08.001. Epub 2017 Aug 4.
Physical, chemical, and biological interactions between groundwater and sedimentary rock directly control the fundamental subsurface properties such as porosity, permeability, and flow. This is true for a variety of subsurface scenarios, ranging from shallow groundwater aquifers to deeply buried hydrocarbon reservoirs. Microfluidic flow cells are now commonly being used to study these processes at the pore scale in simplified pore structures meant to mimic subsurface reservoirs. However, these micromodels are typically fabricated from glass, silicon, or polydimethylsiloxane (PDMS), and are therefore incapable of replicating the geochemical reactivity and complex three-dimensional pore networks present in subsurface lithologies. To address these limitations, we developed a new microfluidic experimental test bed, herein called the Real Rock-Microfluidic Flow Cell (RR-MFC). A porous 500μm-thick real rock sample of the Clair Group sandstone from a subsurface hydrocarbon reservoir of the North Sea was prepared and mounted inside a PDMS microfluidic channel, creating a dynamic flow-through experimental platform for real-time tracking of subsurface reactive transport. Transmitted and reflected microscopy, cathodoluminescence microscopy, Raman spectroscopy, and confocal laser microscopy techniques were used to (1) determine the mineralogy, geochemistry, and pore networks within the sandstone inserted in the RR-MFC, (2) analyze non-reactive tracer breakthrough in two- and (depth-limited) three-dimensions, and (3) characterize multiphase flow. The RR-MFC is the first microfluidic experimental platform that allows direct visualization of flow and transport in the pore space of a real subsurface reservoir rock sample, and holds potential to advance our understandings of reactive transport and other subsurface processes relevant to pollutant transport and cleanup in groundwater, as well as energy recovery.
地下水与沉积岩之间的物理、化学和生物相互作用直接控制着诸如孔隙度、渗透率和水流等基本地下特性。从浅层地下含水层到深埋的油气藏等各种地下场景都是如此。微流控流动池现在常用于在简化的孔隙结构中以孔隙尺度研究这些过程，这些孔隙结构旨在模拟地下储层。然而，这些微模型通常由玻璃、硅或聚二甲基硅氧烷（PDMS）制成，因此无法复制地下岩性中存在的地球化学反应性和复杂的三维孔隙网络。为了解决这些局限性，我们开发了一种新的微流控实验测试平台，在此称为真实岩石 - 微流控流动池（RR - MFC）。制备了一块来自北海地下油气藏的克莱尔组砂岩的500μm厚多孔真实岩石样本，并将其安装在PDMS微流控通道内，创建了一个动态流通实验平台，用于实时跟踪地下反应性输运。使用透射和反射显微镜、阴极发光显微镜、拉曼光谱和共聚焦激光显微镜技术来（1）确定插入RR - MFC中的砂岩内的矿物学、地球化学和孔隙网络，（2）分析二维和（深度受限的）三维非反应性示踪剂的突破情况，以及（3）表征多相流。RR - MFC是第一个能够直接可视化真实地下储层岩石样本孔隙空间中流动和输运的微流控实验平台，并且有潜力推进我们对反应性输运以及与地下水中污染物运移和清理相关的其他地下过程的理解，以及能源回收方面的理解。
