Coupled Fluid Dynamic And Poro-Elastic Effects During Gas Flow In Nanoporous Media: Experiments And Multi-Scale Modelling

该项目将研究气体在微/纳米多孔介质中运移过程中的流体动力学和孔隙弹性效应，特别关注沉积岩。我们将采用综合方法，包括人工和天然微/纳米多孔介质上的气体输运实验室实验（亚琛工业大学）和观察/预期效应的多尺度建模（清华大学）。双方在各自的领域都有长期的研究经验，并在最近开始了成功和富有成效的合作。联合研究的目标是低渗透岩石的流体动力学和孔隙弹性变形问题，包括滑移流动、Knudsen扩散、真实气体效应、粘度的压力依赖性、运移孔隙系统变形/改性引起的渗透系数的应力依赖性、气体和水的吸附/解吸对流体流动的依赖性。微孔和纳米孔介质的渗透系数不是不变的材料特性，而是对流体流动试验边界条件（压力、压力梯度、有效应力变化）的变化非常敏感，特别是在用不同气体测量时。有关孔隙系统性质的信息可以通过实验条件和所用气体的系统变化而得到。本研究将首先利用人工孔隙系统（纳米毛细血管，不同硬度材料中的定义微缝）阐明气体在狭窄、可变形孔隙中的基本关系。随后将对选定的石版进行测量和评估。对孔径相关流变效应和孔隙系统机械变形之间相互作用的更好理解，将极大地改善不同尺度上气体流动过程的预测，从而实现从纳米（实验室）到千米（现场）尺度的升级。虽然许多流体输运建模方法必须依赖于已发表的数据来验证其结果，但在拟议的项目中，实验计划将通过建模者和实验人员之间的直接反馈进行灵活调整。因此，将确保实验结果的质量和可重复性，并验证解释和模型的一致性。

The project will investigate fluid-dynamic and poro-elastic effects during gas transport in micro-/nanoporous media with special focus on sedimentary rocks. We will use a combined approach, involving laboratory experiments of gas transport on artificial and natural micro-/nanoporous media (RWTH Aachen University) and multiscale modeling of the observed/anticipated effects (Tsinghua University). Both partner groups contribute long-term research experience in their respective fields and have started a successful and fruitful co-operation lately.The joint research is targeting issues of fluid dynamics and poro-elastic deformations in low-permeability rocks, including slip flow, Knudsen diffusion, real gas effects, pressure-dependence of viscosity, stress-dependence of permeability coefficients due to deformation/modification of the transport pore system, and dependence of gas and water sorption/desorption on fluid flow. Permeability coefficients of micro- and nanoporous media are not invariable material properties but, particularly when measured with different gases, are very sensitive to changes in the boundary conditions of fluid flow tests (pressure, pressure gradients, changes in effective stress). Information on the pore system properties can be derived by systematic variation of experimental conditions and the gases used.The proposed research will first elucidate fundamental relationships of gas transport in narrow, deformable pores by using artificial pore systems (nanocapillaries, defined micro-slits in materials with different hardness). Subsequently measurements on selected lithotypes will be conducted and evaluated. An improved understanding of the interplay between pore size-dependent rheologic effects and the mechanical deformation of the pore system will greatly improve predictions of gas flow processes on different scales, thus enabling upscaling from the nm (laboratory) to km-range (field) scale. While many fluid transport-modeling approaches have to rely on published data for validation of their results, in the proposed project the experimental program will be adapted flexibly through direct feedback between modelers and experimentalists. The quality and reproducibility of the experimental results will thus be ensured and the consistency of the interpretations and models verified.