Department of Civil and Environmental Engineering, University of Cyprus, Cyprus; Department of Engineering, University of Cambridge, UK.
Department of Engineering, University of Cambridge, UK.
J Contam Hydrol. 2024 Jul;265:104383. doi: 10.1016/j.jconhyd.2024.104383. Epub 2024 Jun 8.
Experiments on fluid flow in porous media, using fluids loaded with solids of various grain sizes, have been conducted in a modified Hele-Shaw setup. This setup utilised weakly cemented porous media with specific hydraulic and mechanical properties. Fluid injection in coarse granular media with clean or low-concentration fine particles, results in infiltration only, with pressure close to the material tensile strength, while injection in finer granular material causes damage alongside infiltration, with the fluid pressure still close to the material tensile strength. When larger particle sizes or higher particle concentrations are used in the mixture, the fluid travels further within the porous medium, primarily influenced by the grain size of the granular medium. In the latter case, the Darcy flow equation with an effective permeability term can be employed to determine the pressure differential. For the largest particle sizes included in the fluid, the equation is still applicable, but the effective permeability requires adjustment for particle size within the fluid rather than the granular medium. This is crucial when the injection point is locally clogged. The experiments show that fracturing conditions are controlled by different mechanisms. Dimensional and statistical analysis was used to classify the injection pressures to regimes predicted by fracturing theory or by Darcy law with modified effective permeabilities. The findings show that both the material properties and fluid composition are important designing parameters.
在改良的 Hele-Shaw 装置中，使用加载有不同粒度固体的流体对多孔介质中的流体流动进行了实验。该装置利用具有特定水力和机械性能的弱固结多孔介质。在清洁或低浓度细颗粒的粗颗粒介质中进行流体注入只会导致渗透，压力接近材料的拉伸强度，而在更细的颗粒材料中进行注入会导致渗透的同时发生损坏，流体压力仍接近材料的拉伸强度。当混合物中使用更大的颗粒尺寸或更高的颗粒浓度时，流体在多孔介质中传播得更远，主要受颗粒介质的颗粒尺寸影响。在后一种情况下，可以使用带有有效渗透率项的达西流方程来确定压差。对于包含在流体中的最大颗粒尺寸，该方程仍然适用，但有效渗透率需要根据流体中的颗粒尺寸而不是颗粒介质进行调整。当注入点局部堵塞时，这一点至关重要。实验表明，压裂条件受不同机制的控制。尺寸和统计分析用于将注入压力分类为压裂理论或修正有效渗透率的达西定律预测的区域。研究结果表明，材料特性和流体成分都是重要的设计参数。
