| Title | Influence of Particle Size on its Transport in Discrete Fractures: Pore-Scale Visualization Using Micromodels |
|---|---|
| Authors | Mohammed ALASKAR, Kewen LI, Roland HORNE |
| Year | 2013 |
| Conference | Stanford Geothermal Workshop |
| Keywords | nanoparticle, microparticle, fracture, micromodel, temperature |
| Abstract | Particle transport in porous and fractured systems is typically investigated through sand columns, rock cores and field studies, where results are interpreted based on the return curves. The use of micromodels provides direct observation of controlling transport mechanisms at pore scale. In this work, we investigated the transport mechanisms of 2, 4.5, 6 and 10 µm fluorescent carboxylate-modified latex (CML) microspheres through a fractured system using micromodels. Flow experiments showed directly (by visual observation) that fractures greatly facilitate the transport of particles. The 4.5 and 6 µm particles were only transported through the fracture. Smaller particles (2 µm) were transported through the pore spaces as well. All particles were plugging at the inlet pores of the porous matrix. The severity of plugging or straining was proportional to particle size, i.e. significant straining was observed with larger particles. Plugging of particles at inlet grains differs greatly as function of relative particle size to depth of the micromodel (an observation made by comparing the flow of particles of the same size though micromodels of different depths). Large particles of 10 and 6 µm in diameter transported through two specific micromodels were retained inside the fracture channel. It was observed that the aspect ratio of depth to particle and aperture to particle of those two experiments were very similar. Gauging experiments involved the transport of the 6 µm particles through 25 and 50 µm fracture apertures, to test the effect of the fracture channel aperture. Particles were able to flow without significant trapping in the fracture. This indicated the impact of the relative particle sizes (both depth and aperture to particle size ratio) on their transport. |