| dc.description.abstract | In this study, we have developed a method for micromodels fabrication. Compared with the previous process, the fabrication is easier to manufacture and the equipment and materials used are less expensive. The micromodel produced has a 2.5D channel structure, and the vertical structure in the channel is not a simple plane, but a complex structure with irregularities. Compared with 2D micromodels, our micromodels can better represent real porous media and can more realistically show the fluids flow in real porous media. After bonding the plastic sheet and the double-sided tape, we use the CNC (Computer Numerical Control) milling machine to process the channel. Because of the high transparency of the material, it is easy to see the fluid flow after only dyeing the fluid. The dyeing fluid will show different color depths in different thicknesses of micromodels, which can be easily observed and analyzed in complex micro-models without the need to go through other complicated instruments.
We made single-layer, four-layer, and eight-layer micromodels for imbibition and imbibition-drainage experiments. The imbibition experiment is to inject the wetting phase fluid (ethanol) into the model to discharge the non-wetting phase fluid (air). In the imbibition-drainage experiment, after the imbibition experiment, to inject non-wetting fluid (air) to discharge the wetting phase fluid (ethanol). Then we use ＂3 μl＂ ⁄＂min＂ , 6 ＂μl＂ ⁄＂min＂ , 60 ＂μl＂ ⁄＂min＂ , 150 ＂μl＂ ⁄＂min＂ and 300 ＂μl＂ ⁄＂min＂ flow rates for experiment.
First, ethanol can flow into the deep pores of the channel in a thin micromodel. With the increase of the thickness of the micromodel, ethanol can only flow at the edge of the micro-model and fill the corner regions in the micromodel, so the ethanol saturation decreases. In the same thickness micromodel, when the capillary number of ethanol is small, corner flow movement dominates ethanol flow in micromodels and most of the air was trapped at narrow pore throats. After the capillary number is gradually increased, bulk meniscus movement dominates ethanol flow in micromodels, the air trapped in the dead-end pores. At the same thickness but the shape of the internal channel is changed, even if the same ethanol saturation we obtained after the imbibition experiment, the position of the air trapped in the channel is completely different. We can know that the simplification of the shape of the flow channel has a great influence on the flow state of the fluid. | en_US |