Investigating drainage rate effects on fractal patterns and capillary fingering in a realistic glass micromodel

摘要

Proper characterization of fluid displacement processes and mechanisms at pore scale is essential to understand and describe the displacement behaviour at larger core and reservoir scales. Detailed visual investigation of displacement phenomena is only realized using real-size glass micromodels similar to what we developed in this study. Different drainage rate experiments are performed with viscosity match fluids to observe flow patterns in a water-wet glass micromodel. Total saturation St, local saturations Sx, front fractal dimension Df and surface fractal dimension Ds, are calculated from high resolution images of the tests and are used for the qualitative and quantitative evaluation of the processes. It is found that St and Ds follow increasing trends and Df tracks a decreasing trend with capillary number. This is due to the more stable patterns and compact structures that are developed in the tests with higher injection rates. Sx curves, however, remained comparable for different capillary number tests due to the same network pattern used in all the experiments. Advanced fractal measures along with high resolution images of the experiments made it possible to precisely describe and investigate the displacement patterns and structures as they initiate and develop with time at different combinations of capillary and viscous forces most likely encountered in real reservoir conditions.