Investigation of Pore-Scale Behaviors of Foam Flow in a Polydimethylsiloxane Micromodel

Foam has great potential in underground fluid displacements in porous media, such as in enhanced oil recovery projects and CO2 geological storage, because of the effectiveness of mobility control. The mechanism of foam flow in porous media is essential to understand the complex process of foam displacement. In this work, pore-scale behaviors of CO2 foam and N2 foam flows have been investigated using a transparent polydimethylsiloxane micromodel. The effects of foam quality and gas type on gas trapping and foam texture were evaluated. Image results gave the phase distribution during foam flow through the porous medium directly. Both trapped gas saturation and trapped gas fraction overall increased with foam quality ranging from 50% to 94%, but foam texture became coarser at foam qualities above 75%. Compared to N2 foam, CO2 foam exhibited lower trapped gas saturation and a wider distribution of bubble size in the porous medium. It was observed that trapped CO2 bubbles within pores shrank with time, which may be the main reason for the instability of trapped CO2 foam in this study. The present research provides fundamental knowledge for describing foam flow in porous media.