Authors: Lars E Nonnekes Simon J Cox William R Rossen
Publish Date: 2014/12/03
Volume: 106, Issue: 3, Pages: 669-689
Abstract
Diffusion of gas across liquid films between bubbles is thought to increase average bubble size in foam in porous media It is cited as one reason why hbox CO 2 foams for enhanced oil recovery EOR are less resistant to flow than hbox N 2 foams and why mixing hbox N 2 with steam increases the resistance of steam foam In porous media diffusion can rapidly destroy bubbles smaller than a pore but in EOR foam bubbles are thought to be larger than pores This study examines the effect of interbubble gas diffusion on flowing bubbles in a periodically constricted tube and in particular its effect on the bubblesize distribution and capillary resistance to flow The study is based on the solution for bubble shapes curvatures and pressure differences between bubbles from previous studies of bubble movement through periodically constricted tubes It uses these results to estimate the diffusion rate between bubbles Bubbles somewhat smaller than a pore can indeed disappear by diffusion as the bubbles move For bubbles larger than a pore as expected in EOR diffusion does not affect bubble size Instead diffusion actually increases capillary resistance to flow because lamellae spend more time in positions where lamella curvature resists forward movement When fit to pressures and diffusion and convection rates representative of field application of foams diffusion is not expected to alter the bubblesize distribution in a foam Instead it modestly increases the resistance to flow The reason for the apparent weakness of hbox CO 2 foam therefore evidently lies in factors other than hbox CO 2’s large diffusion rate through foam
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