Flow Visualization Studies of the Effect of Foamed Gel Microstructure on Gas-Blockage Effectiveness and Its Importance on Foamed Gel Trapping in Porous Media

ABSTRACT

This study describes a pore level approach taken to investigate the complex flow of foamed gels in porous media. Foamed gels can be used as blocking agents to control excessive gas or water production in oil reservoirs. Although the use of foamed gels as plugging agents has been studied for some time, the mechanisms of foamed gel flow in porous media are not so clear. Through visual observation in transparent etched-glass micromodels, the effect of foamed gel microstructure or texture on blockage effectiveness and on trapping mechanisms in porous media are evaluated. The experimental observations demonstrate that foamed gels provide a higher flow restriction capability than conventional aqueous foams. Photographs and videotapes of flooding tests in a micromodel show very high oil recovery, as a result of foamed gel flooding. Visual observations of pore-level behavior indicate that foam bubbles are regenerated and reshaped within the porous media by snap-off, which seems to be the predominant mechanism. To achieve effective fluid flow restriction using foamed gels, it seems important to keep within the porous media a balance between the saturation of trapped discontinuous gas phase, and the gel configuration in the pore space.

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