THEORY OF MOBILIZATION PRESSURE-GRADIENT OF FLOWING FOAMS IN POROUS-MEDIA .3. ASYMMETRIC LAMELLA SHAPES

Even in radially symmetric pores, lamellae can take asymmetric shapes. These shapes result from the multiplicity of shapes satisfying geometric constraints in converging/diverging pore space and from minimization of system energy. This paper extends the theory of the minimum pressure gradient required to mobilize foam in porous media, (∇p)min, to account for this effect. A simplified 2D theory indicates that lamella asymmetry increases the average capillary resistance (Δp)avg as a lamella traverses an angular pore and gives a substantial, positive (Δp)avg in even rounded pores for which the original, 3D, symmetric theory predicts (Δp)avg = 0. As a result, the refined theory predicts a higher (∇p)min for incompressible and slightly compressible foams, such as CO2 foams, at high capillary pressures in oil-field application. © 1990.