Microscopic Behavior of Foam in Porous Media
Authors: Mast R.F. 
Published: December 2007

This paper was prepared for presentation at the 47th Annual Fall Meeting of the Society of Petroleum Engineers held in San Antonio, Tex., Oct. 8–11, 1972. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by who the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
When foam or gas was injected into etched glass micromodels saturated with a detergent solution, flow through portions of the porous system was blocked. As a result of blocking, flow patterns were altered because the resistance to flow in alternate directions through the porous network differed. Apparently, with time, foam breakdown, foam drainage, and foam regeneration altered the capillary resistance to displacement along any given flow path.
Foam drainage was an important factor in determining foam stability and drainage and stability together influenced the blocking mechanism. When foam was present, liquid in the foam was held in the large pore openings. The liquid phase could drain from the foam in these pores and saturate the surrounding small pores pores and saturate the surrounding small pores with liquid. Jamin action resulting from this distribution of fluids was primarily responsible for blocking the flow. Foam was regenerated in porous media as a result of this distribution of porous media as a result of this distribution of fluids combined with the instability of liquid-gas interfaces at pore openings.
In all of the experiments, some liquid and gas were transported as foam, and as the stability of the foam increased, so did the proportion of liquid and gas thus transported through the porous media. Foam stability was increased by porous media. Foam stability was increased by increasing the concentration of detergent in the solutions that were used to generate foam.

Introduction
Some of the mechanisms that operate when foam is injected into porous media have been revealed by microscopy. How foam bubbles are formed or regenerated in a porous system, what factors control the size of the foam bubbles and the stability of foam in porous media, and how gas and liquid are transported through a porous system in the presence of foaming agents were the particular questions investigated during this particular questions investigated during this study.
Several papers have been published on the behavior of foam in porous media in recent years. Much of this work has been concerned with practical uses of foam in oil and gas reservoirs. practical uses of foam in oil and gas reservoirs. From that point of view, foam has been considered as an agent for selective plugging and oil recovery. Interest, therefore, in the mechanics of two-phase (liquid and gas) flow in the presence of foaming agents has been generated.
Fried (1) studied the use of foam in oil recovery.