Oil Displacement by Foams in Relation to Their Physical Properties in Porous Media

Abstract

An investigation was conducted on the leading properties of water-gas foams and on their circulation in porous media. Results were interpreted by using the concept of the quality, or gas content, of foams in circulation. The quality is found to correlate with the foam viscosity as determined by Darcy's law in a given section of the porous medium. Introduction: The use of water-gas foams has been developed in recent years in the field of oil and gas production. Because of their specific properties, foams have found a variety of uses. Some examples follow: 1. The well known use of foam as an aerated drilling fluid has been extended to workover and remedial well operations. Such light fluids are especially suitable for operating in decompressed reservoirs where traditional types of mud might cause damage. 2. The technology of exploiting underground gas storage reservoirs is also involved. Foams have been used to even out the gas injection profile in the case of stratified formations. They have also been suggested as a way of preventing gas leakage through the cap rock of storage reservoirs. 3. Attempts have been made to use foams as a secondary recovery fluid, although this practice is still quite limited. 4. More recently, such fluids have been used as a means of treating wells to reduce water or gas inflow during oil production. Tests of this technique have been carried out on Soviet fields. These divers possible uses of foams take advantage of their varied properties and also take into account their behavior in porous media. This is the point in particular that we shall deal with here. particular that we shall deal with here. Characteristic Properties of Foams The water foams considered here may be defined as relatively stable and homogeneous dispersions of gas in a foaming-agent solution containing 0.1 to 1.0 percent of a surfactant. percent of a surfactant. The simple aspect of such fluids (see Fig. 1) shows that the two phases that make them up are more of less associated with one another to form a structure that becomes more and more orderly as the proportion of gas becomes higher. proportion of gas becomes higher.