In recent years, nonionic surfactants have been very popular in application such as water flooding, fracturing and acidizing treatments. The most attractive features of this class of chemicals used in acidizing treatments, are their contribution to surface and interfacial tension reduction, water wetting, and low adsorption properties. Almost all surfactants, when applied at low concentrations in a system, alter the surface activities of the fluid by forming aggregates which lower free energy of the system, resulting in lower surface and interfacial tensions. However, many of these surfactants and chemicals adsorb to either the interface or to the solid media such as sandstone, reducing their effectiveness. This phenomenon may result in poor performance of these additives throughout the acidizing treatment and also, may promote emulsion tendencies which may lead to formation damage.
This paper presents results of laboratory studies of various nonionic surfactants and outlines the adsorption of these chemicals within the matrix of sandstone formations. Conditions affecting adsorption properties will also be discussed in this paper.