Molecular and Microscopic Interpretation of the Flow of Hydrolyzed Polyacrylamide Solution Through Porous Media

Abstract

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 The flow behavior of partially hydrolyzed polyacrylamide solutions through porous media polyacrylamide solutions through porous media was studied as a function of flow rate, polymer concentration, salt concentration and permeability. permeability. Unsteady-state flows were noticed when the flow velocities or polymer concentrations exceeded a critical value, or when the salt concentrations and pore sizes were below a critical value. Multilayer polymer buildup occurred when the pressure was maintained constant during polymer solution flow. polymer solution flow. Based on the experimental data and data available from the literature, the flow of hydrolyzed polyacrylamide solutions through porous media is described in terms of change in the diffuse double layer of the polyacrylamide polyions. polyions Introduction According to some authors, the interaction between polymer molecules and the rock surface is predominent in governing the flow of polymer solutions in such porous media. Although, others emphasize the role of the rheological properties. This paper shows that the flow behavior of polyacrylamide solutions depends on all of the polyacrylamide solutions depends on all of the parameters which influence the state of the parameters which influence the state of the diffuse double layer surrounding a given polyacrylamide molecule. These parameters are the polyacrylamide molecule. These parameters are the salt environment, local shear forces and the polymer concentration. polymer concentration. Salts play a role of not only affecting the coiling of the polymer molecules, but also have a marked effect on the diffuse double layer surrounding the polyacrylamide polyions. The state of the diffuse double layer is a key factor in determining the mobility of the individual polyacrylamide polyions in solution. The local shear forces are effective not only in unwinding the individual polymer molecules, but can alter the structure of the diffuse double layer around the polymer molecule. This can result in developing a highly viscous layer around the polyacrylamide polyion. This phenomenon will appear as a higher resistance phenomenon will appear as a higher resistance to flow in porous media at higher linear velocities. The local shear forces in a wide pipe at the same average linear velocities are considerably smaller than in fine porous media, therefore, this phenomenon will be noticeable only at very high linear velocities.