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This study has two objectives:(1) to screen and select foaming agents for specific C02 floods and (2) to detennine the effectiveness of foam in improving sweep efficiency in CO 2 flooding. Foaming agents were evaluated on their ability to produce ample, lasting foam and to have low loss from adsorption on reservoir rock and decomposition at reservoir conditions. Foaming agents that perfonned well in shaking, blender, long-tenn stability, and high-pressure stability tests were selected for core-flow experiments. The stability test results demonstrated that foaming agents are reservoir-specific. The extent of the loss depends on the foaming agent, reservoir fluids, reservoir lithology, and reservoir conditions.The core-flow experiments involved the simultaneous injection of CO 2 into two waterflooded Berea cores. The cores were arranged in parallel and had different penneabilities. The test temperature and pressure were constant and above the critical conditions for CO 2 , Three types of core-flow tests, involving injection of CO 2 to displace oil, injection of alternate slugs of CO 2 and brine, and injection of foaming agents, were conducted. The foaming agents were injected before CO 2 injection and after CO 2 had displaced oil from the more penneable core.The results show that in-situ foam generation is an effective method for improving C02 displacement efficiency. Foam was most effective when the foaming agent was injected after C02 displaced the oil from the more penneable core. The improved sweep efficiency was caused by the tendency of the foam to be generated preferentially in the more penneable core. The foam increased resistance to flow in this core and caused more CO 2 to flow through the less permeable core. The second injection method is also more applicable to field implementation.

Matching conductance, viscosity, and density data at 25 ~ intervals between --50 ~ and 125~ have been determined and analyzed for moderately concentrated solutions Of three quaternary ammonium halides in propylene car-bon~te. Detailed results are presented for the fitting of experimental data as functions of molal concentration and temperature to appropriate equations by computer least squares procedures. Calculated results related to moles of solvent displaced per mole of solute and also apparent molal volumes indicate the lack of significant ion-solvent interactions in the solutions of the quaternary ammonium salts in propylene carbonate. Additionally, conductance-viscosity products and activation energies of viscous flow and conductance have been calculated and discussed. Throughout the broadly varying experimental conditions over the 175~ range, the conductances of the three salts have been found to be iairly closely proportional to the fluidity, or reciprocal of the viscosity, of the medium.Conductances and viscosities of moderately concentrated solutions of Bu4NI, KSCN, and NH4Br in N,Ndimethylformamide from --50 ~ to 125~ were dealt with in the first article in this series (1). As a supplementary, parallel investigation on other nonaqueous electrolyte solutions over the unusually broad 175~ range, the present conductance-viscosity study relates to solutions of three quaternary ammonium halides in propylene carbonate, a solvent which like DMF has received much attention during the last 15-20 years.Propylene carbonate or 4-methyl-l,3-dioxolan-2-F -~ I one,H3C--CH--CH2--O--C=O, symbolized by PC, is a commercially available cyclic ester which has become established as a promising electrolytic solvent (2). It has a liquid range extending from --49 ~ to 241~ and is a good solvent for most quaternary ammonium salts, selected alkali metal salts, and organic compounds. PC as a dipolar, aprotic liquid has the following physical properties at 25~ dielectric constant, 64.9 (3) ; viscosity, 2.513 eP (4) ; density, 1.1995 gcm -~ (5); dipole moment, 4.94 debyes (6); Kirkwood correlation factor, 1.01 (3).Other studies dealing with conductances and viscosities of both dilute and concentrated solutions of electrolytes in PC have been reported or summarized (2, 4, 7-i0), but none of these have significantly overlapped with the scope of this work. The quaternary ammoium salts were selected primarily because they were found to be among the most soluble common salts in PC at --50~ The major objective of this study, other than obtaining extensive and valuable new data, was

Conductances, viscosities, and densities have been determined at 25° intervals between −50° and 125°C for moderately concentrated solutions of Bu4NI , KSCN , and NH4normalBr in N,N‐dimethylformamide. Results are summarized for the fitting of the experimental data as functions of temperature and molality to appropriate equations by computer least squares procedures. Activation energies of viscous flow and conductance, molar conductance ‐viscosity products, and specific conductance maxima also are discussed.