A one-pattern, steam-foam mechanistic field trial was conducted in Section 26C of the Midway-Sunset field (upper Monarch sand). The test objectives were (1) to understand the mechanisms of steam diversion caused by foam under reservoir conditions, (2) to establish whether foam can exist in-depth away from the injection well, and (3) to measure incremental oil that can be attributed to foam. Surfactant was injected with steam and nitrogen continuously, and bottomhole injection pressure (BIHP) increased from 100 to 300 psig, indicating good foam generation. Better steam distribution across the injector's perforations occurred when foam was generated. Improvements in both vertical and areal sweep efficiency of steam were observed. Substantial temperature and gas saturation increases coincided with surfactant breakthrough and local reservoir pressure increases at observation wells. Complementary laboratory corefloods showed that foam generation could occur at low-pressure gradients, which are typical of in-depth conditions. Both laboratory and field data were interpreted as evidence that the in-depth presence of foam was the result of local generation wherever surfactant, steam, and nitrogen were present, rather than propagation of a foam bank generated near the injector. Some oil-production increase was also observed during the test; however, an accurate quantitative estimate of incremental oil owing to foam was difficult to establish.

Water solutions containing ceric perchlorate and perchloric acid evolve oxygen when they absorb ultraviolet light and the ceric is reduced to cerous perchlorate.2Baur2a and Weiss and Porret2b studied the photochemical reaction in the full light of a quartz mercury arc lamp. Weiss and Porret obtained maximum gross quantum yields of the order of one-tenth in solutions one-tenth molar in ceric perchlorate and one molar in perchloric acid. Their quantum yields decreased as the cerous perchlorate accumulated.We have measured the quantum yields of the reaction when the solutions are irradiated with monochromatic light of X 254 µ. The light intensity, I, and the concentrations of cerous, c3, and ceric, Ci, perchlorates were varied many fold. The perchloric acid concentration, c2, was held at 1.03 =*= 0.03 M and the ionic strength, µ, at 1.1 ± 0.1, all at 23 ± 3°.Solutions of ceric perchlorate in perchloric acid are thermally unstable at 25°. The equilibrium ratio Ci/Ci is about 10 _8 in molar perchloric acid in equilibrium with the atmosphere (po, = 0.2 atm.), but the rate of the thermal reduction of the ceric perchlorate by water is extremely slow. In one of our stock solutions which was 5.3 M in perchloric acid and was kept in the dark at 25 * 3°, Ci decreased from 1.36 to 1.20 M in eleven months while c3 increased from 0.32 M.Materials.-The chemical reagents were of analytical reagent grade or were prepared from material of this quality. The water was chloride-free distilled water.Stock solutions of ceric and cerous perchlorates were prepared from a sample of snow white granular ceric oxide, 98.5% pure Ce02, which was supplied by the Rohm and Haas Chemical Co., Philadelphia, Pa. The ceric oxide could not be converted directly into ceric perchlorate even when dispersed as a fine hydrous oxide in 72% perchloric acid at room temperature or at 100°f or periods of several months.The ceric perchlorate was finally prepared by reducing the ceric oxide to cerous ions by bromide in perchloric acid. The bromine and excess bromide were removed by boiling. The cerous ions were then oxidized electrolytically to the ceric state. The experimental details follow.Forty grams of the granular ceric oxide and 80 g. of sodium bromide were added to 275 ml. of 72% perchloric acid. The mixture was simmered for two hours under an appropriate hood. The hot solution was filtered by suction through a sintered glass filter. The filtrate was boiled(1) The part of this article concerned with the experimental study of the effect of cerous perchlorate upon the reaction is taken from the thesis submitted by Maynard E. Smith in September, 1946, to the Department of Chemistry of the Massachusetts Institute of Technology in partial fulfillment of the requirements for the degree of Master of Science.(2) (a) E. Baur, Z. physik. Chetn., 63, 683 (1908), was the first to identify oxygen as the gaseous product of the reaction. This was

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