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A previous study (Simjoo and Zitha, 2013) reports enhanced oil recovery by foam injection in corefloods: that is, reduction in oil saturation in the core below waterflood residual. This reduction is achieved by foam in a process with reduced oil-water interfacial tension and increased pressure gradient. Those results, combined with bubble-column experiments, suggest that a new mechanism of oil recovery is involved in these floods: emulsification of oil into the Plateau borders between the bubbles of the foam and transport of oil along with the foam bubbles. Using these data we compute the oil relative permeability during this process of enhanced oil recovery. There is an initial oil bank with oil relative permeability of order 0.1. Thereafter, during the period of highest capillary number and oil production attributed to emulsified oil droplets, oil relative permeability is between 0.001 and 0.0001: far less than with surfactant flooding, for instance, at similar capillary number. Over time in these experiments, the final oil saturation is greater than, but is slowly approaching, that expected at the large capillary number of the experiment. Since in the proposed mechanism emulsified oil must travel with the foam, which has extremely large effective viscosity, but oil relative permeability is computed based on the much-smaller oil viscosity, the low oil relative permeability can be seen to be result of strongly adverse viscous coupling between the phases. Efficient oil recovery by the mechanism of emulsified oil droplets would require a large volume fraction of oil within the foam, a less-viscous foam, and/or a more-viscous oil. Other studies of foam displacing oil briefly examined here reflect a larger oil relative permeability during foam displacement, in large part because of a smaller contrast between foam and oil viscosity, or even a foam effective viscosity less than that of the oil it displaces.

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A study of the point-load breaking strength and the three-point bending strength of three rock types has been made at room [75F] and liquid nitrogen [-320F] temperatures. A factorial design experiment, using three variables at two levels, was made on a limestone rock to evaluate the effects of these variables on the mechanical properties of this rock. The factorial design offered simplicity and economy in this type of testing. The same mechanical tests were applied to basalt and charcoal granite specimens supplied by the USBM. In general, average increases in the point-load breaking strength at the low temperature level were 46 per cent for the limestone, 52 per cent for the basalt, and 21 per cent for the granite. The average modulus of rupture strength increased 59 per cent for limestone, 49 per cent for basalt and 19 per cent for granite. analysis of the data from the factorial experiment indicated that the main effect was temperature, the intermediate effect was sample preparation, and no effect was observed for the two rates of loading used. No interaction between variables was evident. A determination of Young's modulus at the two temperature levels was made on the limestone. The increase in the modulus at liquid nitrogen temperature was approximately 2.5 times that at room temperature. Introduction The advent of lunar exploration is creating interest in the physical properties of rock at very low temperatures. This interest extends not only to the various engineering and space-oriented groups but also to those with an interest in the general field of rock mechanics. Penn and Gaudin indicated that the thermal environment on the lunar surface varies from approximately -250F to +250F. Associated with the temperature effect are the additional complicating environmental factors of reduced gravity in a vacuum. Our discussion, while dealing with only room and liquid nitrogen temperatures, indicates some interesting changes in the point-load breaking strength and modulus of rupture of three rock types. A search of the literature failed to turn up any information on the behavior of rocks at very low temperatures. The most related paper is that of Monfore and Lentz who studied the effects of low temperatures on several different. concrete mixes. Their measurements included compressive strength, splitting strength, Young's modulus, Poisson's ratio, thermal contraction and freeze-thaw resistance over a temperature range from, room to -250F. Of particular interest are the effects-of temperature, the compressive and splitting strengths of concrete. In general, the various concrete samples reached a maximum compressive strength at approximately -150F and decreased with further decreasing temperature. The splitting strengths followed a similar pattern but rather sharply at the freezing joint and a maximum, at -175F, somewhat higher than that observed for compressive strength specification. The lack of data on low temperature effects on rock properties prompted this investigation. The testing program consisted of the point-load breaking strength test after -Reichmuth and the three-point bending [modulus of rupture] test. Test specimens used were limestone obtained from a quarry near Valders, Wis., and basalt and charcoal granite supplied by the Twin Cities Mining Research Center of the USBM. In addition to the above tests, which were run at both room and liquid nitrogen temperatures, Young's modulus was determined for the limestone at the two temperature levels. EXPERIMENTAL PROCEDURE Bulk samples of the limestone as obtained from the quarry were randomly cored using 1/2-in. and 1-in. diameter diamond bits. P. 189^

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