Hydrocarbon foam

In this chapter the properties of nonaqueous hydrocarbon foams will be reviewed and the effects of foam formation on flow of oil—gas mixtures in porous media will be discussed A laboratory technique for investigating the role of foamy-oil behavior in solution gas drive is described, and experimental verification of the in situ formation of non-aqueous foams under solution gas drive conditions is presented The experimental results show that the in situ formation of nonaqueous foam retards the formation of a continuous gas phase and dramatically increases the apparent trapped-gas saturation. This condition provides a natural pressure maintenance mechanism and leads to recovery of a much higher fraction of the original oil in place under solution gas drive. 

All polar compounds are alike in terms of being polar. Therefore, polar compounds are soluble in polar compounds. One of the main reasons polarity is discussed in terms of emergency response is because of the foam used for fighting flammable liquid fires. Two general types of foam are used to extinguish flammable liquid fires hydrocarbon foam and polar-solvent foam, which is sometimes referred to as alcohol-type foam. The reason that different types of foam are necessary for flammable liquid fires is polarity. 

However, in cases where the surface tension of the substrate is no more than about 20 mN/m less than that of water, it is then not necessary to use silicone or perfluorinated hydrocarbon foam inhibitors (with such extreme surface tensions) and cheaper chemicals can be employed, such as glyceryl esters in the form of pork , fat or butter. If fats prove ineffective, then synthetic esters of polyhydric alcohols can be used. 

Economic Aspects. Manufacturing facilities for CFG alternatives are just now coming on line. The size of the markets for the alternatives is estimated to be quite large (several thousand t/yr), but it will not be as large as the prior markets for CFCs themselves. This is largely because of the higher cost of the alternatives, typically 3—5 times that of the incumbents. Low value-in-use appHcations which caimot support the cost of the alternatives will disappear or will switch to not-in-kind alternatives such as hydrocarbons for foam blowing. 

The WAG process has been used extensively in the field, particularly in supercritical CO2 injection, with considerable success (22,157,158). However, a method to further reduce the viscosity of injected gas or supercritical fluid is desired. One means of increasing the viscosity of CO2 is through the use of supercritical C02-soluble polymers and other additives (159). The use of surfactants to form low mobihty foams or supercritical CO2 dispersions within the formation has received more attention (160—162). Foam has also been used to reduce mobihty of hydrocarbon gases and nitrogen. The behavior of foam in porous media has been the subject of extensive study (4). X-ray computerized tomographic analysis of core floods indicate that addition of 500 ppm of an alcohol ethoxyglycerylsulfonate increased volumetric sweep efficiency substantially over that obtained in a WAG process (156). 

Polystyrene. Polystyrene [9003-53-6] is a thermoplastic prepared by the polymerization of styrene, primarily the suspension or bulk processes. Polystyrene is a linear polymer that is atactic, amorphous, inert to acids and alkahes, but attacked by aromatic solvents and chlorinated hydrocarbons such as dry cleaning fluids. It is clear but yellows and crazes on outdoor exposure when attacked by uv light. It is britde and does not accept plasticizers, though mbber can be compounded with it to raise the impact strength, ie, high impact polystyrene (HIPS). Its principal use in building products is as a foamed plastic (see Eoamed plastics). The foams are used for interior trim, door and window frames, cabinetry, and, in the low density expanded form, for insulation (see Styrene plastics). 

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