Phase Relationships in Chemical Flooding

Abstract

Resultsof laboratory cbemicaI jloods are present ed to show that equilibrium pbases observed irr test tubes are representative of phases produced in core flow experiments. Consequently, many performance characteristics of chemical floods can be' explained and predicted from equilibrium surfactant-brin e-oil phase diagrams. An oil reservoir under chemical flooding can be visualized as a series" o/ connected cells with phase equilibrium attained in each. Fluid flow from one cell to the next is governed, not so much by initial properties of the oil, brine, or chemical slug and drive, as by properties o/ equilibrium phases formed from those fluids. Three types o{ equilibrium phase environment are deiined. Results o~interracial ten-"on measurements and laboratory flow experiments indicate that chemical f[oods should be designed to keep as much surfactant as possible /or as long as possible in the "Type iii" phase environment while the surfactant is traversing tbe reservoir.

Microemulsions: a novel approach to enhanced oil recovery: a review

“…The physicochemical properties of microemulsions depend on the alkane carbon number, nature of cosurfactant and types of surfactants. For ionic microemulsion preparation, cosurfactants are added along with surfactant (Healy and Reed 1977;Willhite et al 1980), but some other researchers did not consider cosurfactant as a main component (Nelson and Pope 1978;Osterloh and Jante 1992). Microemulsions actually contain a cosurfactant such as a medium chain alcohol (viz.…”

Chemical Methods for Ugnu Viscous Oils

“…The in situ generated soap lowers the requirement of the externally added surfactant. The amount of in situ generated soaps is in turn dependent on the volume ratio of water and oil (WOR) in the system (Nelson 1978). Prescribed amounts of water, oil, alkali, and surfactant were mixed at different water-to-oil ratio (WOR) and the volumes of equilibrium phases were observed.…”

“…Traditional tertiary chemical flooding of light oil reservoirs use this mechanism (Healy & Reed, 1977;Nelson & Pope, 1978;Pope et al, 1979;Flaaten et al, 2008).…”

“…The oil/brine/surfactant phase behavior was identified as type I (oil in water microemulsion), type II (water in oil microemulsion) or type III (middle phase microemulsion) which exhibits the lowest IFT (Winsor, 1954). Cosurfactant enhanced alkali flooding (Nelson 1978) was introduced which allowed increasing the optimal salinity of the alkali slug high enough for its satisfactory propagation. The phase behavior of oil-brine-surfactant systems would often be accompanied by viscous emulsions, gels or liquid crystals (Hackett and Miller,1988;Levitt et al, 2009).…”

“…Alkaline-surfactant-polymer techniques have been studied for mostly light oils in the past (Nelson & Pope 1978;Flatten et al 2008). Here we extend its application to the viscous oil reservoirs.…”