Shell Oil Comapny

Andrew H Falls

Myron Ira Kuhlman

John K Borchardt

Jimmie B Lawson

George J Hirasaki

In displacing oil by injecting CO.sub.2, water and surfactant at high pressure, surfactant loss by adsorption is reduced by including alkali metal carbonate or bicarbonate salt in the injected water to increase the pH of the solution at the conditions encountered in the reservoir.

Oil recovery with water containing carbonate salt, CO.sub.2, and

A gas flooding process for displacing oil within a reservoir is improved by injections of a surfactant having a composition and concentration correlated with those of the brine used to remain substantially within the water phase of the injected fluid at a concentration below the critical micelle concentration of the surfactant.

Gas flooding with dilute surfactant solutions

In a carbonated waterflood oil recovery process the corrosivity of a premixed solution is reduced by dissolving the CO.sub.2 in water containing enough sodium carbonate or bicarbonate to maintain a pH of at least about 4.

Oil recovery with water containing carbonate salt and CO.sub.2

In a process for injecting a steam-foam-forming mixture into a subterranean reservoir to displace oil, injecting a mixture containing only as much noncondensible gas as required for substantially reducing the mobility of an injected steam-foam-forming mixture containing a given kind and amount of surfactant and electrolyte, which amount of noncondensible gas to add is calculated from a specified equation interrelating the reservoir temperature and pore size.

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Sugarland, TX, United States of America

Andrew H Falls