| abstract |
A process for recovering oil from subterranean reservoirs having connate water containing dissolved divalent metal cations in which small slugs of (1) aqueous alkali metal hydroxide solution, (2) a dilute aqueous alkaline alkali metal silicate solution, and (3) a dilute aqueous solution of an agent that reacts with the alkali metal silicate to form a gelatinous precipitate are alternatively injected into the reservoir through one or more injection wells. A small slug of water is injected between successive slugs of the reactant solutions to separate the reactants during injection. Also, alkali metal carbonate can be incorporated into the aqueous alkali metal hydroxide solution, or aqueous alkali metal carbonate solution can be injected immediately preceding the alkali metal hydroxide solution. |