Abstract A process for recovering petroleum from a subterranean petroleum containing formation by flooding with a surfactant wherein the adsorption of surfactant by the formation rock is inhibited by treating the formation with a preflush slug of a water soluble quaternary ammonium salt such as tetramethylammonium chloride prior to injecting the surfactant. Preferably, treatment is accomplished by injecting an aqueous solution of water soluble quaternary ammonium salt into the formation in an amount sufficient to satisfy substantially all of the adsorption capacity of the formation matrix followed by injection of an aqueous solution of the surfactant into the formation. The quaternary ammonium salt and the surfactant solution can be subsequently displaced through the formation by any convenient aqueous drive fluid including water.
The method of claim 1 wherein said fluid preflush composition is injected in at least an amount sufficient to satisfy substantially all of the adsorption capacity of the formation rock.
Claim 2
Dependent Claim
14 words
The method of claim 1 wherein the quaternary ammonium salt has the following structure:
Claim 3
Dependent Claim
13 words
The method of claim 3 wherein the quaternary ammonium salt is tetramethylammonium chloride.
Claim 4
Dependent Claim
27 words
The method of claim 1 wherein the fluid preflush composition comprises an aqueous solution of from about 0.5 to about 2 percent by weight of tetramethylammonium chloride.
Claim 5
Dependent Claim
25 words
The method of claim 5 wherein from about 1 to about 4 pore volumes of the aqueous tetramethylammonium chloride solution is injected into the formation.
Claim 6
Dependent Claim
32 words
The method of claim 5 wherein from about 50 to about 500 pounds per acre foot of tetramethylammonium chloride per acre foot of formation to be swept are injected into the formation.
Claim 7
Dependent Claim
14 words
The method of claim 1 wherein the fluid preflush composition also contains sodium chloride.
Claim 8
Dependent Claim
18 words
The method of claim 1 wherein the surfactant is in an aqueous solution which also contains sodium chloride.
Claim 9
Dependent Claim
28 words
The method of claim 1 wherein the surfactant is in an aqueous solution which also contains the water soluble quaternary ammonium salt used in the fluid preflush composition.
Claim 10
Dependent Claim
17 words
The method of claim 1 wherein the aqueous flooding medium containing a surfactant also contains tetramethylammonium chloride.