Oil recovery method by oxidation and forming surfactants in situ

Claim 1

The method of claim 1 wherein injection of air is continued after said oil is ignited in step (a) and said in situ combustion zone is propagated into said formation to occupy up to 10 percent of the pore volume of said formation.

Claim 4

A method of producing oil from an oil-containing subsurface formation penetrated by an injection well and a production well, comprising the steps of: a. injecting an oxygen-containing gas via said injection well into said formation in a sufficient amount and at a sufficient pressure to rapidly oxidize said oil and establish a stabilized in situ combustion zone having a temperature of at least 500* F. in said formation; b. injecting a slug of air via said injection well into said formation, said slug of air being of a sufficient size to propagate said in situ combustion zone through up to 10 percent of the pore volume of said formation; c. injecting a slug of aqueous caustic solution via said injection well into said formation to quench said in situ combustion zone and flow liquid aqueous caustic solution through said in situ combustion zone, said slug of aqueous caustic solution being formed of at least one barrel of aqueous caustic solution per 1,000 cubic feet of air in said slug of air in step (b); d. repeating alternately steps (a), (b), and (c); and e. producing oil via said production well from said formation.

Claim 5

A method of producing oil from an oil-containing subsurface formation penetrated by an injection well and a production well, comprising the steps of: a. injecting an oxygen-containing gas via said injection well into said formation in a sufficient amount and at a sufficient pressure to rapidly oxidize said oil and to establish a stabilized in situ combustion zone that overrides a portion of said formation; b. injecting an aqueous caustic solution via said injection well into said formation in a sufficient amount to quench said in situ combustion zone and flow liquid aqueous caustic solution through said in situ combustion zone and into contact with said oil in said formation to form a suRfactant zone about said in situ combustion zone; c. injecting an additional amount of an aqueous liquid via said injection well into said formation to drive said aqueous caustic solution and said surfactant zone into said formation and to underride said formation; d. repeating alternately steps (a), (b), and (c) to produce another in situ combustion zone having a more nearly vertical front; and e. producing oil via said production well from said formation.