Method for recovery of oil

Claim 1

A METHOD OF RECOVERING OIL FROM A SUBTERRANEAN FORMATION HAVING THEREIN CONNATE WATER AND AT LEAST ONE INJECTION WELL AND AT LEAST ONE PREDUCING WELL, COMPRISING PROVIDING STREAM FOR INJECTING INTO SAID FORMATION; MIXING WITH SAID STREAM TO FORM A MIXTURE THEREIN, SMALL AMOUNTS OF AN ALKALI METAL HYDROXIDE, THE CONCENTRATION OF THE HYDROXIDE IN SAID STREAM BEING LESS THAN ABOUT 0.5 WEIGHT PERCENT AFTER SUCH MIXING; INJECTING SAID STREAM HAVING HYDROXIDE THEREIN INTO SAID RESERVOIR AT A PRESSURE NOT SUBSTANTIALLY GREATER THAN FORMATION PRESSURE, THROUGH SAID INJECTION WALL; ALLOWING SAID HYDROXIDE TO REACT IN THE PRESENCE OF STEAM WITH SAID CONNATE WATER IN SAID FORMATION, TO FORM IN SITU SURFACE ACTIVE AGENTS, SAID SURFACE ACTIVE AGENTS BEING EFFECTIVE TO REDUCE THE INTERFACIAL TENSION BETWEEN THE OIL AND WATER IN SAID FORMATION, AND TO FACILITATE REMOVAL OF THE OIL; CONTINUING THE INJECTION OF SAID HYDROXIDE-CONTAINING STEAM FOR A PERIOD OF TIME SUFFICIENT TO ALLOW FOR THE FORMATION OF A SUBSTANTIAL AMOUNT OF SURFACE ACTIVE AGENT; AND PRODUCING OIL THROUGH SAID PRODUCING WELL.

Claim 2

A METHOD OF RECOVERING OIL FROM A SUBTERRANEAN FORMATION HAVING THEREIN CONNATE WATER AND AT LEAST ONE INJECTION WELL AND AT LEAST ONE PREDUCING WELL, COMPRISING PROVIDING STREAM FOR INJECTING INTO SAID FORMATION; MIXING WITH SAID STREAM TO FORM A MIXTURE THEREIN, SMALL AMOUNTS OF AN ALKALI METAL HYDROXIDE, THE CONCENTRATION OF THE HYDROXIDE IN SAID STREAM BEING LESS THAN ABOUT 0.5 WEIGHT PERCENT AFTER SUCH MIXING; INJECTING SAID STREAM HAVING HYDROXIDE THEREIN INTO SAID RESERVOIR AT A PRESSURE NOT SUBSTANTIALLY GREATER THAN FORMATION PRESSURE, THROUGH SAID INJECTION WALL; ALLOWING SAID HYDROXIDE TO REACT IN THE PRESENCE OF STEAM WITH SAID CONNATE WATER IN SAID FORMATION, TO FORM IN SITU SURFACE ACTIVE AGENTS, SAID SURFACE ACTIVE AGENTS BEING EFFECTIVE TO REDUCE THE INTERFACIAL TENSION BETWEEN THE OIL AND WATER IN SAID FORMATION, AND TO FACILITATE REMOVAL OF THE OIL; CONTINUING THE INJECTION OF SAID HYDROXIDE-CONTAINING STEAM FOR A PERIOD OF TIME SUFFICIENT TO ALLOW FOR THE FORMATION OF A SUBSTANTIAL AMOUNT OF SURFACE ACTIVE AGENT; AND PRODUCING OIL THROUGH SAID PRODUCING WELL.

Claim 4

A method of recovering oil from a subterranean formation having therein connate water and at least one injection well and at least one producing well, comprising: providing steam for injecting into said formation; mixing in said steam to form a mixture therein, small amounts of an alkali metal hydroxide, the concentration of the hydroxide in said steam being less than about 0.5 weight percent after such mixing; heating said formation by injecting said steam having hydroxide therein into said reservoir at a pressure not substantially greater than formation pressure, through said injection well; allowing said hydroxide to react in the presence of steam with said connate water in said formation, to form in situ surface active agents, said surface active agents being effective to reduce the interfacial tension between the oil and water in said formation, and to facilitate removal of the oil; continuing the injection of said hydroxide-containing steam for a first period of time sufficient to allow for the formation of a substantial amount of surface active agent; providing additional steam not having hydroxide material added thereto; injecting said additional steam into said formation to drive said hydroxide-containing steam farther into said formation; and, producing oil through said producing well.

Claim 5

A method of recovering oil from a subterranean formation having therein connate water and at least one injection well and at least one producing well, comprising: providing steam for injecting into said formation; mixing in said steam to form a mixture therein, small amounts of an alkali metal hydroxide, the concentration of the hydroxide in said steam being less than about 0.5 weight percent after such mixing; heating said formation by injecting said steam having hydroxide therein into said reservoir at a pressure not substantially greater than formation pressure, through said injection well; allowing said hydroxide to react in the presence of steam with said connate water in said formation, to form in situ surface active agents, said surface active agents being effective to reduce the interfacial tension between the oil and water in said formation, and to facilitate removal of the oil; continuing the injection of said hydroxide-containing steam for a first period of time sufficient to allow for the formation of a substantial amount of surface active agent; providing additional steam not having hydroxide material added thereto; injecting said additional steam into said formation to drive said hydroxide-containing steam farther into said formation; and, producing oil through said producing well.

Claim 8

A method of recovering oil from a subterranean formation having therein connate water and at least one injection well and at least one producing well, comprising: providing steam for injecting into said formation; mixing in said steam to form a mixture therein, small amounts of an alkali metal hydroxide, the concentration of the hydroxide in said steam being less than about 0.5 weight percent after such mixing; injecting said steam having hydroxide therein into said reservoir through said injection well; allowing said hydroxide to react in the presence of steam with said connate water in said formation, to form in situ surface active agents, said surface active agents being effective to reduce the interfacial tension between the oil and water in said formation, and to facilitate removal of the oil; continuing the injection of said hydroxide-containing steam, while decreasing the amount of hydroxide therein, for a period of time sufficient to allow for the formation of a substantial amount of surface active agent; and, producing oil through said producing well.

Claim 9

A method of recovering oil from a subterranean formation having therein connate water and at least one injection well and at least one producing well, comprising: providing steam for injecting into said formation; mixing in said steam to form a mixture therein, small amounts of an alkali metal hydroxide, the concentration of the hydroxide in said steam being less than about 0.5 weight percent after such mixing; injecting said steam having hydroxide therein into said reservoir through said injection well; allowing said hydroxide to react in the presence of steam with said connate water in said formation, to form in situ surface active agents, said surface active agents being effective to reduce the interfacial tension between the oil and water in said formation, and to facilitate removal of the oil; continuing the injection of said hydroxide-containing steam, while decreasing the amount of hydroxide therein, for a period of time sufficient to allow for the formation of a substantial amount of surface active agent; and, producing oil through said producing well.

Claim 14

A method of recovering oil from a subterranean formation having therein connate water and at least one injection well and at least one producing well, comprising: providing steam for injecting into said formation; providing a steam mixture containing small amounts of an alkali metal hydroxide, to provide wet steam with a concentration of hydroxide of about 0.5 weight percent; injecting said steam intermittently with and without said steam mixture into said reservoir through said injection well; allowing said hydroxide to react in the presence of steam with said connate water in said formation, to form in situ surface active agents, said surface active agents being effective to reduce the interfacial tension between the oil and water in said formation, and to facilitate removal of the oil; continuing the intermittent injection of said steam mixture and said steam for a period of time sufficient to allow for the formation of a substantial amount of surface active agent; terminating the intermittent injection of said steam mixture and said steam; and producing oil through said producing well.

Claim 15

A method of recovering oil from a subterranean formation having therein connate water and at least one injection well and at least one producing well, comprising: providing steam for injecting into said formation; providing a steam mixture containing small amounts of an alkali metal hydroxide, to provide wet steam with a concentration of hydroxide of about 0.5 weight percent; injecting said steam intermittently with and without said steam mixture into said reservoir through said injection well; allowing said hydroxide to react in the presence of steam with said connate water in said formation, to form in situ surface active agents, said surface active agents being effective to reduce the interfacial tension between the oil and water in said formation, and to facilitate removal of the oil; continuing the intermittent injection of said steam mixture and said steam for a period of time sufficient to allow for the formation of a substantial amount of surface active agent; terminating the intermittent injection of said steam mixture and said steam; and producing oil through said producing well.