US3977472A — Method of fracturing subterranean formations usin…

Claim 1

Independent Claim 143 words

A method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 70 to about 90 volume percent of an internal liquid hydrocarbon phase, from about 10 to about 30 volume percent of an external aqueous phase, and a nonionic surfactant which gives said emulsion a breaking temperature that is not greater than the temperature of said formation and which is added in an amount sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 2

Independent Claim 143 words

A method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 70 to about 90 volume percent of an internal liquid hydrocarbon phase, from about 10 to about 30 volume percent of an external aqueous phase, and a nonionic surfactant which gives said emulsion a breaking temperature that is not greater than the temperature of said formation and which is added in an amount sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 3

Dependent Claim 22 words

The method as defined in claim 1 wherein said emulsion contains an electrolyte to adjust the temperature at which said emulsion breaks.

Claim 4

Dependent Claim 20 words

The method as defined in claim 2 wherein said electrolyte is one which lowers the cloud point of said surfactant.

Claim 5

Dependent Claim 53 words

The method as defined in claim 3 wherein said electrolyte is selected from the group consisting of sodium citrate, sodium sulfate, potassium sulfate, lithium sulfate, berrylium sulfate, sodium hydroxide, sodium bisulfate, sodium acetate, sodium bromate, magnesium chloride, sodium chloride, calcium chloride, cesium chloride, potassium chloride, lithium chloride, and potassium nitrate and mixtures thereof.

Claim 6

Dependent Claim 20 words

The method as defined in claim 2 wherein said electrolyte is one which raises the cloud point of said surfactant.

Claim 7

Dependent Claim 31 words

The method as defined in claim 5 wherein said electrolyte is selected from the group consisting of magnesium iodide, sodium iodide, berrylium nitrate, magnesium nitrate, and calcium nitrate and mixtures thereof.

Claim 8

Dependent Claim 54 words

The method as defined in claim 1 wherein said emulsion contains not more than about 0.1 weight percent of a polymeric thickening agent in said aqueous phase, said polymer thickening agent imparting a viscosity to said aqueous phase of less than 10 centipoises at 70°F and a shear rate of about 500 reciprocal seconds.

Claim 9

Dependent Claim 20 words

The method as defined in claim 1 wherein said emulsion contains an effective quantity of a particulate fluid loss additive.

Claim 10

Dependent Claim 41 words

The method as defined in claim 1 wherein said hydrocarbon phase contains a liquid hydrocarbon selected from the group consisting of crude oil, diesel oil, gas oil, gasoline, kerosene, benzene, toluene, ethylbenzene, perchloroethylene, cyclohexane, heptane, decane and hexadecane and mixtures therof.

Claim 11

Dependent Claim 30 words

The method as defined in claim 1 wherein said nonionic surfactant is added in an amount equal to from about 1.0 to about 6.0 weight percent of said aqueous phase.

Claim 12

Dependent Claim 15 words

The method as defined in claim 1 wherein said nonionic surfactant is a polyoxyethylene derivative.

Claim 13

Dependent Claim 37 words

The method as defined in claim 11 wherein the oleophilic moeity of said polyoxyethylene derivative is derived from a polar chemical selected from the group consisting of alcohols, alkyl phenols, cresols, fatty acids, amides, amines and mercaptans.

Claim 14

Dependent Claim 39 words

The method as defined in claim 1 wherein said emulsion contains from about 75 to about 85 volume percent of an internal liquid hydrocarbon phase and from about 15 to about 25 volume percent of an external aqueous phase.

Claim 15

Dependent Claim 26 words

The method as defined in claim 1 wherein said emulsion breaking temperature is from about 1°F to about 40°F lower than the temperature of said formation.

Claim 16

Independent Claim 151 words

A method of fracturing a subterranean formation surrounding a well which comprises: a. preparing a fracturing fluid by contacting a liquid hydrocarbon with an aqueous fluid in the presence of sufficient amounts of a nonionic surfactant to form a stable oil-in-water emulsion having a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds and having a breaking temperature that is not greater than the temperature of said formation, said liquid hydrocarbon comprising from about 70 to about 90 volume percent of said emulsion, said aqueous fluid comprising from about 10 to about 30 volume percent of said emulsion; and b. injecting said emulsion down said well at a pressure sufficient ot fracture said formation; and c. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 17

Independent Claim 151 words

A method of fracturing a subterranean formation surrounding a well which comprises: a. preparing a fracturing fluid by contacting a liquid hydrocarbon with an aqueous fluid in the presence of sufficient amounts of a nonionic surfactant to form a stable oil-in-water emulsion having a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds and having a breaking temperature that is not greater than the temperature of said formation, said liquid hydrocarbon comprising from about 70 to about 90 volume percent of said emulsion, said aqueous fluid comprising from about 10 to about 30 volume percent of said emulsion; and b. injecting said emulsion down said well at a pressure sufficient ot fracture said formation; and c. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 18

Dependent Claim 23 words

A method as defined in claim 15 wherein said aqueous fluid contains an electrolyte to adjust the temperature at which said emulsion breaks.

Claim 19

Dependent Claim 56 words

The method as defined in claim 15 wherein said fracturing fluid contains not more than about 0.1 weight percent of a polymeric thickening agent in said aqueous fluid, said polymeric thickening agent imparting a viscosity to the aqueous phase of less than about 10 centipoises at 70°F and a shear rate of about 500 reciprocal seconds.

Claim 20

Dependent Claim 20 words

The method as defined in claim 15 wherein said emulsion contains an effective quantity of a particulate fluid loss additive.

Claim 21

Dependent Claim 30 words

The method as defined in claim 15 wherein said nonionic surfactant is added in an amount equal to from about 1.0 to about 6.0 weight percent of said aqueous fluid.

Claim 22

Independent Claim 161 words

A method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 75 to about 85 volume percent of an internal hydrocarbon phase, from about 15 to about 25 volume percent of an aqueous phase, and a nonionic surfactant which gives said emulsion a breaking temperature that is not greater than the temperature of said formation and which is added in an amount equal to from about 2.0 to about 4.0 weight percent of said aqueous phase, said amount of nonionic surfactant being sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 23

Independent Claim 161 words

A method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 75 to about 85 volume percent of an internal hydrocarbon phase, from about 15 to about 25 volume percent of an aqueous phase, and a nonionic surfactant which gives said emulsion a breaking temperature that is not greater than the temperature of said formation and which is added in an amount equal to from about 2.0 to about 4.0 weight percent of said aqueous phase, said amount of nonionic surfactant being sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 24

Dependent Claim 34 words

The method as defined in claim 20 wherein said emulsion breaking temperature is adjusted by the addition of from about 0.1 weight percent to a saturating amount of an electrolyte to said aqueous phase.

Claim 25

Independent Claim 186 words

The method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 75 to about 85 volume percent of an internal liquid hydrocarbon phase, from about 15 to about 25 volume percent of an aqueous phase, said aqueous phase containing from about 1.0 to about 10.0 weight percent of an electrolyte, and a nonionic surfactant which is added in an amount equal to from about 2.0 to about 4.0 weight percent of said aqueous phase, said amount of nonionic surfactant being sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds, said nonionic surfactant and said electrolyte being combined in proportions which give said emulsion a breaking temperature that is not greater than the temperature of said formation; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 26

Independent Claim 186 words

The method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 75 to about 85 volume percent of an internal liquid hydrocarbon phase, from about 15 to about 25 volume percent of an aqueous phase, said aqueous phase containing from about 1.0 to about 10.0 weight percent of an electrolyte, and a nonionic surfactant which is added in an amount equal to from about 2.0 to about 4.0 weight percent of said aqueous phase, said amount of nonionic surfactant being sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds, said nonionic surfactant and said electrolyte being combined in proportions which give said emulsion a breaking temperature that is not greater than the temperature of said formation; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 27

Independent Claim 222 words

A method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 70 to about 90 volume percent of an internal liquid hydrocarbon phase, from about 10 to about 30 volume percent of an aqueous phase containing from about 1.0 to about 10.0 weight percent of an electrolyte, a nonionic surfactant which is added in an amount equal to from about 1.0 to about 6.0 weight percent of said aqueous phase, said amount of nonionic surfactant being sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds, said nonionic surfactant and said electrolyte being combined in proportions which give said emulsion a breaking temperature which is less than the temperature of the formation, and not more than about 0.1 weight percent of a polymeric thickening agent, said polymeric thickening agent imparting a viscosity to the aqueous phase of less than about 10 centipoises at 70°F and a shear rate of about 500 reciprocal seconds; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Claim 28

Independent Claim 222 words

A method of fracturing a subterranean formation surrounding a wellbore which comprises: a. injecting into said formation, at a pressure sufficient to fracture said formation, an oil-in-water emulsion which contains from about 70 to about 90 volume percent of an internal liquid hydrocarbon phase, from about 10 to about 30 volume percent of an aqueous phase containing from about 1.0 to about 10.0 weight percent of an electrolyte, a nonionic surfactant which is added in an amount equal to from about 1.0 to about 6.0 weight percent of said aqueous phase, said amount of nonionic surfactant being sufficient to stabilize said emulsion and to impart to said emulsion a viscosity of at least 100 centipoises at 70°F and a shear rate of about 500 reciprocal seconds, said nonionic surfactant and said electrolyte being combined in proportions which give said emulsion a breaking temperature which is less than the temperature of the formation, and not more than about 0.1 weight percent of a polymeric thickening agent, said polymeric thickening agent imparting a viscosity to the aqueous phase of less than about 10 centipoises at 70°F and a shear rate of about 500 reciprocal seconds; and b. thereafter breaking said emulsion by leaving said emulsion in said wellbore for a sufficient time to permit the temperature of said emulsion to reach said breaking temperature.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1979-08-31	1980-03-01	1980-08-31	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1983-08-31	1984-03-01	1984-08-31	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1987-08-31	1988-03-01	1988-08-31	$7700.00	Window Closed / Lapsed

Method of fracturing subterranean formations using oil-in-water emulsions

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