US4374545A — Carbon dioxide fracturing process and apparatus

Claim 1

Independent Claim 75 words

A method of fracturing an underground stratigraphic formation penetrated by a well bore comprising the steps of: pumping a stream of liquified gas into said formation to cause the fracturing thereof; introducing proppants into said stream of liquified gas for injection of said proppants into said fractures; and pressurizing and cooling said proppants to substantially the storage pressure and temperature of said liquified gas prior to introducing said proppants into said stream of liquified gas.

Claim 2

Independent Claim 75 words

A method of fracturing an underground stratigraphic formation penetrated by a well bore comprising the steps of: pumping a stream of liquified gas into said formation to cause the fracturing thereof; introducing proppants into said stream of liquified gas for injection of said proppants into said fractures; and pressurizing and cooling said proppants to substantially the storage pressure and temperature of said liquified gas prior to introducing said proppants into said stream of liquified gas.

Claim 3

Dependent Claim 34 words

The method of claim 1 including the step of adding a gelled carrier fluid to said stream of liquid gas such that said stream includes up to 20% by volume of gelled carrier fluid.

Claim 4

Dependent Claim 14 words

The method of claim 1 wherein said proppants are cooled using said liquified gas.

Claim 5

Dependent Claim 25 words

The method of claim 3 wherein the steps of pumping said stream of liquified gas and introducing said proppants into said stream are performed simultaneously.

Claim 6

Dependent Claim 12 words

The method of claim 4 wherein said liquified gas is carbon dioxide.

Claim 7

Dependent Claim 17 words

The method of claim 5 wherein said underground stratigraphic formation is a low permeability, hydrocarbon bearing horizon.

Claim 8

Dependent Claim 37 words

The method of claim 1 wherein said liquified gas is stored prior to pumping into the well bore at a temperature of approximately 0° F. to -40° F. at a pressure of approximately 150 to 250 psi.

Claim 9

Dependent Claim 36 words

The method of claim 7 wherein the pressure of said liquified gas is increased to between 250 and 350 psi prior to the commencement of said pumping of said stream of liquified gas into the formation.

Claim 10

Dependent Claim 35 words

The method of claim 8 including the step of adding a gelled carrier fluid to said stream of liquified gas such that said stream includes up to 20% by volume of said gelled carrier fluid.

Claim 11

Dependent Claim 19 words

The method of claim 9 wherein said stream includes 5% to 10% by volume of said gelled carrier fluid.

Claim 12

Dependent Claim 20 words

The method of claim 2, 9 or 10 wherein said gelled carrier fluid is a gelled alcohol such as methanol.

Claim 13

Dependent Claim 37 words

The method of claim 1 wherein said pumping a stream of liquified gas comprises the step of injecting said stream of liquified gas into said formation at a pressure selected to cause the fracturing of said formation.

Claim 14

Dependent Claim 35 words

The method of claim 12 wherein said stream of liquified gas is injected into said formation by means of high pressure pumps, said proppants being introduced into said stream prior to said high pressure pumps.

Claim 15

Independent Claim 82 words

A method of propping open an hydraulically fractured underground stratigraphic formation penetrated by a well bore comprising the steps of: introducing propping agents into a stream of pressurized liquified gas, said propping agents themselves being pressurized and cooled to the pressure and temperature of the liquified gas, respectively, prior to said introduction; and pumping the mixture of said liquified gas and entrained propping agents down said well bore into said formation to deposit said proppants in the fractures formed in said formation.

Claim 16

Independent Claim 82 words

A method of propping open an hydraulically fractured underground stratigraphic formation penetrated by a well bore comprising the steps of: introducing propping agents into a stream of pressurized liquified gas, said propping agents themselves being pressurized and cooled to the pressure and temperature of the liquified gas, respectively, prior to said introduction; and pumping the mixture of said liquified gas and entrained propping agents down said well bore into said formation to deposit said proppants in the fractures formed in said formation.

Claim 17

Dependent Claim 43 words

The method of claim 14 including the step of introducing a gelled carrier fluid into said stream of pressurized liquified gas to increase the viscosity thereof, said gelled carrier fluid being added to comprise up to 20% of the volume of said stream.

Claim 18

Dependent Claim 19 words

The method of claim 15 wherein said stream includes 5% to 10% by volume of said gelled carrier fluid.

Claim 19

Dependent Claim 12 words

The method of claim 16 wherein said liquified gas is carbon dioxide.

Claim 20

Dependent Claim 17 words

The method of claim 17 wherein said gelled carrier fluid is a gelled alcohol such as methanol.

Claim 21

Dependent Claim 101 words

Apparatus for hydraulically fracturing an underground stratigraphic formation penetrated by a well bore comprising: a high pressure pump for injecting a fracturing fluid down said well bore, said fluid comprising a liquified gas; first storage means to store said liquified gas under pressure; conduit means to provide fluid communication between said pump and said first storage means; second storage means to store proppants at a temperature and pressure substantially equal to the storage pressure and temperature of said liquified gas; and supply means to introduce the proppants from said second storage means into the liquified gas flowing through said conduit means.

Claim 22

Dependent Claim 101 words

Apparatus for hydraulically fracturing an underground stratigraphic formation penetrated by a well bore comprising: a high pressure pump for injecting a fracturing fluid down said well bore, said fluid comprising a liquified gas; first storage means to store said liquified gas under pressure; conduit means to provide fluid communication between said pump and said first storage means; second storage means to store proppants at a temperature and pressure substantially equal to the storage pressure and temperature of said liquified gas; and supply means to introduce the proppants from said second storage means into the liquified gas flowing through said conduit means.

Claim 23

Dependent Claim 33 words

The apparatus of claim 19 further including second conduit means to provide fluid communication between said first and second storage means whereby said liquified gas is used to cool and pressurize said proppants.

Claim 24

Dependent Claim 15 words

The apparatus of claim 20 wherein said first and second storage means comprise pressure vessels.

Claim 25

Dependent Claim 30 words

The apparatus of claim 21 wherein said supply means include an auger extending between said second storage means and said first conduit means so as to transport said proppants therebetween.

Claim 26

Independent Claim 70 words

A method of treating an underground stratigraphic formation penetrated by a well bore comprising the steps of: injecting a stream of liquified gas into said formation; introducing proppants into said stream of liquified gas for injection of said proppants into said formation; and pressurizing and cooling said proppants to substantially the storage pressure and temperature of said liquified gas prior to introducing said proppants into said stream of liquified gas.

Claim 27

Independent Claim 70 words

A method of treating an underground stratigraphic formation penetrated by a well bore comprising the steps of: injecting a stream of liquified gas into said formation; introducing proppants into said stream of liquified gas for injection of said proppants into said formation; and pressurizing and cooling said proppants to substantially the storage pressure and temperature of said liquified gas prior to introducing said proppants into said stream of liquified gas.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1986-02-21	1986-08-23	1987-02-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1990-02-21	1990-08-23	1991-02-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1994-02-21	1994-08-23	1995-02-22	$7700.00	Window Closed / Lapsed

Carbon dioxide fracturing process and apparatus

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