Methods of generating gas in well treating fluids
First Claim
1. An improved method of generating gas in and foaming an alkaline well treating fluid introduced into a subterranean zone penetrated by a well bore comprising the steps of:
- (a) combining one or more gas generating chemicals with said well treating fluid;
(b) combining one or more delayed encapsulated activators having selected release times with said well treating fluid containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said one or more delayed encapsulated activators and gas and foam are formed in said treating fluid while said treating fluid is being pumped or at one or more times after said treating fluid has been placed in said subterranean zone, or both; and
(c) pumping said treating fluid formed in step (b) into said well bore and into said subterranean zone.
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Accused Products
Abstract
Improved methods of generating gas in and foaming well treating fluids introduced into a subterranean zone are provided. A method of the invention includes the steps of combining one or more gas generating chemicals with the well treating fluid and combining one or more delayed encapsulated activators having selected release times with the well treating fluid containing the gas generating chemicals so that the gas generating chemicals react with the delayed encapsulated oxidizing agent activators and gas and foam are formed in the treating fluid while the treating fluid is being pumped and after being placed in the subterranean zone.
268 Citations
32 Claims
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1. An improved method of generating gas in and foaming an alkaline well treating fluid introduced into a subterranean zone penetrated by a well bore comprising the steps of:
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(a) combining one or more gas generating chemicals with said well treating fluid;
(b) combining one or more delayed encapsulated activators having selected release times with said well treating fluid containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said one or more delayed encapsulated activators and gas and foam are formed in said treating fluid while said treating fluid is being pumped or at one or more times after said treating fluid has been placed in said subterranean zone, or both; and
(c) pumping said treating fluid formed in step (b) into said well bore and into said subterranean zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An improved method of generating gas in an alkaline well cement composition introduced into a subterranean zone penetrated by a well bore comprising the steps of:
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(a) combining one or more gas generating chemicals selected from the group consisting of azodicarbonamide, carbohydrazide and mixtures thereof with said cement composition;
(b) combining one or more delayed encapsulated oxidizing agent activators having different selected release times with said cement composition containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said one or more delayed encapsulated oxidizing agent activators and gas is formed in said cement composition while said cement composition is being pumped and at one or more times after said cement composition has been placed in said subterranean zone, said oxidizing agent in said delayed encapsulated oxidizing agent activators having different release times being selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, sodium chlorite, sodium chlorate, hydrogen peroxide, sodium perborate and sodium peroxy carbonate; and
(c) pumping said cement composition formed in step (b) into said well bore and into said subterranean zone. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. An improved method of generating gas in an alkaline well cement composition introduced into a subterranean zone penetrated by a well bore comprising the steps of:
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(a) combining one or more gas generating chemicals selected from the group consisting of azodicarbonamide, carbohydrazide and mixtures thereof with said cement composition;
(b) combining one or more delayed encapsulated oxidizing agent activators having different selected release times with said cement composition containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said one or more delayed encapsulated oxidizing agent activators and gas is formed in said cement composition during one or more of the stages of;
pumping to foam said composition and provide thixotropy thereto;
after being placed in said subterranean zone during the static cement composition gel strength development stage to compensate for cement shrinkage due to fluid loss;
during the cement transition time to prevent the inflow of formation fluids; and
during setting of the cement to provide resiliency thereto, said oxidizing agent in said delayed encapsulated oxidizing agent activators having different release times being selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, sodium chlorite, sodium chlorate, hydrogen peroxide, sodium perborate and sodium peroxy carbonate; and
(c) pumping said cement composition formed in step (b) into said well bore and into said subterranean zone.
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23. An improved method of generating gas in a viscous alkaline well fracturing fluid which is introduced into a subterranean zone penetrated by a well bore, which forms fractures in said subterranean zone and then breaks into a thin fluid comprising the steps of:
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(a) combining one or more gas generating chemicals with said fracturing fluid;
(b) combining one or more delayed encapsulated activators having selected release times with said fracturing fluid containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said delayed encapsulated activators and gas is formed in said fracturing fluid after fractures have been formed in said subterranean zone and during and after said fracturing fluid breaks into a thin fluid whereby said gas facilitates the back flow of said fracturing fluid and its removal from said fractures; and
(c) pumping said fracturing fluid formed in step (b) into said well bore and into said subterranean zone. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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31. An improved method of generating gas in a viscous alkaline well fracturing fluid which is introduced into a subterranean zone penetrated by a well bore, which forms fractures in said subterranean zone and then breaks into a thin fluid comprising the steps of:
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(a) combining one or more gas generating chemicals with said viscous alkaline fracturing fluid wherein said viscous alkaline fracturing fluid is a gelled and cross-linked aqueous fluid;
(b) combining one or more delayed encapsulated activators having selected release times with said fracturing fluid containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said delayed encapsulated activators and gas is formed in said fracturing fluid after fractures have been formed in said subterranean zone and during and after said fracturing fluid breaks into a thin fluid whereby said gas formed in said fracturing fluid is an acidic gas which facilitates the breaking of said viscous fracturing fluid into a thin fluid and whereby said gas facilitates the back flow of said fracturing fluid and its removal from said fractures; and
(c) pumping said fracturing fluid formed in step (b) into said well bore and into said subterranean zone.
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32. An improved method of generating gas in a viscous alkaline well fracturing fluid which is introduced into a subterranean zone penetrated by a well bore, which forms fractures in said subterranean zone and then breaks into a thin fluid comprising the steps of:
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(a) combining a gas generating chemical with said viscous alkaline fracturing fluid wherein said gas generating chemical is azodicarbonamide and wherein said viscous alkaline fracturing fluid is a gelled and cross-linked aqueous fluid;
(b) combining a delayed encapsulated activator having a selected release time, said activator being ammonium persulfate, with said fracturing fluid containing said gas generating chemicals formed in step (a) so that said gas generating chemicals react with said delayed encapsulated activators and gas is formed in said fracturing fluid after fractures have been formed in said subterranean zone and during and after said fracturing fluid breaks into a thin fluid whereby said gas formed in said fracturing fluid is an acidic gas which includes carbon dioxide and which facilitates the breaking of said viscous fracturing fluid into a thin fluid and whereby said gas facilitates the back flow of said fracturing fluid and its removal from said fractures; and
(c) pumping said fracturing fluid formed in step (b) into said well bore and into said subterranean zone.
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Specification