Patent US3707192A successfully refreshed from Google Patents.
US3707192A
Expired / Lapsed
US
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Two-stage injection of acid-producing chemicals for stimulating wells
Assignee: Gulf Research and Development Co
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Filing: 1970-12-28
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Granted: 1972-12-26
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Expires: 1990-12-28
Abstract
Abstract The flow capacity of a subsurface formation penetrated by a well is increased by fracturing the formation, extending the fracture from the well outward into the formation, depositing solid particles of a first reactant the faces of the fracture, and displacing a second reactant into the fracture to react with the first reactant. The reaction product of the two reactants is an acid that will attach the formation and thereby increase the width of the fracture. Reactants that can be used are ammonium salts and aldehydes that react to form acids. Preferred reactants for carbonate formations are ammonium chloride and formaldehyde. Preferred reactants for sandstone formations are formaldehyde and mixtures of ammonium chloride and ammonium fluoride.
Inventors
- 👤 William C Goins Jr
- 👤 Bruce B Mcglothlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:22
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/60; C09K8/62; C09K8/72; C09K8/74
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
25 words
A method as set forth in claim 1 in which the first reactant is an ammonium salt and the second reactant is a water-soluble aldehyde.
Claim 2
Dependent Claim
15 words
A method as set forth in claim 2 in which the water-soluble aldehyde is formaldehyde.
Claim 3
Dependent Claim
51 words
A method as set forth in claim 1 in which the first reactant is an ammonium salt selected from the group consisting of ammonium chloride, ammonium formate, ammonium nitrate and ammonium fluoride, and the second reactant is an aqueous solution of formaldehyde containing 2 percent to 44 percent by weight formaldehyde.
Claim 4
Dependent Claim
43 words
A method as set forth in claim 1 in which the first reactant is deposited in the fracture by suspending the reactant in nonaqueous liquid and displacing the resultant suspension into the fracture, and the second reactant is an aqueous solution of formaldehyde.
Claim 5
Dependent Claim
31 words
A method as set forth in claim 5 in which the subsurface formation is a carbonate formation, the first reactant is ammonium chloride, and the nonaqueous liquid is a hydrocarbon oil.
Claim 6
Independent Claim
131 words
A method of treating a subsurface formation penetrated by a well to increase the flow capacity of the formation to the well comprising pumping a liquid down the well and increasing the pressure thereon to fracture the formation, displacing a liquid having solid particles of a first reactant suspended therein down the well and into the fracture at a rate and for a period to extend the fracture for a desired distance from the well and deposit the first reactant in the fracture, thereafter displacing a second reactant down the well and into the fracture, the first and second reactants being adapted to react with one another and form as a reaction product an acid capable of reacting with at least a portion of the formation to form a soluble salt.
Claim 7
Dependent Claim
56 words
A method as set forth in claim 7 in which the first reactant is an ammonium salt selected from the group consisting of ammonium chloride, ammonium fluoride, ammonium formate and ammonium nitrate, the liquid in which the ammonium salt is displaced s a hydrocarbon oil, and the second reactant is a water-soluble aldehyde in aqueous solution.
Claim 8
Dependent Claim
53 words
A method as set forth in claim 7 in which the first reactant is an ammonium salt selected from the group consisting of ammonium chloride, ammonium fluoride, ammonium formate and ammonium nitrate, the reactant in which the ammonium salt is suspended is a saturated brine, and the second reactant is a water-soluble aldehyde.
Claim 9
Dependent Claim
38 words
A method as set forth in claim 7 in which the first reactant is paraformaldehyde, the liquid in which the paraformaldehyde is suspended is a hydrocarbon oil, and the second reactant is an aqueous solution of ammonium chloride.
Claim 10
Independent Claim
79 words
A method of treating a subsurface formation penetrated by a well to increase the conductivity of the formation to the well comprising fracturing the formation, displacing into the fracture a slurry containing a mixture of solid particles of paraformaldehyde and an ammonium salt selected from the group consisting of ammonium chloride, ammonium fluoride, ammonium formate and ammonium nitrate in a hydrocarbon oil to deposit said mixture of solid particles in the fracture, and then displacing water into the fracture.
Claim 11
Independent Claim
139 words
A method of treating a subsurface formation penetrated by a well to increase the flow capacity of the formation to the well comprising pumping water containing a fluid-loss reducing additive down the well at a rate to cause an increase in pressure in the well and fracturing of the formation, following the water with a slurry of a hydrocarbon oil having suspended therein ammonium chloride and a fluid-loss reducing additive at a rate to extend the fracture from the well and deposit ammonium chloride in the fracture, following the slurry of ammonium chloride in oil with an aqueous solution of formaldehyde, and closing in the well for a period to allow the formaldehyde and ammonium chloride to react and the resultant acidic reaction product to react with at least a portion of the formation to form a water-soluble salt.
Claim 12
Independent Claim
64 words
A method of treating a fractured sandstone formation penetrated by a well to increase the flow capacity of the fracture comprising displacing down the well and into the fracture a slurry in a hydrocarbon oil of a compound selected from the group consisting of ammonium fluoride and ammonium bifluoride, and thereafter displacing down the well and into the fracture an aqueous solution of formaldehyde.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |