Colloid systems and wetting agents; subcombinations thereof; pro – Compositions containing an agent for breaking ; processes of...
Reexamination Certificate
2002-02-28
2004-03-16
Metzmaier, Daniel S. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Compositions containing an agent for breaking ; processes of...
C507S211000, C507S241000, C507S921000
Reexamination Certificate
active
06706769
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to gelled treatment fluids used during hydrocarbon recovery operations, and more particularly relates, in one embodiment, to methods of “breaking” or reducing the viscosity of treatment fluids containing polymer gelling agents used during hydrocarbon recovery operations.
BACKGROUND OF THE INVENTION
Hydraulic fracturing is a method of using pump rate and hydraulic pressure to fracture or crack a subterranean formation. Once the crack or cracks are made, high permeability proppant, relative to the formation permeability, is pumped into the fracture to prop open the crack. When the applied pump rates and pressures are reduced or removed from the formation, the crack or fracture cannot close or heal completely because the high permeability proppant keeps the crack open. The propped crack or fracture provides a high permeability path connecting the producing wellbore to a larger formation area to enhance the production of hydrocarbons.
The development of suitable fracturing fluids is a complex art because the fluids must simultaneously meet a number of conditions. For example, they must be stable at high temperatures and/or high pump rates and shear rates that can cause the fluids to degrade and prematurely settle out the proppant before the fracturing operation is complete. Various fluids have been developed, but most commercially used fracturing fluids are aqueous based liquids that have either been gelled or foamed. When the fluids are gelled, typically a polymeric gelling agent, such as a solvatable polysaccharide is used. The thickened or gelled fluid helps keep the proppants within the fluid. Gelling can be accomplished or improved by the use of crosslinking agents or crosslinkers that promote crosslinking of the polymers together, thereby increasing the viscosity of the fluid. However, crosslinking agents are not always necessary to obtain a suitable gel.
The recovery of fracturing fluids may be accomplished by reducing the viscosity of the fluid to a low value so that it may flow naturally from the formation under the influence of formation fluids. Polymer gels generally require viscosity breakers to be injected to reduce the viscosity or “break” the gel. Enzymes, oxidizers, and inorganic acids are known polymer viscosity breakers. Enzymes are effective within a pH range, typically a 2.0 to 10.0 range, with increasing activity as the pH is lowered towards neutral from a pH of 10.0.
Many viscosity-breaking technologies are most effective only over limited temperature ranges. For instance, persulfate oxidizers are generally too reactive to be properly used above about 140° F. (60° C.) and bromate oxidizers do not work until about 220° F. (104° C.) and above. Enzyme technology generally works between about 150 to 220° F. (66 to 104° C.).
It would be desirable if a viscosity breaking system could be devised to break fracturing fluids gelled with polymers, particularly over a temperature range of about 120° F. (49° C.) and about 280° F. (138° C.), as an alternative to enzyme technology.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method for breaking the viscosity of aqueous treatment fluids gelled with polymers used in hydrocarbon recovery operations.
It is another object of the present invention to provide a composition and method for breaking gelled aqueous fluids over a temperature range of about 120° F. (49° C.) and about 280° F. (138° C.).
Still another object of the invention is to provide a method and composition for breaking the viscosity of aqueous fluids gelled polymers using relatively inexpensive aminocarboxylic acids.
In carrying out these and other objects of the invention, there is provided, in one form, a method for breaking the viscosity of polymer gelled aqueous fluids comprising adding an effective amount of at least one aminocarboxylic acid to act directly break down the gel.
REFERENCES:
patent: 4250044 (1981-02-01), Hinkel
patent: 4486339 (1984-12-01), Young
patent: 4874854 (1989-10-01), Colegrove et al.
patent: 4968442 (1990-11-01), Falk
patent: 4969526 (1990-11-01), Cawiezel
patent: 5010954 (1991-04-01), Falk
patent: 5054552 (1991-10-01), Hall et al.
patent: 5223159 (1993-06-01), Smith et al.
patent: 5224546 (1993-07-01), Smith et al.
patent: 5310489 (1994-05-01), Sharif
patent: 5624886 (1997-04-01), Dawson et al.
patent: 5950731 (1999-09-01), Schuchart et al.
patent: 5981447 (1999-11-01), Chang et al.
patent: 6265355 (2001-07-01), Lai et al.
J. S. Rhudy, “Removal of Mineral Scale From Reservoir Core by Scale Dissolver,” SPE International Symposium on Oilfield Chemistry, New Orleans, LA, Mar. 2-5, 1993, pp. 97-106.
Wayne W. Frenier, “Novel Scale Removers Are Developed for Dissolving Alkaline Earth Deposits,” 2001SPE International Symposium on Oilfield Chemistry, Houston, TX, Feb. 13-16, 2001.
Akzo Nobel Dissolvine(R) Chelates Web pages downloaded Aug. 10, 2001, http://www.dissolvine.com/start.htm.
Dow Chemical Company Versene(R) Chelating Agents Web pages downloaded Aug. 10, 2001, http://www.dow.com/versene/index.htm.
Baker Hughes Incorporated
Madan Mossman & Sriram P.C.
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