CA2108194C - High viscosity crosslinked gelled alcohol - Google Patents
High viscosity crosslinked gelled alcoholInfo
- Publication number
- CA2108194C CA2108194C CA 2108194 CA2108194A CA2108194C CA 2108194 C CA2108194 C CA 2108194C CA 2108194 CA2108194 CA 2108194 CA 2108194 A CA2108194 A CA 2108194A CA 2108194 C CA2108194 C CA 2108194C
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- Prior art keywords
- gel
- alcohol
- guar gum
- group including
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/66—Compositions based on water or polar solvents
- C09K8/68—Compositions based on water or polar solvents containing organic compounds
- C09K8/685—Compositions based on water or polar solvents containing organic compounds containing cross-linking agents
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- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
A fracturing fluid composition for use in fracturing underground formations, such as oil or gas wells is described. It includes at least one anhydrous aliphatic alcohol, a modified guar gum polymer, and as a complexor, a sodium borate salt. A gel breaker which acts over a time period to degrade the guar gum cross linked polymer and thereby reduce the viscosity of the gel is provided as well to aid in the removal thereof from an oil or gas well that has been fractured by application of the fluid under pressure.
Description
- ~101~3194 The present invention relates to the field of oil and gas well fracturing.
In the area of oil and gas field exploration and development, a technique that is utilized to increase production from a well, or to make a non-productive well productive again is hydraulic fracturing. Generally speaking, this involves injection of fluid under high pressure down a well bore. This causes an increase in pressure in the subterranean formation with which the well bore communicates, and fracturing of such formation thereby creating access to the well bore for untapped oil or gas in the formation. The fluid that is introduced into the formation may include various propping agents, such as sand, or walnut shell fragments, to increase the flow of oil or gas through a newly fractured formation.
It is known, moreover, to utilize a gel in fracturing techniques, in order to increase the viscosity of the fracturing fluid, and enhance propant transport. For instance, in Canadian Patent No. 1,174,841, which has been assigned to the present applicant, a fracturing fluid is described that comprises at least one substantially anhydrous aliphatic alcohol, a nonionic homopolymer to form a gel with the alcohol that has a molecular weight from about 4 million to about 5 million. Such a fracturing fluid also includes, as a gel activating agent, an alkali metal halide or an alkaline metal earth halide. The aliphatic alcohol utilized in such a fluid is generally a one to four carbon alcohol, including up to five percent water. The non 21~81g4 ionic homopolymer utilized is a polyalkaline oxide such as poly(ethylene oxide) in an amount of from 0.1% to 3% by volume, and a suitable activating agent is potassium, sodium, calcium or magnesium halide, in amounts generally under 1%. This prior art fracturing fluid of the applicant was developed ta meet a need that was clear from the existing prior art, for a fracturing gel having a low water content, because of the fact that water may be considered as a subterranean formation contaminant.
There have been other attempts to utilize substantially anhydrous alcohol gels, such as is taught in U.S. Patent No.
4,012,327 which relates to the use of alcohols that are thickened, but not necessarily gelled, by aminomethylated polyacrylamide. The gel in such a case, though, is formed by a substantial linear polymer, and so will exhibit limited viscosity, shear strength, and stability.
The object of the present invention is to provide an improved anhydrous alcohol gel, that will exhibit a high degree of shear stability, and high viscosity at elevated temperatures.
A further object of the present invention is to provide an improved fracturing fluid that will form a shear stable gel in an anhydrous alcohol medium at elevated temperature, and exhibit a predictable breakdown rate in view of measured downhole conditions. In this latter regard, it will be understood that injection of a fracturing fluid in the form of a gel is of little use if the gel remains in its gelled state in the formation. It is essential that the gel break down under known physical or chemical conditions.
The fracturing fluid of the present invention therefore includes, as well as a gel complexor, a gel breaker. It will be understood that the gel breaker chosen for use will be relatively slow acting a compared to the complexor or cross linker, so that the fluid gel may perform its fracturing function before the gel is broken. The use of a slow acting gel breaker, that will act in a predictable manner, in combination with a relatively faster acting gelling agent permits the addition of the gel breaker to the fracturing fluid as it is being pumped down a well.
In accordance with the present invention, a fracturing fluid is provided that utilizes a modified guar gum polymer, in anhydrous alcohol, preferably methyl alcohol, to form a gel. As a gel complexor, a sodium borate salt is used.
Guar gum is a known, naturally occurring polymer, the ground endosperms of cyamopsis tetragonalobus. It is a linear polymer of (1 ~ 4)-B-D mannopyranosyl units with ~ - D - galactopyranosyl units attached by (1 ~ 6) linkages. In its uncomplexed linear state it exhibits a molecular weight of about 220,000.
Particularly useful modification of guar gum according to the present invention include hydroxy, carboxy and alkyl guar gums.
The applicant has found that about 6 kg of guar gum, or modified guar gum, per cubic metre of anhydrous alcohol, will form an appropriate gel, when complexed with 14 - 18 litres of sodium 21081g4 borate or sodium tetraborate. The borate solution is prepared on the basis of 0.5 to 4.0 kg per cubic metre of fracturing fluid.
Prior to addition of the cross linking agent, fumaric acid (or another suitable acid) may be added into methanol with guar gum to assist in formation of the base gel.
The gel breaker that is added to the fracturing fluid is chosen for its ability to degrade the cross linked guar gum in a desired time frame, and suitable breakers include ammonium persulfate, sodium persulfate and sodium perborate, in quantities of 0.1 to 10.0 Kg per cubic metre of fracturing fluid. The large degree of variation is a result of combined facts that: (a) depending on the concentration of guar gum polymer in the solution, a more or less thick gel will result; (b) varying amounts of cross linking agent (borate) will have been used, depending on the extent of cross linking, and corresponding viscosity of the gel desired; (c) the desired down hole residence time (d) the downhole depth and temperature, and other factors that will be obvious to one skilled in the art.
Furthermore, the breaker utilized may be coated, in a conventional manner, if desired. The use of a coating on a granular breaker provides a further degree of control, for situations wherein it is desired to have substantially no gel breakdown for a given period of time. Coating a granular breaker achieves such a degree of control by selection of coatings having 210~194 known rates of dissolution in the alcohol chosen as the basis for the fracturing fluid.
It is to be understood that any desirable proppant may be combined on the fly with the fracturing fluid of the present S invention. Suitable proppants for use in conjunction with the fracturing fluid of the present invention include sand, synthetic sand, or synthetic coated sand.
In a broad aspect, then, the present invention relates to a fracturing fluid composition for use in fracturing underground formations, such as oil or gas wells, comprising:
at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol; from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums; from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form;
and from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing.
_, . .. . ..
~1081~
Also preferably, the complexor is sodium tetraborate in a solid or liquid form equivalent to from 0.5 to 4.0 Kg per cubic metre of alcohol.
To obtain an effective fracturing fluid, said modified guar gum polymer is mixed with the alcohol in a concentration of from 0.1 to 2.0% by weight per volume of alcohol, and a sufficient quantity of acidifying agent such as fumaric acid is added. Furthermore, the quantity of gel breaker is selected to break down the polymer within a predetermined time period, usually 1 to 24 hours.
The gel breaker is, in a preferred embodiment, ammonium persulfate, sodium persulfate, sodium perborate or a mixture of one or more of the foregoing and wherein said gel breaker may be coated or covered. The concentration of the breaker may be 0.1 to 10.0 Kg/m3 of alcohol.
The composition, in its preferred form, is admixed with a proppant selected from sand, synthetic sand or synthetic coated sand.
In another broad aspect, the present invention relates to a method of fracturing an underground formation such as an oil or gas well comprising: injecting the formation with an effective amount of a fracturing fluid gel composition ,,--comprising: at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol;
from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums; from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form; and from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing; and applying pressure to the composition in the formation to induce fracture of the formation.
In the method as aforesaid the complexor is sodium tetraborate in a solid or liquid form equivalent to from 0.5 to 4.0 Kg per cubic meter of alcohol, and the modified guar gum polymer is mixed with the alcohol in a concentration of from 0.1 to 2.0% by weight per volume of alcohol. A sufficient quantity of acidifying agent such as fumaric acid is added.
The quantity of gel breaker is selected to break down the polymer within a predetermined time period, such as 1 - 24 hours.
A
- ` 2i1~819~
The order of addition is as follows: the alcohol and guar gum are mixed first, with the fumaric acid, to form a base gel, that is permitted to gel for several minutes. The borate complexor is then added, followed by the gel breaker.
In the method of the present invention, the gel breaker is ammonium persulfate, sodium persulfate, sodium perborate or a mixture of one or more of the foregoing, and said gel breaker may be coated or covered. The concentration of the breaker is 0.1 to 10.0 Kg/m3 of alcohol.
7(a) 210~
Moreover, said alcohol, said guar gum, said complexor and said gel breaker are mixed together as they are being injected in a said well, in a most preferred embodiment.
In the method of the present invention, the order of addition of complexor and breaker is not considered crucial. Of more importance will be the selection of an appropriate quantity of breaker, and in this regard, one must consider the temperature at the bottom of the well. As an example, utilizing a fracturing fluid prepared with 6 Kg of guar gum per cubic metre of 100%
methanol, with about 16 litres of a 3.5% sodium borate solution added as a complexor, and 0.08 Kg of fumaric acid per cubic metre as an acidifying agent, the following results are obtained with sodium perborate breaker:
TABLE I
BREAK TIMES OF METHANOL GEL AT VARIOUS
CONCENTRATIONS AND TEMPERATURES
TEMPERATURE ( C) Breaker Concentration (Kg/m3) 60 70 80 90 O . 1 0.2 4 hrs 3 hrs 2 hrs 0.3 3 hrs 2 hrs 0.4 7 hrs 0.5 6 hrs It will be understood, then, that depending on the extent of fracturing desired at a given location, and the measured down hole temperature, different amounts of breaker will be added to the fracturing fluid as it is pumped down a well.
It a preferred method according to the present invention, after the base fel is formed, the complexor and breaker of the fracturing fluid are mixed together "on the fly", as the fluid is being pumped down a well. In this way, exposure of the guar gum to the complexor and breaker is not effected until just prior to injection of the fluid into a formation. This results in better pumpability into a well, and more accurate determination of when the gel will have broken. Moreover, should there be any delay due to equipment failure or the like, there is no wasted gel/complexor/breaker fluid.
It is to be understood that the examples described above are not meant to limit the scope of the present invention. It is expected that numerous variants will be obvious to the person s~illed in the oil and gas well fracturing fluid design field without any departure from the spirit of the invention. The appended claims, properly construed, form the only limitation upon the scope of the invention.
In the area of oil and gas field exploration and development, a technique that is utilized to increase production from a well, or to make a non-productive well productive again is hydraulic fracturing. Generally speaking, this involves injection of fluid under high pressure down a well bore. This causes an increase in pressure in the subterranean formation with which the well bore communicates, and fracturing of such formation thereby creating access to the well bore for untapped oil or gas in the formation. The fluid that is introduced into the formation may include various propping agents, such as sand, or walnut shell fragments, to increase the flow of oil or gas through a newly fractured formation.
It is known, moreover, to utilize a gel in fracturing techniques, in order to increase the viscosity of the fracturing fluid, and enhance propant transport. For instance, in Canadian Patent No. 1,174,841, which has been assigned to the present applicant, a fracturing fluid is described that comprises at least one substantially anhydrous aliphatic alcohol, a nonionic homopolymer to form a gel with the alcohol that has a molecular weight from about 4 million to about 5 million. Such a fracturing fluid also includes, as a gel activating agent, an alkali metal halide or an alkaline metal earth halide. The aliphatic alcohol utilized in such a fluid is generally a one to four carbon alcohol, including up to five percent water. The non 21~81g4 ionic homopolymer utilized is a polyalkaline oxide such as poly(ethylene oxide) in an amount of from 0.1% to 3% by volume, and a suitable activating agent is potassium, sodium, calcium or magnesium halide, in amounts generally under 1%. This prior art fracturing fluid of the applicant was developed ta meet a need that was clear from the existing prior art, for a fracturing gel having a low water content, because of the fact that water may be considered as a subterranean formation contaminant.
There have been other attempts to utilize substantially anhydrous alcohol gels, such as is taught in U.S. Patent No.
4,012,327 which relates to the use of alcohols that are thickened, but not necessarily gelled, by aminomethylated polyacrylamide. The gel in such a case, though, is formed by a substantial linear polymer, and so will exhibit limited viscosity, shear strength, and stability.
The object of the present invention is to provide an improved anhydrous alcohol gel, that will exhibit a high degree of shear stability, and high viscosity at elevated temperatures.
A further object of the present invention is to provide an improved fracturing fluid that will form a shear stable gel in an anhydrous alcohol medium at elevated temperature, and exhibit a predictable breakdown rate in view of measured downhole conditions. In this latter regard, it will be understood that injection of a fracturing fluid in the form of a gel is of little use if the gel remains in its gelled state in the formation. It is essential that the gel break down under known physical or chemical conditions.
The fracturing fluid of the present invention therefore includes, as well as a gel complexor, a gel breaker. It will be understood that the gel breaker chosen for use will be relatively slow acting a compared to the complexor or cross linker, so that the fluid gel may perform its fracturing function before the gel is broken. The use of a slow acting gel breaker, that will act in a predictable manner, in combination with a relatively faster acting gelling agent permits the addition of the gel breaker to the fracturing fluid as it is being pumped down a well.
In accordance with the present invention, a fracturing fluid is provided that utilizes a modified guar gum polymer, in anhydrous alcohol, preferably methyl alcohol, to form a gel. As a gel complexor, a sodium borate salt is used.
Guar gum is a known, naturally occurring polymer, the ground endosperms of cyamopsis tetragonalobus. It is a linear polymer of (1 ~ 4)-B-D mannopyranosyl units with ~ - D - galactopyranosyl units attached by (1 ~ 6) linkages. In its uncomplexed linear state it exhibits a molecular weight of about 220,000.
Particularly useful modification of guar gum according to the present invention include hydroxy, carboxy and alkyl guar gums.
The applicant has found that about 6 kg of guar gum, or modified guar gum, per cubic metre of anhydrous alcohol, will form an appropriate gel, when complexed with 14 - 18 litres of sodium 21081g4 borate or sodium tetraborate. The borate solution is prepared on the basis of 0.5 to 4.0 kg per cubic metre of fracturing fluid.
Prior to addition of the cross linking agent, fumaric acid (or another suitable acid) may be added into methanol with guar gum to assist in formation of the base gel.
The gel breaker that is added to the fracturing fluid is chosen for its ability to degrade the cross linked guar gum in a desired time frame, and suitable breakers include ammonium persulfate, sodium persulfate and sodium perborate, in quantities of 0.1 to 10.0 Kg per cubic metre of fracturing fluid. The large degree of variation is a result of combined facts that: (a) depending on the concentration of guar gum polymer in the solution, a more or less thick gel will result; (b) varying amounts of cross linking agent (borate) will have been used, depending on the extent of cross linking, and corresponding viscosity of the gel desired; (c) the desired down hole residence time (d) the downhole depth and temperature, and other factors that will be obvious to one skilled in the art.
Furthermore, the breaker utilized may be coated, in a conventional manner, if desired. The use of a coating on a granular breaker provides a further degree of control, for situations wherein it is desired to have substantially no gel breakdown for a given period of time. Coating a granular breaker achieves such a degree of control by selection of coatings having 210~194 known rates of dissolution in the alcohol chosen as the basis for the fracturing fluid.
It is to be understood that any desirable proppant may be combined on the fly with the fracturing fluid of the present S invention. Suitable proppants for use in conjunction with the fracturing fluid of the present invention include sand, synthetic sand, or synthetic coated sand.
In a broad aspect, then, the present invention relates to a fracturing fluid composition for use in fracturing underground formations, such as oil or gas wells, comprising:
at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol; from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums; from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form;
and from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing.
_, . .. . ..
~1081~
Also preferably, the complexor is sodium tetraborate in a solid or liquid form equivalent to from 0.5 to 4.0 Kg per cubic metre of alcohol.
To obtain an effective fracturing fluid, said modified guar gum polymer is mixed with the alcohol in a concentration of from 0.1 to 2.0% by weight per volume of alcohol, and a sufficient quantity of acidifying agent such as fumaric acid is added. Furthermore, the quantity of gel breaker is selected to break down the polymer within a predetermined time period, usually 1 to 24 hours.
The gel breaker is, in a preferred embodiment, ammonium persulfate, sodium persulfate, sodium perborate or a mixture of one or more of the foregoing and wherein said gel breaker may be coated or covered. The concentration of the breaker may be 0.1 to 10.0 Kg/m3 of alcohol.
The composition, in its preferred form, is admixed with a proppant selected from sand, synthetic sand or synthetic coated sand.
In another broad aspect, the present invention relates to a method of fracturing an underground formation such as an oil or gas well comprising: injecting the formation with an effective amount of a fracturing fluid gel composition ,,--comprising: at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol;
from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums; from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form; and from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing; and applying pressure to the composition in the formation to induce fracture of the formation.
In the method as aforesaid the complexor is sodium tetraborate in a solid or liquid form equivalent to from 0.5 to 4.0 Kg per cubic meter of alcohol, and the modified guar gum polymer is mixed with the alcohol in a concentration of from 0.1 to 2.0% by weight per volume of alcohol. A sufficient quantity of acidifying agent such as fumaric acid is added.
The quantity of gel breaker is selected to break down the polymer within a predetermined time period, such as 1 - 24 hours.
A
- ` 2i1~819~
The order of addition is as follows: the alcohol and guar gum are mixed first, with the fumaric acid, to form a base gel, that is permitted to gel for several minutes. The borate complexor is then added, followed by the gel breaker.
In the method of the present invention, the gel breaker is ammonium persulfate, sodium persulfate, sodium perborate or a mixture of one or more of the foregoing, and said gel breaker may be coated or covered. The concentration of the breaker is 0.1 to 10.0 Kg/m3 of alcohol.
7(a) 210~
Moreover, said alcohol, said guar gum, said complexor and said gel breaker are mixed together as they are being injected in a said well, in a most preferred embodiment.
In the method of the present invention, the order of addition of complexor and breaker is not considered crucial. Of more importance will be the selection of an appropriate quantity of breaker, and in this regard, one must consider the temperature at the bottom of the well. As an example, utilizing a fracturing fluid prepared with 6 Kg of guar gum per cubic metre of 100%
methanol, with about 16 litres of a 3.5% sodium borate solution added as a complexor, and 0.08 Kg of fumaric acid per cubic metre as an acidifying agent, the following results are obtained with sodium perborate breaker:
TABLE I
BREAK TIMES OF METHANOL GEL AT VARIOUS
CONCENTRATIONS AND TEMPERATURES
TEMPERATURE ( C) Breaker Concentration (Kg/m3) 60 70 80 90 O . 1 0.2 4 hrs 3 hrs 2 hrs 0.3 3 hrs 2 hrs 0.4 7 hrs 0.5 6 hrs It will be understood, then, that depending on the extent of fracturing desired at a given location, and the measured down hole temperature, different amounts of breaker will be added to the fracturing fluid as it is pumped down a well.
It a preferred method according to the present invention, after the base fel is formed, the complexor and breaker of the fracturing fluid are mixed together "on the fly", as the fluid is being pumped down a well. In this way, exposure of the guar gum to the complexor and breaker is not effected until just prior to injection of the fluid into a formation. This results in better pumpability into a well, and more accurate determination of when the gel will have broken. Moreover, should there be any delay due to equipment failure or the like, there is no wasted gel/complexor/breaker fluid.
It is to be understood that the examples described above are not meant to limit the scope of the present invention. It is expected that numerous variants will be obvious to the person s~illed in the oil and gas well fracturing fluid design field without any departure from the spirit of the invention. The appended claims, properly construed, form the only limitation upon the scope of the invention.
Claims (16)
1. A fracturing fluid composition for use in fracturing underground formations, such as oil or gas wells, comprising:
i) at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol;
ii) from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums;
iii) from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form; and iv) from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing.
i) at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol;
ii) from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums;
iii) from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form; and iv) from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing.
2. A fracturing fluid composition as claimed in claim 1, in which the modified guar gum polymer is selected from the group including carboxy methyl, hydroxy ethyl and hydroxy propyl guar gums.
3. A composition as claimed in claim 2, in which said modified guar gum polymer is mixed with the alcohol in a concentration of from 0.1 to 2.0% by weight per volume of alcohol, and a sufficient quantity of acidifying agent such as fumaric acid is added.
4. A composition as claimed in claim 3 in which the quantity of gel breaker is selected to break down the polymer within a predetermined time period.
5. A composition as claimed in claim 4 in which the quantity of gel breaker is selected to break down the gel in from 1 to 24 hours.
6. A composition as claimed in any of claims 1 - 5, admixed with proppant.
7. A composition as claimed in any of claims 1 - 5, admixed with a proppant selected from sand, synthetic sand or synthetic coated sand.
8. A method of fracturing an underground formation such as an oil or gas well comprising:
i) injecting the formation with an effective amount of a fracturing fluid gel composition comprising:
a) at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol;
b) from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums;
c) from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form;
d) from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing; and ii) applying pressure to the composition in the formation to induce fracture of the formation.
i) injecting the formation with an effective amount of a fracturing fluid gel composition comprising:
a) at least one anhydrous aliphatic alcohol selected from the group including methanol, ethanol and isopropanol;
b) from 0.1 to 2.0 wt %, relative to said alcohol, of a modified guar gum polymer selected from the group including hydroxy carboxy and alkyl guar gums;
c) from 0.5 to 4.0 Kg per m3 of alcohol of a sodium borate salt complexor selected from the group including sodium borate and sodium tetraborate, in solid or liquid form;
d) from 0.1 to 10.0 Kg per m3 of alcohol of a gel breaker which acts over a time period to degrade the guar gum cross linked polymer, and thereby reduce the viscosity of the gel, to aid in the removal thereof from a well, said breaker being selected from the group including ammonium persulfate, sodium persulfate, sodium perborate, or mixtures of one or more of the foregoing; and ii) applying pressure to the composition in the formation to induce fracture of the formation.
9. A method as claimed in claim 8 in which the modified guar gum polymer is selected from the group including carboxy methyl, hydroxy ethyl and hydroxy propyl guar gum.
10. A method as claimed in claim 8, in which said modified guar gum polymer is mixed with the alcohol in a concentration of from 0.1 to 2.0% by weight per volume of alcohol, and a sufficient quantity of acidifying agent such as fumaric acid is added.
11. A method as claimed in claim 9, in which the quantity of gel breaker is selected to break down the polymer within a predetermined time period.
12. A method as claimed in claim 10, in which the quantity of gel breaker is selected to break down the gel in from 1 to 24 hours.
13. A method as claimed in claim 11 wherein said gel breaker is coated or covered.
14. A method as claimed in any of claims 8 - 13, wherein a proppant is admixed with said fracturing fluid gel composition.
15. A method as claimed in any of claims 8 - 13, wherein a proppant selected from sand, synthetic sand or synthetic coated sand is admixed with said fracturing fluid gel composition.
16. A method as claimed in any of claims 8 - 13, wherein said alcohol and said guar gum are premixed together, with fumaric acid to form a base gel, said complexor and said gel breaker are added as they are being injected in a said well.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2108194 CA2108194C (en) | 1993-10-12 | 1993-10-12 | High viscosity crosslinked gelled alcohol |
| PCT/CA1994/000588 WO1995010688A1 (en) | 1993-10-12 | 1994-10-12 | High viscosity cross-linked gelled alcohol |
| AU79356/94A AU686675B2 (en) | 1993-10-12 | 1994-10-12 | High viscosity cross-linked gelled alcohol |
| DE69412998T DE69412998T2 (en) | 1993-10-12 | 1994-10-12 | HIGH VISCOSITY CROSSLINKED GELLY ALCOHOL |
| AT94930136T ATE170594T1 (en) | 1993-10-12 | 1994-10-12 | HIGH VISCOSITY CROSS-LINKED GEL-LIKE ALCOHOL |
| EP94930136A EP0672218B1 (en) | 1993-10-12 | 1994-10-12 | High viscosity cross-linked gelled alcohol |
| NO952211A NO952211L (en) | 1993-10-12 | 1995-06-02 | Cross-linked, high viscosity gel alcohol |
| US08/962,219 US5874385A (en) | 1993-10-12 | 1997-10-31 | High viscosity crosslinked gelled alcohol |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2108194 CA2108194C (en) | 1993-10-12 | 1993-10-12 | High viscosity crosslinked gelled alcohol |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2108194A1 CA2108194A1 (en) | 1995-04-13 |
| CA2108194C true CA2108194C (en) | 1997-05-06 |
Family
ID=4152433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2108194 Expired - Lifetime CA2108194C (en) | 1993-10-12 | 1993-10-12 | High viscosity crosslinked gelled alcohol |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2108194C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10012064B2 (en) | 2015-04-09 | 2018-07-03 | Highlands Natural Resources, Plc | Gas diverter for well and reservoir stimulation |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103254885B (en) * | 2012-02-16 | 2016-01-20 | 中国石油天然气股份有限公司 | The high temperature resistant high density fracturing liquid of a kind of retarded crosslinking |
| US10344204B2 (en) | 2015-04-09 | 2019-07-09 | Diversion Technologies, LLC | Gas diverter for well and reservoir stimulation |
| US10982520B2 (en) | 2016-04-27 | 2021-04-20 | Highland Natural Resources, PLC | Gas diverter for well and reservoir stimulation |
-
1993
- 1993-10-12 CA CA 2108194 patent/CA2108194C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10012064B2 (en) | 2015-04-09 | 2018-07-03 | Highlands Natural Resources, Plc | Gas diverter for well and reservoir stimulation |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2108194A1 (en) | 1995-04-13 |
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