CA1070492A - Stabilizing the viscosity of an aqueous solution of polysaccharide polymer - Google Patents
Stabilizing the viscosity of an aqueous solution of polysaccharide polymerInfo
- Publication number
- CA1070492A CA1070492A CA273,509A CA273509A CA1070492A CA 1070492 A CA1070492 A CA 1070492A CA 273509 A CA273509 A CA 273509A CA 1070492 A CA1070492 A CA 1070492A
- Authority
- CA
- Canada
- Prior art keywords
- solution
- water
- soluble
- deoxygenated
- anionic polysaccharide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- C09K8/84—Compositions based on water or polar solvents
- C09K8/86—Compositions based on water or polar solvents containing organic compounds
- C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/90—Compositions based on water or polar solvents containing organic compounds macromolecular compounds of natural origin, e.g. polysaccharides, cellulose
- C09K8/905—Biopolymers
-
- 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
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/26—Gel breakers other than bacteria or enzymes
Landscapes
- Chemical & Material Sciences (AREA)
- 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)
- Food Preservation Except Freezing, Refrigeration, And Drying (AREA)
- Medicines Containing Plant Substances (AREA)
- Fats And Perfumes (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
- Anti-Oxidant Or Stabilizer Compositions (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
A B S T R A C T
In an oil recovery process in which an aqueous solution thickened with a water-soluble anionic polysaccharide polymer (Xanthan gum) is injected into a subterranean reservoir, the stability of the solution viscosity is improved by de-oxygenating the aqueous liquid and then adding a sulphur-containing antioxidant, a readily oxidizable water-soluble alcohol or glycol, and a polysaccharide polymer.
In an oil recovery process in which an aqueous solution thickened with a water-soluble anionic polysaccharide polymer (Xanthan gum) is injected into a subterranean reservoir, the stability of the solution viscosity is improved by de-oxygenating the aqueous liquid and then adding a sulphur-containing antioxidant, a readily oxidizable water-soluble alcohol or glycol, and a polysaccharide polymer.
Description
The invention relates to an oil recovery process in which an aqueous solution which contains enough water-soluble anionic polysaccharide polymer to reduce its mobility is injected into a subterranean reservoir to displace fluid toward a production well or production wells.
The chemical composition of water-soluble anionic poly-saccharide polymers (or Xanthan gums) which are effective as water-thickening agents is such that the polymers are susceptible to chemical degradation or depolymeriz-ation. The degradation, which tends to increase with increasing temperature, reduces the viscosity of a solution containing the polymers. Two paths by which such a degradation can occur comprise hydrolysis and free-radical reac-tions. The hydrolysis involves the reaction of molecules of water with the ether-type lin~ages in the structure of the polysaccharide polymer. The free-radical reactions are usually those initiated when the polymer solution is mixed with air or oxygen. Such a mixture tends to form hydroperoxides and the decomposition of the hydroperoxides produces reaction-initiating free-radicals that propagate polymer-degrading radical reactions.
Numerous types of materials and techniques for treating aqueous solutions to remove dissolved oxygen are known to those skilled in the art.
In general, such treatments are based on or completed by dissolving a strong reducing agent or oxygen scavenger in the solution. In a solution in which a radical degradable polymer is present, a combination of oxygen and oxygen scavenger creates an oxidation reduction couple or redox system Since free-radical reaction initiating radicals are intermediate products of the reaction between the oxygen scavenger and the oxygen, the reactions are such that, al-though the system will remove the oxygen, it will also degrade the polymer.
Ob3ect of the invention is a method of stabilizing the viscosity of an aqueous solution of polysaccharide polymer which does not show the a~ove-mentioned d~sadYantage.
According to the present invention there is provided oil recovery process comprising the steps of:
treating an aqueous liquid solution to remove substantially all 1~70492 dissolved oxygen;
a~ding to the deoxygenated solution at least one water-soluble sul-phur-containing antioxidant;
adding to the deoxygenated solution at least one water-soluble readily oxidizable alcohol or glycol;
adding to the deoxygenated solution at least one water-soluble anionic polysaccharide polymer; and injecting the polymer-thickened aqueous solution into an oil-con-taining subsurface reservoir via at least one in~ection well for displacing fluids in the reservoir to at least one production well.
;
-2a-~ ~.
.
10~70492 The aqueous li~uid used in the present procesS can be substantially , any fresh or saline water but is preferably a relatively soft and not ! extensively saline water. Such a water preferably has a total dissolved salt content of not more than about 5,000 ppm and a hardness (in terms of parts per million of calcium ions) of not more than about 500 ppm. When deoxygenated for use in the present process, such a water is preferably substantially completely free of dissolved oxygen and contains from about 10 to 100 parts per million S03-group-containing oxygen sca~enger (in terms of S03-group equivalent~. The aqueous liquid may be treated to remove substantially all dissolved oxygen therefrom by adding to it a reducing agent or an oxygen scavenger.
Water-soluble inorganic compounds that contain or form ions that contain an S03-group are particularly suitable for use in the present process as reducing agents or oxygen scavengers. Such compounds include water-soluble al~ali metal sulphites, bisulphites, dithionites, etc. As known to those skilled in the art, such a reducing agent or oxygen scavenger is preferably used in a slight stoichiometric excess (relative to the amount needed to remove substantially all of the dissolved oxygen in the solution being treated). Such an excess is preferably from about 10 to 500% more than stoichiometric.
The sulphur-containing antioxidant used in the present process can comprise substantially any such water-soluble antioxidant composition ~transfer agent, terminator, peroxide decomposer) which is effective with respect to decomposing peroxides in a~ueous solutions. Examples of such compounds include relati~ely water-soluble mercaptans, thioethers, thio-carbinols, and the li~e. Particularly suita~le examples are thiourea, thiodiacetic acid (thiodiglycolic acid), 3,31-thiodiacetic acid ~dithio-diglycolic acid) and their water-soluble homologues.
Suitable readily oxidizable alcohols or glycols for use in the present process include substantially any water-soluble primary and secondary alcohols or glycols that are easily oxidized. Examples of such ~ - 3 -compounds include methanol, ethanol, alkyl alcohol, isopropyl alcohol, isobutyl alcohol, ethylene glycol, and the like.
As indicated in laboratory tests, in a deoxygenated aqueous solution in which an oxygen scavenger is present, a significant beneficial synergistic antioxidant effect is exhibited where a readily oxidizable water-soluble alcohol or glycol is added to the sulphur-containing antioxidant.
'` - 3a -The anionic polysaccharide polymers, or Xanthan gums suitable for use in the present process, can be substantially any such materials pro-duced by the fermentation of carbohydrates by bacteria of the genus Xa~thomonas. In general, the anionic polysaccharide B-1~59 is preferred.
Examples of commercially available polymers comprise the Pfizer Xanthan Biopolymers (trademark) available for Pfizer ~hemical Company, the General Mills Xanthan Biopolymers (trademark) available from General Mills Company, and the Kelzan (trademark) or Xanflood (trademark) anionic polysaccharides available ~rom Kelco Company.
The anionic polysaccharides u::ed in the present process ~and/or the fermentation broth in which they are made) are preferably treated with enzymes such as a proteinase to ensure the removal of (or destruction of) bacterial cells which may impede the flow of a solution into fine pores within subterranean earth formations. Alternatively, such clarifications may be accomplished by or supplemented by means of centrifugation, filtra-tion, and the li~e.
As known to those skilled in the art, in an oil recovery process in which fluids are displaced within a subterranean reservoir by injecting ~ viscosity enhanced aqueous solution, the effective viscosity (or recip-rocal mobility within the reservoir) should be at least substantially equal to and preferably greater than that of the fluid to be displaced.
In the present process, the concentration of anionic polysaccharide in such a solution should be in the order of about 100 to 2,000 parts by weight of pol~acchariae per million parts by weight of aqueous liquid.
Such concentrations gener~lly provide viscosities in the order of from about 2 to 50 centipoises at room temperature, in a water containing about 400 parts per million total solids.
In t~e present process, the concentration of antioxidant can be relatively low, in the order of about 50 parts per million (weight per weight of a~ueous liquid) and preferably from about 200 to 800 parts per million. The readily oxidizable alcohol or glycol concentration can be from about 50 to 2,000 parts per million, snd preferably from about 500 to ~,000 parts per million. In general, the concentrations of the readily oxidizable alcohol or glycol and the polysaccharide polymer are preferably kept at least nearly equal (e.g., at least within about 10% of each other~.
Substantially fresh w~ter solutions containing aQ0 parts per million ~elzan polysaccharidel from about 200 to 800 parts per milli`on thiourea, and 500 to 1,000 parts per millior isoprGpyl alcohol have retained from about 75-90% o~ their original viscosity after eight months storage at 97C. In such storage tests, the best and most consistant results were obtaired uhen the isopropyl alcohol and Kelzan concentrations were about equal and the thiourea concentration was about half ~he isopro~yl alcohol concentratîon.
Stability in the presence of air was indicated by the follouing laboratory tests. Enzyme clarified solutionswere stored at 97C, said solutions containing 1,000 parts per million Kelzan MF polysaccharide polymer (available from Kelco Company~, 3,000 parts per million sodium chloride, 1,000 parts per mill-on of each of sodium sulphite, isopropyl alcohol, 500 parts per million thiourea, and 20 parts per million Dowicide G (trademark) available from Dow Chemical Company.
In order to simulate the contacts with air which are l;kely to occur (due to leaks) in a water~lood oil recovery system in the field, 35 cc samples of the polymer solution were retained in bottles containing 1 cc of air above the liquid. The so stored sa~ples retained more than 80% of their initial viscosity after storage for seven months.
The drawing shows a graph of viscosity (in cps at 7.3 sec 1, Brcokfield) vers~s time ~ lin months) at 97C. The cur~e labe~ed A relates to a basic test solution of 80o ppm o~ each of Kelzan MF polysaccharide polymer, sodium chloride and sodium sulphite in distilled water; which also contained ~00 ppm thiourea and 80~ ppm isopropyl alcohol (IPA~. The curves labe~ed B, C and D relate to solutions in which the compositions were the same except for the ommission~of IPA in curve B; thiou~ea in curve C; and IPA and thiourea in curYe D.
The unobviously beneficial results pro~ided by the combination of the sulphur-containing antioxidant and the readily oxidizable alcohol are indicated by the retention of a Yiscosity of substantially 15 cps throughout the six-month test period.
(~
In prepsring an aqueous solution in accordance with the present process, the water should be deoxygenated before the other components are added. This avoids any chance that the anionic polysacchi~ride polymer, oxygen, and oxygen scavenger will be mixed together within the solution. The antioxidant (and any antibacterial agent, or the like, to be used) can be added before, with, or after the anionic polysaccharide polymer.
If the antioxidants are added before or simultaneously with the oxygen scavenger they may be comsumed in the reactions that ensue.
Antibacterial agents suitable for use in the present process can comprise sodium ss-ts of tri- and pentachlorophenols, form-aldehyde, aliphatic diamine salts and alkyldimethyl-benzylsmmonium chlorides.
The chemical composition of water-soluble anionic poly-saccharide polymers (or Xanthan gums) which are effective as water-thickening agents is such that the polymers are susceptible to chemical degradation or depolymeriz-ation. The degradation, which tends to increase with increasing temperature, reduces the viscosity of a solution containing the polymers. Two paths by which such a degradation can occur comprise hydrolysis and free-radical reac-tions. The hydrolysis involves the reaction of molecules of water with the ether-type lin~ages in the structure of the polysaccharide polymer. The free-radical reactions are usually those initiated when the polymer solution is mixed with air or oxygen. Such a mixture tends to form hydroperoxides and the decomposition of the hydroperoxides produces reaction-initiating free-radicals that propagate polymer-degrading radical reactions.
Numerous types of materials and techniques for treating aqueous solutions to remove dissolved oxygen are known to those skilled in the art.
In general, such treatments are based on or completed by dissolving a strong reducing agent or oxygen scavenger in the solution. In a solution in which a radical degradable polymer is present, a combination of oxygen and oxygen scavenger creates an oxidation reduction couple or redox system Since free-radical reaction initiating radicals are intermediate products of the reaction between the oxygen scavenger and the oxygen, the reactions are such that, al-though the system will remove the oxygen, it will also degrade the polymer.
Ob3ect of the invention is a method of stabilizing the viscosity of an aqueous solution of polysaccharide polymer which does not show the a~ove-mentioned d~sadYantage.
According to the present invention there is provided oil recovery process comprising the steps of:
treating an aqueous liquid solution to remove substantially all 1~70492 dissolved oxygen;
a~ding to the deoxygenated solution at least one water-soluble sul-phur-containing antioxidant;
adding to the deoxygenated solution at least one water-soluble readily oxidizable alcohol or glycol;
adding to the deoxygenated solution at least one water-soluble anionic polysaccharide polymer; and injecting the polymer-thickened aqueous solution into an oil-con-taining subsurface reservoir via at least one in~ection well for displacing fluids in the reservoir to at least one production well.
;
-2a-~ ~.
.
10~70492 The aqueous li~uid used in the present procesS can be substantially , any fresh or saline water but is preferably a relatively soft and not ! extensively saline water. Such a water preferably has a total dissolved salt content of not more than about 5,000 ppm and a hardness (in terms of parts per million of calcium ions) of not more than about 500 ppm. When deoxygenated for use in the present process, such a water is preferably substantially completely free of dissolved oxygen and contains from about 10 to 100 parts per million S03-group-containing oxygen sca~enger (in terms of S03-group equivalent~. The aqueous liquid may be treated to remove substantially all dissolved oxygen therefrom by adding to it a reducing agent or an oxygen scavenger.
Water-soluble inorganic compounds that contain or form ions that contain an S03-group are particularly suitable for use in the present process as reducing agents or oxygen scavengers. Such compounds include water-soluble al~ali metal sulphites, bisulphites, dithionites, etc. As known to those skilled in the art, such a reducing agent or oxygen scavenger is preferably used in a slight stoichiometric excess (relative to the amount needed to remove substantially all of the dissolved oxygen in the solution being treated). Such an excess is preferably from about 10 to 500% more than stoichiometric.
The sulphur-containing antioxidant used in the present process can comprise substantially any such water-soluble antioxidant composition ~transfer agent, terminator, peroxide decomposer) which is effective with respect to decomposing peroxides in a~ueous solutions. Examples of such compounds include relati~ely water-soluble mercaptans, thioethers, thio-carbinols, and the li~e. Particularly suita~le examples are thiourea, thiodiacetic acid (thiodiglycolic acid), 3,31-thiodiacetic acid ~dithio-diglycolic acid) and their water-soluble homologues.
Suitable readily oxidizable alcohols or glycols for use in the present process include substantially any water-soluble primary and secondary alcohols or glycols that are easily oxidized. Examples of such ~ - 3 -compounds include methanol, ethanol, alkyl alcohol, isopropyl alcohol, isobutyl alcohol, ethylene glycol, and the like.
As indicated in laboratory tests, in a deoxygenated aqueous solution in which an oxygen scavenger is present, a significant beneficial synergistic antioxidant effect is exhibited where a readily oxidizable water-soluble alcohol or glycol is added to the sulphur-containing antioxidant.
'` - 3a -The anionic polysaccharide polymers, or Xanthan gums suitable for use in the present process, can be substantially any such materials pro-duced by the fermentation of carbohydrates by bacteria of the genus Xa~thomonas. In general, the anionic polysaccharide B-1~59 is preferred.
Examples of commercially available polymers comprise the Pfizer Xanthan Biopolymers (trademark) available for Pfizer ~hemical Company, the General Mills Xanthan Biopolymers (trademark) available from General Mills Company, and the Kelzan (trademark) or Xanflood (trademark) anionic polysaccharides available ~rom Kelco Company.
The anionic polysaccharides u::ed in the present process ~and/or the fermentation broth in which they are made) are preferably treated with enzymes such as a proteinase to ensure the removal of (or destruction of) bacterial cells which may impede the flow of a solution into fine pores within subterranean earth formations. Alternatively, such clarifications may be accomplished by or supplemented by means of centrifugation, filtra-tion, and the li~e.
As known to those skilled in the art, in an oil recovery process in which fluids are displaced within a subterranean reservoir by injecting ~ viscosity enhanced aqueous solution, the effective viscosity (or recip-rocal mobility within the reservoir) should be at least substantially equal to and preferably greater than that of the fluid to be displaced.
In the present process, the concentration of anionic polysaccharide in such a solution should be in the order of about 100 to 2,000 parts by weight of pol~acchariae per million parts by weight of aqueous liquid.
Such concentrations gener~lly provide viscosities in the order of from about 2 to 50 centipoises at room temperature, in a water containing about 400 parts per million total solids.
In t~e present process, the concentration of antioxidant can be relatively low, in the order of about 50 parts per million (weight per weight of a~ueous liquid) and preferably from about 200 to 800 parts per million. The readily oxidizable alcohol or glycol concentration can be from about 50 to 2,000 parts per million, snd preferably from about 500 to ~,000 parts per million. In general, the concentrations of the readily oxidizable alcohol or glycol and the polysaccharide polymer are preferably kept at least nearly equal (e.g., at least within about 10% of each other~.
Substantially fresh w~ter solutions containing aQ0 parts per million ~elzan polysaccharidel from about 200 to 800 parts per milli`on thiourea, and 500 to 1,000 parts per millior isoprGpyl alcohol have retained from about 75-90% o~ their original viscosity after eight months storage at 97C. In such storage tests, the best and most consistant results were obtaired uhen the isopropyl alcohol and Kelzan concentrations were about equal and the thiourea concentration was about half ~he isopro~yl alcohol concentratîon.
Stability in the presence of air was indicated by the follouing laboratory tests. Enzyme clarified solutionswere stored at 97C, said solutions containing 1,000 parts per million Kelzan MF polysaccharide polymer (available from Kelco Company~, 3,000 parts per million sodium chloride, 1,000 parts per mill-on of each of sodium sulphite, isopropyl alcohol, 500 parts per million thiourea, and 20 parts per million Dowicide G (trademark) available from Dow Chemical Company.
In order to simulate the contacts with air which are l;kely to occur (due to leaks) in a water~lood oil recovery system in the field, 35 cc samples of the polymer solution were retained in bottles containing 1 cc of air above the liquid. The so stored sa~ples retained more than 80% of their initial viscosity after storage for seven months.
The drawing shows a graph of viscosity (in cps at 7.3 sec 1, Brcokfield) vers~s time ~ lin months) at 97C. The cur~e labe~ed A relates to a basic test solution of 80o ppm o~ each of Kelzan MF polysaccharide polymer, sodium chloride and sodium sulphite in distilled water; which also contained ~00 ppm thiourea and 80~ ppm isopropyl alcohol (IPA~. The curves labe~ed B, C and D relate to solutions in which the compositions were the same except for the ommission~of IPA in curve B; thiou~ea in curve C; and IPA and thiourea in curYe D.
The unobviously beneficial results pro~ided by the combination of the sulphur-containing antioxidant and the readily oxidizable alcohol are indicated by the retention of a Yiscosity of substantially 15 cps throughout the six-month test period.
(~
In prepsring an aqueous solution in accordance with the present process, the water should be deoxygenated before the other components are added. This avoids any chance that the anionic polysacchi~ride polymer, oxygen, and oxygen scavenger will be mixed together within the solution. The antioxidant (and any antibacterial agent, or the like, to be used) can be added before, with, or after the anionic polysaccharide polymer.
If the antioxidants are added before or simultaneously with the oxygen scavenger they may be comsumed in the reactions that ensue.
Antibacterial agents suitable for use in the present process can comprise sodium ss-ts of tri- and pentachlorophenols, form-aldehyde, aliphatic diamine salts and alkyldimethyl-benzylsmmonium chlorides.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Oil recovery process comprising the steps of: treating an aqueous liquid solution to remove substantially all dissolved oxygen; adding to the deoxygenated solution at least one water-soluble sulphur-containing antioxidant; adding to the deoxygenated solution at least one water-soluble readily oxidizable alcohol or glycol; adding to the deoxygenated solution at least one water-soluble anionic polysaccharide polymer; and injecting the polymer-thickened aqueous solution into an oil-containing subsurface reservoir via at least one injection well for displacing fluids in the reservoir to at least one production well.
2. The process of claim 1 wherein oxygen is removed from the aqueous liquid solution by means of a reducing agent.
3. The process of claim 2 in which the reducing agent is a water-soluble compound that contains or forms ions that contain an SO3-group.
4. The process of any one of the claims 1-3 in which the sulphur-containing antioxidant is a member of the group consisting of mercaptans, thioethers and thiocarbinols.
5. The process of any one of the claims 1-3 in which the antioxidant which is added is thiourea and the readily oxidizable alcohol which is added is isopropyl alcohol.
6. The process of any one of the claims 1-3 in which the anionic polysaccharide which is added is clarified by reacting it with a proteinase.
7. In a process in which an anionic polysaccharide-thickened aqueous solution is flowed into a relatively remote location in which the solution viscosity may be decreased by a relatively long exposure to a relatively high temperature, an improved process for preparing the thickened aqueous solution which comprises: treating an aqueous liquid solution to remove substantially all dissolved oxygen;
adding to the deoxygenated solution at least one water-soluble sulphur-containing antioxidant; adding to the deoxygenated solution at least one water-soluble readily oxidizable alcohol or glycol; and adding to the deoxy-genated solution at least one water-soluble anionic polysaccharide polymer.
adding to the deoxygenated solution at least one water-soluble sulphur-containing antioxidant; adding to the deoxygenated solution at least one water-soluble readily oxidizable alcohol or glycol; and adding to the deoxy-genated solution at least one water-soluble anionic polysaccharide polymer.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67351876A | 1976-04-05 | 1976-04-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070492A true CA1070492A (en) | 1980-01-29 |
Family
ID=24702987
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA273,509A Expired CA1070492A (en) | 1976-04-05 | 1977-03-09 | Stabilizing the viscosity of an aqueous solution of polysaccharide polymer |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1070492A (en) |
| DE (1) | DE2715026C2 (en) |
| GB (1) | GB1518628A (en) |
| NL (1) | NL7703635A (en) |
| NO (1) | NO150573C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4331543A (en) * | 1978-10-16 | 1982-05-25 | Mobil Oil Corporation | Method of retarding degradation of surfactants employed in waterflooding |
| US4425246A (en) | 1981-09-18 | 1984-01-10 | Exxon Research & Engineering Co. | Oil recovery using stabilized saline heat-treated heteropolysaccharide solutions |
| FR2945542B1 (en) * | 2009-05-18 | 2013-01-11 | Snf Sas | NOVEL WATER SOLUBLE POLYMER FORMULATIONS AND STABILIZING ADDITIVES FOR THE INJECTION OF A SINGLE COMPOUND USEFUL IN INJECTION FLUIDS FOR THE CHEMICAL ASSISTED RECOVERY OF PETROLEUM |
-
1977
- 1977-03-09 CA CA273,509A patent/CA1070492A/en not_active Expired
- 1977-04-04 DE DE2715026A patent/DE2715026C2/en not_active Expired
- 1977-04-04 NO NO771181A patent/NO150573C/en unknown
- 1977-04-04 NL NL7703635A patent/NL7703635A/en not_active Application Discontinuation
- 1977-04-04 GB GB14145/77A patent/GB1518628A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NO150573C (en) | 1984-11-14 |
| NO771181L (en) | 1977-10-06 |
| DE2715026A1 (en) | 1977-10-13 |
| DE2715026C2 (en) | 1986-05-15 |
| NO150573B (en) | 1984-07-30 |
| NL7703635A (en) | 1977-10-07 |
| GB1518628A (en) | 1978-07-19 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |