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WO1992007881A1 - Procede permettant d'inhiber l'hydrolyse du polyacrylamide - Google Patents

Procede permettant d'inhiber l'hydrolyse du polyacrylamide Download PDF

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Publication number
WO1992007881A1
WO1992007881A1 PCT/US1991/004734 US9104734W WO9207881A1 WO 1992007881 A1 WO1992007881 A1 WO 1992007881A1 US 9104734 W US9104734 W US 9104734W WO 9207881 A1 WO9207881 A1 WO 9207881A1
Authority
WO
WIPO (PCT)
Prior art keywords
solution
polyacrylamide
hydrolysis
partially hydrolyzed
aqueous
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.)
Ceased
Application number
PCT/US1991/004734
Other languages
English (en)
Inventor
James E. Tackett, Jr.
Wayne E. Luetzelschwab
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Marathon Oil Co
Original Assignee
Marathon Oil Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Marathon Oil Co filed Critical Marathon Oil Co
Publication of WO1992007881A1 publication Critical patent/WO1992007881A1/fr
Priority to GB9300880A priority Critical patent/GB2262529B/en
Priority to NO931616A priority patent/NO931616D0/no
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/12—Hydrolysis

Definitions

  • the present invention relates to a method for storing aqueous solutions of partially hydrolyzed polyacrylamid ⁇ without increasing the percentage of polyacrylamide hydrolysis.
  • Polyacrylamide has many uses in the petroleum industry. Of particular importance is the use of polyacrylamide for matrix conformance gels during enhanced oil recovery. When used to improve matrix conformance, aqueous solutions of polyacrylamide are crosslinked to form gels within subterranean hydrocarbon-bearing formations. Inventions employing matrix conformance gels are exemplified by U.S. Patent Nos. 4,548,272, 4,561 ,502, and 4,679,625 and 4,683,949. Controlling temperature and pH during polymerization reactions influences the molecular weight and degree of hydrolysis (polymer qualities) of the polyacrylamide product. For example, U.S. Patent No.
  • Polyacrylamide that has undergone partial hydrolysis i.e., partially hydrolyzed polyacrylamide (PHPA) will have less than 100% of the amide moiety (CONH2) replaced by a carboxylate moiety (COO * ) via hydrolysis that occurs either during acrylamide monomer polymerization or after polymerization has taken place.
  • PHPA partially hydrolyzed polyacrylamide
  • Partially hydrolyzed polyacrylamide will have the general structure:
  • Aqueous solutions of very low hydrolysis polyacrylamide are useful for obtaining delayed gelation during gel treatments of oil-containing formations.
  • the gels obtain improved conformance and flow properties of fluids within formations (see commonly assigned, copending U. S. patent application to J. E. Tackett entitled “Process for Enhanced Delayed In Situ Gelation of Chromium Polyacrylamide Gels", which is being filed concurrently herewith).
  • the amount of hydrolysis of the partially hydrolyzed polyacrylamide increases, the gelation delay time decreases. Therefore, it is desirable to be able to store aqueous solutions of very low hydrolysis polyacrylamide without the level of hydrolysis increasing.
  • aqueous solutions of polyacrylamide are adjusted to a pH of about 3.5 to about 6.8 prior to storage to inhibit autohydroiysis.
  • Figure 1 is a graph showing the functional relationship between hydrolysis over time at 180°F (82°C);
  • Figure 2 is a graph showing the portion of Figure 1 between 0 and 16 hours in expanded scale which details the functional relationship between hydrolysis and pH over time at 180°F (82°C).
  • the process of the present invention is conducted by adjusting the pH of an aqueous polyacrylamide solution to a pH of about 3.5 to about 6.8, preferably from about 3.5 to about 6 and most preferably from about 3.5 to about 5 prior to storage.
  • the level of polyacrylamide hydrolysis is less than about 5 mole %, preferably less than about 1 mole % and most preferably less than about 0.1 mole %.
  • the polyacrylamide is present in solution from about 2% to about 20%, preferably from about 5% to about 12% and most preferably from about 6% to about 10% by weight. Solutions should be stored with polyacrylamide concentration above 2% because solutions containing less than about 2% by weight of polyacrylamide tend to hydrolyze faster than solutions containing higher polyacrylamide concentrations.
  • Mineral acids such as hydrochloric, sulfuric or nitric acids or bases such as sodium hydroxide or aniline are used to adjust the pH of the polyacrylamide solution.
  • Buffers are ideally used to adjust and maintain polyacrylamide solution pH. Buffers with pKa values of about 3.5 to about 6.8 are preferred, such as monocarboxylates, hydrogen phosphates, and polyamines such as triethylene tetraamine, tetraethylene pentamine and hexamethylene tetraamine or mixtures thereof.
  • the end use of the polymer should be considered in buffer selection.
  • dicarboxylate or tricarboxylic buffers such as malonic, oxalic and citric acids should be avoided if the polymer will eventually be used with chromium (III) gelation agents because the closely spaced dicarboxylates and tricarboxylates will chelate the gelation agents and thereby effectively prevent gelation.
  • Acetate buffers can also be used advantageously as is suggested by a commonly assigned, copending U. S. patent application to J. E. Tackett, entitled “Process for Enhanced Delayed In Situ Gelation of Chromium Polyacrylamide Gels", which was filed concurrently herewith.
  • the water that makes up the bulk of the solution can be fresh water or brine containing a total dissolved solids concentration up to the solubility limit of the solids in water.
  • the practice of this invention is best illustrated by specific examples.
  • a 6% by weight aqueous poiyacryiamide solution containing less than 0.1 mole % polyacrylamide hydrolysis is stored at a room temperature of approximately 68°F (20°C) at a pH of 4.8 for 2 years. After storage, the hydrolysis levels are measured and the hydrolysis level is less than 0.1 mole
  • Sample 1 is stored at room temperature (68°F/20°C)
  • sample 2 is stored in a refrigerator at between 32°F (0°C) to 50°F (10°C)
  • sample 3 is stored in a freezer at less than 32°F (0°C). All three samples are stored for 1 year.
  • the hydrolysis levels of sample 1 increases to 0.4 mole % and pH increases to 7.6.
  • the hydrolysis levels of samples 2 and 3 remain less than 0.1 mole % and the pH remains at 6.8.
  • EXAMPLE 3 A 6% by weight aqueous polyacrylamide solution containing less than 0.1 mole % hydrolysis and having a pH of 6.8 is heated at 180°F (82°C) while pH and percent hydrolysis are monitored. These results are shown in Figures 1 and 2. These data suggest that while the solution pH is below 7 the carboxyl content remains low. However, after about 40 minutes, the pH and the percent hydrolysis increases. This incubation period is probably due to the slight buffering capacity of the amide groups. Once it is exceeded, the pH increases significantly and so does the percent hydrolysis.
  • EXAMPLE 4 A 6% by weight aqueous polyacrylamide solution containing less than 0.1 mole % hydrolysis is buffered with ammonium phosphate to a pH of 5.9. The buffered solution is heated to 230°F (110°C) for 170 hours. No significant increase of hydrolysis content is noted.
  • EXAMPLE 5 A 2% by weight aqueous polyacrylamide solution containing less than 0.1 mole % hydrolysis and having a pH of 7.1 is heated for 20 hours at 175°F (79.4°C). The solution pH increases to 8.3 and hydrolysis increases to 1.2 mole %.
  • a 2% by weight aqueous polyacrylamide solution containing 0.3 mole % hydrolysis is buffered to a pH of 5.9 using ammonium phosphate.
  • the solution is then heated at 175°F (79.4°C) for 40 hours.
  • the solution pH remains at 5.9 and the solution hydrolysis increases to 0.6 mole %.
  • a 2% by weight aqueous polyacrylamide solution containing 0.3 mole % hydrolysis is buffered to a pH of 5.4 using ammonium phosphate.
  • the solution is then heated at 162°F (72°C) for 20 hours.
  • the solution pH remains at 5.4 and the solution hydrolysis remains at 0.3 mole %.
  • EXAMPLE 8 A 2% by weight aqueous polyacrylamide solution containing 0.3 mole % hydrolysis is buffered to a pH of 6.5 using ammonium phosphate. The solution is then heated at 110 ⁇ F (43 ⁇ C) for 170 hours. The solution pH remains at 6.5 and the solution hydrolysis remains at 0.3 mole %.
  • an aqueous polyacrylamide solution can be stored without a significant increase in hydrolysis at temperatures below 175°F (79.4°C) if the solution pH is adjusted to about 3.5 to about 6.8 prior to storage and thereafter maintained within this pH range. While the results set forth in the Examples illustrate that aqueous solutions of partially hydrolyzed polyacrylamide are ' storable for 2 years, aqueous solutions of partially hydrolyzed polyacrylamide may be stored for longer periods of time in accordance with the process of the present invention.
  • This process allows for an aqueous polyacrylamide solution to be stored and transported in a form that is ready for use, for example the aqueous polyacrylamide solution may be used in a gelation process, without an increase in polymer hydrolysis that decreases the solution's gelation utility.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Medicinal Preparation (AREA)
  • Saccharide Compounds (AREA)

Abstract

On peut stocker des solutions aqueuses de polyacrylamide partiellement hydrolysées en ajustant et en maintenant le pH de la solution à des valeurs comprises entre environ 3,5 et 6,8 avant le stockage. Le stockage à un pH supérieur à 6,8 ou inférieur à 3,5 provoque l'hydrolyse. On obtient le pH désiré de la solution en ajoutant des acides ou des bases inorganiques appropriées ou en ajoutant des systèmes de tampon dont les valeurs de pKa sont comprises entre environ 3,5 et environ 6,8.
PCT/US1991/004734 1990-11-05 1991-07-03 Procede permettant d'inhiber l'hydrolyse du polyacrylamide Ceased WO1992007881A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9300880A GB2262529B (en) 1990-11-05 1993-01-18 A method for inhibiting hydrolysis of polyacrylamide
NO931616A NO931616D0 (no) 1990-11-05 1993-05-04 Fremgangsmaate for aa hemme hydrolyse av polyakrylamid

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US60949290A 1990-11-05 1990-11-05
US609,492 1990-11-05

Publications (1)

Publication Number Publication Date
WO1992007881A1 true WO1992007881A1 (fr) 1992-05-14

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1991/004734 Ceased WO1992007881A1 (fr) 1990-11-05 1991-07-03 Procede permettant d'inhiber l'hydrolyse du polyacrylamide

Country Status (7)

Country Link
CN (1) CN1061226A (fr)
AR (1) AR245150A1 (fr)
AU (1) AU8845191A (fr)
CA (1) CA2086597A1 (fr)
GB (1) GB2262529B (fr)
TN (1) TNSN91094A1 (fr)
WO (1) WO1992007881A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1072617A1 (fr) * 1999-07-30 2001-01-31 Universiteit van Utrecht Polymères sensibles à la température
US7425581B2 (en) 1999-07-30 2008-09-16 Universiteit Utrecht Temperature sensitive polymers

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2446257A1 (de) * 1973-09-29 1975-04-03 Nitto Chemical Industry Co Ltd Verfahren zur herstellung von wasserloeslichem hochmolekularem polyacrylamid
JPS52137483A (en) * 1976-05-13 1977-11-16 Nitto Chem Ind Co Ltd Preparation of partially hydrolyzed polyacrylamide
JPS60108404A (ja) * 1983-11-17 1985-06-13 Mitsubishi Chem Ind Ltd 部分加水分解されたアクリルアミド系重合体の製造法
EP0176757A2 (fr) * 1984-09-24 1986-04-09 Polypure Inc. Préparation d'un polymère cationique soluble dans l'eau et produit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2446257A1 (de) * 1973-09-29 1975-04-03 Nitto Chemical Industry Co Ltd Verfahren zur herstellung von wasserloeslichem hochmolekularem polyacrylamid
JPS52137483A (en) * 1976-05-13 1977-11-16 Nitto Chem Ind Co Ltd Preparation of partially hydrolyzed polyacrylamide
JPS60108404A (ja) * 1983-11-17 1985-06-13 Mitsubishi Chem Ind Ltd 部分加水分解されたアクリルアミド系重合体の製造法
EP0176757A2 (fr) * 1984-09-24 1986-04-09 Polypure Inc. Préparation d'un polymère cationique soluble dans l'eau et produit

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
WORLD PATENTS INDEX Derwent Publications Ltd., London, GB; AN 78-01037A & JP,A,52 137 483 (NITTO CHEM IND KK) 16 November 1977 see abstract *
WORLD PATENTS INDEX LATEST Derwent Publications Ltd., London, GB; AN 85-180724 & JP,A,60 108 404 (MITSUBISHI CHEM IND KK) 13 June 1985 see abstract *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1072617A1 (fr) * 1999-07-30 2001-01-31 Universiteit van Utrecht Polymères sensibles à la température
WO2001009198A1 (fr) * 1999-07-30 2001-02-08 Stichting Voor De Technische Wetenschappen Polymeres sensibles a la temperature
US7425581B2 (en) 1999-07-30 2008-09-16 Universiteit Utrecht Temperature sensitive polymers

Also Published As

Publication number Publication date
CN1061226A (zh) 1992-05-20
CA2086597A1 (fr) 1992-05-06
TNSN91094A1 (fr) 1992-10-25
GB2262529A (en) 1993-06-23
GB2262529B (en) 1994-04-06
GB9300880D0 (en) 1993-03-31
AR245150A1 (es) 1993-12-30
AU8845191A (en) 1992-05-26

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