CA1135490A - Aqueous emulsion of an acrylamide polymer for oil recovery - Google Patents
Aqueous emulsion of an acrylamide polymer for oil recoveryInfo
- Publication number
- CA1135490A CA1135490A CA000364592A CA364592A CA1135490A CA 1135490 A CA1135490 A CA 1135490A CA 000364592 A CA000364592 A CA 000364592A CA 364592 A CA364592 A CA 364592A CA 1135490 A CA1135490 A CA 1135490A
- Authority
- CA
- Canada
- Prior art keywords
- water
- acrylamide
- oil
- crude
- oil emulsion
- 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
- 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
- C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
- C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
- C08F20/52—Amides or imides
- C08F20/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
- C08F20/56—Acrylamide; Methacrylamide
-
- 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
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
- C09K8/588—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific polymers
Abstract
ABSTRACT OF THE DISCLOSURE
In a process for recovering oil from underground formations of the type wherein a dilute aqueous solution of an acrylamide polymer is injected into one or more wells the improvement which comprises: establishing near the one or more wells a small chemical plant and a source of acrylonitrile for producing an acrylamide polymer in the form of water-in oil emulsion, which plant performs the following sequence of steps:
1. Forming a water-in-oil emulsion of acrylonitrile utilizing as an oil source crude oil recovered from the underground formation;
2. Contacting said emulsion with a conversion catalyst under reaction conditions to convert a substantial portion of the acrylonitrile to acrylamide thereby forming a water-in-crude-oil emulsion which contains a substantial portion of acrylamide;
3. Polymerizing the water-in-crude-oil emulsion of acrylamide in the presence of a free radical catalyst to provide a water-in-crude-oil emulsion of acrylamide polymers, and then;
Injecting the water-in-crude-oil emulsion of the acrylamide polymer in the presence of an inverting agent into the underground formation under conditions whereby the formation is contacted with a dilute solution of the acrylamide polymer.
In a process for recovering oil from underground formations of the type wherein a dilute aqueous solution of an acrylamide polymer is injected into one or more wells the improvement which comprises: establishing near the one or more wells a small chemical plant and a source of acrylonitrile for producing an acrylamide polymer in the form of water-in oil emulsion, which plant performs the following sequence of steps:
1. Forming a water-in-oil emulsion of acrylonitrile utilizing as an oil source crude oil recovered from the underground formation;
2. Contacting said emulsion with a conversion catalyst under reaction conditions to convert a substantial portion of the acrylonitrile to acrylamide thereby forming a water-in-crude-oil emulsion which contains a substantial portion of acrylamide;
3. Polymerizing the water-in-crude-oil emulsion of acrylamide in the presence of a free radical catalyst to provide a water-in-crude-oil emulsion of acrylamide polymers, and then;
Injecting the water-in-crude-oil emulsion of the acrylamide polymer in the presence of an inverting agent into the underground formation under conditions whereby the formation is contacted with a dilute solution of the acrylamide polymer.
Description
~'~3S~
It is now well-known that acrylamide polymers, which term means homopolymers of acrylamlde and more specifically acrylamide polymers which contains from .8 up to 7Q percent by weight of acrylic acid in a water-soluble form, when used as dilute aqueous solutions and injected into underground petroleum bearing formations, are capahle of impro~ing the yield of crude oil from producing wells. This phenomenon which is known as water flooding with polymers, polymer flooding, tertiary recovery, etc., ls described ln United States
It is now well-known that acrylamide polymers, which term means homopolymers of acrylamlde and more specifically acrylamide polymers which contains from .8 up to 7Q percent by weight of acrylic acid in a water-soluble form, when used as dilute aqueous solutions and injected into underground petroleum bearing formations, are capahle of impro~ing the yield of crude oil from producing wells. This phenomenon which is known as water flooding with polymers, polymer flooding, tertiary recovery, etc., ls described ln United States
2,827,964, and United States 3,039,529.
In United States 2,827,964, polymer flooding is described as follows:
"The present invention is based on our discovery that certain water-soluble partially hydrolyzed acrylamide polymers are particularly well adapted for use as viscosity-increasing additives in aqueous flooding media, and that increased recovery of oil can be realized by the above described flooding or driving techniques employing a viscous aqueous solution of such agent as the flooding or driving medium. Such polymers are exceptionally stable - with respect to precipitatiOn from aqueous solutions by heat and/or mineral anions and cations, and relatively small amounts are effective in achieving the desired in-crease in viscosity. The invention thus consists in a secondary recoYery process in which a flooding medium con-sisting essentially of a viscous aqueous solution of a water-soluble partially hydrolyzed acrylamide polymer of the type hereinafter described is injected into an input well which penetrates an oil-bearing formation and is thereafter forced through said formation toward an output well penetrat-ing the same. In the interests of economy, lt is preferred 1~3~ 0 to employ the viscous flooding medium as a relatively small volume plug in advance of a conventional non-viscous flooding medium, eOg., water.
The partially hydrolyzed acrylamide.polymers which are employed in accordance with the invention are water~soluble acrylamide polymers which have been hydrolyzed to such an extent that between about 0~8 and about 10 percent of the amide groups have been converted to carboxyl groups. As herein employed, the term "acrylamide polymer" is inclusive ~ the homopolymers of acrylamide, i~e~, pol~acrylamide, and water soluble copolymers of acrylamide with up to about 15 percent by weight of other polymeriæable vinyl compounds such as the alkyl esters of acrylic and methacrylic acids, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile/ vinyl alkyl ethers, vinyl chloride, ~inylidene chloride, etc~ C;uch copolymers are conventionally obtained by subjecting a suitable mixture of the monomers to polymerizing conditions r u5ually under the influence of a polymerization catalyst ~uch as benzoyl peroxidec In addition to the aforementioned limitatio~ on the extent of hydrolysis~ ~he acrylamide polymers suitable ~or use in accordance with the invention axe of sufficiently high molecular weight that a ~.S percent b~ weight aqueous solution thereof has a viscosity of at least about 4 r preferably at least about :L0 r centipoises (Ostwald) at 21~4C. In order to facilitate ready solution o~ tlle polymer in the aqueous flooding medium it is preerable that it be employed in fine~y~divided orm. The general manner in which acrylamide is polymerized or copolymerized and there~
after partially hydrolyzed to fo~m the present ViSCQSity~
increasing additives is well known in the polymer art~
1~13~
Preferably the polymerization or copolymerization catalysts and/or specific conditions of temperature and pressure to form long chain polymeric molecules which are character-ized by a minimum of cross-linkages. The molecular weight is likewise controlled by varying the polymerization ;
conditions and/or the catalyst employed. Ilydrolysis of the polymers is accomplished by reacting the polymer with sufficient of a base, e.g., sodium hydroxide, to hydrolyze between about 0.8 and about 10 percent of the amide groups present in the polymer molecule. The resulting product consists of a long hydrocarbon chain the alternate carbon atoms of which bear either amide or carboxylic groups, with the ratio of amide to carbto~ylic groups being between about 9/1 and about 124/1. A number of partially hydrolyzed -acrylamide polymers suitable for use in practice of the in-ventian are commercially availa'ble, one of such products being marketed by The Dow Chemical Company under the trade name t'Separan~
This patent teaches the use of acrylamide polymers having from Q.8 to 10 percent by weight of the amide groups hydrolyzed to acrylic acid groups. United States 3,039,529 teaches the recoyery of crude oil is improved further the acrylamide polymers contain between 12 to about 7a percent by weight of acrylic acid salt groups.
Further improvements in the processes described by these patents are set orth in United States 3,343,601, United States
In United States 2,827,964, polymer flooding is described as follows:
"The present invention is based on our discovery that certain water-soluble partially hydrolyzed acrylamide polymers are particularly well adapted for use as viscosity-increasing additives in aqueous flooding media, and that increased recovery of oil can be realized by the above described flooding or driving techniques employing a viscous aqueous solution of such agent as the flooding or driving medium. Such polymers are exceptionally stable - with respect to precipitatiOn from aqueous solutions by heat and/or mineral anions and cations, and relatively small amounts are effective in achieving the desired in-crease in viscosity. The invention thus consists in a secondary recoYery process in which a flooding medium con-sisting essentially of a viscous aqueous solution of a water-soluble partially hydrolyzed acrylamide polymer of the type hereinafter described is injected into an input well which penetrates an oil-bearing formation and is thereafter forced through said formation toward an output well penetrat-ing the same. In the interests of economy, lt is preferred 1~3~ 0 to employ the viscous flooding medium as a relatively small volume plug in advance of a conventional non-viscous flooding medium, eOg., water.
The partially hydrolyzed acrylamide.polymers which are employed in accordance with the invention are water~soluble acrylamide polymers which have been hydrolyzed to such an extent that between about 0~8 and about 10 percent of the amide groups have been converted to carboxyl groups. As herein employed, the term "acrylamide polymer" is inclusive ~ the homopolymers of acrylamide, i~e~, pol~acrylamide, and water soluble copolymers of acrylamide with up to about 15 percent by weight of other polymeriæable vinyl compounds such as the alkyl esters of acrylic and methacrylic acids, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile/ vinyl alkyl ethers, vinyl chloride, ~inylidene chloride, etc~ C;uch copolymers are conventionally obtained by subjecting a suitable mixture of the monomers to polymerizing conditions r u5ually under the influence of a polymerization catalyst ~uch as benzoyl peroxidec In addition to the aforementioned limitatio~ on the extent of hydrolysis~ ~he acrylamide polymers suitable ~or use in accordance with the invention axe of sufficiently high molecular weight that a ~.S percent b~ weight aqueous solution thereof has a viscosity of at least about 4 r preferably at least about :L0 r centipoises (Ostwald) at 21~4C. In order to facilitate ready solution o~ tlle polymer in the aqueous flooding medium it is preerable that it be employed in fine~y~divided orm. The general manner in which acrylamide is polymerized or copolymerized and there~
after partially hydrolyzed to fo~m the present ViSCQSity~
increasing additives is well known in the polymer art~
1~13~
Preferably the polymerization or copolymerization catalysts and/or specific conditions of temperature and pressure to form long chain polymeric molecules which are character-ized by a minimum of cross-linkages. The molecular weight is likewise controlled by varying the polymerization ;
conditions and/or the catalyst employed. Ilydrolysis of the polymers is accomplished by reacting the polymer with sufficient of a base, e.g., sodium hydroxide, to hydrolyze between about 0.8 and about 10 percent of the amide groups present in the polymer molecule. The resulting product consists of a long hydrocarbon chain the alternate carbon atoms of which bear either amide or carboxylic groups, with the ratio of amide to carbto~ylic groups being between about 9/1 and about 124/1. A number of partially hydrolyzed -acrylamide polymers suitable for use in practice of the in-ventian are commercially availa'ble, one of such products being marketed by The Dow Chemical Company under the trade name t'Separan~
This patent teaches the use of acrylamide polymers having from Q.8 to 10 percent by weight of the amide groups hydrolyzed to acrylic acid groups. United States 3,039,529 teaches the recoyery of crude oil is improved further the acrylamide polymers contain between 12 to about 7a percent by weight of acrylic acid salt groups.
Further improvements in the processes described by these patents are set orth in United States 3,343,601, United States
3,399,725, and United States 3,282,337. They basically teach that acrylamide polymers described aboye are more effective in their operational efficiency if the aqueous flooding media is substantially free of molecular oxygen.
_ 3 --~3~'9~1 Acrylamide polymers as well as other water-soluble vinyl polymers and copolymers may be formed into or prepared by polymeri-zation in the form of water-in-oil emulsions. Such emulsions are described in Vanderhoff United States 3,284,393. This patent teaches that acrylamide and other water-soluble vinyl polymers may be polymerized by forming a water-in-oil emulsion of these monomers utilizing a water-in-oil emulsion agent which has a low HLB, e.g.,
_ 3 --~3~'9~1 Acrylamide polymers as well as other water-soluble vinyl polymers and copolymers may be formed into or prepared by polymeri-zation in the form of water-in-oil emulsions. Such emulsions are described in Vanderhoff United States 3,284,393. This patent teaches that acrylamide and other water-soluble vinyl polymers may be polymerized by forming a water-in-oil emulsion of these monomers utilizing a water-in-oil emulsion agent which has a low HLB, e.g.,
4-9. This emulsion is then polymerized in the presence of a free radical catalyst under conditions where~y the monomers are conYert-ed into a water-in-oil emulsion of their corresponding polymers.
The Vanderhoff patent then treats these emulsions to precipitate the polymers as a substantially dry product. This patent does not teach direct solubilization of the polymers in water.
It is also known that the water-in-oil emulsions of water-soluble vinyl polymers and particularly acrylamide polymers, e.g., those containing from 0.8 - 70 percent by weight of acrylic acid or its salts may be inverted into water under conditions whereby the water-soluble polymers are dissolved rapidly, e.g.s usually within two minutes and often times within a few seconds. This technique of rapid dissolution is described in Anderson/Frisque United States patent Re 28,474, and Re 28,576.
A preferred method of inverting the water-in-oil emulsions of the water-soluble vinyl polymers as taught in the Anderson/
Frisque patents is to add the emulsions of the polymers to water which contains a surfactant which has a high HLB, e.g., in excess of 9 and usually greater than 11 ~Yhich causes the inversion to occur.
The surfactant may be added separately to the water into which the emulsions may be inverted or may be added to the elnulsion of the polymer prior to addition to water.
It is further known that water-in-oil emulsions may be in-verted in accordance with Anderson/Frisque disclosures to prodllce 1~3~4~
improved results in water flood operations. This is shown in the Bott United States patents, 3,724,547, United States 3,780,806 United States 3,721,295 and United States 3,779,316. These patents show that the water-in-oil emulsions containing the water-soluble vinyl polymers may be either inverted into water which is then in-jected into the underground formations or the emulsion per se either as produced or diluted with a hydrocarbon liquid may be injected into the formation in the presence of a surfactant to cause inversion to take place in the fo~mation.
W~ile the teachings of the Bott patents described above represent an improved method of secondary recovery they have not been used extensively to increase crude oil production using water flood-ing techniques. The reason attributed towards not using the Bott teclmiques is due to the high cost of manufacturing both acrylamide monomer and acrylamide polymers in the form of water-in-oil emulsions.
If it were possible to economically produce the water-in-oil emul-sion so as to reduce their cost to those using water flooding tech-niques, an advance would be made in the art. Of ~urther advantage would be the manufacture of these emulsions directly at the site of the water flooding operations. This would eliminate the shipping of the emulsion from a distant manufacture site.
Also of further advantage would be the manufacture of the emulsions of the acrylamide polymers at the well site which would utilize a portion of the crude oil produced from the field and in certain instances the produced connate water.
Thus this invention provides in a process for recovering oil from underground formations of the type wherein a dilute aqueous solu-tion of an acrylamide po]ymer is injected into one or more wells the improvement which comprises: establishing near the one or more wells a small chemical plant and a source of acrylonitrile for producing an acrylamide polymer in the Il ( ( I ~L~3~6;1 ¦ form of water-in-oil emulsion, which plant performs the following ¦ sequence of steps ¦ 1~ Forming a water-in-oil emulsion of acrylonitrile ¦ utilizing as an oil source crude oil recovered from the underground formation;
2. Contacting said emulsion with a conversion catalyst under reaction conditions to con~ert a substantial portion of the acrylonitrile to acrylamide thereby forming a water~
¦ in~crude-oil emulsion which contains a substantial portion ¦ of acrylamide;
¦ 30 Polymerizing the water-in-cxude-oil emulsion of ¦ acrylamide in the presence of a free radical catalyst to ¦ provide a water-in~crude oil emulsion of acrylamide polymer, ¦ and then;
¦Injecting the water-in-crude-oil emulsion of the acrylamide polymer ¦in the presence of an inverting agent into the underground formation ¦under conditions whereby the format:ion is contacted with a dilut~, ¦solution of the acrylamide polymer.
¦ In a preferrea form of the invention, a small chemical plant ¦is set up near the injection point located at the crude oil recovery ¦fieldO ~ne of the main items of this plant is a storage vessel i ¦for acrylonitrile which may be supplied by either truck or from a ¦rail siding~ A parked tank truck or a sided railway tank car which contains acrylonitrile coulb be used as the acrylonitrile stora~e tank.
As indicated a preferred mode of the invention utilizes the crude oil as the source of oil to prepare the water-in-oil emulsions.
l~he first reaction conducted in the plant for the conversion of the acrylonitrile in the form of a water-in-oil emulsion into acrylonitrile. This comprises producing acrylamide from acrylo-nitrile in the presence of a metallic converison catalyst which Il ( ~
~3~4~
comprises contacting a water~in-crude-oil emulsion of acrylonitrile ¦ which is contained in the dispersed aqueous phase of the emulsion ¦ under conditions whereby a substantial portion of the acrylonitrile .
is converted to acrylamide~ which acrylamide remains in the aqueous ¦ phase of the emulsionsO
~ _7_ I
1 1135~L90 In a preEerred embodiment of the invention the catalyst used is a finely diviaed metallic copper catalyst hav;ng a high degree of activity and~ most pre~erably t a Raney coppex catal~7st which contains 2 - 45~ by weight vE aluminum~ In another embodi.ment of the invention, it is possible to incorporate into the acrylonitrlle i rater-in-crude-oil emulsion suficient amounts of caustic such as sodium hydroxide'or c~rbonate to'cohver't by hydrol~7zing the' acrylonitrile or'the;proaù`ced'ac.rylamide'to sodium acrylate~
¦ The Metallic Nitrile Conversion Catalyst ¦ During the last several ~ears, numerous me~allic catalysJ~s for converting nitrile and water into amides ha~e heen patented ~r ,described in the literature~ ~ su~nary of ~hese eatalyst:s as well ¦as literature references thereto is set forl:h below:
¦ Catal~st Litera~ure Reference l Rane~ copper, ~llman copperl Canadlan Patent ~9~,3~0 ¦ reduced copper~ copper on a carrier~ silver cobalt, nickel r palladium and platinumO .¦
l Copper in combination with Canadian Paten~ 930 J 377 ¦ nickel, chromium manganese, zinc, ¦ molybdenum, as wel~ ~s ~xides o~
¦ sulf ides of said metal~
l Combina~ions consisting essentiall~7 U.S~ 3,597,481 ¦ of 10 to ~0% by weight c oxides of ' copper, silver, zinc or cadmium and 10 to 90% by weiyht of oxldes of chromium or molybdenum.
Urushibara - copper chloride Watanabe in Bullr Chemr /SOc precipitate with zinc dust. Japdn, 37. L325 tlg64) -8-`
1~L354~0 Catalyst Literature Reference Copper, copper oxide, copper- U~S. 3~631,1~4 chromium oxide, copper-molyh-d~num oxide or mixture~ thereof.
Reduced copper oxides in combïna- U~S 3,696,1S2 tion with other metal oxides, particularly rare earth metal oxidesO
Copper prepared by reducing U S~ ~j758,~78 copper hydroxide or a copper saltr Copper metal. U~S. 3~767,706 ~ighly active Rane~ copper. ~ 3,~20~740 Zinc and cadmium oxides. German 551,869 Lithium hydroxide~ V.S~ 3,686,307 Ruthenium, rhodium, palladium, U.S. 3~670,021 osmium, iridium or platinum.
Fatty acid ~alts of cadmium, ~ap. 70/21,2950 zinc, copper, co~alt, lead, tin, Inoue et alO, ~shi ~asei titaniumO nickel7 iron, mercury; Co., 7-18-70 sulfates, nitrates and halides o~ lead~ tin~ titanium, nickel, iron~ mercury; tin~ cadmium &
copper oxides; copper powders~
Cupric hydroxide, manganese Jap~n 72/33,327 dioxide~ chromium, tungsten, iron or nickel oxide.
Boron hydroxide & inorganic ~apan 73/36118 phosphorous contain1ng acids.
_9_ Il ~L3S~
Catalyst Literature Reference Cobalt chromiLIm catalyst. Japan 73/39424 Nickel chromium catalyst. Japan 73/39426 Ruthenium or rhodium. Japan 73/54,021 ~anganese dioxide. Haefele et al.~ Ind. Eng.
Chem. Prod. Res. Develop.
11(3), 364-365 (1972) Zinc, copper cobalt F~ cadmium Spanish Patent Appl.
thiocyanates, sulfates, nitrates, Public No. 695205 halides and cyanides as ~ell as metallic zinc and metallic copper.
Metal salts of cation exchange United States 3,674,848 resins.
Cuprous dihydrogen phosphate. United States 3,679,745 Copper salts. United States 3,381,034 Of the above catalysts, I prefer to use in the practice of my invention a special ~aney copper catalyst which contains from about 2 to 45~ ~y weight of aluminum. This catalyst in its pre-ferred embodiment contains particles having an average particle dia-meter ranging from 0.002 to 0.5 inches and has a relative activity of at least about 2. Catalysts of this type as ~ell as their method of preparation are di$closed in United States Pat. No. 3~920,740,.
~s will be shown hereafter, it is important that the metal-lic catalyst be capable of producing acrylamide from acrylonitrile and water in yields of at least 30% and, preferably, at least 50%. In certain instances, certain of the catalysts listed above are in-capable of producing acrylamide in such yields under normal commercial operating conditions. It is understood, therefore, that only those catalysts capable of producing acrylamide in a 30% yield are intended to be included in my definition of a metallic conversion catalyst.
IL3,~
I, The ~ater-i-n-Crude-Oil Emulsions of Acrylonitrile l l The components of the emulsions are listed belo-.7 in te~ns of their weight percentages: I
A. Acrylonitrile: 5 i lo Generally from 5 60%;
The Vanderhoff patent then treats these emulsions to precipitate the polymers as a substantially dry product. This patent does not teach direct solubilization of the polymers in water.
It is also known that the water-in-oil emulsions of water-soluble vinyl polymers and particularly acrylamide polymers, e.g., those containing from 0.8 - 70 percent by weight of acrylic acid or its salts may be inverted into water under conditions whereby the water-soluble polymers are dissolved rapidly, e.g.s usually within two minutes and often times within a few seconds. This technique of rapid dissolution is described in Anderson/Frisque United States patent Re 28,474, and Re 28,576.
A preferred method of inverting the water-in-oil emulsions of the water-soluble vinyl polymers as taught in the Anderson/
Frisque patents is to add the emulsions of the polymers to water which contains a surfactant which has a high HLB, e.g., in excess of 9 and usually greater than 11 ~Yhich causes the inversion to occur.
The surfactant may be added separately to the water into which the emulsions may be inverted or may be added to the elnulsion of the polymer prior to addition to water.
It is further known that water-in-oil emulsions may be in-verted in accordance with Anderson/Frisque disclosures to prodllce 1~3~4~
improved results in water flood operations. This is shown in the Bott United States patents, 3,724,547, United States 3,780,806 United States 3,721,295 and United States 3,779,316. These patents show that the water-in-oil emulsions containing the water-soluble vinyl polymers may be either inverted into water which is then in-jected into the underground formations or the emulsion per se either as produced or diluted with a hydrocarbon liquid may be injected into the formation in the presence of a surfactant to cause inversion to take place in the fo~mation.
W~ile the teachings of the Bott patents described above represent an improved method of secondary recovery they have not been used extensively to increase crude oil production using water flood-ing techniques. The reason attributed towards not using the Bott teclmiques is due to the high cost of manufacturing both acrylamide monomer and acrylamide polymers in the form of water-in-oil emulsions.
If it were possible to economically produce the water-in-oil emul-sion so as to reduce their cost to those using water flooding tech-niques, an advance would be made in the art. Of ~urther advantage would be the manufacture of these emulsions directly at the site of the water flooding operations. This would eliminate the shipping of the emulsion from a distant manufacture site.
Also of further advantage would be the manufacture of the emulsions of the acrylamide polymers at the well site which would utilize a portion of the crude oil produced from the field and in certain instances the produced connate water.
Thus this invention provides in a process for recovering oil from underground formations of the type wherein a dilute aqueous solu-tion of an acrylamide po]ymer is injected into one or more wells the improvement which comprises: establishing near the one or more wells a small chemical plant and a source of acrylonitrile for producing an acrylamide polymer in the Il ( ( I ~L~3~6;1 ¦ form of water-in-oil emulsion, which plant performs the following ¦ sequence of steps ¦ 1~ Forming a water-in-oil emulsion of acrylonitrile ¦ utilizing as an oil source crude oil recovered from the underground formation;
2. Contacting said emulsion with a conversion catalyst under reaction conditions to con~ert a substantial portion of the acrylonitrile to acrylamide thereby forming a water~
¦ in~crude-oil emulsion which contains a substantial portion ¦ of acrylamide;
¦ 30 Polymerizing the water-in-cxude-oil emulsion of ¦ acrylamide in the presence of a free radical catalyst to ¦ provide a water-in~crude oil emulsion of acrylamide polymer, ¦ and then;
¦Injecting the water-in-crude-oil emulsion of the acrylamide polymer ¦in the presence of an inverting agent into the underground formation ¦under conditions whereby the format:ion is contacted with a dilut~, ¦solution of the acrylamide polymer.
¦ In a preferrea form of the invention, a small chemical plant ¦is set up near the injection point located at the crude oil recovery ¦fieldO ~ne of the main items of this plant is a storage vessel i ¦for acrylonitrile which may be supplied by either truck or from a ¦rail siding~ A parked tank truck or a sided railway tank car which contains acrylonitrile coulb be used as the acrylonitrile stora~e tank.
As indicated a preferred mode of the invention utilizes the crude oil as the source of oil to prepare the water-in-oil emulsions.
l~he first reaction conducted in the plant for the conversion of the acrylonitrile in the form of a water-in-oil emulsion into acrylonitrile. This comprises producing acrylamide from acrylo-nitrile in the presence of a metallic converison catalyst which Il ( ~
~3~4~
comprises contacting a water~in-crude-oil emulsion of acrylonitrile ¦ which is contained in the dispersed aqueous phase of the emulsion ¦ under conditions whereby a substantial portion of the acrylonitrile .
is converted to acrylamide~ which acrylamide remains in the aqueous ¦ phase of the emulsionsO
~ _7_ I
1 1135~L90 In a preEerred embodiment of the invention the catalyst used is a finely diviaed metallic copper catalyst hav;ng a high degree of activity and~ most pre~erably t a Raney coppex catal~7st which contains 2 - 45~ by weight vE aluminum~ In another embodi.ment of the invention, it is possible to incorporate into the acrylonitrlle i rater-in-crude-oil emulsion suficient amounts of caustic such as sodium hydroxide'or c~rbonate to'cohver't by hydrol~7zing the' acrylonitrile or'the;proaù`ced'ac.rylamide'to sodium acrylate~
¦ The Metallic Nitrile Conversion Catalyst ¦ During the last several ~ears, numerous me~allic catalysJ~s for converting nitrile and water into amides ha~e heen patented ~r ,described in the literature~ ~ su~nary of ~hese eatalyst:s as well ¦as literature references thereto is set forl:h below:
¦ Catal~st Litera~ure Reference l Rane~ copper, ~llman copperl Canadlan Patent ~9~,3~0 ¦ reduced copper~ copper on a carrier~ silver cobalt, nickel r palladium and platinumO .¦
l Copper in combination with Canadian Paten~ 930 J 377 ¦ nickel, chromium manganese, zinc, ¦ molybdenum, as wel~ ~s ~xides o~
¦ sulf ides of said metal~
l Combina~ions consisting essentiall~7 U.S~ 3,597,481 ¦ of 10 to ~0% by weight c oxides of ' copper, silver, zinc or cadmium and 10 to 90% by weiyht of oxldes of chromium or molybdenum.
Urushibara - copper chloride Watanabe in Bullr Chemr /SOc precipitate with zinc dust. Japdn, 37. L325 tlg64) -8-`
1~L354~0 Catalyst Literature Reference Copper, copper oxide, copper- U~S. 3~631,1~4 chromium oxide, copper-molyh-d~num oxide or mixture~ thereof.
Reduced copper oxides in combïna- U~S 3,696,1S2 tion with other metal oxides, particularly rare earth metal oxidesO
Copper prepared by reducing U S~ ~j758,~78 copper hydroxide or a copper saltr Copper metal. U~S. 3~767,706 ~ighly active Rane~ copper. ~ 3,~20~740 Zinc and cadmium oxides. German 551,869 Lithium hydroxide~ V.S~ 3,686,307 Ruthenium, rhodium, palladium, U.S. 3~670,021 osmium, iridium or platinum.
Fatty acid ~alts of cadmium, ~ap. 70/21,2950 zinc, copper, co~alt, lead, tin, Inoue et alO, ~shi ~asei titaniumO nickel7 iron, mercury; Co., 7-18-70 sulfates, nitrates and halides o~ lead~ tin~ titanium, nickel, iron~ mercury; tin~ cadmium &
copper oxides; copper powders~
Cupric hydroxide, manganese Jap~n 72/33,327 dioxide~ chromium, tungsten, iron or nickel oxide.
Boron hydroxide & inorganic ~apan 73/36118 phosphorous contain1ng acids.
_9_ Il ~L3S~
Catalyst Literature Reference Cobalt chromiLIm catalyst. Japan 73/39424 Nickel chromium catalyst. Japan 73/39426 Ruthenium or rhodium. Japan 73/54,021 ~anganese dioxide. Haefele et al.~ Ind. Eng.
Chem. Prod. Res. Develop.
11(3), 364-365 (1972) Zinc, copper cobalt F~ cadmium Spanish Patent Appl.
thiocyanates, sulfates, nitrates, Public No. 695205 halides and cyanides as ~ell as metallic zinc and metallic copper.
Metal salts of cation exchange United States 3,674,848 resins.
Cuprous dihydrogen phosphate. United States 3,679,745 Copper salts. United States 3,381,034 Of the above catalysts, I prefer to use in the practice of my invention a special ~aney copper catalyst which contains from about 2 to 45~ ~y weight of aluminum. This catalyst in its pre-ferred embodiment contains particles having an average particle dia-meter ranging from 0.002 to 0.5 inches and has a relative activity of at least about 2. Catalysts of this type as ~ell as their method of preparation are di$closed in United States Pat. No. 3~920,740,.
~s will be shown hereafter, it is important that the metal-lic catalyst be capable of producing acrylamide from acrylonitrile and water in yields of at least 30% and, preferably, at least 50%. In certain instances, certain of the catalysts listed above are in-capable of producing acrylamide in such yields under normal commercial operating conditions. It is understood, therefore, that only those catalysts capable of producing acrylamide in a 30% yield are intended to be included in my definition of a metallic conversion catalyst.
IL3,~
I, The ~ater-i-n-Crude-Oil Emulsions of Acrylonitrile l l The components of the emulsions are listed belo-.7 in te~ns of their weight percentages: I
A. Acrylonitrile: 5 i lo Generally from 5 60%;
5~ 20 Preferably from 20 - 40%; and ! 3O Most preferably f xom 2 5 - ~ 5 %, 't B D Wa ter O . 7 ' lo Generally from 20 - 9Q%;
Preferably from ~0 70%r and 3~ Most preferably rom 3~ - 55~, i CO Crude Oil: ' ! 1~ Generally from 5 - 75%, . 2. Pre~erably from 5 ~ 40~; and : , 3. Most preferably from 2~ - 30%~ and Do Water-in-oil emuls:ifyin~ a~gent:
¦ 1. Generally from Q~1 ~ 2].~;
2. Preferably from l - 15~, !
3. Most preferably from 1. 2 - 10%n ¦ In the above, the general range of acrylonitrile in the ¦emulsivn is shown to be 5 - 60%. Th:is concentration of acrylonitrile ¦can be achieved in the aqueous phase of ~he ~-nulsion even ~hough iit is only soluble in water up to abou, /% by weight~ It is con~
¦templated that the emulsions can be a dis~ersion of acrylonitrile at. the beginning of the reaction but the nitrile would be rapidly solubilized into ,the water as it was converted to acrylamide.
jAcrylamide-water solutions tend to form a solvent s~stem for ¦acrylonitrile. This is demonstrated below in Table I~
1i i ,j I
!! I
!, . , 1~3~
TABLE I
N rile Solubilitx Percent by Weigh~ Percent by Weight of Acrylamide of Nitrile in Solution Solution Based on Water O - ~
12 . ~9 16 ~ 0 58 O ~6 185 . 6 2~6 . 0 .
: .
-Il ~( ( ~L~3~9~
~ s indica-ted, in certain instances it is desirable that the acrylonitrilc emulsions, in addition to their conversion catalyst~
also contain amoun-ts of alkali metal calculated ~o convert varyin~
amounts of the nitrile and~or acrylamide to sodium acrylate. The presence of the alkali also enhances the solubility of the nitrile in the aqueous phase of the emulsion as the conversion of the nitrile to the amide pro~resses~
It is also possible to further characterize the water~in-crude oil emulsions of acrylonitrile with respect to the aqueous phase of the emulsions. This a~ueous phase is generally defined as the ~urn of the acrylonitrile present in the emulsion plus the amount of water. This terminology may also be utilized in describing the water-in-crude-oil emulsions which are useful in this invention~ Utilizing this terminology, the aqueous phase of the ~ater~in-~rude-oil emulsions of this invention generally consists of 25 - 95% by weight of the emulsion. Preferably, the aqueous phase is between 60 ~ ~0%
and, most preferably, from ~5 - 85~ by wei~ht of the emulsion.
The emulsions also may be chara~terized in relation to the water~oil ratiosO This figure is simpl~ a xatio of the amoun~ of water present in the emulsion divided by the amount of hydropho~io liquid present in the emulsionO Generall~r the water-in-crude-oil emulsions o~ this invention will ha~Te a water/oil ratio of from 0.25 to 18. Preferably, the water in-crude-oil ratio will ran~e from 0.5 - 14 and, most preferably, from 1.0 - 2075 ~L~3~i~9a~
THE CRUDE OILS
As indicated, the invention contemplates utilizing as a source of oil crude oil which has been produced from the formation.
The crude oils utilized in preparing the emulsions may be selected from a wide variety of crude oils. As previously indicated, in most instances they would be derived from a water flood area which was being polymer flooded. The production from these floods would be subjected to conventional crude oil water separation techniques and a small portion of this crude oil would be utilized in preparing the polymer containing emulsions of the invention. Many of the crude oil emulsions produced by polymer flooding will be of the water-in-oil type. This indicates that the crude oils contain quantities oF
naturally occurring water-in-oil emulsifiers. Even after the crude oils are separated from their emulsions, these emulsifiers remain with the crude oil and are capable, either alone or in combination with other water-in-oil emulsifiers, of producing water-in-oil emulsions ; of the water-solube vinyl addition polymer which can be polymerized to produce emulsions of these polymers which can be inverted into the formation to provide improved polymer flooding and oil recovery.
The composition of crude oil or petroleum is varied. It is disclosed in detail in ~olume 14, Encyclopedia o~ Chemlcal Tech-nology, 2nd Edit~on, publisher, Inter-Science, 1~67, at page 845.
This article indicates that crude oil is composed predominantly of hydrocarbons, primarily saturated hydrocarbons. Their compositions ~3~
are never the same. Oftentimes variations occur in samples of crude oil taken from the same well.
THE WATER
While any convenient source of water may be used to produce the water-in-crude oil emulsions it is contemplated in a preferred practice of the invention that the water receovered as a result of the water flooding operation and separated from the crude oil, would be employed. Such waters would be used alone or they may be blended with other water so~lrces such as well waters, pond, river and stream waters.
The Water-in-Oil Emulsifying Agents Any conventional water-in-oil emulsifying agent can be used such .
as sorbitan monostearate, sorbitan monooleate, and the so-called low HLB
materials which are all documented in ~he literature and are summarized in the Atlas HLB Surfactants Selector. Although the mentioned emulsifiers are used in producing good water-in-oil emulsions, other surfactants may be used as long as they are capable of producing these emulsions. It is also con-templated, however, that other water-in-oil emulsifyi.ng agents can be util-ized.
United States Patent, 3,997,492, shows the use of emulsifiers generally having higher HLB values to produce stable emulsions. With the use of the equations present in this reference, emulsifiers having HLB
values between 4 - 9 can be utilized in the practice of this invention.
As indicated, it is possible to conduct the conversion of the acrylonitrile to acrylamide in the presence of an alkali such as sodium hydroxide or carbonate which converts a portion of the nitrile or amide groups to sodium acrylate groups. The rate of caustic hydrolysis of acryl-onitrile sodium acrylate is described in the work, The Chemistry of _rylonitrile, American Cyanamid Company, 1959, Page 11 and 258 . For the alkaline hydrolysis of 1737. Mamiya, J. Soc. Chem. Ind., Japan 44,860 (19~1) ~:1354~
acrylamide, reference should be made to the publication, Chemistry of Acrylamide, American Cyanamid Company, 1969, page 7.
One of the interesting features of the invention is that when the emulsions of the acrylonitrile are prepared using suf-ficient quantities of lo~ HLB ~ater-in-oil emulsion agents, the acylamide produced remains in the aqueous phase of the water-in-oil emulsion. rn this form it can be utilized directly in the water-in-oil polymerization system previously described.
Conversion Conditions As a general rule, the conYersion of the acrylonitrile to acrylamide may be conducted at temperature ranges from 15Q-300F with temperatures in the range of 16QQ-250 being preferred.
The preferred catalyst is a Raney copper catalyst of the type described in United States 3,920,740. This patent also shows additional reaction conditions that may be used. ~hile I prefer to use a metallic catalyst such as Raney copper or reduced copper catalyst of the type already described, it is to be Imderstood that homogeneous catalysts, e.g. those which are soluble in water, may be used. Such catalysts would be amine complexes of copper.
In such complexes, the copper must be in the zero valence state.
THE CONVERSION OF THE ACRYLA~IDE E~LSIONS INTO ACRYLA~IIDE POLYMERS
~fter preparing the acrylamide emulsions as described above, they are then pumped to another reactor such as a vessel or tubular reactor where they are subjected to polymerization conditions to produce the water-in-crude-oil emulsions of the acrylamide poly-mers. The feed for this reaction may contain substantially pure acrylamide, a blend of acrylamide and acrylic acid or a blend of acrylamide-acrylic acid having acrylonitrile present in small amounts.
The acrylic acid would be in its salt form.
~3~
The general method for the preparation of emulsions of the type described above is contained in Vanderhoff, United States 3,284,393. The emulsions described above are polymerized in the presence of a free radical ca*alyst. As to choice of free radical catalyst, these materials may be either oil or water-soluble and may be from the group consisting of organic peroxides, Vazo type mate-rials, redox type initiator systems, etc. Additionally, ultra-violet light, microwaves, etc., will also cause the polymerization of water-in-oil emulsions of this type.
In the manufacture of emulsions of this type, which are further detailed in United States 3,624,019 reissue 28,474, United States 3,734,873 reissue 28,576, United States 3,826,771, the use of air may be employed to control polymerization. This technique is described in United States 3,767,629.
ln addition to the above references, United States 3,996,180 describes the preparation of water-in-oil emulsions of the types utilized in this invention by first forming an emulsion containing small particle size droplets between the oil, water, monomer and water-in-oil emulsifying agent utilizing a high shear mixing technique followed by subjecting this emulsion to free radical polymerization conditions. Also of interest is United States 4,024,097 which describes water-in-oil emulsions such as those des-cribed above utilizing particular surfactant systems for the water-in-oil emulsifying agent, allowing for the preparation of latexes having small polymer particle sizes and improved storage stability.
Another reference, United States 3,915,920 discloses stabi-lizing water-in-oil emulsions of the type above described utilizing various oil-soluble polymers such as polyisobutylene. Employment techniques of this type provides for superior stabilized emulsions.
~L35490 f still further interes-t is U.S. 3,997t492 which describes ¦ the formation of water-in-oil emulsions of the type above described ¦ utili~in~ emulsifiers having HLB values of between 4-9 ¦ The water-in-oil emulsions of the acrylamide primari]y are ¦ prepared all charged to a polymerization reactor, present is a ¦ free radical polymerization catalyst with the amount of such ¦ catalyst being within the range of 0.001 - 1~ by weight based on the ¦ oil or monomer phase depending upon the solubility of initiator, and ¦ polymerizaing said charge using a free radical polymerization ¦ catalyst or other means under free radical ~ormin~ conditions and ¦ recovering the resultant water-in-oil emulsion which contains the ¦ water-soluble vinyl addition polymer.
I THE FREE RADICAI, CATALYSTS
¦ These catalysts may be either oil or water-soluble. Such ¦ catalysts are described in U.S~ 3,767,629.
Both the amounts and types of free radical initiatoxs applicable¦
¦ are well known in the art. If an initiator is used r amounts up to ¦ 0.5 weight percent, based on the monomer r ~ive good results. Pre-¦ erably, the amount of initiator used will be ahout 0.001% ~ 0.2%.
¦ Peroxygen compounds, in ~eneral, function well as initiators~ These ¦ peroxygen compounds include, or example, ammonium persul~ate, ¦ potassium persulfate, and hydrogen peroxide~ ara'~azo-bisisobutyro-¦ nitrile also works well as an initiator. An initiator may be used ¦ alone or in combination with an activator to reduce the induction ¦ period of the polymerization reaction. Likewise~ these activators ¦ are well known in the art. These activators form a redox system ¦ with an initiator. Sodium bisulfite and ferrous chloride activators ¦ work ~uite successfully in combination with potassium persulfate and hydrogen peroxide initiators, respective]y, in accordance with the present invention.
Il ( 1135~30 ( 1l I~ addition to using chemical catalysts, other free radical generating systems such as Van de Graaf~ generators, radio-active rays, X-rays, and the like may be employed.
The reaction time is widely variably depending upon the catalyst system, and ranges generally between about 10 minutes and two hours at temperatures between about 20 and 100C.
PHYSICAL PRO~ERTIES OF
THE WAT~R-IN-CRU~E-OIL EMUI,SIONS
These polymers dispersed in the emulsion are quite stable when the particle size of the polymer is from the range of 0.1 microns up to about 5 microns~ The preferred particle siæe is generally within the range of 0.2 microns to about 3 microns~ A most preferred partlcle size is generally within the ran~e of 0.~ to 2.0 ¦microns.
¦ The emulsions prepared having the above composition generally ¦have a viscosity in the range of from 50 to 1000 cps. It will be ¦seenl however, that the viscosity of the5e emulsions can be affected ¦greatly by increasing or decreasing the polymer content, oil content, ¦or water content as well as the choice of a suitable water~in-oil ¦emulsifier.
¦ Another factor attributing to the viscosity of these types of ¦emulsions is the particle size of the polymer which is dispersed in ¦-the discontinuous aqueous phaseO Generally, the smaller the ¦particle obtained the less viscous the emulsion. At any rate, it will ¦be readily apparent to those skilled in the art as to how the ¦viscosity of these types of materials can be altered. It will be ¦seen that all that is important in this invention is the fact that the ¦ mulsion be so~ewhat fluid, i.e.: pumpable.
ll -19-, 113~ 9~
It is possible to produce the emulsions containing acrylamide homopolymers whereby the emulsions may be treated to convert a portion of the amide groups to acylic acid salt groups. A method for doing this is set forth in United States 4,171,296. It is also possible to treat polyacrylic emulsions ~ith caustic directly to convert a portion of the amide groups into sodium carboxylate groups.
This under certain cases will tend to destabilize the emulsions. Thus does not generally present a problem since they can be used as soon as they are hydrolyzed.
THE REACTOR
The reactor for performing the reaction described thus far may be conventional design and would contain heating and cooling means such as coils. Preferably, it would be skid mounted and through appropriate piping connect to the acrylonitrile source and would also be connected to additional reaction devices which will be described hereafter.
INVERSION OF THE POLY~IERIC E~ULSIONS
The water-in-crude-oil emulsions of the polymer described above as indicated in the ~ott patents may be inverted to produce ~ s~
dilute solutions of the polymers which would then be pumped into the formation through one or more injection wells. Alternatively, the emulsions containing the polymers may be directly fed to the formation. The emulsions may contain the inverting agent or the inverting agent may be previously injected into the formation~
¦ The invention also contemplates that the iormation would be ¦ pretreated or treated along with the injection of the inverted ¦ emulsions with an appropriate oxygen scavenger such as sodium ¦ sulfite to render the injection water containing the polymer oxyyen ¦ free~ These operations as described would be accomplished by ¦ mixing vessels. pumps, storage tanks and the like would be connected ¦ by appropriate piping and valving to the plant segments previously ¦ described.
¦ Thus the expression is used herein, "injecting" the water-in-¦ crude oil emulsion in the presence of an inverting agent into the ¦ underground formation under conditions whereby the formation is ¦ contacted with the dilute soltuion of the acrylamide polymer means ¦ the scheme as set forth above.
¦ As previously indicated, the emulsions are inverted by means of a surfactant which has an HLB greater than ~ and usually greater than llo Such suractants are described in Anderson/Frisque. The preferred inverting agent are nonionic in character and are illust-rated by the following:
Examples of suitable nonionic surfactants are condensation ¦products of higher fatty alcohols with ethylene oxide, such as the ¦reaction product of oleyl alcohol with 10 ethylene oxide uni-~s;
¦condensat on products of alxylphenols and ethylene oxide, such ss ~35~19~
the reaction products of isooctylphenol with 12 ethylene oxide units;
condensation products of higher fatty acid amides with five, or more, ethylene oxide units; polyethylene glycol es-ters of long chain fatty acid, such as tetraethylene glycol monopalmitate, hexaethylene-glycol, monolaurate, nonaethyleneglycol monostearate, nonaethylene-glycol dioleate, tridecaethyleneglycol monoarachidate, tricosa-ethylene glycol monobehenate, tricosaethyleneglycol dibellenate;
polyhydric alcohol partial higher fatty acid esters such as sorbitan tristearate; ethylene oxide condensation products of polyhydric alcohol partial higher fatty esters, and their inner anhydrides ~mannitolanhydride, called Mannitan, and sorbitol-anhydride, called Sorbitan), such as the products obtained with 10 molecules of ethylene oxide, pentaerythritolmonooleate reacted with 12 molecules of ethylene oxide, sorbitan monostearate reacted with 10 to 15 mol-ecules of ethylene oxide; long chain polyglycols in which one hydroxyl group is esterified with a higher fatty acid and the other hydroxyl group is etherified with a low molecular alcohol, such as methoxypolyethylene glycol 550 monostearate ~550 meaning the average molecular ~Yeight of the PO1Yg1YCO1 ether). A combination of two or more of these surfactants may be used, e.g. a cationic may be blended with a nonionic or anionic with a nonionic.
By using the arrangement described above, the invention allows inexpensive water-in-crude-oil emulsion polymers to be used to improve crude oil production.
Preferably from ~0 70%r and 3~ Most preferably rom 3~ - 55~, i CO Crude Oil: ' ! 1~ Generally from 5 - 75%, . 2. Pre~erably from 5 ~ 40~; and : , 3. Most preferably from 2~ - 30%~ and Do Water-in-oil emuls:ifyin~ a~gent:
¦ 1. Generally from Q~1 ~ 2].~;
2. Preferably from l - 15~, !
3. Most preferably from 1. 2 - 10%n ¦ In the above, the general range of acrylonitrile in the ¦emulsivn is shown to be 5 - 60%. Th:is concentration of acrylonitrile ¦can be achieved in the aqueous phase of ~he ~-nulsion even ~hough iit is only soluble in water up to abou, /% by weight~ It is con~
¦templated that the emulsions can be a dis~ersion of acrylonitrile at. the beginning of the reaction but the nitrile would be rapidly solubilized into ,the water as it was converted to acrylamide.
jAcrylamide-water solutions tend to form a solvent s~stem for ¦acrylonitrile. This is demonstrated below in Table I~
1i i ,j I
!! I
!, . , 1~3~
TABLE I
N rile Solubilitx Percent by Weigh~ Percent by Weight of Acrylamide of Nitrile in Solution Solution Based on Water O - ~
12 . ~9 16 ~ 0 58 O ~6 185 . 6 2~6 . 0 .
: .
-Il ~( ( ~L~3~9~
~ s indica-ted, in certain instances it is desirable that the acrylonitrilc emulsions, in addition to their conversion catalyst~
also contain amoun-ts of alkali metal calculated ~o convert varyin~
amounts of the nitrile and~or acrylamide to sodium acrylate. The presence of the alkali also enhances the solubility of the nitrile in the aqueous phase of the emulsion as the conversion of the nitrile to the amide pro~resses~
It is also possible to further characterize the water~in-crude oil emulsions of acrylonitrile with respect to the aqueous phase of the emulsions. This a~ueous phase is generally defined as the ~urn of the acrylonitrile present in the emulsion plus the amount of water. This terminology may also be utilized in describing the water-in-crude-oil emulsions which are useful in this invention~ Utilizing this terminology, the aqueous phase of the ~ater~in-~rude-oil emulsions of this invention generally consists of 25 - 95% by weight of the emulsion. Preferably, the aqueous phase is between 60 ~ ~0%
and, most preferably, from ~5 - 85~ by wei~ht of the emulsion.
The emulsions also may be chara~terized in relation to the water~oil ratiosO This figure is simpl~ a xatio of the amoun~ of water present in the emulsion divided by the amount of hydropho~io liquid present in the emulsionO Generall~r the water-in-crude-oil emulsions o~ this invention will ha~Te a water/oil ratio of from 0.25 to 18. Preferably, the water in-crude-oil ratio will ran~e from 0.5 - 14 and, most preferably, from 1.0 - 2075 ~L~3~i~9a~
THE CRUDE OILS
As indicated, the invention contemplates utilizing as a source of oil crude oil which has been produced from the formation.
The crude oils utilized in preparing the emulsions may be selected from a wide variety of crude oils. As previously indicated, in most instances they would be derived from a water flood area which was being polymer flooded. The production from these floods would be subjected to conventional crude oil water separation techniques and a small portion of this crude oil would be utilized in preparing the polymer containing emulsions of the invention. Many of the crude oil emulsions produced by polymer flooding will be of the water-in-oil type. This indicates that the crude oils contain quantities oF
naturally occurring water-in-oil emulsifiers. Even after the crude oils are separated from their emulsions, these emulsifiers remain with the crude oil and are capable, either alone or in combination with other water-in-oil emulsifiers, of producing water-in-oil emulsions ; of the water-solube vinyl addition polymer which can be polymerized to produce emulsions of these polymers which can be inverted into the formation to provide improved polymer flooding and oil recovery.
The composition of crude oil or petroleum is varied. It is disclosed in detail in ~olume 14, Encyclopedia o~ Chemlcal Tech-nology, 2nd Edit~on, publisher, Inter-Science, 1~67, at page 845.
This article indicates that crude oil is composed predominantly of hydrocarbons, primarily saturated hydrocarbons. Their compositions ~3~
are never the same. Oftentimes variations occur in samples of crude oil taken from the same well.
THE WATER
While any convenient source of water may be used to produce the water-in-crude oil emulsions it is contemplated in a preferred practice of the invention that the water receovered as a result of the water flooding operation and separated from the crude oil, would be employed. Such waters would be used alone or they may be blended with other water so~lrces such as well waters, pond, river and stream waters.
The Water-in-Oil Emulsifying Agents Any conventional water-in-oil emulsifying agent can be used such .
as sorbitan monostearate, sorbitan monooleate, and the so-called low HLB
materials which are all documented in ~he literature and are summarized in the Atlas HLB Surfactants Selector. Although the mentioned emulsifiers are used in producing good water-in-oil emulsions, other surfactants may be used as long as they are capable of producing these emulsions. It is also con-templated, however, that other water-in-oil emulsifyi.ng agents can be util-ized.
United States Patent, 3,997,492, shows the use of emulsifiers generally having higher HLB values to produce stable emulsions. With the use of the equations present in this reference, emulsifiers having HLB
values between 4 - 9 can be utilized in the practice of this invention.
As indicated, it is possible to conduct the conversion of the acrylonitrile to acrylamide in the presence of an alkali such as sodium hydroxide or carbonate which converts a portion of the nitrile or amide groups to sodium acrylate groups. The rate of caustic hydrolysis of acryl-onitrile sodium acrylate is described in the work, The Chemistry of _rylonitrile, American Cyanamid Company, 1959, Page 11 and 258 . For the alkaline hydrolysis of 1737. Mamiya, J. Soc. Chem. Ind., Japan 44,860 (19~1) ~:1354~
acrylamide, reference should be made to the publication, Chemistry of Acrylamide, American Cyanamid Company, 1969, page 7.
One of the interesting features of the invention is that when the emulsions of the acrylonitrile are prepared using suf-ficient quantities of lo~ HLB ~ater-in-oil emulsion agents, the acylamide produced remains in the aqueous phase of the water-in-oil emulsion. rn this form it can be utilized directly in the water-in-oil polymerization system previously described.
Conversion Conditions As a general rule, the conYersion of the acrylonitrile to acrylamide may be conducted at temperature ranges from 15Q-300F with temperatures in the range of 16QQ-250 being preferred.
The preferred catalyst is a Raney copper catalyst of the type described in United States 3,920,740. This patent also shows additional reaction conditions that may be used. ~hile I prefer to use a metallic catalyst such as Raney copper or reduced copper catalyst of the type already described, it is to be Imderstood that homogeneous catalysts, e.g. those which are soluble in water, may be used. Such catalysts would be amine complexes of copper.
In such complexes, the copper must be in the zero valence state.
THE CONVERSION OF THE ACRYLA~IDE E~LSIONS INTO ACRYLA~IIDE POLYMERS
~fter preparing the acrylamide emulsions as described above, they are then pumped to another reactor such as a vessel or tubular reactor where they are subjected to polymerization conditions to produce the water-in-crude-oil emulsions of the acrylamide poly-mers. The feed for this reaction may contain substantially pure acrylamide, a blend of acrylamide and acrylic acid or a blend of acrylamide-acrylic acid having acrylonitrile present in small amounts.
The acrylic acid would be in its salt form.
~3~
The general method for the preparation of emulsions of the type described above is contained in Vanderhoff, United States 3,284,393. The emulsions described above are polymerized in the presence of a free radical ca*alyst. As to choice of free radical catalyst, these materials may be either oil or water-soluble and may be from the group consisting of organic peroxides, Vazo type mate-rials, redox type initiator systems, etc. Additionally, ultra-violet light, microwaves, etc., will also cause the polymerization of water-in-oil emulsions of this type.
In the manufacture of emulsions of this type, which are further detailed in United States 3,624,019 reissue 28,474, United States 3,734,873 reissue 28,576, United States 3,826,771, the use of air may be employed to control polymerization. This technique is described in United States 3,767,629.
ln addition to the above references, United States 3,996,180 describes the preparation of water-in-oil emulsions of the types utilized in this invention by first forming an emulsion containing small particle size droplets between the oil, water, monomer and water-in-oil emulsifying agent utilizing a high shear mixing technique followed by subjecting this emulsion to free radical polymerization conditions. Also of interest is United States 4,024,097 which describes water-in-oil emulsions such as those des-cribed above utilizing particular surfactant systems for the water-in-oil emulsifying agent, allowing for the preparation of latexes having small polymer particle sizes and improved storage stability.
Another reference, United States 3,915,920 discloses stabi-lizing water-in-oil emulsions of the type above described utilizing various oil-soluble polymers such as polyisobutylene. Employment techniques of this type provides for superior stabilized emulsions.
~L35490 f still further interes-t is U.S. 3,997t492 which describes ¦ the formation of water-in-oil emulsions of the type above described ¦ utili~in~ emulsifiers having HLB values of between 4-9 ¦ The water-in-oil emulsions of the acrylamide primari]y are ¦ prepared all charged to a polymerization reactor, present is a ¦ free radical polymerization catalyst with the amount of such ¦ catalyst being within the range of 0.001 - 1~ by weight based on the ¦ oil or monomer phase depending upon the solubility of initiator, and ¦ polymerizaing said charge using a free radical polymerization ¦ catalyst or other means under free radical ~ormin~ conditions and ¦ recovering the resultant water-in-oil emulsion which contains the ¦ water-soluble vinyl addition polymer.
I THE FREE RADICAI, CATALYSTS
¦ These catalysts may be either oil or water-soluble. Such ¦ catalysts are described in U.S~ 3,767,629.
Both the amounts and types of free radical initiatoxs applicable¦
¦ are well known in the art. If an initiator is used r amounts up to ¦ 0.5 weight percent, based on the monomer r ~ive good results. Pre-¦ erably, the amount of initiator used will be ahout 0.001% ~ 0.2%.
¦ Peroxygen compounds, in ~eneral, function well as initiators~ These ¦ peroxygen compounds include, or example, ammonium persul~ate, ¦ potassium persulfate, and hydrogen peroxide~ ara'~azo-bisisobutyro-¦ nitrile also works well as an initiator. An initiator may be used ¦ alone or in combination with an activator to reduce the induction ¦ period of the polymerization reaction. Likewise~ these activators ¦ are well known in the art. These activators form a redox system ¦ with an initiator. Sodium bisulfite and ferrous chloride activators ¦ work ~uite successfully in combination with potassium persulfate and hydrogen peroxide initiators, respective]y, in accordance with the present invention.
Il ( 1135~30 ( 1l I~ addition to using chemical catalysts, other free radical generating systems such as Van de Graaf~ generators, radio-active rays, X-rays, and the like may be employed.
The reaction time is widely variably depending upon the catalyst system, and ranges generally between about 10 minutes and two hours at temperatures between about 20 and 100C.
PHYSICAL PRO~ERTIES OF
THE WAT~R-IN-CRU~E-OIL EMUI,SIONS
These polymers dispersed in the emulsion are quite stable when the particle size of the polymer is from the range of 0.1 microns up to about 5 microns~ The preferred particle siæe is generally within the range of 0.2 microns to about 3 microns~ A most preferred partlcle size is generally within the ran~e of 0.~ to 2.0 ¦microns.
¦ The emulsions prepared having the above composition generally ¦have a viscosity in the range of from 50 to 1000 cps. It will be ¦seenl however, that the viscosity of the5e emulsions can be affected ¦greatly by increasing or decreasing the polymer content, oil content, ¦or water content as well as the choice of a suitable water~in-oil ¦emulsifier.
¦ Another factor attributing to the viscosity of these types of ¦emulsions is the particle size of the polymer which is dispersed in ¦-the discontinuous aqueous phaseO Generally, the smaller the ¦particle obtained the less viscous the emulsion. At any rate, it will ¦be readily apparent to those skilled in the art as to how the ¦viscosity of these types of materials can be altered. It will be ¦seen that all that is important in this invention is the fact that the ¦ mulsion be so~ewhat fluid, i.e.: pumpable.
ll -19-, 113~ 9~
It is possible to produce the emulsions containing acrylamide homopolymers whereby the emulsions may be treated to convert a portion of the amide groups to acylic acid salt groups. A method for doing this is set forth in United States 4,171,296. It is also possible to treat polyacrylic emulsions ~ith caustic directly to convert a portion of the amide groups into sodium carboxylate groups.
This under certain cases will tend to destabilize the emulsions. Thus does not generally present a problem since they can be used as soon as they are hydrolyzed.
THE REACTOR
The reactor for performing the reaction described thus far may be conventional design and would contain heating and cooling means such as coils. Preferably, it would be skid mounted and through appropriate piping connect to the acrylonitrile source and would also be connected to additional reaction devices which will be described hereafter.
INVERSION OF THE POLY~IERIC E~ULSIONS
The water-in-crude-oil emulsions of the polymer described above as indicated in the ~ott patents may be inverted to produce ~ s~
dilute solutions of the polymers which would then be pumped into the formation through one or more injection wells. Alternatively, the emulsions containing the polymers may be directly fed to the formation. The emulsions may contain the inverting agent or the inverting agent may be previously injected into the formation~
¦ The invention also contemplates that the iormation would be ¦ pretreated or treated along with the injection of the inverted ¦ emulsions with an appropriate oxygen scavenger such as sodium ¦ sulfite to render the injection water containing the polymer oxyyen ¦ free~ These operations as described would be accomplished by ¦ mixing vessels. pumps, storage tanks and the like would be connected ¦ by appropriate piping and valving to the plant segments previously ¦ described.
¦ Thus the expression is used herein, "injecting" the water-in-¦ crude oil emulsion in the presence of an inverting agent into the ¦ underground formation under conditions whereby the formation is ¦ contacted with the dilute soltuion of the acrylamide polymer means ¦ the scheme as set forth above.
¦ As previously indicated, the emulsions are inverted by means of a surfactant which has an HLB greater than ~ and usually greater than llo Such suractants are described in Anderson/Frisque. The preferred inverting agent are nonionic in character and are illust-rated by the following:
Examples of suitable nonionic surfactants are condensation ¦products of higher fatty alcohols with ethylene oxide, such as the ¦reaction product of oleyl alcohol with 10 ethylene oxide uni-~s;
¦condensat on products of alxylphenols and ethylene oxide, such ss ~35~19~
the reaction products of isooctylphenol with 12 ethylene oxide units;
condensation products of higher fatty acid amides with five, or more, ethylene oxide units; polyethylene glycol es-ters of long chain fatty acid, such as tetraethylene glycol monopalmitate, hexaethylene-glycol, monolaurate, nonaethyleneglycol monostearate, nonaethylene-glycol dioleate, tridecaethyleneglycol monoarachidate, tricosa-ethylene glycol monobehenate, tricosaethyleneglycol dibellenate;
polyhydric alcohol partial higher fatty acid esters such as sorbitan tristearate; ethylene oxide condensation products of polyhydric alcohol partial higher fatty esters, and their inner anhydrides ~mannitolanhydride, called Mannitan, and sorbitol-anhydride, called Sorbitan), such as the products obtained with 10 molecules of ethylene oxide, pentaerythritolmonooleate reacted with 12 molecules of ethylene oxide, sorbitan monostearate reacted with 10 to 15 mol-ecules of ethylene oxide; long chain polyglycols in which one hydroxyl group is esterified with a higher fatty acid and the other hydroxyl group is etherified with a low molecular alcohol, such as methoxypolyethylene glycol 550 monostearate ~550 meaning the average molecular ~Yeight of the PO1Yg1YCO1 ether). A combination of two or more of these surfactants may be used, e.g. a cationic may be blended with a nonionic or anionic with a nonionic.
By using the arrangement described above, the invention allows inexpensive water-in-crude-oil emulsion polymers to be used to improve crude oil production.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for recovering oil from underground formations of the type wherein a dilute aqueous solution of an acrylamide polymer is injected into one or more wells the improvements which comprises: establishing near the one or more wells a small chemical plant and a source of acrylonitrile for producing an acrylamide polymer in the form of water-in-oil emulsion, which plant performs the following sequence of steps:
1. forming a water-in-oil emulsion of acrylonitrile utilizing as an oil source crude oil recovered from the underground formation;
2. contacting said emulsion with a conversion catalyst under reaction conditions to convert a substantial portion of the acrylonitrile to acrylamide thereby forming a water-in-crude-oil emulsion which contains a substantial portion of acrylamide;
3. polymerizing the water-in-crude-oil emulsion of acrylamide in the presence of a free radical catalyst to provide a water-in-crude-oil emul-sion of acrylamide polymers, and then:
injecting the water-in-crude-oil emulsion of the acrylamide polymer in the presence of an inverting agent into the underground formation under conditions whereby the formation is contacted with a dilute solution of the acrylamide polymer.
2. contacting said emulsion with a conversion catalyst under reaction conditions to convert a substantial portion of the acrylonitrile to acrylamide thereby forming a water-in-crude-oil emulsion which contains a substantial portion of acrylamide;
3. polymerizing the water-in-crude-oil emulsion of acrylamide in the presence of a free radical catalyst to provide a water-in-crude-oil emul-sion of acrylamide polymers, and then:
injecting the water-in-crude-oil emulsion of the acrylamide polymer in the presence of an inverting agent into the underground formation under conditions whereby the formation is contacted with a dilute solution of the acrylamide polymer.
2. The process of claim 1 where the water-in-crude-oil emulsion of the acrylamide polymer is inverted into water prior to being injected into one or more of the wells.
3. The process of claim 1 where the water-in-crude-oil emulsion of the acrylamide polymer is inverted after being injected into the underground formation.
4. The process of claim 1 were the underground formation is maintained in an oxygen free condition by the use of an oxygen scavenger.
5. The process of claim 1 where the acrylamide polymer contains between .8 - 70 percent by weight water of acrylic acid formed by the hydro-lysis of acrylamide groups.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/094,991 US4248304A (en) | 1979-11-16 | 1979-11-16 | Large scale production of inexpensive flooding polymers for tertiary oil recovery |
| US94,991 | 1979-11-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1135490A true CA1135490A (en) | 1982-11-16 |
Family
ID=22248401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000364592A Expired CA1135490A (en) | 1979-11-16 | 1980-11-13 | Aqueous emulsion of an acrylamide polymer for oil recovery |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4248304A (en) |
| CA (1) | CA1135490A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109153748A (en) * | 2016-04-26 | 2019-01-04 | 巴斯夫欧洲公司 | The method for preparing polyacrylamide solution |
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|---|---|---|---|---|
| US4433727A (en) * | 1981-06-19 | 1984-02-28 | Marathon Oil Company | Oil recovery process |
| CA1205935A (en) | 1981-09-14 | 1986-06-10 | Union Carbide Corporation | Process for producing a polymer water-in-oil emulsion |
| DE3268898D1 (en) * | 1981-11-28 | 1986-03-13 | British Petroleum Co Plc | Compounds and compositions for oil recovery |
| US5080809A (en) * | 1983-01-28 | 1992-01-14 | Phillips Petroleum Company | Polymers useful in the recovery and processing of natural resources |
| US5186257A (en) * | 1983-01-28 | 1993-02-16 | Phillips Petroleum Company | Polymers useful in the recovery and processing of natural resources |
| US4867239A (en) * | 1988-08-31 | 1989-09-19 | Marathon Oil Company | Oil recovery process using a treated polymer solution |
| NO310581B1 (en) * | 1999-09-24 | 2001-07-23 | Procom As | Emulsified gelling agent |
| US7186673B2 (en) * | 2000-04-25 | 2007-03-06 | Exxonmobil Upstream Research Company | Stability enhanced water-in-oil emulsion and method for using same |
| AU2002360596A1 (en) * | 2001-12-17 | 2003-07-24 | Exxonmobil Upstream Research Company | Solids-stabilized oil-in-water emulsion and a method for preparing same |
| US7338924B2 (en) * | 2002-05-02 | 2008-03-04 | Exxonmobil Upstream Research Company | Oil-in-water-in-oil emulsion |
| US7866394B2 (en) * | 2003-02-27 | 2011-01-11 | Halliburton Energy Services Inc. | Compositions and methods of cementing in subterranean formations using a swelling agent to inhibit the influx of water into a cement slurry |
| US7642223B2 (en) * | 2004-10-18 | 2010-01-05 | Halliburton Energy Services, Inc. | Methods of generating a gas in a plugging composition to improve its sealing ability in a downhole permeable zone |
| US7690429B2 (en) * | 2004-10-21 | 2010-04-06 | Halliburton Energy Services, Inc. | Methods of using a swelling agent in a wellbore |
| US7891424B2 (en) * | 2005-03-25 | 2011-02-22 | Halliburton Energy Services Inc. | Methods of delivering material downhole |
| US7870903B2 (en) * | 2005-07-13 | 2011-01-18 | Halliburton Energy Services Inc. | Inverse emulsion polymers as lost circulation material |
| WO2007078379A2 (en) | 2005-12-22 | 2007-07-12 | Exxonmobil Upstream Research Company | Method of oil recovery using a foamy oil-external emulsion |
| CN102838980B (en) * | 2012-07-26 | 2014-05-07 | 中国石油化工股份有限公司胜利油田分公司采油工艺研究院 | High temperature resistant cleansing emulsion or microemulsion fracturing fluid and preparation method thereof |
| CN107922821A (en) * | 2015-08-07 | 2018-04-17 | 艺康美国股份有限公司 | Nonionic transforming agent and application method for Water-In-Oil latex |
| AR113377A1 (en) | 2017-10-25 | 2020-04-22 | Basf Se | PROCESS TO PRODUCE AQUEOUS POLYACRYLAMIDE SOLUTIONS |
| CA3076548A1 (en) | 2017-10-25 | 2019-05-02 | Basf Se | Process for producing aqueous polyacrylamide solutions |
| MX2020004308A (en) | 2017-10-25 | 2020-08-13 | Basf Se | Process for producing aqueous polyacrylamide solutions. |
| WO2019081004A1 (en) | 2017-10-25 | 2019-05-02 | Basf Se | Process for producing aqueous polyacrylamide solutions |
| AR113375A1 (en) | 2017-10-25 | 2020-04-22 | Basf Se | PROCESS TO PRODUCE AQUEOUS POLYACRYLAMIDE SOLUTIONS |
| WO2019081003A1 (en) | 2017-10-25 | 2019-05-02 | Basf Se | Process for producing aqueous polyacrylamide solutions |
| WO2019081323A1 (en) | 2017-10-25 | 2019-05-02 | Basf Se | Process for producing aqueous polyacrylamide solutions |
| WO2020079124A1 (en) | 2018-10-18 | 2020-04-23 | Basf Se | Process for producing aqueous polyacrylamide compositions |
| MX2021004420A (en) | 2018-10-18 | 2021-07-06 | Basf Se | Process for producing an aqueous polyacrylamide concentrate. |
| WO2020079119A1 (en) | 2018-10-18 | 2020-04-23 | Basf Se | Method of providing aqueous polyacrylamide concentrates |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2827964A (en) * | 1956-06-11 | 1958-03-25 | Union Oil Co | Secondary recovery of petroleum |
| US3002960A (en) * | 1958-08-18 | 1961-10-03 | American Cyanamid Co | Polyacrylamide preparation |
| US3039529A (en) * | 1959-05-19 | 1962-06-19 | Dow Chemical Co | Secondary recovery of petroleum |
| US3284393A (en) * | 1959-11-04 | 1966-11-08 | Dow Chemical Co | Water-in-oil emulsion polymerization process for polymerizing watersoluble monomers |
| US3282337A (en) * | 1963-12-09 | 1966-11-01 | Dow Chemical Co | Water flooding process for the recovery of petroleum |
| US3734873A (en) * | 1970-12-15 | 1973-05-22 | Nalco Chemical Co | Rapid dissolving water-soluble polymers |
| USRE28576E (en) | 1970-12-15 | 1975-10-21 | Process for rapid dissolving water-soluble vinyl addition polymers using water-in-oil emulsions | |
| US3624019A (en) * | 1970-12-15 | 1971-11-30 | Nalco Chemical Co | Process for rapidly dissolving water-soluble polymers |
| US4016086A (en) * | 1972-01-26 | 1977-04-05 | Marathon Oil Company | Polyacrylamide polymers derived from acrylonitrile without intermediate isolation |
| US3724547A (en) * | 1972-01-31 | 1973-04-03 | Nalco Chemical Co | Inverted latex water flooding method |
| US3780806A (en) * | 1972-01-31 | 1973-12-25 | Nalco Chemical Co | Inverted mixed latex for water flooding |
| US3852234A (en) * | 1972-02-28 | 1974-12-03 | Nalco Chemical Co | Process and apparatus for dissolving water soluble polymers and gums in water involving inversion of water-in-oil emulsions |
| US3868997A (en) * | 1973-01-03 | 1975-03-04 | Marathon Oil Co | Process for preparing and using aqueous polyacrylamide solutions for the secondary recovery of oil |
| US3841399A (en) * | 1973-01-29 | 1974-10-15 | Nalco Chemical Co | Secondary oil recovery |
| US3893510A (en) * | 1974-08-12 | 1975-07-08 | Halliburton Co | Emulsion method of introducing polymers into a subterranean formation |
| US4034809A (en) * | 1976-03-17 | 1977-07-12 | Nalco Chemical Company | Hydrolyzed polyacrylamide latices for secondary oil recovery |
| US4182417A (en) * | 1977-07-08 | 1980-01-08 | The Dow Chemical Company | Method for controlling permeability of subterranean formations |
-
1979
- 1979-11-16 US US06/094,991 patent/US4248304A/en not_active Expired - Lifetime
-
1980
- 1980-11-13 CA CA000364592A patent/CA1135490A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109153748A (en) * | 2016-04-26 | 2019-01-04 | 巴斯夫欧洲公司 | The method for preparing polyacrylamide solution |
Also Published As
| Publication number | Publication date |
|---|---|
| US4248304A (en) | 1981-02-03 |
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