CA1098689A - Oil recovery process involving the injection of thickened water - Google Patents
Oil recovery process involving the injection of thickened waterInfo
- Publication number
- CA1098689A CA1098689A CA324,099A CA324099A CA1098689A CA 1098689 A CA1098689 A CA 1098689A CA 324099 A CA324099 A CA 324099A CA 1098689 A CA1098689 A CA 1098689A
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- CA
- Canada
- Prior art keywords
- copolymer
- molecular weight
- water
- polymer
- oil
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S507/00—Earth boring, well treating, and oil field chemistry
- Y10S507/935—Enhanced oil recovery
- Y10S507/936—Flooding the formation
Abstract
Abstract of the Disclosure Waterflood oil recovery process involving the use of an amphoteric polyelectrolyte as a thickening agent for mobility control. The amphoteric polyelectrolyte is a copolymer of a quaternary vinyl pyridinium sulfonate and a water-insoluble alpha olefin or hydrogenated diene.
Specifically disclosed are vinyl pyridinium sulfonate-styrene block copolymers. The amphoteric polyelectrolytes are stable in high temperature and high brine environments.
Specifically disclosed are vinyl pyridinium sulfonate-styrene block copolymers. The amphoteric polyelectrolytes are stable in high temperature and high brine environments.
Description
9707 Back~round of the Invent.ion This invention relates to the recovery of oil from subterranean oil reservoirs and more particularly to improved waterflooding operations involving the injection of thickened aqueous solutions of copolymers of amphoteric polyelectrolytes for mobility control.
In the recovery of oil from oil-bearing reservoirs 9 it usually is possible to recover only minor portions of the original oil in place by the so called primary recovery methods which utilize only the natural forces present in the reservoir. Thus a variety of supplemental recovery techniques have been employed in order to increase the recovery of oil from subterranean reservoirs. The most widely used supplemental recovery technique is waterflooding which involv~s the injection of water into an oil-bearing reservoir. As the water moves through the reservoir, it acts ~o displace oil therein ~o a - production system comp~sed of one or more wells through which the oil is recoyered.
One diffi ulty often encountered in waterflooding operations is the relatively poor sweep efficiRncy of the aqueous displa~cing medium; that is, the inJected displacing medium tends to channel through cerkain portions of the reservoir as it ~ravels from the injection system to the production system and to bypass other portions. Such poor ~ 25 swee~ efficiency or macroscopic displacement efficiency - may be due to a number o~ factors such as differences in the mobilities of the injected displacing liquids and the
In the recovery of oil from oil-bearing reservoirs 9 it usually is possible to recover only minor portions of the original oil in place by the so called primary recovery methods which utilize only the natural forces present in the reservoir. Thus a variety of supplemental recovery techniques have been employed in order to increase the recovery of oil from subterranean reservoirs. The most widely used supplemental recovery technique is waterflooding which involv~s the injection of water into an oil-bearing reservoir. As the water moves through the reservoir, it acts ~o displace oil therein ~o a - production system comp~sed of one or more wells through which the oil is recoyered.
One diffi ulty often encountered in waterflooding operations is the relatively poor sweep efficiRncy of the aqueous displa~cing medium; that is, the inJected displacing medium tends to channel through cerkain portions of the reservoir as it ~ravels from the injection system to the production system and to bypass other portions. Such poor ~ 25 swee~ efficiency or macroscopic displacement efficiency - may be due to a number o~ factors such as differences in the mobilities of the injected displacing liquids and the
-2- `
' : -., ; . . , . .
. .
~ ~3~
9707 displaced reservoir oil and permeability variations within the reservoir which encourage preferential flow through - some por~ions of the reservoir at the expense of other portions.
- Various techniques ha~e been.proposed in order to improve the sweep efficiency of the injected displacing medium and thus avoid prematu:re breakthrough at one or more of the wells comprising the production system. The most widely used procedure involves the addition of thickening agents to the injected displacing medium in order to increase the viscosity thereof and thus decrease its mobility to a value equal to or less than the mobility of the displaced reservoir oil, resulting in a "mobility ratio" of oil to ; water which is less than or equal to one. Many polymeric thickening agents including both anionic and cationic polyelectrolytes have been proposed for use in such mobili~y control opera~ions. Thus, U.S. Patent No. 3,085,063 to Turback disclose~ waterflooding in which the water is : thicken~d by the addition of polyvinyl aromatic sulfonates such as sulfonated polystyrene and copolymers of such vinyl aromatic sulfonates. Similarly, U.S. Patent No. 3 7 984~333 to Kraats et al. discl~ses waterflooding involving the injection of an aqueous solution thickened by block copolymers in which the water-soluble blocks are sulfonated polyvinylarenes i , and t~e relatively water-insoluble blocks are polymerized - alpha olefins and/or hydrogenated dienes such as polyisoprene and polybutadiene. Synthetic anionic polymers such as ~hose ` _~,, 3 ' , ' . ' ,,' . ...... ' : ,`
' ~
36~
.
.
9707 disclosed in Turback and Kraats et al., as well as the more widely used partially hydrolyzed polyacrylamides, suffer a number of disadvantages in actual operations.
~here the injected water or the reservoir water contain~
.
significant quantities of dissolved inorganic salts, ... .
their viscosity yield is decreased ma~eriallyO In addi~ion, -- the presence of divalent cations such as magnesium and calcium tend to cause precipitation of these anionic polymers.
- BiopolymPrs such as the Xanthomonas polysaccharides retain much of their thickening power in the presence of inorganic . . .
salts and thus may be employed in high brine environments7 -. .
However, in the absence of special stabilizing procedures, these polysaccharides a~e subject to s~vere thermal-hydrolytic ., .
degradation at temperatures of about 60 C. and above which , ~ 15 limits their application in relatively high temperature .
reservoirs.
,, .
It also has been proposed to employ ca~ionic polyelectrolyt~s as thickeners in waterflood applications.
... . . .
Thus, U.S. Patent No. 3,744,566 to Sæabo et al. discloses - 20 the use of a water-soluble polymer containing at least 1%
.... .
cationic mon~mer units characterized as acrylamido quaternæ y ammonium halides, sulfonates, carboxylates, e~c. The cationic ~onomer may be copolymerized with other .
: copolymerizable water-soluble monomers such as acrylamideg ~ . .. .. .. ~
alkali metal styrene sulfonates, and N vinylpyridine. The polymers d:isclosed in Szabo et al. are said to be particular:ly useful in brines having over 2% dissolved solids.
:..... .
. .
. ,, . ~
. --4--., - ' ~
- . .: ,. : :. - . . -- , .
Summary of -the_Inven on In accordance with the present invention, there is provided a new and improved waterflooding process employing an amphoteric polyelectrolyte which is an effective thickening agent at high temperatures and in saline aqueous media which include the presence of significant quantities of divalent metal ions. The invention is carried out in a subterranean oil-containing reservoir penetrated by spaced injection and production systems. In accordance with the invention, at least a portion of the injected fluid is a thickened aqueous liquid containing a water-soluble copolymer having a molecular weight of at least 50,000 and including at least 20% by weight of quaternary pyridinium sulfonate monomers of the formula:
-CH - CH -~ _ ~ N -R - SO3 wherein R is a Cl-C4 alkylene group. The quaternary pyridinium sulfonate is copolymerized with a water-insoluble alpha olefin or hydrogenated diene. A preferred application of the present invention is in oil reservoirs in which the formation waters exhibit high salinities and/or divalent metal ion concentrations or in instances in which the available in~ection waters exhibit high salinities and/or divalent metal ion concentrations. Thus, a preferred application of the invention is in cases where the formation waters or the injection waters or both contain divalent metal ion concentrations of at least 0.1 weight percent.
:
-- S --9707 In a preferred embodiment of the invention, the amphoteric polymer employed as a thickening agent is a vinylpyridinium sulfonate-styrene block copolymer characterizPd by the formula:
T c c ~ c c ~
l-m m wherein R is a Cl-C~ alkylene group and m is a mole fraction : within the range of ~2-~9o Brief Description of ~he Drawing Thë drawing is a graph illustrating the relationship between the concentra~ion of he amphoteric polyelectrolyte and low shear rate viscosity.
Description of ~he Spec_fic Embodiments The present ;nvention involves a process for the . recovery of oil employing as a water thic~ening agent an - amphoteric polyelectrolyte having both quaternary ammonium groups and ~ulfonate groups covalently bonded to ~he polymer s~ructure. The amphoteric function is provided by vinyl pyridinium sulfonate in which a Cl-C4 alkylene group links the anionic ~ulfonate group to the ca~ionic qua~ernary . pyridinium group. The amphoteric polyelectrolyte contains pyridinium sulfonate monom~rs and copolymerizable ~.
~ -6- .
~' . - .
. . .
. .
~ ~9 ~
9707 water-insoluble monomers to form either random or block copolymers. Block copolymers are preferred for use in carrying out the present invention since comparable viscosity yields are produced at significantly lower molecular weight for the block copolymers than fbr the random copolymers and the block copolymers exhibit good shear stability. The amphoteric polyelectrolytes may be linear block copolymers of AB, ABA, or BAB configuration or they may be of nonlinear configura~ion such as may be formed by grafting of two or mor~ polymer chains. In the graft polymer configurations, the polymer chains themselves may be homopolymeric or copolymeric in nature. It is desirable to employ block copolymers of narrow molecular weight distribution in order to retard permanent shear degradation under the high shear stress attendant to - injec~ion of the polymer solution into the reservoir.
- Preferably the block copolymer has a molecular weight distribu~ion as defined by the ratio of the weigh~ average molecular weight (Mw) to the number average molecular -weight (Mn) within the range o~ 1.0 to 1.4.
The water-solu~le polymer blocks~comprise quaternary pyridinium sulfonate monomers characterized by the fornLIla:
,~ CH CH2 ~ + - ~ - SO3 (1) . .
~ -7-~ 6 ~
9707 wherein R is a Cl ~4 alkylene group Polymers of such quaternary pyridinium sulfonates are described by Hart et al., "New Polyampholytes: ~le Polysulfobetaines", Journal of Polymer Science, Vol. XXVIII, Issue No. 118~ pp. 638-640 (1958). As disclosed by Hart et al., homopolymers or acrylamide copol~mers of polyvinylpyridine butylsulfobetaine can be prepared by reaction of vinylpyridine with butane sultone and subsequent polymeri2ation or by reaction of polyvinylpyridine with butane sultone.
The water-insoluble blocks of the amphoteric polyelectrolyte are derived from hydrogenated dienes or alpha olefins. Thus, the wate.r insoluble blocks may be formed by polymerization of dienes such as isoprene~
butadiene, 2,3-dimethylbutadiene, and chloroprene. The polymerized dienes are then hydrogenated to convert the diene polymer blocks ~o essentially the equivalent of alpha-olefin polymer blocks Al~erna~ively~ the water-insoluble^blockæ may be provided by alpha-olefin polymers such as polyisobutene, polyethylene, polypropylene, and other water-in~oluble vinyl addition polymers such as vinylarene polymers and water-insoluble acrylic polymer~.
Examples of vinylarenes which may be copolymerized with the vinylpyridine include styrene, alpha-methyl styrene, vinyl toluene, and ~inyl naphthalene. Examples of more polar but s~ i water-insoluble acrylic polymer blocks ara polyac~llonitrile and polymethylacrylonitrile.
.
.
8~
~707 The amphoteric polyelectrolyte employed in the present invention may be fo~ed by copolymeriæation of - vinylpyridine with the appropriate alpha olefin or hydrogenated diene with subsequent sulfonation. Random copolymers may be prepared by free radical initiated copolymerization of vinylpyridine a~d the water-insoluble monomer~ Block copolymers may be prepared by anionic copolymerization of vinylpyridine and the water-insoluble monomer by serially feeding the monomers to the polymerization system one at a time in a manner to form the desired block structure. The molecular weight distribution of the block copolymer may be retained within narrow limits due to the : "living" nature of the polymerization process. The block or random copolymers may be sulfonated by quaternization of the pyridine functional group with a sultone or a halogenated alkane sulfonate. Thus, pyri~inium sulfonate monomers as characterized by formula ~1? of the type in which R is a C3 or C4`group may be prepared by react;ng the vinylpyridine copolymer with propane sultone or butane sultone in the manner described in the article by Hart et al.
Pyridinium sulfonates in which the alkylene linkage contains 1 or 2 carbon atoms may be prepared by reacting the vinylpyridine copolymer wi~h a halogenated alkane sulfonate such as chloromethane sulfonate or chloroethane sulfonate~
In experimental work relative to the invention7 viscosity measurements were taken of ~mphoteric poly.electrolyte solutions under various conditions of `.. ~1 ....
_9 _ ,. . .
- . . . . ..
9707 temperature and salinity. In each set of experiments the polyelectrolyte employed was a block copolymer of - vinyl pyridinium ~pylene sulfonate and styrene. This polymer was derived by quaternization of a block copolymer containing 25% styrene ~nd 75% 2-vinylpyridine an~ having a molecular weight of about 100~000. In preparing the polyelectrolyte,the vinylpyridine-styrene copolymer was dissolved in tetr~hydrofuran and a molar equivalen~ amount of propane sultone was added to the solution and the mixture then re~luxed ~or 16 hours. A gelatinous polymer settled ou~
of the refluxe~ solution. Excass water was then added to the mi~ture with stirring and the homogenized mixture was dialyzed against distilled wat r to remove the excess small molecules.
The dialyzed solution was fr eze-dried and the polymer was obtained in the form of a white solid. This procedure produced 100% quaternization of the vinylpyridine por~ion of the polymer as indicated by elementa~ analysis.
The aqueous liquids employed in the experimental work were mixed brines, designated herein as brines "A", ?'B", "C'l~ and "D". Brine A contained 13~2 weight percent sodium chloride~ 9500 ppm calcium io~, and 187~ ppm magnesium ions to provide a total salinity of 16~6 weight percent. BrinP B
conta;ned 6.4 weight percent sodium chloride, 9272 ppm calci~m ions, and 2552 ppm magnesium ions to provide a total salinity of L0 weight percent. Brine C contained 6.2 weight percent sodium chloridQ/ 259 ppm magnesium ions~ 1160 ppm calciuDl ions, and 92 ppm barium ions to provide a total 10- .
' 9707 salinity of 6.6 weight percent. Brine D contained 3.9 weight percent sodium chloride, 5563 ppm calcium ions, and 1531 ppm magnesium ions to provide a total salinity of 6.0 weight percent. In each of the brines employed, the divalent metal S ions were presen~ in the form of their chloride salts. In de~cribing the invention and the supporting experimental data, weight percents set forth herein are calculated on a weight (solute)/volume ~solution) basis. Thus, brine A3 for example, had . a total dissolved salts content of 16.6 grams per deciliter of solution.
The results of this experimental work are shown in Tables I, II, and III. In each of these tables the first column gives ~he shear rate at which the viscosity measurements were taken with a Brookfield viscometer. In Table I the viscosities measured at room tempera~ure (a~out 24 C.) ~or the polymer in brine D at concentrations of 0.25, - . 0.5, ~.0, 1.5, and 2.0 weight percent a~e set forth in columns 2 through 6, respectiv~ y. The critical micelle concen~ration ~CMC) at which.a sharp increase in viscosity yield occurs for this block copo~ymer is between i and 1.5 weight percent. However, as indicated by ~he data in Table I, the polymer has a significant thickening effect at low shear rates at concentrations well below the CMC. In waterflood processes bec~use of the radial flow geometry associated - with the fl~w of flùid to or rom a well, the flow velocity and thus the shear rates are e~tremely high immediately adjacent the well and relatively low at more remote locations . , . , ~. .
, .
9707 in the reservoir. Typica71y, the shear rate in the intermediate portion of the reservoir between the injection and production wells ;s on the order of one sec~l.
m e low shear rate viscosities given in Table I
are presen~ed in the drawing in which ~he curves shown are graphs of the log of the viseosity V, in centipoises, on the ordinate versus th~ pol~ner concen~ration C, in weight percent, on the abscissa. In the dxawingS curves 2, 4, and 6 are straight lines drawn interpretively through the 1~ viscosity data points at shear rates of 0.37, 0.73, and 1.84 sec~l, respectively. As can be seen from an examination of the drawing, ex~rapolation of curves 2 3 4, and 6 to a polymer concentration of 0.1 percent (l,000 ppm) would still indicate a two- to threefold increaæe in viscosity. As described in greater detail hereinafterg the viscosity yield of t~e amphoteric polyelectrolytes is a ~unction not only of the polymer molecular weight but also of the relative amount of water-Insoluble blocks in the copolymer. Thus, in r~gard to the vinyl pyridinium sulfonate-styrene copolymer described above~ similar viseosity yields can be achieved at lower polymer concentrations by increasing the molecular weight of the copolymer or the mole fraction of the styrene blocks, or both.
" ? .~. .
' ~
~9W~
Shear Rate, Sec 1 Pol~ner_Conc. ,/0 0.25 0.5 1.0 1.5 ~ ~
O . 37 Viscosity2. cp . 6 . 00 6 . 00 22 . 00 58 . 00 156. 00 `
0.73 ~.00 6.00 15.00 ~4.00 142.~0.
1.8~ 2.80 5.20 14.00 41.60 127.20,
' : -., ; . . , . .
. .
~ ~3~
9707 displaced reservoir oil and permeability variations within the reservoir which encourage preferential flow through - some por~ions of the reservoir at the expense of other portions.
- Various techniques ha~e been.proposed in order to improve the sweep efficiency of the injected displacing medium and thus avoid prematu:re breakthrough at one or more of the wells comprising the production system. The most widely used procedure involves the addition of thickening agents to the injected displacing medium in order to increase the viscosity thereof and thus decrease its mobility to a value equal to or less than the mobility of the displaced reservoir oil, resulting in a "mobility ratio" of oil to ; water which is less than or equal to one. Many polymeric thickening agents including both anionic and cationic polyelectrolytes have been proposed for use in such mobili~y control opera~ions. Thus, U.S. Patent No. 3,085,063 to Turback disclose~ waterflooding in which the water is : thicken~d by the addition of polyvinyl aromatic sulfonates such as sulfonated polystyrene and copolymers of such vinyl aromatic sulfonates. Similarly, U.S. Patent No. 3 7 984~333 to Kraats et al. discl~ses waterflooding involving the injection of an aqueous solution thickened by block copolymers in which the water-soluble blocks are sulfonated polyvinylarenes i , and t~e relatively water-insoluble blocks are polymerized - alpha olefins and/or hydrogenated dienes such as polyisoprene and polybutadiene. Synthetic anionic polymers such as ~hose ` _~,, 3 ' , ' . ' ,,' . ...... ' : ,`
' ~
36~
.
.
9707 disclosed in Turback and Kraats et al., as well as the more widely used partially hydrolyzed polyacrylamides, suffer a number of disadvantages in actual operations.
~here the injected water or the reservoir water contain~
.
significant quantities of dissolved inorganic salts, ... .
their viscosity yield is decreased ma~eriallyO In addi~ion, -- the presence of divalent cations such as magnesium and calcium tend to cause precipitation of these anionic polymers.
- BiopolymPrs such as the Xanthomonas polysaccharides retain much of their thickening power in the presence of inorganic . . .
salts and thus may be employed in high brine environments7 -. .
However, in the absence of special stabilizing procedures, these polysaccharides a~e subject to s~vere thermal-hydrolytic ., .
degradation at temperatures of about 60 C. and above which , ~ 15 limits their application in relatively high temperature .
reservoirs.
,, .
It also has been proposed to employ ca~ionic polyelectrolyt~s as thickeners in waterflood applications.
... . . .
Thus, U.S. Patent No. 3,744,566 to Sæabo et al. discloses - 20 the use of a water-soluble polymer containing at least 1%
.... .
cationic mon~mer units characterized as acrylamido quaternæ y ammonium halides, sulfonates, carboxylates, e~c. The cationic ~onomer may be copolymerized with other .
: copolymerizable water-soluble monomers such as acrylamideg ~ . .. .. .. ~
alkali metal styrene sulfonates, and N vinylpyridine. The polymers d:isclosed in Szabo et al. are said to be particular:ly useful in brines having over 2% dissolved solids.
:..... .
. .
. ,, . ~
. --4--., - ' ~
- . .: ,. : :. - . . -- , .
Summary of -the_Inven on In accordance with the present invention, there is provided a new and improved waterflooding process employing an amphoteric polyelectrolyte which is an effective thickening agent at high temperatures and in saline aqueous media which include the presence of significant quantities of divalent metal ions. The invention is carried out in a subterranean oil-containing reservoir penetrated by spaced injection and production systems. In accordance with the invention, at least a portion of the injected fluid is a thickened aqueous liquid containing a water-soluble copolymer having a molecular weight of at least 50,000 and including at least 20% by weight of quaternary pyridinium sulfonate monomers of the formula:
-CH - CH -~ _ ~ N -R - SO3 wherein R is a Cl-C4 alkylene group. The quaternary pyridinium sulfonate is copolymerized with a water-insoluble alpha olefin or hydrogenated diene. A preferred application of the present invention is in oil reservoirs in which the formation waters exhibit high salinities and/or divalent metal ion concentrations or in instances in which the available in~ection waters exhibit high salinities and/or divalent metal ion concentrations. Thus, a preferred application of the invention is in cases where the formation waters or the injection waters or both contain divalent metal ion concentrations of at least 0.1 weight percent.
:
-- S --9707 In a preferred embodiment of the invention, the amphoteric polymer employed as a thickening agent is a vinylpyridinium sulfonate-styrene block copolymer characterizPd by the formula:
T c c ~ c c ~
l-m m wherein R is a Cl-C~ alkylene group and m is a mole fraction : within the range of ~2-~9o Brief Description of ~he Drawing Thë drawing is a graph illustrating the relationship between the concentra~ion of he amphoteric polyelectrolyte and low shear rate viscosity.
Description of ~he Spec_fic Embodiments The present ;nvention involves a process for the . recovery of oil employing as a water thic~ening agent an - amphoteric polyelectrolyte having both quaternary ammonium groups and ~ulfonate groups covalently bonded to ~he polymer s~ructure. The amphoteric function is provided by vinyl pyridinium sulfonate in which a Cl-C4 alkylene group links the anionic ~ulfonate group to the ca~ionic qua~ernary . pyridinium group. The amphoteric polyelectrolyte contains pyridinium sulfonate monom~rs and copolymerizable ~.
~ -6- .
~' . - .
. . .
. .
~ ~9 ~
9707 water-insoluble monomers to form either random or block copolymers. Block copolymers are preferred for use in carrying out the present invention since comparable viscosity yields are produced at significantly lower molecular weight for the block copolymers than fbr the random copolymers and the block copolymers exhibit good shear stability. The amphoteric polyelectrolytes may be linear block copolymers of AB, ABA, or BAB configuration or they may be of nonlinear configura~ion such as may be formed by grafting of two or mor~ polymer chains. In the graft polymer configurations, the polymer chains themselves may be homopolymeric or copolymeric in nature. It is desirable to employ block copolymers of narrow molecular weight distribution in order to retard permanent shear degradation under the high shear stress attendant to - injec~ion of the polymer solution into the reservoir.
- Preferably the block copolymer has a molecular weight distribu~ion as defined by the ratio of the weigh~ average molecular weight (Mw) to the number average molecular -weight (Mn) within the range o~ 1.0 to 1.4.
The water-solu~le polymer blocks~comprise quaternary pyridinium sulfonate monomers characterized by the fornLIla:
,~ CH CH2 ~ + - ~ - SO3 (1) . .
~ -7-~ 6 ~
9707 wherein R is a Cl ~4 alkylene group Polymers of such quaternary pyridinium sulfonates are described by Hart et al., "New Polyampholytes: ~le Polysulfobetaines", Journal of Polymer Science, Vol. XXVIII, Issue No. 118~ pp. 638-640 (1958). As disclosed by Hart et al., homopolymers or acrylamide copol~mers of polyvinylpyridine butylsulfobetaine can be prepared by reaction of vinylpyridine with butane sultone and subsequent polymeri2ation or by reaction of polyvinylpyridine with butane sultone.
The water-insoluble blocks of the amphoteric polyelectrolyte are derived from hydrogenated dienes or alpha olefins. Thus, the wate.r insoluble blocks may be formed by polymerization of dienes such as isoprene~
butadiene, 2,3-dimethylbutadiene, and chloroprene. The polymerized dienes are then hydrogenated to convert the diene polymer blocks ~o essentially the equivalent of alpha-olefin polymer blocks Al~erna~ively~ the water-insoluble^blockæ may be provided by alpha-olefin polymers such as polyisobutene, polyethylene, polypropylene, and other water-in~oluble vinyl addition polymers such as vinylarene polymers and water-insoluble acrylic polymer~.
Examples of vinylarenes which may be copolymerized with the vinylpyridine include styrene, alpha-methyl styrene, vinyl toluene, and ~inyl naphthalene. Examples of more polar but s~ i water-insoluble acrylic polymer blocks ara polyac~llonitrile and polymethylacrylonitrile.
.
.
8~
~707 The amphoteric polyelectrolyte employed in the present invention may be fo~ed by copolymeriæation of - vinylpyridine with the appropriate alpha olefin or hydrogenated diene with subsequent sulfonation. Random copolymers may be prepared by free radical initiated copolymerization of vinylpyridine a~d the water-insoluble monomer~ Block copolymers may be prepared by anionic copolymerization of vinylpyridine and the water-insoluble monomer by serially feeding the monomers to the polymerization system one at a time in a manner to form the desired block structure. The molecular weight distribution of the block copolymer may be retained within narrow limits due to the : "living" nature of the polymerization process. The block or random copolymers may be sulfonated by quaternization of the pyridine functional group with a sultone or a halogenated alkane sulfonate. Thus, pyri~inium sulfonate monomers as characterized by formula ~1? of the type in which R is a C3 or C4`group may be prepared by react;ng the vinylpyridine copolymer with propane sultone or butane sultone in the manner described in the article by Hart et al.
Pyridinium sulfonates in which the alkylene linkage contains 1 or 2 carbon atoms may be prepared by reacting the vinylpyridine copolymer wi~h a halogenated alkane sulfonate such as chloromethane sulfonate or chloroethane sulfonate~
In experimental work relative to the invention7 viscosity measurements were taken of ~mphoteric poly.electrolyte solutions under various conditions of `.. ~1 ....
_9 _ ,. . .
- . . . . ..
9707 temperature and salinity. In each set of experiments the polyelectrolyte employed was a block copolymer of - vinyl pyridinium ~pylene sulfonate and styrene. This polymer was derived by quaternization of a block copolymer containing 25% styrene ~nd 75% 2-vinylpyridine an~ having a molecular weight of about 100~000. In preparing the polyelectrolyte,the vinylpyridine-styrene copolymer was dissolved in tetr~hydrofuran and a molar equivalen~ amount of propane sultone was added to the solution and the mixture then re~luxed ~or 16 hours. A gelatinous polymer settled ou~
of the refluxe~ solution. Excass water was then added to the mi~ture with stirring and the homogenized mixture was dialyzed against distilled wat r to remove the excess small molecules.
The dialyzed solution was fr eze-dried and the polymer was obtained in the form of a white solid. This procedure produced 100% quaternization of the vinylpyridine por~ion of the polymer as indicated by elementa~ analysis.
The aqueous liquids employed in the experimental work were mixed brines, designated herein as brines "A", ?'B", "C'l~ and "D". Brine A contained 13~2 weight percent sodium chloride~ 9500 ppm calcium io~, and 187~ ppm magnesium ions to provide a total salinity of 16~6 weight percent. BrinP B
conta;ned 6.4 weight percent sodium chloride, 9272 ppm calci~m ions, and 2552 ppm magnesium ions to provide a total salinity of L0 weight percent. Brine C contained 6.2 weight percent sodium chloridQ/ 259 ppm magnesium ions~ 1160 ppm calciuDl ions, and 92 ppm barium ions to provide a total 10- .
' 9707 salinity of 6.6 weight percent. Brine D contained 3.9 weight percent sodium chloride, 5563 ppm calcium ions, and 1531 ppm magnesium ions to provide a total salinity of 6.0 weight percent. In each of the brines employed, the divalent metal S ions were presen~ in the form of their chloride salts. In de~cribing the invention and the supporting experimental data, weight percents set forth herein are calculated on a weight (solute)/volume ~solution) basis. Thus, brine A3 for example, had . a total dissolved salts content of 16.6 grams per deciliter of solution.
The results of this experimental work are shown in Tables I, II, and III. In each of these tables the first column gives ~he shear rate at which the viscosity measurements were taken with a Brookfield viscometer. In Table I the viscosities measured at room tempera~ure (a~out 24 C.) ~or the polymer in brine D at concentrations of 0.25, - . 0.5, ~.0, 1.5, and 2.0 weight percent a~e set forth in columns 2 through 6, respectiv~ y. The critical micelle concen~ration ~CMC) at which.a sharp increase in viscosity yield occurs for this block copo~ymer is between i and 1.5 weight percent. However, as indicated by ~he data in Table I, the polymer has a significant thickening effect at low shear rates at concentrations well below the CMC. In waterflood processes bec~use of the radial flow geometry associated - with the fl~w of flùid to or rom a well, the flow velocity and thus the shear rates are e~tremely high immediately adjacent the well and relatively low at more remote locations . , . , ~. .
, .
9707 in the reservoir. Typica71y, the shear rate in the intermediate portion of the reservoir between the injection and production wells ;s on the order of one sec~l.
m e low shear rate viscosities given in Table I
are presen~ed in the drawing in which ~he curves shown are graphs of the log of the viseosity V, in centipoises, on the ordinate versus th~ pol~ner concen~ration C, in weight percent, on the abscissa. In the dxawingS curves 2, 4, and 6 are straight lines drawn interpretively through the 1~ viscosity data points at shear rates of 0.37, 0.73, and 1.84 sec~l, respectively. As can be seen from an examination of the drawing, ex~rapolation of curves 2 3 4, and 6 to a polymer concentration of 0.1 percent (l,000 ppm) would still indicate a two- to threefold increaæe in viscosity. As described in greater detail hereinafterg the viscosity yield of t~e amphoteric polyelectrolytes is a ~unction not only of the polymer molecular weight but also of the relative amount of water-Insoluble blocks in the copolymer. Thus, in r~gard to the vinyl pyridinium sulfonate-styrene copolymer described above~ similar viseosity yields can be achieved at lower polymer concentrations by increasing the molecular weight of the copolymer or the mole fraction of the styrene blocks, or both.
" ? .~. .
' ~
~9W~
Shear Rate, Sec 1 Pol~ner_Conc. ,/0 0.25 0.5 1.0 1.5 ~ ~
O . 37 Viscosity2. cp . 6 . 00 6 . 00 22 . 00 58 . 00 156. 00 `
0.73 ~.00 6.00 15.00 ~4.00 142.~0.
1.8~ 2.80 5.20 14.00 41.60 127.20,
3 . 67 2 . 20 4 . 20 14 . 00 3~ , 60 123 . 40.`
7.34 - 1.90 3.80 13.~0 ~0.20 -- ..
.
14.68 1.85 3.7û 12.75 37.15 --36.70 1.8~ 3.50 11.56 -- -- .`.
73.~0 1.~4 3~50 -~ .
Table II sets forth the viscosities observed for - solutions of the vinyl pyridinium sulfonate-styrene copolymer in brine C at room temperature and at 89 C. In Table II the .
second and third columns give the room temperature viscosities .
for polymer concentrations o l.O and 1.5 weight percent~ ;
respectively, and the fouxth and if~h columns give ~he viscosities at 89 C. a~ copolymer concentrations of 1.0 and 1.5 weight percent~ ~esp~ctively. As can be sePn from -an examination of the data in Table II, the decrease in viscosity associated with the 6~ C. rise in temperature F.
is relatively small. Furthermore, the specific viscosities : of the polymer solutions, as indicated by a water viscosity t~'."
:~ of about 0.3 cp~ at 89 C.. as contrasted with a ~iscosity L
of about 0.9 cp. at room temperature, are somewhat-higher `~25 at 89 ~. than at room tempera~ure. . ..
.:.
, 1,~ .~, . .
....
.' ~
..
Shear Rate, Sec 1 Poly,mer Conc.,/~ Room Temp ~
- 0.37 Viscosity~ cp.20.00 5~.0016.00 30.00 0.73 22.0~ 48.0011.~0 26.00 1.84 '~4.80 42.40~.80 18.40 3.67 - 13.00 38.605.60 15.8G
12.30 35.705.~0' 14.00 1~.68 11.70 32.75 4.65 12.4 3~.71 10.80 -- 4.30 l~.9g Table III presents a comparison of viscosity measuremen~s observed for the pyridinium,sulfonate-styrene copolymer in brines A, B, and C at 89 C. In Table III, ~he second and third columns set forth the viscosities measured for polymer concentration$ of 1.0 and 1.5 weight percen~
respectively, in brine A. Viscosity data ~or these same polymer concentrations are set forth for polymer solutions in brine B in columns 4 and 5, and for polymer solu~ions in brine C in columns 6 ahd 7. It will be recalled that brines A, , B, and C h~ve salinities of 16.6, 10, and 6.6 weight percent, -with divalent metal ion concentrations ranging from 1500 ppm for brine ~ to between 11~000-12,000 ppm fo~ brines A and B4 From an examination o~ the data set for~h in Table III, it can be seen that neither the ~otal salinity nor the divalent metal ion content of the brines had an adverse impact upon the ViSCosit~J yield. In fact it will be noted that the highe~t viscosities were generally obtained in the high salinit~ brine A'.
.
, ;
, .
: ~ , o ~ o o o o oo u~ O O ~ a7 0 ~ ~
t ~ ~i O ~S> 7 u7 ~ c~l C;
3 ol o o ~ c oo 7 ~ U~
O o o o o u~ ~1 O 0 00 ~ ~ ~ ~'~
O O C::~ O O U~
o C~ C~ ~ ~ a c~ 1~ U7 ~_i .1 g H ¢ ~ OL
H t: tr) c~
1~ ~1 O O O O O u~ ~t O
~ ~ :~ O o ~ ~ r~
~i . ~i ,~ O a7 1~ ~7 ~7 u~ u~
~1 .
C;7 P`
~ 3~ _ a~ ~
1~ t~7 r-l ~q O .,.~
1:4 ~
.
~l :: t) a3 cq ~ .
~ ~ 7 ~ C~l t 7, 1~ L7 C~7 ~L7 1 . . o ~ . . . .
_ ~ O ~ L7 `: 15-.
-.
: :
~ ~3 ~
9707 . The amphoteric polyelectrolyte may be employed in accordance with the present :invention in any suitable concentration depending upon the desired viscosity of the displacing medi~m. Normally the mobility ratio of the reservoir oil to the injected water as defined, for example, in U.S. Patent No. 3,025,237 to ~oper, should be equal to or less than 1. In many cases, the relative permeabilities of the reservoir to oil and water are discounted in arriving at the mobility ratio or, stated otherwise, the desired viscosity of the mob~lity control fluid is equal to or greater than the viscosity of the reser~oir oil. Typically the thickened water inj~cted for mobility control purposes exhibits a viscosity in the range of 1 to 4 times that of the - res-ervoir oil.
As noted previously, the viscosity yield of the amphoteric polyelec~rolyte is related to its molecular weight and also to its configuration. Where the amphoteric polyelectrolyte employed is a block copolymer, it is preferred that it exhibit a molecular weight of at least 50,000 for 20. adequate thickening of the injection water without ~he use of excessively-high polymer concentrations. Where the amphoteric p~lyelectrolyte is a random copol~mer3 it desirably should have a molecular weight o at leas~ 5007000 in view of these same considerations.
The viscosity yield of the amphoteric polyelectrolyte is also related to the relative amount of water-insoluble polymer units or polymer blocks~ As a general rule, the .
-16 ~
'~ .
~ ~ , 9707 critical micelle concentration is reduced and the viscosity yield at a given polymer concentration is increased by increasing the proportionate amount of water-insoluble polymer blocks up to a point less than that at which the - total polymer becomes water-insoluble... The water solubility of the amphoteric polyelectrolyte is inversely related to the proportion of water-insoluble polymer blocks and as a practical matter the copolymer should contain at least 20% by weight of the vinyl pyridinium sulfonate units.
1~ A preferred class of amphoteric polyelectrolytes for use in the present invention is vinyl pyridinium sulfonate-styxene block copolymers characterized by the formula:
L ~ R so3 ~
wherein R is a Cl~C4 alkylene group and m is a mole fraction within the range of .2-.9.
The value o m may vary within the aforPmentioned range depending upon the salinity of the water and the desired viscosity yi.eld. For example, the copolymer employed in the previousl~ described experimental work was soluble with some di.fficult~ in distilled water but was readily soluble in all of the brine solutions employed. Thus, th~ relative amount of vinyl pyridinium sulonate in ,., .~:
~ ~3 ~
9707 the polymer may be lower in the more saline solutions than in rela~ively fresh solutions. Preferably the value of m is within the range of .5-.8 in order to provide for an enhanced viscosity yield of the amphoteric polyelectrolyte at relatively low polymer concentrations.
As indioated by fo~ulas (1) and ~2~, the quaterniæed nitrogen may be at the 2, 3, or 4 position with respect to the vinyl group. However, it is preferred that the amphoteric polyelectrolyte comprise 2 vinyl pyridinium lV sulfonate since in this position the amphoteric structure tends to stiffen the polymer backbone. The amphoteric polyelectrolyte may be derived from mixtures of 2- and
7.34 - 1.90 3.80 13.~0 ~0.20 -- ..
.
14.68 1.85 3.7û 12.75 37.15 --36.70 1.8~ 3.50 11.56 -- -- .`.
73.~0 1.~4 3~50 -~ .
Table II sets forth the viscosities observed for - solutions of the vinyl pyridinium sulfonate-styrene copolymer in brine C at room temperature and at 89 C. In Table II the .
second and third columns give the room temperature viscosities .
for polymer concentrations o l.O and 1.5 weight percent~ ;
respectively, and the fouxth and if~h columns give ~he viscosities at 89 C. a~ copolymer concentrations of 1.0 and 1.5 weight percent~ ~esp~ctively. As can be sePn from -an examination of the data in Table II, the decrease in viscosity associated with the 6~ C. rise in temperature F.
is relatively small. Furthermore, the specific viscosities : of the polymer solutions, as indicated by a water viscosity t~'."
:~ of about 0.3 cp~ at 89 C.. as contrasted with a ~iscosity L
of about 0.9 cp. at room temperature, are somewhat-higher `~25 at 89 ~. than at room tempera~ure. . ..
.:.
, 1,~ .~, . .
....
.' ~
..
Shear Rate, Sec 1 Poly,mer Conc.,/~ Room Temp ~
- 0.37 Viscosity~ cp.20.00 5~.0016.00 30.00 0.73 22.0~ 48.0011.~0 26.00 1.84 '~4.80 42.40~.80 18.40 3.67 - 13.00 38.605.60 15.8G
12.30 35.705.~0' 14.00 1~.68 11.70 32.75 4.65 12.4 3~.71 10.80 -- 4.30 l~.9g Table III presents a comparison of viscosity measuremen~s observed for the pyridinium,sulfonate-styrene copolymer in brines A, B, and C at 89 C. In Table III, ~he second and third columns set forth the viscosities measured for polymer concentration$ of 1.0 and 1.5 weight percen~
respectively, in brine A. Viscosity data ~or these same polymer concentrations are set forth for polymer solutions in brine B in columns 4 and 5, and for polymer solu~ions in brine C in columns 6 ahd 7. It will be recalled that brines A, , B, and C h~ve salinities of 16.6, 10, and 6.6 weight percent, -with divalent metal ion concentrations ranging from 1500 ppm for brine ~ to between 11~000-12,000 ppm fo~ brines A and B4 From an examination o~ the data set for~h in Table III, it can be seen that neither the ~otal salinity nor the divalent metal ion content of the brines had an adverse impact upon the ViSCosit~J yield. In fact it will be noted that the highe~t viscosities were generally obtained in the high salinit~ brine A'.
.
, ;
, .
: ~ , o ~ o o o o oo u~ O O ~ a7 0 ~ ~
t ~ ~i O ~S> 7 u7 ~ c~l C;
3 ol o o ~ c oo 7 ~ U~
O o o o o u~ ~1 O 0 00 ~ ~ ~ ~'~
O O C::~ O O U~
o C~ C~ ~ ~ a c~ 1~ U7 ~_i .1 g H ¢ ~ OL
H t: tr) c~
1~ ~1 O O O O O u~ ~t O
~ ~ :~ O o ~ ~ r~
~i . ~i ,~ O a7 1~ ~7 ~7 u~ u~
~1 .
C;7 P`
~ 3~ _ a~ ~
1~ t~7 r-l ~q O .,.~
1:4 ~
.
~l :: t) a3 cq ~ .
~ ~ 7 ~ C~l t 7, 1~ L7 C~7 ~L7 1 . . o ~ . . . .
_ ~ O ~ L7 `: 15-.
-.
: :
~ ~3 ~
9707 . The amphoteric polyelectrolyte may be employed in accordance with the present :invention in any suitable concentration depending upon the desired viscosity of the displacing medi~m. Normally the mobility ratio of the reservoir oil to the injected water as defined, for example, in U.S. Patent No. 3,025,237 to ~oper, should be equal to or less than 1. In many cases, the relative permeabilities of the reservoir to oil and water are discounted in arriving at the mobility ratio or, stated otherwise, the desired viscosity of the mob~lity control fluid is equal to or greater than the viscosity of the reser~oir oil. Typically the thickened water inj~cted for mobility control purposes exhibits a viscosity in the range of 1 to 4 times that of the - res-ervoir oil.
As noted previously, the viscosity yield of the amphoteric polyelec~rolyte is related to its molecular weight and also to its configuration. Where the amphoteric polyelectrolyte employed is a block copolymer, it is preferred that it exhibit a molecular weight of at least 50,000 for 20. adequate thickening of the injection water without ~he use of excessively-high polymer concentrations. Where the amphoteric p~lyelectrolyte is a random copol~mer3 it desirably should have a molecular weight o at leas~ 5007000 in view of these same considerations.
The viscosity yield of the amphoteric polyelectrolyte is also related to the relative amount of water-insoluble polymer units or polymer blocks~ As a general rule, the .
-16 ~
'~ .
~ ~ , 9707 critical micelle concentration is reduced and the viscosity yield at a given polymer concentration is increased by increasing the proportionate amount of water-insoluble polymer blocks up to a point less than that at which the - total polymer becomes water-insoluble... The water solubility of the amphoteric polyelectrolyte is inversely related to the proportion of water-insoluble polymer blocks and as a practical matter the copolymer should contain at least 20% by weight of the vinyl pyridinium sulfonate units.
1~ A preferred class of amphoteric polyelectrolytes for use in the present invention is vinyl pyridinium sulfonate-styxene block copolymers characterized by the formula:
L ~ R so3 ~
wherein R is a Cl~C4 alkylene group and m is a mole fraction within the range of .2-.9.
The value o m may vary within the aforPmentioned range depending upon the salinity of the water and the desired viscosity yi.eld. For example, the copolymer employed in the previousl~ described experimental work was soluble with some di.fficult~ in distilled water but was readily soluble in all of the brine solutions employed. Thus, th~ relative amount of vinyl pyridinium sulonate in ,., .~:
~ ~3 ~
9707 the polymer may be lower in the more saline solutions than in rela~ively fresh solutions. Preferably the value of m is within the range of .5-.8 in order to provide for an enhanced viscosity yield of the amphoteric polyelectrolyte at relatively low polymer concentrations.
As indioated by fo~ulas (1) and ~2~, the quaterniæed nitrogen may be at the 2, 3, or 4 position with respect to the vinyl group. However, it is preferred that the amphoteric polyelectrolyte comprise 2 vinyl pyridinium lV sulfonate since in this position the amphoteric structure tends to stiffen the polymer backbone. The amphoteric polyelectrolyte may be derived from mixtures of 2- and
4-vinylpyridine since this is a readily available commercial product~ Preferably R contains 3 or 4 carbon atoms since these derivatives can be easily prepared by the reaction of the vinylpyridine polymerie units with propane sultone . or bu~ane sultone. Usually it will be desirable or preferred to effect sulfonation through the use of propane sultones since the addition reaction of sultone with the vinylpyridine proceeds readily under relatively moderate temperature conditions, as evidenced by the above examp~lP.
A preferred application o~ the present invention is in reservoirs exhibiting relatively high temp~ra~ures of 60 C. or above and in reservoirs in which the connate wa~er " 3`_ _ or t~é availahle 100ding medium contains high concentrations o salt and significant divalent metal ion concentrations which are inconsistent with the use of eonventional anionic . i~ ...
:
:
9707 polyelectrolytes such as partially hydrolyzed polyacrylamides or hydrophobic-llydrophilic block copolymers containing such structures. Thus a preferred application of the present invention is in those situat:ions in which the reservoir waters and/or the waters emp:Loyed in ormulating the floodLng medium exhibit a divalent metal ion conc~ntration of at least 0.1 weight percent. A similar consideration applies with regard to ~hose situations iII which t~e reservoir and/or injection waters exhibit moderate to relatively high salinities even though the.divalent metal ion concentration may be low. Thus another application o~ the invention is in those si~uations in which the reservoir water and/or.
injec~ion waters have salinities of at least 1~0 weight . percent regardless of whether provided by monovalent salts such as sodium chloride or divalent salts such as calcium or magnesium chloride.
.. The thickened aqueous solution of amphoteric polyelectrolyte~may be employed in conjunction with various other additives such as surface-active agents which are . added to the injected water in order.to reduce the oil-wa~er interfacial tension. The amphoteric polyel~ctrolyte may be employed in the surfactant slug or employed as a separate mobility control slug injected subsequent to the aqueous solution of surface-active agent. The amphoteric polyelectrolyte ~ ~ .
may be addecl in concentrations so as to provide a graded - viscosity at: the trailing edge o~ the mobility cvntrol slug as described for ex~mple in Foster, W. R., I'A Low-Tension f ~
: -19-' ' ' . ' ~ 6 ~
9707 l~aterflooding Process", Journal of Petroleum Technology, Vol. 25, February 1973~.pp. 205-210. Alternatively, the - amphoteric polymer may be employed in concentrations to provide graded viscosities at both the leading and trailing edges of the mobility control slug as disclosed in U.S.
Patent No. 4,018,281 to Chang or the thick~ning agent concentration may be relatively constant throughout the mobility control slug. In any case, it normally will be desirable ~o employ the amphoteric polyelectrolyte in a concentration such that the viscosity of at least.a portion of ~he mobility control slug is equal to or greater than tha~ of the reservoir oil as described previously.
Typically, the mobility control slug will be injected in an amount within the range of .2 to .6 pore volume.
~ . ;,~
. . ~ .... . :
.
,
A preferred application o~ the present invention is in reservoirs exhibiting relatively high temp~ra~ures of 60 C. or above and in reservoirs in which the connate wa~er " 3`_ _ or t~é availahle 100ding medium contains high concentrations o salt and significant divalent metal ion concentrations which are inconsistent with the use of eonventional anionic . i~ ...
:
:
9707 polyelectrolytes such as partially hydrolyzed polyacrylamides or hydrophobic-llydrophilic block copolymers containing such structures. Thus a preferred application of the present invention is in those situat:ions in which the reservoir waters and/or the waters emp:Loyed in ormulating the floodLng medium exhibit a divalent metal ion conc~ntration of at least 0.1 weight percent. A similar consideration applies with regard to ~hose situations iII which t~e reservoir and/or injection waters exhibit moderate to relatively high salinities even though the.divalent metal ion concentration may be low. Thus another application o~ the invention is in those si~uations in which the reservoir water and/or.
injec~ion waters have salinities of at least 1~0 weight . percent regardless of whether provided by monovalent salts such as sodium chloride or divalent salts such as calcium or magnesium chloride.
.. The thickened aqueous solution of amphoteric polyelectrolyte~may be employed in conjunction with various other additives such as surface-active agents which are . added to the injected water in order.to reduce the oil-wa~er interfacial tension. The amphoteric polyel~ctrolyte may be employed in the surfactant slug or employed as a separate mobility control slug injected subsequent to the aqueous solution of surface-active agent. The amphoteric polyelectrolyte ~ ~ .
may be addecl in concentrations so as to provide a graded - viscosity at: the trailing edge o~ the mobility cvntrol slug as described for ex~mple in Foster, W. R., I'A Low-Tension f ~
: -19-' ' ' . ' ~ 6 ~
9707 l~aterflooding Process", Journal of Petroleum Technology, Vol. 25, February 1973~.pp. 205-210. Alternatively, the - amphoteric polymer may be employed in concentrations to provide graded viscosities at both the leading and trailing edges of the mobility control slug as disclosed in U.S.
Patent No. 4,018,281 to Chang or the thick~ning agent concentration may be relatively constant throughout the mobility control slug. In any case, it normally will be desirable ~o employ the amphoteric polyelectrolyte in a concentration such that the viscosity of at least.a portion of ~he mobility control slug is equal to or greater than tha~ of the reservoir oil as described previously.
Typically, the mobility control slug will be injected in an amount within the range of .2 to .6 pore volume.
~ . ;,~
. . ~ .... . :
.
,
Claims (10)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method for the recovery of oil from an oil-containing subterranean reservoir penetrated by spaced injection and production systems wherein fluid is introduced into said reservoir via said injection system to displace oil therein to said production system, the improvement comprising employing as at least a portion of the fluid introduced into said injection system an aqueous liquid containing a water-soluble compolymer having a molecular weight of at least 50,000 and including at least 20% by weight of quaternary pyridinium sulfonate monomers of the formula:
wherein R is a C1-C4 alkylene group copolymerized with a water-insoluble alpha olefin or hydrogenated diene, said polymer being present in said aqueous liquid in a concentration sufficient to increase the viscosity thereof at the temperature of said reservoir.
wherein R is a C1-C4 alkylene group copolymerized with a water-insoluble alpha olefin or hydrogenated diene, said polymer being present in said aqueous liquid in a concentration sufficient to increase the viscosity thereof at the temperature of said reservoir.
2. The method of claim 1 wherein R is a -C3H6-group.
3. The method of claim 1 wherein said copolymer is a block copolymer having a molecular weight distribution within the range of 1.0-1.4 as defined by the ratio:
wherein:
MW is the weight average molecular weight of said copolymer, and MN is the number average molecular weight of said copolymer.
wherein:
MW is the weight average molecular weight of said copolymer, and MN is the number average molecular weight of said copolymer.
4. The method of claim 1 wherein said polymer is a vinyl pyridinium sulfonate-styrene block copolymer characterized by the formula:
wherein R is a C1-C4 alkylene group and m is a mole fraction within the range of .2-.9.
wherein R is a C1-C4 alkylene group and m is a mole fraction within the range of .2-.9.
5. The method of claim 4 wherein said copolymer contains 2-vinyl pyridinium sulfonate.
6. The method of claim 4 wherein m is a mole fraction within the range of .5 to .8.
7. The method of claim 4 wherein said block copolymer has a molecular weight distribution within the range of 1.0-1.4 as defined by the ratio:
wherein:
MW is the weight average molecular weight of said copolymer, and Mn is the number average molecular weight of said copolymer.
wherein:
MW is the weight average molecular weight of said copolymer, and Mn is the number average molecular weight of said copolymer.
8. The method of claim 4 wherein R is a -C3H6-group.
9. The method of claim 4 wherein said aqueous liquid has a divalent metal ion concentration of at last .1 weight percent.
10. The method of claim 4 wherein said subterranean reservoir contains water having a divalent metal ion concentration of at least 0.1 weight percent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US901,555 | 1978-05-01 | ||
| US05/901,555 US4222881A (en) | 1978-05-01 | 1978-05-01 | Oil recovery process involving the injection of thickened water |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1098689A true CA1098689A (en) | 1981-04-07 |
Family
ID=25414415
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA324,099A Expired CA1098689A (en) | 1978-05-01 | 1979-03-26 | Oil recovery process involving the injection of thickened water |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4222881A (en) |
| CA (1) | CA1098689A (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4451623A (en) * | 1981-01-16 | 1984-05-29 | Mobil Oil Corporation | Water soluble phenolic-formaldehyde polymer which is a surfactant mobility control agent in oil recovery |
| US4374740A (en) * | 1981-01-16 | 1983-02-22 | Mobil Oil Corporation | Water soluble surfactant mobility control agent in oil recovery |
| US4814096A (en) * | 1981-02-06 | 1989-03-21 | The Dow Chemical Company | Enhanced oil recovery process using a hydrophobic associative composition containing a hydrophilic/hydrophobic polymer |
| US4432881A (en) * | 1981-02-06 | 1984-02-21 | The Dow Chemical Company | Water-dispersible hydrophobic thickening agent |
| US4476931A (en) * | 1982-09-17 | 1984-10-16 | Hughes Tool Company | Water control well treating solution and method |
| US4505827A (en) * | 1983-09-19 | 1985-03-19 | The Dow Chemical Company | Triblock polymers of the BAB type having hydrophobic association capabilities for rheological control in aqueous systems |
| US4653585A (en) * | 1985-01-31 | 1987-03-31 | Mobil Oil Corporation | Oil reservoir permeability control |
| US5132285A (en) * | 1988-04-26 | 1992-07-21 | National Starch And Chemical Investment Holding Corporation | Method for thickening or stabilizing aqueous media with polyamphoteric polysaccharides |
| US5132284A (en) * | 1988-04-26 | 1992-07-21 | National Starch And Chemical Investment Holding Corporation | Polyamphoteric polysaccharide graft copolymers neutrally charged |
| US5185415A (en) * | 1989-07-12 | 1993-02-09 | Japane Vilene Co., Ltd. | Adsorptive resin for microorganisms |
| USRE34740E (en) * | 1989-07-12 | 1994-09-27 | Japane Vilkene Company, Ltd. | Adsorptive resin for microorganisms |
| US4976315A (en) * | 1989-11-06 | 1990-12-11 | Texaco Inc. | Use of taurine additives in enhanced oil recovery with anionic surfactants |
| US5344891A (en) * | 1990-07-07 | 1994-09-06 | Mitsubishi Rayon Co., Ltd. | Biodegradable polymers |
| US6306815B1 (en) * | 1999-09-10 | 2001-10-23 | National Starch And Chemical Investment Holding Corporation | Quaternary polyvinylpyrridinium derivatives as anti-dye transfer agents |
| EP2205826A4 (en) * | 2007-10-31 | 2011-06-29 | Rhodia | Addition of zwitterionic surfactant to water soluble polymer to increase the stability of the polymers in aqueous solutions containing salt and/or surfactants |
| US7789160B2 (en) * | 2007-10-31 | 2010-09-07 | Rhodia Inc. | Addition of nonionic surfactants to water soluble block copolymers to increase the stability of the copolymer in aqueous solutions containing salt and/or surfactants |
| CN110016325B (en) * | 2018-01-10 | 2021-05-04 | 中国石油化工股份有限公司 | Shear strength improving agent for water-based drilling fluid and preparation method thereof |
| CN114478906B (en) | 2020-10-26 | 2023-05-02 | 中国石油化工股份有限公司 | Polyacrylamide-based symmetrical branched polymer surfactant, and preparation method and application thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3085063A (en) * | 1959-12-30 | 1963-04-09 | Jersey Prod Res Co | Secondary recovery waterflooding technique |
| US3399249A (en) * | 1966-01-12 | 1968-08-27 | Rexall Drug Chemical | Sulfopropylated olefin block copolymers having terminal segments containing amno groups |
| US3744566A (en) * | 1972-03-16 | 1973-07-10 | Calgon Corp | Secondary oil recovery process |
| US3948783A (en) * | 1974-04-30 | 1976-04-06 | Calgon Corporation | Process for the secondary and tertiary recovery of petroleum |
| US3984333A (en) * | 1975-04-07 | 1976-10-05 | Shell Oil Company | Oil-displacing aqueous solution thickened with reservoir-tailored block copolymer |
-
1978
- 1978-05-01 US US05/901,555 patent/US4222881A/en not_active Expired - Lifetime
-
1979
- 1979-03-26 CA CA324,099A patent/CA1098689A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4222881A (en) | 1980-09-16 |
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