CN116239722A - Variable viscosity double-aqueous-phase polymer for deep shale fracturing and preparation method thereof - Google Patents
Variable viscosity double-aqueous-phase polymer for deep shale fracturing and preparation method thereof Download PDFInfo
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- CN116239722A CN116239722A CN202211685733.4A CN202211685733A CN116239722A CN 116239722 A CN116239722 A CN 116239722A CN 202211685733 A CN202211685733 A CN 202211685733A CN 116239722 A CN116239722 A CN 116239722A
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- 229920000642 polymer Polymers 0.000 title claims abstract description 114
- 239000008346 aqueous phase Substances 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 239000000178 monomer Substances 0.000 claims abstract description 61
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 43
- 239000002612 dispersion medium Substances 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 25
- 238000006243 chemical reaction Methods 0.000 claims abstract description 24
- 239000003999 initiator Substances 0.000 claims abstract description 23
- 239000003381 stabilizer Substances 0.000 claims abstract description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 30
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 29
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical group [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 28
- 239000012071 phase Substances 0.000 claims description 27
- 235000002639 sodium chloride Nutrition 0.000 claims description 27
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 22
- 238000006116 polymerization reaction Methods 0.000 claims description 19
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 17
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 17
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 17
- 229910052757 nitrogen Inorganic materials 0.000 claims description 17
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 16
- 239000011780 sodium chloride Substances 0.000 claims description 16
- DZSVIVLGBJKQAP-UHFFFAOYSA-N 1-(2-methyl-5-propan-2-ylcyclohex-2-en-1-yl)propan-1-one Chemical compound CCC(=O)C1CC(C(C)C)CC=C1C DZSVIVLGBJKQAP-UHFFFAOYSA-N 0.000 claims description 15
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 14
- PBIDWHVVZCGMAR-UHFFFAOYSA-N 1-methyl-3-prop-2-enyl-2h-imidazole Chemical compound CN1CN(CC=C)C=C1 PBIDWHVVZCGMAR-UHFFFAOYSA-N 0.000 claims description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 10
- KWYHDKDOAIKMQN-UHFFFAOYSA-N N,N,N',N'-tetramethylethylenediamine Chemical compound CN(C)CCN(C)C KWYHDKDOAIKMQN-UHFFFAOYSA-N 0.000 claims description 10
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 10
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 9
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 8
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 8
- 235000011152 sodium sulphate Nutrition 0.000 claims description 8
- XDFFVDDBWQREAJ-UHFFFAOYSA-M trimethyl(2-prop-2-enoyloxyethyl)azanium;bromide Chemical compound [Br-].C[N+](C)(C)CCOC(=O)C=C XDFFVDDBWQREAJ-UHFFFAOYSA-M 0.000 claims description 8
- RRHXZLALVWBDKH-UHFFFAOYSA-M trimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azanium;chloride Chemical compound [Cl-].CC(=C)C(=O)OCC[N+](C)(C)C RRHXZLALVWBDKH-UHFFFAOYSA-M 0.000 claims description 8
- NLVXSWCKKBEXTG-UHFFFAOYSA-N vinylsulfonic acid Chemical compound OS(=O)(=O)C=C NLVXSWCKKBEXTG-UHFFFAOYSA-N 0.000 claims description 8
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 7
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 7
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 7
- OSSNTDFYBPYIEC-UHFFFAOYSA-N 1-ethenylimidazole Chemical compound C=CN1C=CN=C1 OSSNTDFYBPYIEC-UHFFFAOYSA-N 0.000 claims description 6
- XLXCHZCQTCBUOX-UHFFFAOYSA-N 1-prop-2-enylimidazole Chemical compound C=CCN1C=CN=C1 XLXCHZCQTCBUOX-UHFFFAOYSA-N 0.000 claims description 6
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 6
- VMSBGXAJJLPWKV-UHFFFAOYSA-N 2-ethenylbenzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1C=C VMSBGXAJJLPWKV-UHFFFAOYSA-N 0.000 claims description 6
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 claims description 6
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 6
- 229920002125 Sokalan® Polymers 0.000 claims description 6
- 239000004584 polyacrylic acid Substances 0.000 claims description 6
- MAGFQRLKWCCTQJ-UHFFFAOYSA-N 4-ethenylbenzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=C(C=C)C=C1 MAGFQRLKWCCTQJ-UHFFFAOYSA-N 0.000 claims description 5
- FGKCGMMQJOWMFW-UHFFFAOYSA-M trimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azanium;bromide Chemical compound [Br-].CC(=C)C(=O)OCC[N+](C)(C)C FGKCGMMQJOWMFW-UHFFFAOYSA-M 0.000 claims description 5
- 239000003002 pH adjusting agent Substances 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 2
- 239000012530 fluid Substances 0.000 abstract description 42
- 238000002156 mixing Methods 0.000 abstract description 29
- 239000000839 emulsion Substances 0.000 abstract description 15
- 230000008901 benefit Effects 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 12
- 238000012674 dispersion polymerization Methods 0.000 abstract description 5
- 230000003993 interaction Effects 0.000 abstract description 5
- 239000002609 medium Substances 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 230000002708 enhancing effect Effects 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 45
- 238000004090 dissolution Methods 0.000 description 22
- 239000000047 product Substances 0.000 description 21
- 238000013461 design Methods 0.000 description 15
- 230000001965 increasing effect Effects 0.000 description 13
- 229920002401 polyacrylamide Polymers 0.000 description 13
- ZRALSGWEFCBTJO-UHFFFAOYSA-N Guanidine Chemical compound NC(N)=N ZRALSGWEFCBTJO-UHFFFAOYSA-N 0.000 description 12
- 239000007864 aqueous solution Substances 0.000 description 12
- 230000000694 effects Effects 0.000 description 12
- 239000003638 chemical reducing agent Substances 0.000 description 11
- 239000003795 chemical substances by application Substances 0.000 description 11
- 238000011084 recovery Methods 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 150000003839 salts Chemical class 0.000 description 10
- 125000000129 anionic group Chemical group 0.000 description 9
- 230000009467 reduction Effects 0.000 description 9
- 239000007762 w/o emulsion Substances 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 239000004576 sand Substances 0.000 description 8
- 239000004908 Emulsion polymer Substances 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- CHJJGSNFBQVOTG-UHFFFAOYSA-N N-methyl-guanidine Natural products CNC(N)=N CHJJGSNFBQVOTG-UHFFFAOYSA-N 0.000 description 6
- 230000009471 action Effects 0.000 description 6
- SWSQBOPZIKWTGO-UHFFFAOYSA-N dimethylaminoamidine Natural products CN(C)C(N)=N SWSQBOPZIKWTGO-UHFFFAOYSA-N 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
- 230000001502 supplementing effect Effects 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 229920002521 macromolecule Polymers 0.000 description 5
- 230000001376 precipitating effect Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000004132 cross linking Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 239000008399 tap water Substances 0.000 description 4
- 235000020679 tap water Nutrition 0.000 description 4
- 241000612182 Rexea solandri Species 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 230000003068 static effect Effects 0.000 description 3
- 229920001059 synthetic polymer Polymers 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000009881 electrostatic interaction Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- 125000002883 imidazolyl group Chemical group 0.000 description 2
- 229910017053 inorganic salt Inorganic materials 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- FQPSGWSUVKBHSU-UHFFFAOYSA-N methacrylamide Chemical compound CC(=C)C(N)=O FQPSGWSUVKBHSU-UHFFFAOYSA-N 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 239000011833 salt mixture Substances 0.000 description 2
- 229910000342 sodium bisulfate Inorganic materials 0.000 description 2
- -1 sulfonate anion Chemical class 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 229920000536 2-Acrylamido-2-methylpropane sulfonic acid Polymers 0.000 description 1
- XHZPRMZZQOIPDS-UHFFFAOYSA-N 2-Methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonic acid Chemical compound OS(=O)(=O)CC(C)(C)NC(=O)C=C XHZPRMZZQOIPDS-UHFFFAOYSA-N 0.000 description 1
- 230000005526 G1 to G0 transition Effects 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
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- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- VHKXNGIBELBONZ-UHFFFAOYSA-M ethyl-dimethyl-(prop-2-enoyloxymethyl)azanium bromide Chemical compound [Br-].CC[N+](C)(C)COC(=O)C=C VHKXNGIBELBONZ-UHFFFAOYSA-M 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
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- 238000010438 heat treatment Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 238000000593 microemulsion method Methods 0.000 description 1
- 238000012703 microemulsion polymerization Methods 0.000 description 1
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- 239000002245 particle Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000000710 polymer precipitation Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical group 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000003079 shale oil Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- FZGFBJMPSHGTRQ-UHFFFAOYSA-M trimethyl(2-prop-2-enoyloxyethyl)azanium;chloride Chemical compound [Cl-].C[N+](C)(C)CCOC(=O)C=C FZGFBJMPSHGTRQ-UHFFFAOYSA-M 0.000 description 1
- 238000000196 viscometry Methods 0.000 description 1
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- 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
- C08F220/00—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
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/52—Amides or imides
- C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
- C08F220/56—Acrylamide; Methacrylamide
-
- 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
- C08F2/00—Processes of polymerisation
- C08F2/32—Polymerisation in water-in-oil emulsions
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/66—Compositions based on water or polar solvents
- C09K8/68—Compositions based on water or polar solvents containing organic compounds
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/84—Compositions based on water or polar solvents
- C09K8/86—Compositions based on water or polar solvents containing organic compounds
- C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/882—Compositions based on water or polar solvents containing organic compounds macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
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Abstract
The invention discloses a viscosity-variable double-aqueous-phase polymer for deep shale fracturing and a preparation method thereof, wherein the polymer comprises the following components in percentage by mass: 15-30% of water-soluble monomer, 1.5-7% of stabilizer, 18-25% of dispersion medium, 0.001-1.8% of pH regulator, 0.015-0.15% of initiator and the balance of water; the invention synthesizes the double aqueous phase emulsion by utilizing the water dispersion polymerization method, and generates various supermolecule interaction forces among polymer molecules by introducing supermolecule monomers, thereby reducing the molecular weight of the polymer, enhancing the tackifying of the product, solving the limitation that the prior art can not realize both quick solubility and tackifying, and realizing the low molecular weight tackifying of the product. The product has the advantages of quick solubility, tackifying property and emulsion stability, has the advantages of environmental protection and low cost, solves the problem that the existing fracturing fluid cannot be subjected to on-line tackifying and continuous blending, and meets the technical requirement of continuous blending fracturing in the whole shale reservoir process by realizing continuous quick conversion of low viscosity, medium viscosity and high viscosity.
Description
Technical Field
The invention relates to a viscosity-variable double-aqueous-phase polymer for deep shale fracturing and a preparation method thereof, and belongs to the technical field of reservoir fracturing.
Background
The effective development of unconventional oil and gas resources such as shale oil and gas plays a significant role in guaranteeing national energy safety. Because of poor physical properties of the reservoir, unconventional oil and gas reservoirs need to rely on large-scale fracturing to 'break up' the reservoir to realize volume transformation, the contact area between the wall surface of a crack and the matrix of the reservoir is increased, the distance from the matrix to the crack of reservoir fluid is shortened, and the pressure difference required by the seepage of the fluid in the matrix to the crack is reduced, so that the yield of a single well is improved, the recovery ratio is improved, and finally the maximization of reserve utilization is realized.
Compared with the traditional guanidine gum fracturing fluid system, the slickwater fracturing fluid can reduce the flow friction of a fluid pipe column by 70-80%, greatly improve the injection displacement of the fracturing fluid, and achieve the purpose of forming a complex fracture network while reducing drag; meanwhile, the slickwater fracturing fluid has fewer solid phase residues and low cost, so that the slickwater fracturing fluid is one of the most widely used fracturing fluid systems in the non-conventional oil and gas reservoir reconstruction process. However, when the staged fracturing of the long horizontal well is carried out, in order to meet the requirements of main joint making, complex joint network formation, drag reduction, sand carrying and the like, low-viscosity slickwater (1-5 mPas) and high-viscosity linear gel or crosslinked guanidine gum fracturing fluid (30-50 mPas) are required to be injected circularly and alternately for mixed fracturing operation. The shale volume transformation characteristics of long horizontal well sections, multiple sections and large liquid volume lead to the fact that the viscosity of the fracturing fluid needs to be changed up to hundreds of times when the fracturing fluid is subjected to staged fracturing, wherein the linear gel and guanidine gel are slow in dissolution speed, are required to be hydrated in advance, cannot be continuously mixed with slick water, and have the defects of complex working procedures, more required equipment, large occupied space and liquid switching hysteresis, and the fracturing effect is seriously affected. Therefore, the core main agent of the fracturing fluid needs to have quick solubility and viscosity increasing property so as to realize on-line mixing and one-agent viscosity increasing.
The polyacrylamide polymer has low cost, flexible design and better drag reduction and sand carrying performance, and is the main agent which has the highest potential of meeting the viscosity-changing requirement of fracturing fluid. Polyacrylamide polymers are classified into dry powders and emulsions according to the state. The dry powder is usually prepared by aqueous solution polymerization, and the method has the advantages of simple operation, high polymerization yield and higher molecular weight of the product, so that the product has better tackifying effect and is convenient to store and transport. However, the dissolution rate of the dry powder polymer is slow, and the online mixing requirement of the fracturing fluid during shale reservoir fracturing cannot be met. The emulsion products (most of water-in-oil emulsion) are enhanced in temperature resistance and salt resistance by introducing sulfonate anion monomers, have the advantage of high dissolution speed, and can realize on-site compounding. However, the products have the defects of poor emulsion stability, low molecular weight, low effective concentration and insufficient viscosity increasing effect, can be used as slick water drag reducing agents, and cannot be continuously viscosity-changed to realize multifunctional applications such as drag reduction, sand carrying and the like.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a viscosity-variable double-aqueous-phase polymer for deep shale fracturing and a preparation method thereof.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
on the one hand, the invention discloses a viscosity-variable double-aqueous-phase polymer for deep shale fracturing, which comprises the following components in percentage by mass: 15-30% of water-soluble monomer, 1.5-7% of stabilizer, 18-25% of dispersion medium, 0.001-1.8% of pH regulator, 0.015-0.15% of initiator and the balance of water;
the water-soluble monomer comprises acrylamide, a monomer A and a monomer B;
the monomer A comprises one or more of vinylsulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid and vinylbenzenesulfonic acid;
the monomer B comprises one or more of 1-allyl-3-methylimidazole chloride, 1-allyl-3-methylimidazole bromide, 1-allyl-3-vinylimidazole chloride, N-allylimidazole, 1-vinylimidazole, methacryloxyethyltrimethylammonium chloride, acryloxyethyltrimethylammonium bromide and methacrylamidopropyl-N, N-dimethylpropanesulfonate.
In one possible design, the stabilizer comprises one or more of polyvinylpyrrolidone, polyacrylic acid, poly 2-acrylamide-2-methylpropanesulfonic acid, poly 4-styrenesulfonic acid, and poly (methacryloyloxyethyl trimethyl ammonium bromide).
In one possible design, the dispersion medium includes one or more of sodium chloride, ammonium sulfate, and sodium sulfate.
In one possible design, the pH adjuster comprises 33% by mass aqueous sodium hydroxide solution.
In one possible design, the initiator is ammonium persulfate, or is a water-soluble azo initiator, or is a mixture of ammonium persulfate and sodium bisulfite, or is a mixture of potassium persulfate and tetramethyl ethylenediamine.
In one possible design, the mass ratio of ammonium persulfate to sodium bisulfite in the mixture of ammonium persulfate and sodium bisulfite is 1:1; in the mixture of the potassium persulfate and the tetramethyl ethylenediamine, the mass ratio of the potassium persulfate to the tetramethyl ethylenediamine is 1:1.
In a second aspect, the invention also discloses a preparation method of the viscosity-variable aqueous two-phase polymer for deep shale fracturing, which comprises the following steps:
s1, dissolving the water-soluble monomer, the stabilizer and the dispersion medium in water, and uniformly stirring to obtain a first solution;
s2, adding the pH regulator into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, introducing nitrogen into the second solution, and adding the initiator at a set temperature to perform polymerization reaction;
and S4, after the reaction is finished, cooling to obtain the viscosity-changing double-aqueous-phase polymer for deep shale fracturing.
In one possible design, the set temperature in S3 is 25-40 ℃.
In one possible design, the polymerization time in S3 is 24 hours.
In a third aspect, the invention also discloses application of the viscosity-variable aqueous two-phase polymer for deep shale fracturing in the field of reservoir reformation.
The technical scheme provided by the invention has the beneficial effects that at least:
in the prior art, an inverse microemulsion polymerization method is utilized, and an anionic monomer is introduced to synthesize an emulsion type polyacrylamide drag reducer, so that the product has the advantage of high dissolution rate, but has poor stability, low molecular weight, low effective concentration and poor viscosity, so that the product can be only used as a slickwater drag reducer; or by utilizing an aqueous solution polymerization method, the dry powder modified polyacrylamide is synthesized by introducing hydrophobic long chains and other monomers, and the product has the advantages of higher molecular weight and strong tackifying property due to hydrophobic association, but has slow dissolution rate due to the existence of the hydrophobic long chains in the product and the product, so that on-site continuous blending cannot be realized, and the method is not well suitable for a deep shale reservoir viscosity-changing fracturing process.
The invention provides a viscosity-variable double-aqueous-phase polymer for shale fracturing and a preparation method thereof, the product is synthesized into double-aqueous-phase emulsion by utilizing a water dispersion polymerization method, and by introducing supermolecule monomers, namely monomers B, various supermolecule interaction forces are generated among polymer molecules, so that the viscosity increase of the product is enhanced under the condition of low molecular weight of the polymer, the limitation that the prior art cannot achieve both the quick solubility and the viscosity increase is solved, and the low molecular weight viscosity increase of the product is realized. The product has the advantages of quick solubility, tackifying and emulsion stability, is environment-friendly and low in cost, solves the problem that the existing fracturing fluid cannot be subjected to online tackifying and continuous blending, realizes continuous and quick conversion of low viscosity, medium viscosity and high viscosity of the fracturing fluid by adjusting the concentration, and meets the technical requirements of continuous blending fracturing of the whole shale reservoir.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a graph of viscosity versus concentration for polymer sample A, B, C in an embodiment of the invention;
FIG. 2 is a graph showing the evaluation of low-viscosity and high-viscosity shear recovery of polymer sample A in example 1 of the present invention, wherein (a) is a schematic view showing the evaluation of low-viscosity shear recovery of a polymer having a concentration of 0.1%, and (b) is a schematic view showing the evaluation of high-viscosity shear recovery of a polymer having a concentration of 0.6%;
FIG. 3 is a graph showing the resistivity of polymer sample B at various concentrations in example 2;
FIG. 4 is a graph of the direct mixing dissolution time versus the polymer sample B prepared in example 2, a commercially available anionic polyacrylamide, and an industrial grade water-in-oil emulsion drag reducer for use in the field.
Specific embodiments of the present invention have been shown by way of the above drawings and will be described in more detail below. The drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but rather to illustrate the inventive concepts to those skilled in the art by reference to the specific embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The fracturing technology is a reservoir reconstruction technology for improving fluid flowing capacity in an oil-gas layer by utilizing hydraulic action to form artificial cracks in the oil-gas layer, a ground high-pressure pump set is utilized, large-displacement and high-viscosity liquid is injected into a stratum through a shaft, high pressure is held down at the bottom of the shaft, when the pressure exceeds the bearing capacity of the stratum, cracks are formed in the stratum nearby the bottom of the shaft, the liquid carrying propping agent is continuously injected, the cracks gradually extend forwards, the propping agent plays a role of supporting the cracks, sand filling cracks with a certain size and high flow guiding capacity are formed, so that oil gas flows into the well through the cracks, and the effects of increasing yield and injection are achieved.
The fracturing fluid is a working fluid for fracturing construction, is a fluid with certain viscosity, and has the functions of transferring energy, forming and extending cracks and carrying propping agents. Compared with the traditional guanidine gum fracturing fluid system, the slickwater fracturing fluid can reduce the flow friction of a fluid column by 70-80%, greatly improve the injection displacement of the fracturing fluid, achieve the purpose of forming a complex seam mesh while reducing drag, and become one of the most widely used fracturing fluid systems in the process of modifying unconventional oil and gas reservoirs at present.
However, when the staged fracturing of the long horizontal well is carried out, in order to meet the requirements of main joint making, complex joint network formation, drag reduction, sand carrying and the like, low-viscosity slick water and high-viscosity linear glue or cross-linked guanidine glue fracturing fluid are required to be injected circularly and alternately to carry out mixed fracturing operation. The shale volume transformation characteristics of long horizontal well sections, multiple sections and large liquid volume lead to the fact that the viscosity of the fracturing fluid needs to be changed up to hundreds of times when the fracturing fluid is subjected to staged fracturing, wherein the linear gel and guanidine gel are slow in dissolution speed, are required to be hydrated in advance, cannot be continuously mixed with slick water, and have the defects of complex working procedures, more required equipment, large occupied space and liquid switching hysteresis, and the fracturing effect is seriously affected. Therefore, the core main agent of the fracturing fluid needs to have quick solubility and viscosity increasing property so as to realize on-line mixing and one-agent viscosity increasing.
Polyacrylamide polymers are the most potential main agents for meeting the viscosity-changing requirements of fracturing fluids. Polyacrylamide polymers are classified into dry powders and emulsions according to the state. However, the dissolution rate of the dry powder polymer is slow, and the online mixing requirement of the fracturing fluid during shale reservoir fracturing cannot be met. Emulsion products have the common limitations of poor stability, low molecular weight and effective concentration and insufficient tackifying effect, can be used as slick water drag reducer, and cannot be continuously tackified to realize multifunctional applications such as drag reduction, sand carrying and the like.
The embodiment of the invention provides a viscosity-variable double-aqueous-phase polymer for deep shale fracturing, which comprises the following components in percentage by mass: 15-30% of water-soluble monomer, 1.5-7% of stabilizer, 18-25% of dispersion medium, 0.001-1.8% of pH regulator, 0.015-0.15% of initiator and the balance of water;
the water-soluble monomers comprise acrylamide, a monomer A and a monomer B;
the monomer A comprises one or more of vinylsulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid and vinylbenzenesulfonic acid;
the monomer B comprises one or more of 1-allyl-3-methylimidazole chloride, 1-allyl-3-methylimidazole bromide, 1-allyl-3-vinylimidazole chloride, N-allylimidazole, 1-vinylimidazole, methacryloxyethyl trimethyl ammonium chloride, acryloxyethyl trimethyl ammonium bromide and methacrylamidopropyl-N, N-dimethylpropanesulfonate.
The fracturing fluid needed by shale reservoirs is required to meet the requirement of rapidly changing viscosity. On one hand, the core main agent of the fracturing fluid needs to have quick solubility, so that the construction is convenient, the working procedure is reduced, and the time is saved; on the other hand, the main agent is required to have tackifying property, so that the effect of drag reduction and sand carrying can be realized.
In the prior art, in order to realize continuous mixing, an inverse microemulsion method is generally adopted to synthesize the water-in-oil emulsion polymer, and an anionic monomer is introduced to participate in polymerization in order to realize temperature resistance and salt resistance, but the viscosity increasing effect cannot be realized, and the polymer can only be used as a slick water drag reducer and cannot be applied in the viscosity changing form of slick water, linear rubber and crosslinking liquid.
The viscosity-variable double-aqueous-phase polymer for deep shale fracturing provided by the embodiment of the invention is synthesized into double-aqueous-phase emulsion by utilizing a water dispersion polymerization method, is emulsion-like, greatly enhances the solubility, has an instant effect, and meets the operation requirement of on-site on-line mixing; on the other hand, by introducing the supermolecular monomer B, various supermolecular interaction forces such as strong hydrogen bonds, anion-cation static electricity and the like are generated among polymer molecules, the tackifying performance of the product is enhanced under the condition of low molecular weight of the polymer, the limitation that the prior art cannot consider both the quick solubility and the tackifying performance is solved, the functions of various fracturing fluids such as slickwater, linear gel and crosslinking liquid are realized, and the use of the tackifying performance is achieved. The viscosity-variable double-aqueous-phase polymer for deep shale fracturing provided by the embodiment of the invention has the advantages of quick solubility, viscosity increment and emulsion stability, has the advantages of low molecular weight, environment friendliness and low cost, solves the limitation that the existing fracturing fluid cannot be subjected to online viscosity-variable and continuous mixing, and meets the technical requirement of continuous mixing fracturing in the whole shale reservoir process by realizing continuous quick conversion between low viscosity and medium viscosity and high viscosity.
In one possible design, the stabilizer comprises one or more of polyvinylpyrrolidone, polyacrylic acid, poly 2-acrylamide-2-methylpropanesulfonic acid, poly 4-styrenesulfonic acid, and poly (methacryloyloxyethyl trimethyl ammonium bromide).
Optionally, the stabilizer is poly-2-acrylamide-2-methylpropanesulfonic acid.
In one possible design, the dispersion medium comprises one or more of sodium chloride, ammonium sulfate, sodium sulfate.
Alternatively, the dispersion medium is a mixture of ammonium sulfate and sodium chloride.
The stabilizer is an oligomer with a certain steric hindrance or anion/cation, and is adsorbed on the surface of the oligomer in the process of polymer chain growth and precipitation to form the steric hindrance and electrostatic interaction so as to achieve the stabilizing effect; the choice of the dispersion medium plays an important role in the dispersion polymerization. Poor precipitation of the synthetic polymer by the dispersion medium causes the synthetic system to tend to polymerize in aqueous solution, making it difficult for the polymer to precipitate out of phase. If the polymer precipitation is strong, the synthetic system tends to precipitate and polymerize, so that the polymers mutually polymerize and settle. The salt water system with relatively weak precipitation degree is selected as a dispersion medium, and the obtained polymer has relatively large molecular weight, and does not need to be added with an organic solvent, so that the system is clean and environment-friendly. According to the Hofmeister sequence arrangement of the capability of precipitating macromolecules of salt ions, finally, three inorganic salt mixtures which are cheap and easy to obtain and have different capability of precipitating macromolecules are selected as dispersion media, wherein the three inorganic salt mixtures comprise ammonium sulfate with the strongest capability of precipitating macromolecules, sodium chloride with moderate capability of precipitating macromolecules and sodium sulfate with stronger capability of precipitating macromolecules.
In one possible design, the pH adjuster comprises 33% by mass aqueous sodium hydroxide solution.
In one possible design, the initiator is ammonium persulfate, or is a water-soluble azo initiator, or is a mixture of ammonium persulfate and sodium bisulfite, or is a mixture of potassium persulfate and tetramethyl ethylenediamine.
In one possible design, the mass ratio of ammonium persulfate to sodium bisulfite in the mixture of ammonium persulfate and sodium bisulfite is 1:1; in the mixture of potassium persulfate and tetramethyl ethylenediamine, the mass ratio of the potassium persulfate to the tetramethyl ethylenediamine is 1:1.
Alternatively, the initiator is a water-soluble azo initiator.
In a second aspect, the invention also discloses a preparation method of the viscosity-variable aqueous two-phase polymer for deep shale fracturing, which comprises the following steps:
s1, dissolving a water-soluble monomer, a stabilizer and a dispersion medium in water in proportion, and uniformly stirring to obtain a first solution;
s2, adding a pH regulator into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, introducing nitrogen into the second solution, and adding an initiator at a set temperature to perform polymerization reaction;
and S4, cooling after the reaction is finished to obtain the viscosity-variable double-aqueous-phase polymer for deep shale fracturing.
In one possible design, the set temperature in S3 is 25-40 ℃.
It should be noted that the relatively low initiation temperature can delay the reaction rate of the polymer, so that the product has a longer molecular chain to ensure the drag reduction and viscosity enhancement of the product, and meanwhile, the explosion polymerization phenomenon caused by the too fast reaction due to high temperature is avoided.
In one possible design, the polymerization time in S3 is 24 hours.
It should be noted that the conversion rate and viscosity of the synthetic polymer tend to be stable after increasing along with the increase of the reaction time, mainly because the exothermic reaction provides additional energy for the reaction to initiate the polymerization of the monomer during the polymerization reaction, which is beneficial to continuously increasing the chain length of the polymer molecule. After the reaction reaches a certain degree, the polymerization reaction enters a stationary phase, the reaction gradually becomes gentle, and the free radicals of the monomers are continuously consumed until the reaction is finished. The reaction was initiated more slowly and reacted for 24 hours to ensure that the reaction proceeded sufficiently to obtain a polymer of higher chain length.
In a third aspect, the invention also discloses application of the viscosity-variable aqueous two-phase polymer for deep shale fracturing in the field of reservoir reformation.
Any combination of the above optional solutions may be adopted to form the optional embodiments of the present disclosure, which are not described herein.
The invention will be further described by means of specific examples.
The experimental methods used in the following specific examples are conventional methods unless otherwise specified.
The operations referred to in the following specific examples were performed under conventional conditions or conditions recommended by the manufacturer, without any reference to the conditions. The raw materials used are not specified by the manufacturer and the specification are all conventional products which can be obtained by commercial purchase.
In the following specific examples:
acrylamide (AR, 99%), acrylic acid (> 99%), methacrylic acid (> 99%), vinylbenzenesulfonic acid (95%), 1-allyl-3-methylimidazole chloride (96%), 1-vinylimidazole (99%), methacryloyloxyethyl trimethyl ammonium chloride (75 wt%), acryloyloxyethyl trimethyl ammonium bromide (80%), polyvinylpyrrolidone (500 g gauge), polyacrylic acid (25 g gauge), poly 4-styrenesulfonic acid (100 g gauge), methacryloyloxyethyl trimethyl ammonium bromide (100 g gauge), water-soluble azo initiators (azobisis Ding Mi hydrochloride, 98%) were all purchased from shanghai microphone biochemistry limited;
vinyl sulfonic acid (> 97%), 1-allyl-3-methylimidazole bromide (97%), 1-allyl-3-vinylimidazole chloride (98%), N-allylimidazole (> 97%) were purchased from Shanghai Ala Biochemical technologies Co., ltd;
methacrylamidopropyl-N, N-dimethylpropanesulfonate (> 97%) was purchased from Boschizandra Shanghai chemical industry development Co., ltd;
poly (2-acrylamido-2-methylpropanesulfonic acid) (25 g gauge) was purchased from Shanghai Seiyaka Biotechnology Co., ltd;
sodium chloride (more than or equal to 99.5%), ammonium sulfate (more than or equal to 99%), sodium hydroxide (more than or equal to 96%), ammonium persulfate (more than or equal to 98%), potassium persulfate (more than or equal to 99.5%), sodium bisulfate (AR), and tetramethyl ethylenediamine (more than or equal to 98%) are all purchased from national pharmaceutical set chemical reagent company;
the polymethyl acryloyloxy ethyl trimethyl ammonium bromide is synthesized by self:
the synthetic process of the polymethyl acryloyloxyethyl trimethyl ammonium bromide comprises the following steps: 25g of methacryloyloxyethyl trimethyl ammonium bromide and 74.925g of deionized water are mixed and then added into a four-neck flask connected with a stirrer, a thermometer, a condenser tube and a nitrogen guide pipe, the mixture is placed into a constant-temperature water bath for heating and stirring, nitrogen is introduced into the mixture to deoxidize for 30min, when the temperature is raised to 50 ℃, 0.075g of water-soluble azo initiator solution is added into the system by a syringe to initiate polymerization, and after 8 hours of reaction, transparent viscous liquid polymethyl acryloyloxyethyl trimethyl ammonium bromide is obtained.
Example 1
S1, sequentially dissolving 7g of stabilizer polyvinylpyrrolidone and polymethyl acryloyloxyethyl trimethyl ammonium chloride mixture (mass ratio is 5:1), 30g of water-soluble monomer and 25g of dispersion medium in 25g of water, and uniformly stirring to obtain a first solution;
the water-soluble monomer consists of acrylamide, temperature-resistant and salt-resistant monomer vinylsulfonic acid and supermolecule monomer methacryloyloxyethyl trimethyl ammonium chloride, wherein the mass ratio of the acrylamide to the vinylsulfonic acid to the methacryloyloxyethyl trimethyl ammonium chloride is 6.5:1.5:1;
the dispersion medium consists of ammonium sulfate and sodium chloride, wherein the mass ratio of the ammonium sulfate to the sodium chloride is 3:1;
s2, adding a pH regulator sodium hydroxide aqueous solution into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, supplementing water into the second solution to enable the total mass of the solution to be 99.85g, introducing nitrogen for 30min, adding 15g of ammonium persulfate-sodium bisulfate initiator at 25 ℃ and carrying out polymerization reaction for 24h;
and S4, after the reaction is finished, cooling to obtain a milky emulsion polymer sample A.
Example 2
S1, sequentially dissolving 1.5g of stabilizer poly 2-acrylamide-2-methylpropanesulfonic acid, 15g of water-soluble monomer and 18g of dispersion medium in 30g of water, and uniformly stirring to obtain a first solution;
the water-soluble monomer consists of acrylamide, temperature-resistant and salt-resistant monomer acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and supermolecule monomer 1-vinylimidazole, wherein the mass ratio of the acrylamide to the acrylic acid to the 2-acrylamide-2-methylpropanesulfonic acid to the 1-vinylimidazole is 7:1:4:1.2;
the dispersion medium consists of ammonium sulfate and sodium sulfate, wherein the mass ratio of the ammonium sulfate to the sodium sulfate is 5:1;
s2, adding a pH regulator sodium hydroxide aqueous solution into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, supplementing water into the second solution to enable the total mass of the solution to be 99.985g, introducing nitrogen for 30min, adding 0.015g of water-soluble azo initiator at 35 ℃, and carrying out polymerization reaction for 24h;
and S4, after the reaction is finished, cooling to obtain a milky emulsion polymer sample B.
Example 3
S1, sequentially dissolving 5g of stabilizer poly 4-styrenesulfonic acid, 20g of water-soluble monomer and 20g of dispersion medium in 35g of water, and uniformly stirring to obtain a first solution;
the water-soluble monomer consists of acrylamide, temperature-resistant and salt-resistant monomer vinyl benzene sulfonic acid and supermolecule monomer methyl acrylamide propyl-N, N-dimethyl propane sulfonate, wherein the mass ratio of the acrylamide to the vinyl benzene sulfonic acid to the methyl acrylamide propyl-N, N-dimethyl propane sulfonate is 7:2:1.2;
the dispersion medium consists of ammonium sulfate;
s2, adding a pH regulator sodium hydroxide aqueous solution into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, supplementing water into the second solution to enable the total mass of the solution to be 99.98g, introducing nitrogen for 30min, adding 0.02g of ammonium persulfate initiator at 40 ℃ and carrying out polymerization reaction for 24h;
and S4, after the reaction is finished, cooling to obtain a milky emulsion polymer sample C.
Example 4
S1, sequentially dissolving 2g of stabilizer poly (2-acrylamide-2-methylpropanesulfonic acid) and polyacrylic acid mixture (the mass ratio is 1:1), 18g of water-soluble monomer and 22g of dispersion medium in 30g of water, and uniformly stirring to obtain a first solution;
wherein the water-soluble monomer consists of acrylamide, temperature-resistant and salt-resistant monomer vinylsulfonic acid and methacrylic acid, and supermolecule monomer 1-allyl-3-methylimidazole chloride, wherein the mass ratio of the acrylamide to vinylsulfonic acid to the methacrylic acid to the 1-allyl-3-methylimidazole chloride is 8:1.5:1:0.2;
the dispersion medium consists of ammonium sulfate, sodium sulfate and sodium chloride, wherein the mass ratio of the ammonium sulfate to the sodium chloride is 4:1:1;
s2, adding a pH regulator sodium hydroxide aqueous solution into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, supplementing water into the second solution to enable the total mass of the solution to be 99.982g, introducing nitrogen for 30min, adding 0.018g of potassium persulfate-tetramethyl ethylenediamine initiator at 30 ℃ and carrying out polymerization reaction for 24h;
and S4, after the reaction is finished, cooling to obtain a milky emulsion polymer sample D.
Example 5
S1, 6g of stabilizer polyvinylpyrrolidone, polyacrylic acid (the mass ratio is 1:3), 22g of water-soluble monomer and 18g of dispersion medium are sequentially dissolved in 25g of water and uniformly stirred to obtain a first solution;
the water-soluble monomer consists of acrylamide, a temperature-resistant and salt-tolerant monomer 2-acrylamide-2-methylpropanesulfonic acid, and a supermolecule monomer N-allylimidazole and acryloyloxyethyl trimethyl ammonium bromide, wherein the mass ratio of the acrylamide to the 2-acrylamide-2-methylpropanesulfonic acid to the N-allylimidazole to the acryloyloxyethyl trimethyl ammonium bromide is 7:2.5:0.3:1;
the dispersion medium consists of ammonium sulfate and sodium chloride, wherein the mass ratio of the ammonium sulfate to the sodium chloride is 3:1;
s2, adding a pH regulator sodium hydroxide aqueous solution into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, supplementing water to the second solution to enable the total mass of the solution to be 99.89g, introducing nitrogen for 30min, adding 0.11g of water-soluble azo initiator at 33 ℃, and carrying out polymerization reaction for 24h;
and S4, after the reaction is finished, cooling to obtain a milky emulsion polymer sample E.
Example 6
S1, sequentially dissolving 5g of stabilizer polyvinylpyrrolidone, 20g of water-soluble monomer and 25g of dispersion medium in 40g of water, and uniformly stirring to obtain a first solution;
wherein the water-soluble monomer consists of acrylamide, a temperature-resistant and salt-tolerant monomer 2-acrylamide-2-methylpropanesulfonic acid, and a supermolecule monomer 1-allyl-3-methylimidazole bromide and methacryloyloxyethyl trimethyl ammonium chloride, wherein the mass ratio of the acrylamide to the 2-acrylamide-2-methylpropanesulfonic acid to the 1-allyl-3-methylimidazole bromide to the methacryloyloxyethyl trimethyl ammonium chloride is 6:2.8:0.2:1;
the dispersion medium consists of ammonium sulfate and sodium sulfate, wherein the mass ratio of the ammonium sulfate to the sodium chloride is 4:1;
s2, adding a pH regulator sodium hydroxide aqueous solution into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, supplementing water into the second solution to enable the total mass of the solution to be 99.94g, introducing nitrogen for 30min, adding 0.06g of ammonium persulfate-sodium bisulfite initiator at 25 ℃ and carrying out polymerization reaction for 24h;
and S4, after the reaction is finished, cooling to obtain a milky emulsion polymer sample F.
Test example 1 viscometry
Measurement of 170s with Hake MARS 60 high temperature high pressure rheometer -1 Viscosity versus concentration for polymer samples A, B, C of examples 1, 2, and 3 at shear rate. FIG. 1 is a plot of viscosity versus polymer sample A, B, CThe experimental result shows that in the concentration range of 0.1-0.6%, the polymer sample A, B, C has better adhesion capability, the viscosity increases along with the increase of the concentration, and the viscosity increases from about 5 mPa.s to 35 mPa.s, because the introduced supermolecular monomer (monomer B) forms strong hydrogen bonds, electrostatic interactions and other supermolecular forces with the monomer B or other monomers, the formed physical network enhances the interactions among polymer molecules, and the low molecular weight higher viscosity of the product is realized. When the variable viscosity fracturing fluid is applied on site, the concentration can be timely adjusted according to different requirements of drag reduction or sand carrying, so that variable viscosity fracturing operation is realized.
Test example 2 direct mixing solubility determination
The direct mixing dissolution time of the polymer sample A, B, C in examples 1, 2 and 3 was measured using a fracturing fluid friction measuring instrument, the test was conducted using a pipe diameter of 8mm, the test temperature was 25℃and the test flow rate was set to 6.5 mS -1 The differential pressure time is set to be 20min, the differential pressure frequency is recorded to be 2s, after parameters are set, the whole pipeline is filled with tap water and water circulates in the pipeline, 0.1% of double-water-phase polymer is added when differential pressure indication is stable, and the direct mixing dissolution time is obtained when the differential pressure value change is less than 2%. The results are shown in Table 1. Table 1 shows the direct mixing dissolution times for polymer samples A, B, C. The test result shows that the direct mixing dissolution time of the double water phase polymer under the tap water condition is 28-40s, the double water phase polymer has good dissolution effect, and the requirement of on-line mixing is met. The polymer particles obtained by synthesis are separated out and phase-separated under the action of high-concentration salt, and are uniformly dispersed under the action of a stabilizer. Therefore, in the process of preparing the aqueous solution, the high-concentration salt environment is diluted, the long chain of the polymer is stretched and lengthened, the specific surface area is increased, the polymer can be rapidly diffused into the aqueous solution, water molecules continuously permeate into polymer molecules, the volume of the polymer is continuously expanded, more polymer molecule units are in mixed contact with solvent molecule units, and when the whole molecular chain is uniformly dispersed into the solvent, the polymer can be rapidly and completely dissolved. The aqueous two-phase polymer can meet the requirements of continuous mixing and quick viscosity switching of shale fracturing sites.
TABLE 1 Polymer sample A, B, C direct mixing dissolution time
Test example 3 shear recovery test
Shear recovery of the aqueous two-phase polymer at low viscosity (0.1%) and high viscosity (0.6%) was measured using a Hake MARS 60 high temperature high pressure rheometer, represented by polymer sample a prepared in example 1, and the results are shown in fig. 2. FIG. 2 is a schematic diagram of a low-viscosity and high-viscosity shear recovery evaluation of a polymer sample, wherein (a) is the low-viscosity shear recovery evaluation of a polymer with a concentration of 0.1%, and (b) is the high-viscosity shear recovery evaluation of a polymer with a concentration of 0.6%, and it can be seen that after the polymer is subjected to cyclic shearing for more than 1 hour, the viscosity retention rate of the polymer reaches 98.55% of low viscosity (FIG. 2 a) and 98.3% of high viscosity (FIG. 2 b) which are higher than those of commercially available high-molecular-weight powdery polyacrylamide (molecular weight 1000w, concentration of 0.6% and viscosity retention rate of less than 92%), and the two-aqueous-phase polymer has excellent shear recovery under the conditions of low viscosity and high viscosity, so that the supermolecular force is proved to form a dynamic physical network to endow the polymer with better shear recovery capability.
Test example 4 resistivity determination
The polymer sample B prepared in example 2 is used as a representative of a fracturing fluid friction tester, a 10mm pipe diameter is selected, the testing temperature is set to 25 ℃, and the two-aqueous-phase polymer resistance reduction rate under different concentrations is measured, and the result is shown in figure 3. FIG. 3 is a graph showing the resistivity of the polymer sample in example 2 at different concentrations, and the result shows that in the concentration range of 0.05-0.15%, the resistivity of the aqueous two-phase polymer slightly rises with the increase of the polymer concentration and the discharge capacity, the resistivity of the aqueous two-phase polymer with the concentration of 0.05% reaches more than 70% after the discharge capacity is more than or equal to 45/min, and the highest resistivity reaches 73%, meets the line standard requirement, and the effect is remarkable at lower concentration, so that the aqueous two-phase polymer can be used as drag-reducing deep shale reservoir fracturing water in low viscosity.
Comparative example 1 tackifying
Measurement of 170s with Hake MARS 60 high temperature high pressure rheometer -1 Polymer sample B prepared in example 2 at shear rate, commercially available anionic polyacrylamide (500 Wan molecular weight, shanghai Michelin Biochemical technologies Co., ltd.) and viscosity of an on-site applied commercial grade water-in-oil emulsion drag reducer. The experimental results are shown in table 2. The results show that the polymer sample B prepared in example 2 of the present invention has a shear rate of 170s at a concentration of 0.1% -1 The viscosity under the condition reaches 6.18 mPa.s, which is higher than that of anionic polyacrylamide and industrial water-in-oil emulsion drag reducer, has excellent viscosity increasing performance, can be used for viscosity changing, and is suitable for various requirements of deep shale reservoir fracturing. The anionic groups such as carboxyl, sulfonic group and the like in the negative charge in the synthetic polymer can generate strong electrostatic action with imidazole ring or quaternary ammonium salt group which is easy to protonate and positive charge, and the amide group can generate strong hydrogen bond action with the imidazole ring, so that the association between polymer molecular chains is promoted by the action of static electricity and hydrogen bond supermolecules, an intermolecular physical network crosslinking structure is formed, and the supermolecular physical network structure endows the lower molecular weight aqueous two-phase polymer with better tackifying capability.
TABLE 2 comparison of the viscosities of different polymers
Comparative example 2 dissolution Rate
The direct mixing dissolution time of polymer sample B prepared in example 2, commercially available anionic polyacrylamide (500 tens of thousands molecular weight, shanghai Meilin Biotechnology Co., ltd.) and on-site application of technical grade water-in-oil emulsion drag reducer was compared using the test method in test example 2. The results are shown in FIG. 4. FIG. 4 is a graph of the direct mixing dissolution time versus the polymer sample B prepared in example 2, a commercially available anionic polyacrylamide, and an industrial grade water-in-oil emulsion drag reducer for use in the field. The result shows that the direct mixing dissolution time of the double water phase polymer under the tap water condition is 28s, which is far faster than that of dry powder type anionic polyacrylamide and water-in-oil emulsion type polymer drag reducer used in the oil field; and under the condition of standard saline (prepared according to the industry standard SY/T5107-2016), the direct mixing dissolution time is 32s, and the influence of the standard saline environment on the dissolution performance is small, so that the instant dissolving effect is good. The preparation method is characterized in that a high-concentration composite dispersion medium system is selected in a polymer synthesis system, a high-concentration salt environment is diluted in the process of preparing a polymer aqueous solution, a long chain of a double-aqueous-phase polymer is stretched and lengthened, the specific surface area is increased, the double-aqueous-phase polymer can be rapidly diffused into an aqueous solvent, water molecules continuously permeate into polymer molecules, the volume of the polymer is continuously expanded, more polymer molecule units are mixed and contacted with solvent molecule units, and when the whole molecular chain is uniformly dispersed into the solvent, the polymer can be rapidly and completely dissolved. Meanwhile, the polymer is dissolved in a standard saline environment, which is equivalent to the process of diluting a high-concentration solution with a low-concentration solution, and the concentration of a dispersion medium can be rapidly reduced, so that the molecular chain of the polymer can be stretched and rapidly dissolved, and compared with the dissolution in tap water, the dissolution speed is slowed down, but the influence is smaller. Compared with the traditional water-in-oil emulsion which needs oil-based dispersing and redissolving in water in the dissolving process, the water-in-water emulsion has obvious dissolving advantage.
In conclusion, the viscosity-variable double-aqueous-phase polymer for deep shale fracturing provided by the invention is synthesized into double-aqueous-phase emulsion by utilizing a water dispersion polymerization method, is emulsion-like, has greatly enhanced solubility, has an instant effect, and meets the operation requirement of on-site on-line mixing; on the other hand, by introducing the supermolecular monomer B, various supermolecular interaction forces such as strong hydrogen bonds, anion-cation static electricity and the like are generated among polymer molecules, so that the viscosity of a product is enhanced while the molecular weight of the polymer is reduced, the limitation that the prior art cannot consider both quick solubility and viscosity enhancement is solved, the viscosity enhancement effect of the product under low molecular weight is achieved, the functions of various fracturing fluids such as slickwater, linear gel and crosslinking liquid are realized, and the viscosity-changing use is realized. In addition, the viscosity-changing double-aqueous-phase polymer for deep shale fracturing provided by the invention only contains a pure water phase, and compared with the on-site common reverse-phase emulsion polymer slickwater, the viscosity-changing double-aqueous-phase polymer for deep shale fracturing does not contain oil phase, surfactant and other organic solvents, and has the advantages of low cost, environmental friendliness, less residues and low injury. The viscosity-variable double-aqueous-phase polymer for deep shale fracturing provided by the embodiment of the invention has the advantages of quick solubility, viscosity increment and emulsion stability, has the advantages of low molecular weight, environment friendliness and low cost, solves the limitation that the existing fracturing fluid cannot be subjected to online viscosity-variable and continuous mixing, and meets the technical requirement of continuous mixing fracturing in the whole shale reservoir process by realizing continuous quick conversion between low viscosity and medium viscosity and high viscosity.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described.
Claims (10)
1. The viscosity-variable aqueous two-phase polymer for deep shale fracturing is characterized by comprising the following components in percentage by mass: 15-30% of water-soluble monomer, 1.5-7% of stabilizer, 18-25% of dispersion medium, 0.001-1.8% of pH regulator, 0.015-0.15% of initiator and the balance of water;
the water-soluble monomer comprises acrylamide, a monomer A and a monomer B;
the monomer A comprises one or more of vinylsulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid and vinylbenzenesulfonic acid;
the monomer B comprises one or more of 1-allyl-3-methylimidazole chloride, 1-allyl-3-methylimidazole bromide, 1-allyl-3-vinylimidazole chloride, N-allylimidazole, 1-vinylimidazole, methacryloxyethyltrimethylammonium chloride, acryloxyethyltrimethylammonium bromide and methacrylamidopropyl-N, N-dimethylpropanesulfonate.
2. The viscosifying aqueous two-phase polymer for deep shale fracturing of claim 1, wherein the stabilizer comprises one or more of polyvinylpyrrolidone, polyacrylic acid, poly 2-acrylamide-2-methylpropanesulfonic acid, poly 4-styrenesulfonic acid, and poly (methacryloyloxyethyl trimethyl ammonium bromide).
3. The viscosifying aqueous two-phase polymer for deep shale fracturing of claim 1, wherein the dispersion medium comprises one or more of sodium chloride, ammonium sulfate, and sodium sulfate.
4. The viscosifying aqueous two-phase polymer for deep shale fracturing of claim 1, wherein the pH adjuster comprises 33% aqueous sodium hydroxide by mass.
5. The viscosifying two-aqueous polymer for deep shale fracturing of claim 1, wherein the initiator is ammonium persulfate, or is a water-soluble azo initiator, or is a mixture of ammonium persulfate and sodium bisulfite, or is a mixture of potassium persulfate and tetramethyl ethylenediamine.
6. The viscosifying two-phase polymer for deep shale fracturing of claim 5, wherein the mass ratio of ammonium persulfate to sodium bisulfite in the mixture of ammonium persulfate and sodium bisulfite is 1:1; in the mixture of the potassium persulfate and the tetramethyl ethylenediamine, the mass ratio of the potassium persulfate to the tetramethyl ethylenediamine is 1:1.
7. The preparation method of the viscosity-variable aqueous two-phase polymer for deep shale fracturing is characterized by comprising the following steps of:
s1, dissolving the water-soluble monomer, the stabilizer and the dispersion medium in water according to the proportion, and uniformly stirring to obtain a first solution;
s2, adding a pH regulator into the first solution to regulate the pH value to 7, so as to obtain a second solution;
s3, introducing nitrogen into the second solution, and adding the initiator at a set temperature to perform polymerization reaction;
and S4, after the reaction is finished, cooling to obtain the viscosity-changing double-aqueous-phase polymer for deep shale fracturing.
8. The method for preparing a viscosity-changing aqueous two-phase polymer for deep shale fracturing according to claim 7, wherein the set temperature in the step S3 is 25-40 ℃.
9. The method for preparing a viscosity-changing aqueous two-phase polymer for deep shale fracturing according to claim 7, wherein the polymerization reaction time in the step S3 is 24 hours.
10. Use of a viscosified aqueous bi-phase polymer for deep shale fracturing according to any of claims 1-6 in the field of reservoir reformation.
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