CN106867497B - Oil displacement system and method for low-permeability oil reservoir - Google Patents
Oil displacement system and method for low-permeability oil reservoir Download PDFInfo
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- 238000006073 displacement reaction Methods 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title description 12
- 229920000642 polymer Polymers 0.000 claims abstract description 182
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 169
- 239000000178 monomer Substances 0.000 claims abstract description 52
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 27
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims abstract description 10
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 5
- 239000003921 oil Substances 0.000 claims description 170
- 235000019198 oils Nutrition 0.000 claims description 167
- 239000004094 surface-active agent Substances 0.000 claims description 54
- 230000035699 permeability Effects 0.000 claims description 48
- -1 N-dioctyl acrylamide Chemical compound 0.000 claims description 47
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims description 21
- 239000000463 material Substances 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 239000003945 anionic surfactant Substances 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 9
- 150000007942 carboxylates Chemical class 0.000 claims description 6
- 238000011549 displacement method Methods 0.000 claims description 6
- 239000003208 petroleum Substances 0.000 claims description 6
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 5
- XQPVIMDDIXCFFS-UHFFFAOYSA-N n-dodecylprop-2-enamide Chemical compound CCCCCCCCCCCCNC(=O)C=C XQPVIMDDIXCFFS-UHFFFAOYSA-N 0.000 claims description 4
- BKWMQCLROIZNLX-UHFFFAOYSA-N n-hexadecylprop-2-enamide Chemical compound CCCCCCCCCCCCCCCCNC(=O)C=C BKWMQCLROIZNLX-UHFFFAOYSA-N 0.000 claims description 4
- AGBXYHCHUYARJY-UHFFFAOYSA-N 2-phenylethenesulfonic acid Chemical compound OS(=O)(=O)C=CC1=CC=CC=C1 AGBXYHCHUYARJY-UHFFFAOYSA-N 0.000 claims description 3
- KWIUHFFTVRNATP-UHFFFAOYSA-N Betaine Natural products C[N+](C)(C)CC([O-])=O KWIUHFFTVRNATP-UHFFFAOYSA-N 0.000 claims description 3
- 229920001732 Lignosulfonate Polymers 0.000 claims description 3
- KWIUHFFTVRNATP-UHFFFAOYSA-O N,N,N-trimethylglycinium Chemical compound C[N+](C)(C)CC(O)=O KWIUHFFTVRNATP-UHFFFAOYSA-O 0.000 claims description 3
- 239000002280 amphoteric surfactant Substances 0.000 claims description 3
- 125000000129 anionic group Chemical group 0.000 claims description 3
- 229960003237 betaine Drugs 0.000 claims description 3
- 239000002736 nonionic surfactant Substances 0.000 claims description 3
- 235000015112 vegetable and seed oil Nutrition 0.000 claims description 3
- 239000008158 vegetable oil Substances 0.000 claims description 3
- NLVXSWCKKBEXTG-UHFFFAOYSA-N vinylsulfonic acid Chemical compound OS(=O)(=O)C=C NLVXSWCKKBEXTG-UHFFFAOYSA-N 0.000 claims description 3
- 239000004711 α-olefin Substances 0.000 claims description 3
- LCPUCXXYIYXLJY-UHFFFAOYSA-N 1,1,2,4,4,4-hexafluorobutyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OC(F)(F)C(F)CC(F)(F)F LCPUCXXYIYXLJY-UHFFFAOYSA-N 0.000 claims description 2
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 claims description 2
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 claims description 2
- GMSCBRSQMRDRCD-UHFFFAOYSA-N dodecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCOC(=O)C(C)=C GMSCBRSQMRDRCD-UHFFFAOYSA-N 0.000 claims description 2
- 125000003438 dodecyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 claims description 2
- ZNAOFAIBVOMLPV-UHFFFAOYSA-N hexadecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCCCCCOC(=O)C(C)=C ZNAOFAIBVOMLPV-UHFFFAOYSA-N 0.000 claims description 2
- PZDUWXKXFAIFOR-UHFFFAOYSA-N hexadecyl prop-2-enoate Chemical compound CCCCCCCCCCCCCCCCOC(=O)C=C PZDUWXKXFAIFOR-UHFFFAOYSA-N 0.000 claims description 2
- PBOSTUDLECTMNL-UHFFFAOYSA-N lauryl acrylate Chemical compound CCCCCCCCCCCCOC(=O)C=C PBOSTUDLECTMNL-UHFFFAOYSA-N 0.000 claims description 2
- AWGZKFQMWZYCHF-UHFFFAOYSA-N n-octylprop-2-enamide Chemical compound CCCCCCCCNC(=O)C=C AWGZKFQMWZYCHF-UHFFFAOYSA-N 0.000 claims description 2
- DBLNSVZHOZOZQX-UHFFFAOYSA-N n-tetradecylprop-2-enamide Chemical compound CCCCCCCCCCCCCCNC(=O)C=C DBLNSVZHOZOZQX-UHFFFAOYSA-N 0.000 claims description 2
- SNQQPOLDUKLAAF-UHFFFAOYSA-N nonylphenol Chemical compound CCCCCCCCCC1=CC=CC=C1O SNQQPOLDUKLAAF-UHFFFAOYSA-N 0.000 claims description 2
- 125000000913 palmityl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- ATZHWSYYKQKSSY-UHFFFAOYSA-N tetradecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCCCOC(=O)C(C)=C ATZHWSYYKQKSSY-UHFFFAOYSA-N 0.000 claims description 2
- 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 2
- 150000007530 organic bases Chemical class 0.000 claims 1
- 238000011084 recovery Methods 0.000 abstract description 51
- 125000001165 hydrophobic group Chemical group 0.000 abstract description 10
- 230000000694 effects Effects 0.000 abstract description 9
- 230000032683 aging Effects 0.000 abstract description 7
- 239000007864 aqueous solution Substances 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 abstract description 5
- 239000000243 solution Substances 0.000 description 55
- 239000007788 liquid Substances 0.000 description 47
- 238000002347 injection Methods 0.000 description 41
- 239000007924 injection Substances 0.000 description 41
- 239000000203 mixture Substances 0.000 description 27
- 238000002474 experimental method Methods 0.000 description 24
- 238000011056 performance test Methods 0.000 description 23
- 239000011435 rock Substances 0.000 description 21
- 229920006395 saturated elastomer Polymers 0.000 description 21
- 229920002401 polyacrylamide Polymers 0.000 description 20
- 239000010779 crude oil Substances 0.000 description 19
- 239000011148 porous material Substances 0.000 description 19
- 238000011049 filling Methods 0.000 description 17
- 239000003513 alkali Substances 0.000 description 16
- 238000010008 shearing Methods 0.000 description 16
- 239000004576 sand Substances 0.000 description 15
- 229910002056 binary alloy Inorganic materials 0.000 description 14
- 230000014759 maintenance of location Effects 0.000 description 14
- 239000003708 ampul Substances 0.000 description 13
- 238000012360 testing method Methods 0.000 description 13
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 12
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 12
- 125000005250 alkyl acrylate group Chemical group 0.000 description 12
- 239000011575 calcium Substances 0.000 description 12
- 229910001424 calcium ion Inorganic materials 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 12
- 239000011737 fluorine Chemical group 0.000 description 12
- 229910052731 fluorine Inorganic materials 0.000 description 12
- 229910001425 magnesium ion Inorganic materials 0.000 description 12
- 239000000843 powder Substances 0.000 description 9
- 238000005507 spraying Methods 0.000 description 9
- 125000003342 alkenyl group Chemical group 0.000 description 8
- 125000000217 alkyl group Chemical group 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 7
- 150000003926 acrylamides Chemical class 0.000 description 7
- 125000001153 fluoro group Chemical group F* 0.000 description 7
- 150000003871 sulfonates Chemical group 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 6
- CERQOIWHTDAKMF-UHFFFAOYSA-M Methacrylate Chemical compound CC(=C)C([O-])=O CERQOIWHTDAKMF-UHFFFAOYSA-M 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 239000012452 mother liquor Substances 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- 125000000547 substituted alkyl group Chemical group 0.000 description 6
- 238000005303 weighing Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 5
- 239000011218 binary composite Substances 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- 230000018109 developmental process Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 125000000623 heterocyclic group Chemical group 0.000 description 4
- 230000008569 process Effects 0.000 description 4
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- 150000003458 sulfonic acid derivatives Chemical class 0.000 description 4
- 230000002195 synergetic effect Effects 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 238000004132 cross linking Methods 0.000 description 3
- 238000004945 emulsification Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 229920002521 macromolecule Polymers 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
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- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 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 2
- 125000003903 2-propenyl group Chemical group [H]C([*])([H])C([H])=C([H])[H] 0.000 description 2
- SOGAXMICEFXMKE-UHFFFAOYSA-N Butylmethacrylate Chemical compound CCCCOC(=O)C(C)=C SOGAXMICEFXMKE-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000033558 biomineral tissue development Effects 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000000344 soap Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- XRRGYHIBRPYSTH-UHFFFAOYSA-L tetramethylazanium dibromide Chemical compound [Br-].[Br-].C[N+](C)(C)C.C[N+](C)(C)C XRRGYHIBRPYSTH-UHFFFAOYSA-L 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- 229920000536 2-Acrylamido-2-methylpropane sulfonic acid Polymers 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- WYOGCOYRCIOUSZ-UHFFFAOYSA-M butyl-dimethyl-phenylazanium bromide Chemical compound [Br-].C1(=CC=CC=C1)[N+](C)(C)CCCC WYOGCOYRCIOUSZ-UHFFFAOYSA-M 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006392 deoxygenation reaction Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- SUPCQIBBMFXVTL-UHFFFAOYSA-N ethyl 2-methylprop-2-enoate Chemical compound CCOC(=O)C(C)=C SUPCQIBBMFXVTL-UHFFFAOYSA-N 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 125000001421 myristyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- RCNSZOSXOKUSCL-UHFFFAOYSA-N n-octylpropanamide Chemical compound CCCCCCCCNC(=O)CC RCNSZOSXOKUSCL-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- ALURCLVYPAFOOF-UHFFFAOYSA-M sodium 2-methyl-2-(prop-2-enoylamino)dodecane-1-sulfonate Chemical compound C(C=C)(=O)NC(CS(=O)(=O)[O-])(CCCCCCCCCC)C.[Na+] ALURCLVYPAFOOF-UHFFFAOYSA-M 0.000 description 1
- UHDWLRNWCQMFSU-UHFFFAOYSA-M sodium N-(1-sulfotetradecan-2-yl)prop-2-enimidate Chemical compound [Na+].CCCCCCCCCCCCC(CS([O-])(=O)=O)NC(=O)C=C UHDWLRNWCQMFSU-UHFFFAOYSA-M 0.000 description 1
- 229920001059 synthetic polymer Polymers 0.000 description 1
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
-
- 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
- C09K8/584—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 surfactants
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Geochemistry & Mineralogy (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention provides an oil displacement system for a low-permeability reservoir, which comprises an associative polymer; the molecular weight of the associated polymer is 101.4-997.5 ten thousand; the associative polymer is obtained by polymerizing acrylamide, 0.09-10.2% of hydrophobic monomer and 0-15.4% of functional monomer in molar percentage; the concentration of the associated polymer in the oil displacement system is 200-3500 mg/L. Compared with the prior art, the invention adopts the associative polymer obtained by introducing a small amount of hydrophobic monomers and functional monomers on a polymer molecular chain, hydrophobic groups are associated into a space network structure in aqueous solution, thereby greatly improving the viscosity of the system, establishing high resistance coefficient and high residual resistance coefficient, and introducing the functional monomers and the space network structure, so that the system has good temperature resistance, salt resistance, shear resistance and aging stability, has better effect of improving the oil-water fluidity ratio of a low-permeability reservoir, improves the injected water wave and efficiency, and further better improves the recovery ratio of the low-permeability reservoir.
Description
Technical Field
The invention belongs to the technical field of oil exploitation, and particularly relates to an oil displacement system and an oil displacement method for a low-permeability oil reservoir.
Background
With the development of oil exploration, the proportion of low permeability oil fields in newly explored reserves is increasing. The low-permeability oil reservoir occupies more than half of oil and gas fields found in China, the capacity construction scale of the low-permeability oil reservoir accounts for more than 70% of the total amount, and the low-permeability oil and gas fields become main battlefields for oil and gas development and construction. Because the pore throat and the crack of the low-permeability reservoir are small in size, the capillary phenomenon is prominent, the oil-gas flow resistance is large, the development difficulty is large, the recovery ratio is low, and therefore, how to develop the low-permeability reservoir better is a necessary trend of current research.
For low permeability reservoirs, polymer flooding, a chemical flooding, has gained wide attention as an important method. With the addition of the polymer, the viscosity of the system rises, the formed high-permeability zone or crack is blocked, the water flooding wave and volume are enlarged, and the stratum water injection section is adjusted, so that the method has a considerable application potential. Research shows that the polymer can not block an oil layer as long as the matching of the rock pore throat radius and the polymer molecule coil gyration radius is satisfied. Meanwhile, compared with surfactant flooding and alkali water flooding, polymer flooding has the advantages of convenient construction, small dosage, low cost and good effect, so that the research of the polymer matched with the low-permeability reservoir to improve the recovery ratio after water flooding is the key point of the current research. The surfactant or alkali has considerable advantages in the aspect of improving the recovery efficiency, the surfactant or alkali is added into a polymer flooding system to prepare a binary system or a ternary system to reduce the cost, the surfactant and alkali are fully exerted to reduce the interfacial tension, the oil washing efficiency is improved, the cost is reduced, and the performance advantages of the polymer in improving the water absorption profile are also paid extensive attention, so that the polymer flooding system has great potential.
For low permeability reservoirs, the polymer molecular weight should not be too high, otherwise the formation is easily blocked, making subsequent displacement fluids difficult to inject. The molecular weight of natural high molecular weight is not easy to control, a large amount of residues are easily generated after decomposition to block the stratum, the natural high molecular weight oil deposit is not suitable for being used in a low-permeability oil deposit, the natural high molecular weight oil deposit is limited by times and regions, the cost is high, the thermal stability and the biological stability are relatively poor, and the natural high molecular weight oil deposit is easy to degrade, so that the application in a high-temperature high-salinity oil deposit is limited; although polyacrylamide is used as a mature synthetic polymer, the viscosity of an aqueous solution can be improved to a certain extent, long molecular chains can be easily broken due to the strong shearing action of blast holes in the construction process, and the viscosity of the displacement fluid is irreversibly lost; the method is easily influenced by the formation environment (temperature and mineralization degree), and has the following problems: 1) when the polyacrylamide is applied under the conditions of high temperature and high mineralization, the hydrolysis of the polyacrylamide is serious when the temperature is higher; 2) after the formation temperature exceeds 75 ℃, the formation of hydrolyzed polyacrylamide precipitates is accelerated along with the increase of the formation temperature; 3) the high temperature and high salt easily cause the hydrolyzed polyacrylamide to be precipitated from the aqueous solution, and the phenomenon is more remarkable when the hydrolysis degree is higher; 4) the solution viscosity is very sensitive to temperature and salinity, and the retained viscosity of the solution is very low in a high-temperature and high-salinity environment. The use of polyacrylamide under slightly harsh reservoir conditions is greatly limited. Importantly, because the molecular weight of the polymer in the low-permeability reservoir is not too high, the polyacrylamide can simply reduce the molecular weight to match with a low-permeability stratum, but the viscosity of the polymer is lower after the molecular weight is reduced, the concentration is increased for displacement of reservoir oil, the cost is bound to be increased, and if the high-molecular-weight polymer is used for displacement of reservoir oil, the size of a molecular coil of the polymer is possibly larger than the pore throat size of the low-permeability reservoir, the stratum is easily blocked, and the injection is difficult; and the molecular coil size is determined to be single, the matching performance with the pore throat of the low-permeability reservoir is poor, the established resistance coefficient and the residual resistance coefficient are small, and the effects of effectively expanding swept volume and plugging a water drive dominant channel cannot be well played. When a binary (ternary) system is prepared by adding a surfactant and alkali, the viscosity and viscoelasticity of the binary (ternary) system are reduced to different degrees under the action of most surfactants and alkali (negative synergistic effect); and has weak structure, poor viscoelasticity and reduced fluidity control capability at low concentration and low viscosity. In order to solve the problems, the common polyacrylamide can only adjust the molecular weight and the hydrolysis degree and has a limited adjusting range, and is difficult to further overcome on the basis of the existing molecular structure, so that the demand of efficient development of low-permeability oil fields cannot be met.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide an oil displacement system and an oil displacement method for a low permeability reservoir, wherein the oil displacement system has a small usage amount and excellent performance, can establish a real high resistance coefficient and a real high residual resistance coefficient, and can greatly improve the recovery ratio of water flooding and polymer flooding of the low permeability reservoir.
The invention provides an oil displacement system for a low-permeability reservoir, which comprises an associative polymer; the molecular weight of the associated polymer is 101.4-997.5 ten thousand; the associative polymer is obtained by polymerizing acrylamide, 0.09-10.2% of hydrophobic monomer and 0-15.4% of functional monomer in molar percentage; the concentration of the associated polymer in the oil displacement system is 200-3500 mg/L;
the hydrophobic monomer is selected from one or more of N-alkyl substituted acrylamide and derivatives thereof, alkyl acrylate, alkyl methacrylate, fluorine substituted alkyl acrylate, fluorine substituted alkyl methacrylate, allyl alkyl quaternary ammonium salt, acrylamide alkyl sulfonic acid and sulfonate thereof, alkylphenol polyoxyethylene acrylate and polyoxyethylene alkyl acrylate;
the functional monomer is selected from one or more of a sulfonic acid derivative containing terminal alkenyl and a sulfonate derivative thereof and a heterocyclic derivative containing terminal alkenyl.
Preferably, the number of carbon atoms of the alkyl group in the N-alkyl substituted acrylamide and derivatives thereof, alkyl acrylate, alkyl methacrylate, allyl alkyl quaternary ammonium salt, alkyl sulfonic acid and sulfonates thereof, alkylphenol polyoxyethylene acrylate, polyoxyethylene alkyl acrylate, fluorine substituted alkyl acrylate and fluorine substituted alkyl methacrylate is 4 to 40, respectively.
Preferably, the functional monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid and sulfonate thereof, vinylsulfonic acid and sulfonate thereof, styrenesulfonic acid and sulfonate thereof, and N-vinyl-2-pyrrolidone.
Preferably, the detergent also comprises a surfactant; the mass of the surfactant is 0.001-0.73% of that of the associated polymer.
Preferably, the surfactant is one or more of petroleum sulfonate anionic surfactant, alkylbenzene sulfonate anionic surfactant, α -olefin sulfonate anionic surfactant, betaine amphoteric surfactant, alkanolamide nonionic surfactant, nonionic gemini surfactant, anionic gemini surfactant, alkyl naphthalene sulfonate, lignosulfonate, vegetable oil carboxylate, petroleum carboxylate, biological surfactant and composite surfactant.
Preferably, the composition also comprises an alkaline substance; the mass of the alkaline substance is 0.09-2.17% of that of the associated polymer.
Preferably, the alkaline substance is NaOH or Na2CO3And one or more of amine organic bases.
Preferably, the water permeability of the low-permeability reservoir is a, and a is more than or equal to 3mD and less than 50 mD.
The invention also provides an oil displacement method of the low-permeability reservoir, and the oil displacement system for the low-permeability reservoir is adopted for oil displacement.
Compared with the prior art, the invention provides an oil displacement system for a low-permeability reservoir, which comprises an associative polymer; the molecular weight of the associated polymer is 101.4-997.5 ten thousand; the associative polymer is obtained by polymerizing acrylamide, 0.09-10.2% of hydrophobic monomer and 0-15.4% of functional monomer in molar percentage; the concentration of the associated polymer in the oil displacement system is 200-3500 mg/L; the hydrophobic monomer is selected from one or more of N-alkyl substituted acrylamide and derivatives thereof, alkyl acrylate, alkyl methacrylate, fluorine substituted alkyl acrylate, fluorine substituted alkyl methacrylate, allyl alkyl quaternary ammonium salt, acrylamide alkyl sulfonic acid and sulfonate thereof, alkylphenol polyoxyethylene acrylate and polyoxyethylene alkyl acrylate; the functional monomer is selected from one or more of a sulfonic acid derivative containing terminal alkenyl and a sulfonate derivative thereof and a heterocyclic derivative containing terminal alkenyl. Compared with the prior art, the invention adopts the associative polymer obtained by introducing a small amount of hydrophobic groups and functional monomers on polymer molecules as an oil displacement system, and with the introduction of the hydrophobic groups, the hydrophobic groups in the macromolecules or among the molecules are mutually associated in aqueous solution due to hydrophobic effect to form a reversible three-dimensional space dynamic physical crosslinking network, so that the polymer has higher viscosity and elasticity at lower molecular weight and lower concentration, and saves cost; the molecular coil aggregate can be reversibly deformed, and under the condition of ensuring good injectivity of an oil reservoir, due to the introduction of a hydrophobic monomer, a real high resistance coefficient and a real high residual resistance coefficient are established, so that the permeability of a relatively high-permeability area is effectively reduced, a better profile adjusting effect is achieved, and the water wave and efficiency of subsequent injection is improved; the strength of the network structure of the functional monomer introduction and association space is increased along with the increase of the polarity of the solution, so that the system has good temperature resistance, salt resistance, shear resistance and aging stability; the size of the molecular coil can be changed through the content, the type and the molecular weight change of the hydrophobic monomer, so that the molecular coil is matched with the pore throat of a low-permeability reservoir under low molecular weight and low concentration, the polymer injection property is ensured, and deep conduction oil displacement can be realized; the method has better effect of improving the oil-water fluidity ratio of the low-permeability reservoir and improving the subsequent water wave injection efficiency; due to the existence of a three-dimensional space dynamic physical cross-linked network in the solution, the elasticity of the system is greatly improved, and the microscopic oil displacement efficiency of the polymer is improved, so that the recovery ratio of the low-permeability reservoir after water flooding can be better improved; when the surfactant and the alkali are added to prepare a binary (ternary) system, the advantages of the associated polymer are ensured, the properties such as viscosity, elasticity and the like of the system can be greatly improved (a positive synergistic effect is generated), and the oil washing efficiency of the system can be greatly improved by the added surfactant and the added alkali, so that the recovery ratio of water flooding and polymer flooding can be greatly improved under the low-permeability oil reservoir conditions with high water content and high extraction degree.
Experimental results show that the solution for the low-permeability reservoir has the concentration of 200-3500 mg/L, the viscosity of 3.2-250.0 mPa.s, the mechanical shear viscosity retention rate of 61.43-97.00%, the aging viscosity retention rate of 56.80-99.50% after 90 days, the resistance coefficient of 84.0-764.2, the residual resistance coefficient of 23.4-206.0 and the enhanced recovery degree of 8.14-26.93%.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides an oil displacement system for a low-permeability reservoir, which comprises an associative polymer; the molecular weight of the associated polymer is 101.4-997.5 ten thousand; the associative polymer is obtained by polymerizing acrylamide, 0.09-10.2% of hydrophobic monomer and 0-15.4% of functional monomer in molar percentage; the concentration of the associated polymer in the oil displacement system is 200-3500 mg/L; the hydrophobic monomer is selected from one or more of N-alkyl substituted acrylamide and derivatives thereof, alkyl acrylate, alkyl methacrylate, fluorine substituted alkyl acrylate, fluorine substituted alkyl methacrylate, allyl alkyl quaternary ammonium salt, acrylamide alkyl sulfonic acid and sulfonate thereof, alkylphenol polyoxyethylene acrylate and polyoxyethylene alkyl acrylate; the functional monomer is selected from one or more of a sulfonic acid derivative containing terminal alkenyl and a sulfonate derivative thereof and a heterocyclic derivative containing terminal alkenyl.
In some embodiments provided herein, the associative polymer preferably has a molecular weight of 103.6 ten thousand; in some embodiments provided herein, the associative polymer preferably has a molecular weight of 112.4 ten thousand; in some embodiments provided herein, the associative polymer preferably has a molecular weight of 201.5 ten thousand; in some embodiments provided herein, the associative polymer preferably has a molecular weight of 587.4 million; in some embodiments provided herein, the associative polymer preferably has a molecular weight of 610.2 ten thousand; in other embodiments provided herein, the associative polymer preferably has a molecular weight of 996.7 Wan.
In some embodiments provided herein, the hydrophobic monomer is preferably present at 0.1%; in some embodiments provided herein, the hydrophobic monomer is preferably present at 0.83%; in some embodiments provided herein, the hydrophobic monomer is preferably present at 3.6%; in some embodiments provided herein, the hydrophobic monomer is preferably present in an amount of 4.25%; in some embodiments provided herein, the hydrophobic monomer is preferably present at 6.24%; in other embodiments provided herein, the hydrophobic monomer is preferably present at 9.96%.
The hydrophobic monomer is selected from one or more of N-alkyl substituted acrylamide and derivatives thereof, alkyl acrylate, alkyl methacrylate, fluorine substituted alkyl acrylate, fluorine substituted alkyl methacrylate, allyl alkyl quaternary ammonium salt, acrylamide alkyl sulfonic acid and sulfonate thereof, alkylphenol polyoxyethylene acrylate and polyoxyethylene alkyl acrylate; wherein the number of carbon atoms of the alkyl group in the N-alkyl substituted acrylamide and its derivatives, alkyl acrylate, alkyl methacrylate, allyl alkyl quaternary ammonium salt, acrylic acid alkyl sulfonic acid and its sulfonates, alkylphenol polyoxyethylene acrylate, fluorine substituted alkyl acrylate and fluorine substituted alkyl methacrylate, allyl alkyl quaternary ammonium salt, acrylamide alkyl sulfonic acid and its sulfonates, alkylphenol polyoxyethylene acrylate or polyoxyethylene acrylate is 4 to 40, more preferably 4 to 20, and still more preferably 6 to 20, independently.
The N-alkyl substituted acrylamide derivative is preferably a derivative having a benzene ring structure; the polymerization degrees of polyoxyethylene in the alkylphenol polyoxyethylene acrylate and the polyoxyethylene alkyl acrylate are respectively and independently preferably 7-20, and more preferably 7-16; the number of fluorine atoms in the fluorine-substituted alkyl acrylate and the fluorine-substituted alkyl methacrylate is preferably 4-10, more preferably 6-8, and most preferably 2- (N-ethyl perfluorosulfonic acid amine) ethyl methacrylate or 2- (N-ethyl perfluorooctane) butyl methacrylate; the hydrophobic monomer in the present invention is most preferably lauryl acrylate, cetyl acrylate, lauryl methacrylate, cetyl methacrylate, N-dodecylacrylamide, N-hexadecylacrylamide, N-octylpropionamide, sodium 2-acrylamido-2-methyldicosyl sulfonate, N-tetradecylacrylamide, N-dioctylacrylamide, hexafluorobutyl methacrylate, tetradecyl methacrylate, hexadecylallyldibromotetramethylethylenediamine, sodium 2-acrylamidotetradecanesulfonate, sodium 2-acrylamido-2-methyldodecanesulfonate, nonylphenol polyoxyethylene acrylate, octylphenol polyoxyethylene acrylate, dodecylpolyoxyethylene acrylate, octadecylallyldimethylethylenediamine dibromide, octadecylallyldimethylethylenediamine, N-dodecylacrylamide, N-hexadecylacrylamide, N-dodecylacrylamide, N-dioctylacrylamide, N-octylphenol polyoxyethylene acrylate, N-, Cetyl polyoxyethylene acrylate, N-hexadecyl acrylamide, N-octyl acrylamide, dodecyl allyl tetramethyl ammonium dibromide, tetradecyl allyl tetramethyl ammonium dibromide and (4-acrylamide) phenyl N-butyl dimethyl ammonium bromide.
In some embodiments provided herein, the functional monomer is preferably present at 0%; in some embodiments provided herein, the functional monomer is preferably present at 3.8%; in some embodiments provided herein, the functional monomer is preferably present in an amount of 4.1%; in some embodiments provided herein, the functional monomer is preferably present at 11.9%; in some embodiments provided herein, the functional monomer is preferably present at 12.2%; in some embodiments provided herein, the functional monomer is preferably present at 13.8%; in other embodiments provided herein, the functional monomer is preferably present at 14.6%.
The functional monomer is selected from one or more of a sulfonic acid derivative containing terminal alkenyl and a sulfonate derivative thereof and a heterocyclic derivative containing terminal alkenyl; the carbon number of the functional monomer is preferably 2-20, more preferably 2-15, and further preferably 2-10; in the present invention, the functional monomer is most preferably one or more of 2-acrylamido-2-methylpropanesulfonic Acid (AMPS) and its sulfonate, vinylsulfonic acid and its sulfonate, styrenesulfonic acid and its sulfonate, and N-vinyl-2-pyrrolidone (NVP).
The invention provides an oil displacement system for a low-permeability oil reservoir; the low-permeability reservoir is a low-permeability reservoir known to those skilled in the art, and is not limited in particular, and the water permeability of the low-permeability reservoir in the invention is a, and a is more than or equal to 3mD and less than 50 mD.
The oil displacing system comprises an associative polymer, and the concentration of the associative polymer in the oil displacing system is 200-3500 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 400 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 500 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 800 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1800 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 2500 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 700 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 2800 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 3000 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 2000 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1000 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1200 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1300 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 2600 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 3500 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 600 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1600 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1500 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 3100 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 800 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 2200 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 2400 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 1100 mg/L; in some embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 900 mg/L; in other embodiments provided herein, the concentration of the associative polymer in the chaser system is preferably 3200 mg/L.
The invention adopts the associative polymer obtained by introducing a small amount of hydrophobic groups and functional monomers on polymer molecules as an oil displacement system, and with the introduction of the hydrophobic groups, the hydrophobic groups in the macromolecules or among the molecules are mutually associated in aqueous solution due to hydrophobic effect to form a reversible three-dimensional space dynamic physical crosslinking network, so that the polymer has higher viscosity and elasticity at lower molecular weight and lower concentration, and the cost is saved; the molecular coil aggregate can be reversibly deformed, and under the condition of ensuring good injectivity of an oil reservoir, due to the introduction of a hydrophobic monomer, a real high resistance coefficient and a real high residual resistance coefficient are established, so that the permeability of a relatively high-permeability area is effectively reduced, a better profile adjusting effect is achieved, and the water wave and efficiency of subsequent injection is improved; the strength of the network structure of the functional monomer introduction and association space is increased along with the increase of the polarity of the solution, so that the system has good temperature resistance, salt resistance, shear resistance and aging stability; the size of the molecular coil can be changed through the content, the type and the molecular weight change of the hydrophobic monomer, so that the molecular coil is matched with the pore throat of a low-permeability reservoir under low molecular weight and low concentration, the polymer injection property is ensured, and deep conduction oil displacement can be realized; the method has better effect of improving the oil-water fluidity ratio of the low-permeability reservoir and improving the subsequent water wave injection efficiency; due to the existence of a three-dimensional space dynamic physical cross-linked network in the solution, the elasticity of the system is greatly improved, and the microscopic oil displacement efficiency of the polymer is improved, so that the recovery ratio of the low-permeability reservoir after water flooding can be better improved; when the surfactant and the alkali are added to prepare a binary (ternary) system, the advantages of the associated polymer are ensured, the properties such as viscosity, elasticity and the like of the system can be greatly improved (a positive synergistic effect is generated), and the oil washing efficiency of the system can be greatly improved by the added surfactant and the added alkali, so that the recovery ratio of water flooding and polymer flooding can be greatly improved under the low-permeability oil reservoir conditions with high water content and high extraction degree.
Therefore, the oil displacement system provided by the invention preferably further comprises a surfactant, wherein the mass of the surfactant is 0.001-0.73% of that of the associated polymer; in some embodiments provided herein, the surfactant is preferably 0.001% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.06% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.59% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.01% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.69% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.011% of the associative polymer mass; in some embodiments provided herein, the surfactant is preferably 0.0098% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.15% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.73% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.05% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.12% of the mass of the associative polymer; in some embodiments provided herein, the surfactant is preferably 0.09% of the mass of the associative polymer; in other embodiments provided herein, the surfactant is preferably 0.096% of the mass of the associative polymer.
The surfactant is not particularly limited as long as it is a surfactant known to those skilled in the art, and in the present invention, one or more of petroleum sulfonate anionic surfactant, alkylbenzene sulfonate anionic surfactant, α -olefin sulfonate anionic surfactant, betaine amphoteric surfactant, alkanolamide nonionic surfactant, nonionic gemini surfactant, anionic gemini surfactant, alkylnaphthalene sulfonate, lignosulfonate, vegetable oil carboxylate, petroleum carboxylate, biological surfactant and complex surfactant are preferable.
The oil displacement system provided by the invention preferably further comprises an alkaline substance, wherein the mass of the alkaline substance is 0.09-2.17% of that of the associated polymer. At the moment, the oil displacement system is ASP ternary combination flooding, and the main oil displacement mechanism is that alkali and acid components in crude oil act to generate soaps in situ, and the soaps and added surfactant act synergistically to generate ultralow interfacial tension; the surface active agent/polymer system is added with alkali, the alkali and the mineral on the rock surface generate ion exchange, so that the mineral composition on the rock surface is changed, the electrical property of the rock particle surface is improved, the absorption and retention loss of the surface active agent with higher price and the polymer on the rock surface is reduced, the dosage of the surface active agent required by the compound flooding is greatly reduced, and the cost is saved.
In some embodiments provided herein, the mass of the basic material is preferably 0.09% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.27% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.83% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 2.17% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.12% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 1.9% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.77% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 1.57% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.15% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 2.17% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.74% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 1.8% of the mass of the associative polymer; in some embodiments provided herein, the mass of the basic material is preferably 0.1% of the mass of the associative polymer; in other embodiments provided herein, the amount of the basic material is preferably 0.31% of the amount of the associative polymer.
The alkaline substance is not particularly limited as long as it is known to those skilled in the art, and NaOH or Na is preferred in the present invention2CO3And one or more of amine organic bases.
The invention adopts the associative polymer obtained by introducing a small amount of hydrophobic groups and functional monomers on polymer molecules as an oil displacement system, and with the introduction of the hydrophobic groups, the hydrophobic groups in the macromolecules or among the molecules are mutually associated in aqueous solution due to hydrophobic effect to form a reversible three-dimensional space dynamic physical crosslinking network, so that the polymer has higher viscosity and elasticity at lower molecular weight and lower concentration, and the cost is saved; the molecular coil aggregate can be reversibly deformed, and under the condition of ensuring good injectivity of an oil reservoir, due to the introduction of a hydrophobic monomer, a real high resistance coefficient and a real high residual resistance coefficient are established, so that the permeability of a relatively high-permeability area is effectively reduced, a better profile adjusting effect is achieved, and the water wave and efficiency of subsequent injection is improved; the strength of the network structure of the functional monomer introduction and association space is increased along with the increase of the polarity of the solution, so that the system has good temperature resistance, salt resistance, shear resistance and aging stability; the size of the molecular coil can be changed through the content, the type and the molecular weight change of the hydrophobic monomer, so that the molecular coil is matched with the pore throat of a low-permeability reservoir under low molecular weight and low concentration, the polymer injection property is ensured, and deep conduction oil displacement can be realized; the method has better effect of improving the oil-water fluidity ratio of the low-permeability reservoir and improving the subsequent water wave injection efficiency; due to the existence of a three-dimensional space dynamic physical cross-linked network in the solution, the elasticity of the system is greatly improved, and the microscopic oil displacement efficiency of the polymer is improved, so that the recovery ratio of the low-permeability reservoir after water flooding can be better improved; when the surfactant and the alkali are added to prepare a binary (ternary) system, the advantages of the associated polymer are ensured, the properties such as viscosity, elasticity and the like of the system can be greatly improved (a positive synergistic effect is generated), and the oil washing efficiency of the system can be greatly improved by the added surfactant and the added alkali, so that the recovery ratio of water flooding and polymer flooding can be greatly improved under the low-permeability oil reservoir conditions with high water content and high extraction degree.
The invention also provides an oil displacement method of the low-permeability reservoir, and the oil displacement system for the low-permeability reservoir is adopted for oil displacement.
In order to further explain the present invention, the following describes in detail an oil displacement system and an oil displacement method for a low permeability reservoir, which are provided by the present invention, with reference to the following embodiments.
The reagents used in the following examples are all commercially available.
1. When the flooding system only comprises the associative polymer and water, the evaluation flow standard is as follows:
1.1 preparation of the Polymer mother liquor
Opening the water bath kettle, heating to a required temperature, weighing calculated amount of water (the water is required to be filtered by a 500-mesh screen firstly when being filled with water) in the beaker, putting the beaker into the water bath kettle, opening the vertical stirrer, and selecting a proper rotating speed to enable the water in the beaker to form a vortex for preheating. Weighing the calculated amount of polymer dry powder, uniformly scattering the polymer dry powder along the vortex wall, and stirring until the polymer dry powder is dissolved into the mother solution with the required concentration.
1.2 preparing a target solution with a certain concentration
According to the requirement, taking a proper amount of polymer mother liquor, adding calculated amount of water, stirring for 1 hour at proper rotating speed by using a vertical stirrer, and diluting into the target solution with the required concentration.
1.3 solution viscosity measurement
A Brookfield viscometer is selected, a certain amount of polymer target solution is filled into a sample containing cylinder, and preheating is carried out at a required temperature. And selecting a proper rotor and a proper rotating speed, measuring viscosity values for 3 min, 5 min and 8min, and then taking an average value to obtain a target liquid viscosity value.
1.4 mechanical shear Retention
An appropriate amount of the polymer target fluid was taken and the solution viscosity (viscosity before shearing) was measured. Stirring and shearing the solution for 30s under the I gear by adopting a waring stirrer, and standing at normal temperature for defoaming. After defoaming, the clear solution was taken and the viscosity (viscosity after shearing) thereof was measured. The mechanical shear retention is the ratio of the viscosity after shearing to the viscosity before shearing.
Aged viscosity Retention at 1.590 days
And introducing nitrogen into the prepared polymer target solution with the measured viscosity for deoxidization, subpackaging the polymer target solution into a plurality of ampoule bottles, sintering and sealing the ampoule bottles at high temperature, placing the ampoule bottles in a drying oven at corresponding temperature, taking out one ampoule bottle at certain intervals for measuring the viscosity of the ampoule bottle, comparing the change of the polymer target solution viscosity within 90 days, and obtaining the ratio of the solution viscosity to the initial viscosity within 90 days.
1.6 determination of drag coefficient and residual drag coefficient
Selecting a natural rock core or an artificial rock core with measured basic parameters, putting the natural rock core or the artificial rock core into a rock core holder, and adding proper ring pressure; or selecting a sand filling pipe with the measured basic parameters, and putting the sand filling pipe into an oven heated to the experimental temperature for heating.
The water used in the experiment and the prepared polymer target solution are filtered and then filled into an intermediate container. A precision pump is adopted to saturate water for the rock core or the sand filling pipe at proper flow rate; after the saturated water is finished, continuously injecting water until the pressure is stable P1(ii) a Injecting the polymer target solution to a pressure value stable P at the same flow rate as the water injection2The viscosity of the effluent liquid at the outlet is stable; finally, water is injected at the same speed until the pressure is stable P3。
The drag coefficient is the ratio of P2 to P1.
The residual drag coefficient is the ratio of P3 to P1.
1.7 degree of enhanced recovery
Homogeneous oil reservoir oil displacement experiments can adopt homogeneous sand filling pipes, artificial homogeneous cores and natural cores, and the following artificial square core oil displacement experiments with various parameters measured are taken as examples:
firstly, connecting a device pipeline, and after setting the temperature of the oven, performing saturated water operation on the rock core at a proper flow rate. After the saturated water is finished, carrying out saturated crude oil or simulated oil operation, collecting effluent liquid, recording the volume of the effluent oil water, and calculating the pore volume and the saturated oil volume; and (5) immediately sealing the sand filling pipe after the saturated oil process is finished, curing for a certain time, and preparing for a water drive experiment.
During the water drive experiment, the core outlet is opened first, the self-spraying oil in the model is released until no oil is produced, the self-spraying oil volume is recorded, and the self-spraying oil volume is deducted from the saturated oil volume. Connecting the outlet of the holder with an oil-water separator, injecting water into the core through a constant speed pump according to the required flow rate, collecting outlet-end effluent, recording the pressure, the upper and lower liquid levels of the oil-water separator and the volume of the effluent at certain intervals, and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery rate and the injection pore volume multiple; and when the instantaneous water content reaches the required transferring polymerization condition, immediately transferring polymerization.
When the polymer is driven, the water injection is stopped, the polymer is injected at the required flow rate, and the liquid is collected at the outlet. Reading the pressure, the upper and lower liquid levels of the oil-water separator and the volume of effluent liquid once every 10min, and recording and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery ratio and the injection pore volume multiple; during polymer injection, when the accumulated output liquid reaches the polymer injection amount required by the experiment, the subsequent water drive is immediately carried out.
Stopping injecting the polymer during subsequent water flooding, injecting water at a required flow rate, and collecting liquid at an outlet end; reading the pressure, the upper and lower liquid levels of the oil-water separator and the volume of effluent liquid every 10min, and recording and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery rate and the injection pore volume multiple; and (5) displacing until oil-free output or the water content reaches the requirement, and ending the experiment.
Adding a demulsifier with a certain concentration into an oil-water separator, uniformly mixing, standing for 24h at the experimental temperature, reading the upper and lower liquid level values of the separator, calculating the enhanced recovery rate value (the total recovery rate minus the early water drive recovery rate) at the moment, and correcting the recovery rate error possibly caused by crude oil emulsification compared with the enhanced recovery rate at the moment when the experiment is just finished.
The oil displacement system is evaluated according to the standard, the performance test result of the oil displacement system is shown in table 2 when the permeability of the low-permeability reservoir is evaluated to be 3mD, the composition of the polymer in the oil displacement system is shown in table 1, and polyacrylamide with the molecular weight of 300 ten thousand is used as comparative example 1.
The test conditions are as follows:
temperature: 72 ℃; TDS: 50000 mg/L; calcium and magnesium ions: 8000 mg/L; viscosity of crude oil: 100 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 1 composition of polymers in oil displacing systems
Table 2 performance test results of the flooding system when the permeability of the low permeability reservoir is 3mD
The oil displacement system is evaluated according to the standard, the performance test result of the oil displacement system is shown in table 4 when the permeability of the low-permeability reservoir is evaluated to be 12mD, the composition of the polymer in the oil displacement system is shown in table 3, and polyacrylamide with the molecular weight of 600 ten thousand is used as comparative example 2.
The test conditions are as follows:
temperature: 70 ℃; TDS: 65000 mg/L; calcium and magnesium ions: 10000 mg/L; viscosity of crude oil: 120 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 3 composition of polymers in oil displacing systems
TABLE 4 Performance test results of the flooding system at a permeability of 12mD for a low permeability reservoir
The oil displacement system is evaluated according to the standard, the performance test result of the oil displacement system is shown in table 6 when the permeability of the low-permeability reservoir is evaluated to be 23mD, the composition of the polymer in the oil displacement system is shown in table 5, and polyacrylamide with the molecular weight of 800 ten thousand is used as comparative example 3.
The test conditions are as follows:
temperature: 85 ℃; TDS: 68000 mg/L; calcium and magnesium ions: 8000 mg/L; viscosity of crude oil: 150 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 5 composition of polymers in oil displacing systems
TABLE 6 Performance test results of the flooding system at a permeability of the low permeability reservoir of 23mD
The oil displacement system is evaluated according to the standard, the performance test result of the oil displacement system is shown in table 8 when the permeability of the low-permeability reservoir is evaluated to be 49mD, the composition of the polymer in the oil displacement system is shown in table 7, and polyacrylamide with the molecular weight of 1000 ten thousand is used as comparative example 4.
The test conditions are as follows:
temperature: 78 ℃; TDS: 72000 mg/L; calcium and magnesium ions: 15000 mg/L; viscosity of crude oil: 200 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 7 composition of polymers in oil displacing systems
TABLE 8 Performance test results of the flooding system at 49mD permeability of the low permeability reservoir
2. When the oil displacement system comprises the associative polymer and the surfactant, namely the binary combination flooding, the evaluation criteria are as follows:
2.1 preparation of the Polymer mother liquor
Opening the water bath kettle, heating to a required temperature, weighing calculated amount of water (the water is required to be filtered by a 500-mesh screen firstly when being filled with water) in the beaker, putting the beaker into the water bath kettle, opening the vertical stirrer, and selecting a proper rotating speed to enable the water in the beaker to form a vortex for preheating. Weighing the calculated amount of polymer dry powder, uniformly scattering the polymer dry powder along the vortex wall, and stirring until the polymer dry powder is dissolved into the mother solution with the required concentration.
2.2 preparing a target solution with a certain concentration
According to the requirement, the calculated amount of the polymer mother liquor is taken, the calculated amount of the corresponding surfactant solution and water are added, and the mixture is stirred for 1 hour at a proper rotating speed by a vertical stirrer to prepare the binary system target liquor with the required concentration.
2.3 solution viscosity measurement
A Brookfield viscometer is selected, a certain amount of binary system target solution is put into a sample containing cylinder, and preheating is carried out at a required temperature. And selecting a proper rotor and a proper rotating speed, measuring viscosity values for 3 min, 5 min and 8min, and then taking an average value to obtain a target liquid viscosity value.
2.4 mechanical shear Retention
A proper amount of the binary system target liquid is taken, and the viscosity of the solution (viscosity before shearing) is measured. Stirring and shearing the solution for 30s under the I gear by adopting a waring stirrer, and standing at normal temperature for defoaming. After defoaming, the clear solution was taken and the viscosity (viscosity after shearing) thereof was measured. The mechanical shear retention is the ratio of the viscosity after shearing to the viscosity before shearing.
Viscosity retention at 2.590 days aging
And introducing nitrogen into the prepared binary system target solution with the measured viscosity (initial viscosity) for deoxygenation, subpackaging the solution into a plurality of ampoule bottles, sintering and sealing the ampoule bottles at high temperature, placing the ampoule bottles in an oven with corresponding temperature, taking out one ampoule bottle at certain intervals to measure the viscosity, comparing the viscosity change of the binary system target solution within 90 days, and obtaining the viscosity retention rate which is the ratio of the solution viscosity to the initial viscosity within 90 days.
2.6 determination of drag coefficient and residual drag coefficient
Selecting a natural rock core or an artificial rock core with measured basic parameters, putting the natural rock core or the artificial rock core into a rock core holder, and adding proper ring pressure; or selecting a sand filling pipe with the measured basic parameters, and putting the sand filling pipe into an oven heated to the experimental temperature for heating.
And filtering the water used in the experiment and the prepared binary system target solution, and filling the filtered solution into an intermediate container. A precision pump is adopted to saturate water for the rock core or the sand filling pipe at proper flow rate; after the saturated water is finished, continuously injecting water until the pressure is stable P1(ii) a Injecting the binary system target solution to a pressure value stable P at the same flow rate as the water injection2The viscosity of the effluent liquid at the outlet is stable; finally, water is injected at the same speed until the pressure is stable P3。
The drag coefficient is the ratio of P2 to P1.
The residual drag coefficient is the ratio of P3 to P1.
2.7 enhanced recovery degree
Homogeneous oil reservoir oil displacement experiments can adopt homogeneous sand filling pipes, artificial homogeneous cores and natural cores, and the following artificial square core oil displacement experiments with various parameters measured are taken as examples:
firstly, connecting a device pipeline, and after setting the temperature of the oven, performing saturated water operation on the rock core at a proper flow rate. After the saturated water is finished, carrying out saturated crude oil or simulated oil operation, collecting effluent liquid, recording the volume of the effluent oil water, and calculating the pore volume and the saturated oil volume; and (5) immediately sealing the sand filling pipe after the saturated oil process is finished, curing for a certain time, and preparing for a water drive experiment.
During the water drive experiment, the core outlet is opened first, the self-spraying oil in the model is released until no oil is produced, the self-spraying oil volume is recorded, and the self-spraying oil volume is deducted from the saturated oil volume. Connecting the outlet of the holder with an oil-water separator, injecting water into the core through a constant speed pump according to the required flow rate, collecting outlet-end effluent, recording the pressure, the upper and lower liquid levels of the oil-water separator and the volume of the effluent at certain intervals, and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery rate and the injection pore volume multiple; and when the instantaneous water content reaches the required transfer polymerization condition, immediately transferring the binary system.
And when the binary system is transferred, stopping water injection, injecting the binary system at the required flow rate, and collecting liquid at an outlet. Reading the pressure, the upper and lower liquid levels of the oil-water separator and the volume of effluent liquid once every 10min, and recording and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery ratio and the injection pore volume multiple; when the binary system is injected, when the accumulated liquid output reaches the injection amount of the binary system required by the experiment, the subsequent water drive is immediately carried out.
Stopping injecting the binary system during subsequent water flooding, injecting water at a required flow rate, and collecting liquid at an outlet end; reading the pressure, the upper and lower liquid levels of the oil-water separator and the volume of effluent liquid every 10min, and recording and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery rate and the injection pore volume multiple; and (5) displacing until oil-free output or the water content reaches the requirement, and ending the experiment.
Adding a demulsifier with a certain concentration into an oil-water separator, uniformly mixing, standing for 24h at the experimental temperature, reading the upper and lower liquid level values of the separator, calculating the enhanced recovery rate value (the total recovery rate minus the early water drive recovery rate) at the moment, and correcting the recovery rate error possibly caused by crude oil emulsification compared with the enhanced recovery rate at the moment when the experiment is just finished.
The oil displacement system is evaluated according to the standard, the performance test result of the binary composite flooding oil displacement system is shown in table 10 when the permeability of the low-permeability reservoir is evaluated to be 3mD, the composition of the polymer in the oil displacement system is shown in table 9, and polyacrylamide with the molecular weight of 300 ten thousand is used as comparative example 5.
The test conditions are as follows:
temperature: 72 ℃; TDS: 50000 mg/L; calcium and magnesium ions: 8000 mg/L; viscosity of crude oil: 100 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 9 composition of polymers in oil displacing systems
TABLE 10 Performance test results of binary combination flooding system for 3mD permeability of low permeability reservoir
The oil displacement system is evaluated according to the standard, the performance test result of the binary composite flooding oil displacement system is shown in table 12 when the permeability of the low-permeability reservoir is evaluated to be 12mD, the composition of the polymer in the oil displacement system is shown in table 11, and polyacrylamide with the molecular weight of 600 ten thousand is used as comparative example 6.
The test conditions are as follows:
temperature: 70 ℃; TDS: 65000 mg/L; calcium and magnesium ions: 10000 mg/L; viscosity of crude oil: 120 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 11 composition of polymers in oil displacing systems
TABLE 12 Performance test results of binary combination flooding system with 12mD permeability of low-permeability reservoir
The oil displacement system is evaluated according to the standard, the performance test result of the binary composite flooding oil displacement system is shown in table 14 when the permeability of the low-permeability reservoir is evaluated to be 23mD, the composition of the polymer in the oil displacement system is shown in table 13, and polyacrylamide with the molecular weight of 800 ten thousand is used as comparative example 7.
The test conditions are as follows:
temperature: 85 ℃; TDS: 68000 mg/L; calcium and magnesium ions: 8000 mg/L; viscosity of crude oil: 150 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 13 composition of polymers in oil displacing systems
TABLE 14 Performance test results of binary combination flooding oil displacing system with low permeability reservoir permeability of 23mD
The oil displacement system is evaluated according to the standard, the performance test result of the binary composite flooding oil displacement system is shown in table 16 when the permeability of the low-permeability reservoir is evaluated to be 49mD, the composition of the polymer in the oil displacement system is shown in table 15, and polyacrylamide with the molecular weight of 1000 ten thousand is used as comparative example 8.
The test conditions are as follows:
temperature: 78 ℃; TDS: 72000 mg/L; calcium and magnesium ions: 15000 mg/L; viscosity of crude oil: 200 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 15 composition of polymers in oil displacing systems
TABLE 16 Performance test results of binary combination flooding oil displacing system with low permeability reservoir permeability of 49mD
3. When the oil displacement system comprises an associative polymer, a surfactant and an alkaline substance, namely the ternary combination flooding, the evaluation criteria are as follows:
3.1 preparation of Polymer mother liquor
Opening the water bath kettle, heating to a required temperature, weighing calculated amount of water (the water is required to be filtered by a 500-mesh screen firstly when being filled with water) in the beaker, putting the beaker into the water bath kettle, opening the vertical stirrer, and selecting a proper rotating speed to enable the water in the beaker to form a vortex for preheating. Weighing the calculated amount of polymer dry powder, uniformly scattering the polymer dry powder along the vortex wall, and stirring until the polymer dry powder is dissolved into the mother solution with the required concentration.
3.2 preparing a target solution with a certain concentration
According to the requirements, the calculated amount of polymer mother liquor is taken, the calculated amount of mixed solution of the corresponding surfactant and alkali and the calculated amount of water are added, and a vertical stirrer is adopted to stir for 1 hour at a proper rotating speed to prepare the ternary system target solution with the required concentration.
3.3 solution viscosity measurement
A Brookfield viscometer is selected, a certain amount of ternary system target solution is filled into a sample containing cylinder, and preheating is carried out at a required temperature. And selecting a proper rotor and a proper rotating speed, measuring viscosity values for 3 min, 5 min and 8min, and then taking an average value to obtain a target liquid viscosity value.
3.4 mechanical shear Retention
Taking a proper amount of ternary system target liquid, and measuring the viscosity of the solution (viscosity before shearing). Stirring and shearing the solution for 30s under the I gear by adopting a waring stirrer, and standing at normal temperature for defoaming. After defoaming, the clear solution was taken and the viscosity (viscosity after shearing) thereof was measured. The mechanical shear retention is the ratio of the viscosity after shearing to the viscosity before shearing.
Viscosity retention at 3.590 days aging
And introducing nitrogen into the prepared ternary system target solution with the measured viscosity (initial viscosity) for deoxidization, subpackaging the solution into a plurality of ampoule bottles, sintering and sealing the ampoule bottles at high temperature, placing the ampoule bottles in an oven with corresponding temperature, taking out one ampoule bottle at certain intervals to measure the viscosity, comparing the viscosity change of the ternary system target solution within 90 days, and obtaining the viscosity retention rate which is the ratio of the solution viscosity to the initial viscosity within 90 days.
3.6 determination of drag coefficient and residual drag coefficient
Selecting an artificial core or a natural core with measured basic parameters, putting the artificial core or the natural core into a core holder, and adding proper ring pressure; or selecting a sand filling pipe with the measured basic parameters, and putting the sand filling pipe into an oven heated to the experimental temperature for heating.
And filtering the water used in the experiment and the prepared ternary system target solution, and filling the filtered ternary system target solution into an intermediate container. A precision pump is adopted to saturate water for the rock core or the sand filling pipe at proper flow rate; after the saturated water is finished, continuously injecting water until the pressure is stable P1(ii) a Injecting the ternary system target solution to a pressure value stable P at the same flow rate as the water injection2The viscosity of the effluent liquid at the outlet is stable; finally, water is injected at the same speed until the pressure is stable P3。
The drag coefficient is the ratio of P2 to P1.
The residual drag coefficient is the ratio of P3 to P1.
3.7 degree of enhanced recovery
Homogeneous oil reservoir oil displacement experiments can adopt homogeneous sand filling pipes, artificial homogeneous cores and natural cores, and the following artificial square core oil displacement experiments with various parameters measured are taken as examples:
firstly, connecting a device pipeline, and after setting the temperature of the oven, performing saturated water operation on the rock core at a proper flow rate. After the saturated water is finished, carrying out saturated crude oil or simulated oil operation, collecting effluent liquid, recording the volume of the effluent oil water, and calculating the pore volume and the saturated oil volume; and (5) immediately sealing the sand filling pipe after the saturated oil process is finished, curing for a certain time, and preparing for a water drive experiment.
During the water drive experiment, the core outlet is opened first, the self-spraying oil in the model is released until no oil is produced, the self-spraying oil volume is recorded, and the self-spraying oil volume is deducted from the saturated oil volume. Connecting the outlet of the holder with an oil-water separator, injecting water into the core through a constant speed pump according to the required flow rate, collecting outlet-end effluent, recording the pressure, the upper and lower liquid levels of the oil-water separator and the volume of the effluent at certain intervals, and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery rate and the injection pore volume multiple; and when the instantaneous water content reaches the required transfer polymerization condition, immediately transferring the ternary system.
And when the ternary system is injected, stopping injecting water, injecting the ternary system at the required flow rate, and collecting liquid at an outlet. Reading the pressure, the upper and lower liquid levels of the oil-water separator and the volume of effluent liquid once every 10min, and recording and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery ratio and the injection pore volume multiple; and when the three-component system is injected, when the accumulated liquid output reaches the injection quantity of the three-component system required by the experiment, the subsequent water drive is immediately carried out.
Stopping injecting the ternary system during subsequent water flooding, injecting water at a required flow rate, and collecting liquid at an outlet end; reading the pressure, the upper and lower liquid levels of the oil-water separator and the volume of effluent liquid every 10min, and recording and calculating the instantaneous liquid outlet amount, the instantaneous water content, the instantaneous oil outlet rate, the recovery rate and the injection pore volume multiple; and (5) displacing until oil-free output or the water content reaches the requirement, and ending the experiment.
Adding a demulsifier with a certain concentration into an oil-water separator, uniformly mixing, standing for 24h at the experimental temperature, reading the upper and lower liquid level values of the separator, calculating the enhanced recovery rate value (the total recovery rate minus the early water drive recovery rate) at the moment, and correcting the recovery rate error possibly caused by crude oil emulsification compared with the enhanced recovery rate at the moment when the experiment is just finished.
The oil displacement system is evaluated according to the standard, the performance test result of the ternary combination flooding oil displacement system is shown in table 18 when the permeability of the low-permeability reservoir is evaluated to be 3mD, the composition of the oil displacement system is shown in table 17, polyacrylamide with the molecular weight of 300 ten thousand is used as comparative example 9, and the solution concentration is 3500 mg/L.
The test conditions are as follows:
temperature: 72 ℃; TDS: 50000 mg/L; calcium and magnesium ions: 8000 mg/L; viscosity of crude oil: 100 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 17 composition of oil displacing system
TABLE 18 Performance test results of ASP flooding system with 3mD permeability of low permeability reservoir
The oil displacement system is evaluated according to the standard, the performance test result of the ternary combination flooding oil displacement system is shown in a table 20 when the permeability of the low-permeability reservoir is evaluated to be 12mD, the composition of the oil displacement system is shown in a table 19, polyacrylamide with the molecular weight of 600 ten thousand is used as a comparative example 10, and the solution concentration is 3500 mg/L.
The test conditions are as follows:
temperature: 70 ℃; TDS: 65000 mg/L; calcium and magnesium ions: 10000 mg/L; viscosity of crude oil: 120 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
Composition of oil displacing system of table 19
TABLE 20 Performance test results of ASP flooding system with 12mD permeability of low permeability reservoir
The oil displacement system is evaluated according to the standard, the performance test result of the ternary complex flooding oil displacement system is shown in table 22 when the permeability of the low-permeability reservoir is evaluated to be 23mD, the composition of the oil displacement system is shown in table 21, polyacrylamide with the molecular weight of 800 ten thousand is used as comparative example 11, and the solution concentration is 3300 mg/L.
The test conditions are as follows:
temperature: 85 ℃; TDS: 68000 mg/L; calcium and magnesium ions: 8000 mg/L; viscosity of crude oil: 150 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 21 composition of oil displacing system
TABLE 22 results of performance testing of ASP flooding system with low permeability reservoir permeability of 23mD
The oil displacement system is evaluated according to the standard, the performance test result of the ternary combination flooding oil displacement system is shown in a table 24 when the permeability of the low-permeability reservoir is evaluated to be 49mD, the composition of the oil displacement system is shown in a table 23, polyacrylamide with the molecular weight of 1000 ten thousand is used as a comparative example 12, and the solution concentration is 3500 mg/L.
The test conditions are as follows:
temperature: 78 ℃; TDS: 72000 mg/L; calcium and magnesium ions: 15000 mg/L; viscosity of crude oil: 200 mPa.s; the specification of the core is as follows: an artificial core of 4.5 × 4.5 × 30 cm; and measuring the resistance coefficient RF and the residual resistance coefficient RRF of the system at the injection speed of 3m/d, improving the recovery ratio amplitude after water flooding, and continuing water flooding to 98% after injecting the polymer 0.3PV when the water content is 98%.
TABLE 23 composition of oil displacing system
TABLE 24 Performance test results of ASP flooding system with low permeability reservoir permeability of 49mD
Claims (6)
1. An oil displacing system for a low permeability reservoir comprising an associative polymer; the molecular weight of the associated polymer is 101.4-997.5 ten thousand; the associative polymer is obtained by polymerizing acrylamide, 0.09-10.2% of hydrophobic monomer and 3.8-14.6% of functional monomer in terms of mole percentage; the concentration of the associated polymer in the oil displacement system is 200-3500 mg/L;
the hydrophobic monomer is selected from one or more of lauryl acrylate, cetyl acrylate, lauryl methacrylate, cetyl methacrylate, N-dodecyl acrylamide, N-tetradecyl acrylamide, N-dioctyl acrylamide, hexafluorobutyl methacrylate, tetradecyl methacrylate, nonylphenol polyoxyethylene acrylate, octylphenol polyoxyethylene acrylate, dodecyl polyoxyethylene acrylate, hexadecyl polyoxyethylene acrylate, N-hexadecyl acrylamide and N-octyl acrylamide;
the functional monomer is selected from one or more of 2-acrylamide-2-methyl propane sulfonic Acid (AMPS) and sulfonate thereof, vinyl sulfonic acid and sulfonate thereof, styrene sulfonic acid and sulfonate thereof and N-vinyl-2-pyrrolidone (NVP);
the oil displacement system is used for a low-permeability oil reservoir with water logging permeability a, and a is not less than 3mD and less than 50 mD.
2. The chaser system of claim 1, further comprising a surfactant; the mass of the surfactant is 0.001-0.73% of that of the associated polymer.
3. The system of claim 2, wherein the surfactant is one or more of petroleum sulfonate anionic surfactant, alkylbenzene sulfonate anionic surfactant, α -olefin sulfonate anionic surfactant, betaine amphoteric surfactant, alkanolamide nonionic surfactant, nonionic gemini surfactant, anionic gemini surfactant, alkyl naphthalene sulfonate, lignin sulfonate, vegetable oil carboxylate, petroleum carboxylate, and biological surfactant.
4. The displacement system of claim 2, further comprising a basic material; the mass of the alkaline substance is 0.09-2.17% of that of the associated polymer.
5. The flooding system of claim 4 wherein the alkaline material is NaOH or Na2CO3With organic bases of aminesOne or more of (a).
6. An oil displacement method of a low-permeability reservoir is characterized in that the oil displacement system for the low-permeability reservoir is adopted for oil displacement.
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