CN111040745B - Natural degradation environment-friendly drilling fluid - Google Patents
Natural degradation environment-friendly drilling fluid Download PDFInfo
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- CN111040745B CN111040745B CN201911188133.5A CN201911188133A CN111040745B CN 111040745 B CN111040745 B CN 111040745B CN 201911188133 A CN201911188133 A CN 201911188133A CN 111040745 B CN111040745 B CN 111040745B
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- 238000005553 drilling Methods 0.000 title claims abstract description 122
- 239000012530 fluid Substances 0.000 title claims abstract description 93
- 230000015556 catabolic process Effects 0.000 title claims description 11
- 238000006731 degradation reaction Methods 0.000 title claims description 11
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 66
- 238000005520 cutting process Methods 0.000 claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000000314 lubricant Substances 0.000 claims abstract description 16
- 239000003112 inhibitor Substances 0.000 claims abstract description 15
- 239000003963 antioxidant agent Substances 0.000 claims abstract description 13
- 230000003078 antioxidant effect Effects 0.000 claims abstract description 13
- 238000002360 preparation method Methods 0.000 claims abstract description 13
- -1 methyl hydroxyethyl siloxane Chemical class 0.000 claims abstract description 11
- 239000002981 blocking agent Substances 0.000 claims abstract description 7
- 150000002016 disaccharides Chemical class 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 17
- 150000004676 glycans Chemical class 0.000 claims description 17
- 229920001282 polysaccharide Polymers 0.000 claims description 17
- 239000005017 polysaccharide Substances 0.000 claims description 17
- 238000003756 stirring Methods 0.000 claims description 16
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 15
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 12
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 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 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 239000003999 initiator Substances 0.000 claims description 8
- 229910052708 sodium Inorganic materials 0.000 claims description 8
- 239000011734 sodium Substances 0.000 claims description 8
- 239000012075 bio-oil Substances 0.000 claims description 7
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 claims description 6
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 6
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 6
- 159000000000 sodium salts Chemical class 0.000 claims description 6
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims description 6
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 5
- 229960000583 acetic acid Drugs 0.000 claims description 5
- 239000001913 cellulose Substances 0.000 claims description 5
- 229920002678 cellulose Polymers 0.000 claims description 5
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 5
- WBJINCZRORDGAQ-UHFFFAOYSA-N ethyl formate Chemical compound CCOC=O WBJINCZRORDGAQ-UHFFFAOYSA-N 0.000 claims description 5
- 239000012362 glacial acetic acid Substances 0.000 claims description 5
- 239000012280 lithium aluminium hydride Substances 0.000 claims description 5
- VBTQNRFWXBXZQR-UHFFFAOYSA-N n-bromoacetamide Chemical compound CC(=O)NBr VBTQNRFWXBXZQR-UHFFFAOYSA-N 0.000 claims description 5
- 239000004854 plant resin Substances 0.000 claims description 5
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- CCJAYIGMMRQRAO-UHFFFAOYSA-N 2-[4-[(2-hydroxyphenyl)methylideneamino]butyliminomethyl]phenol Chemical compound OC1=CC=CC=C1C=NCCCCN=CC1=CC=CC=C1O CCJAYIGMMRQRAO-UHFFFAOYSA-N 0.000 claims description 4
- GUBGYTABKSRVRQ-XLOQQCSPSA-N Alpha-Lactose Chemical compound O[C@@H]1[C@@H](O)[C@@H](O)[C@@H](CO)O[C@H]1O[C@@H]1[C@@H](CO)O[C@H](O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-XLOQQCSPSA-N 0.000 claims description 4
- GUBGYTABKSRVRQ-QKKXKWKRSA-N Lactose Natural products OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)C(O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O GUBGYTABKSRVRQ-QKKXKWKRSA-N 0.000 claims description 4
- GUBGYTABKSRVRQ-PICCSMPSSA-N Maltose Natural products O[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@@H]1[C@@H](CO)OC(O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-PICCSMPSSA-N 0.000 claims description 4
- 239000004111 Potassium silicate Substances 0.000 claims description 4
- 229920002472 Starch Polymers 0.000 claims description 4
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 claims description 4
- 229930006000 Sucrose Natural products 0.000 claims description 4
- GUBGYTABKSRVRQ-QUYVBRFLSA-N beta-maltose Chemical compound OC[C@H]1O[C@H](O[C@H]2[C@H](O)[C@@H](O)[C@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@@H]1O GUBGYTABKSRVRQ-QUYVBRFLSA-N 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- 239000008157 edible vegetable oil Substances 0.000 claims description 4
- 239000001341 hydroxy propyl starch Substances 0.000 claims description 4
- 235000013828 hydroxypropyl starch Nutrition 0.000 claims description 4
- 239000008101 lactose Substances 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- WFIZEGIEIOHZCP-UHFFFAOYSA-M potassium formate Chemical compound [K+].[O-]C=O WFIZEGIEIOHZCP-UHFFFAOYSA-M 0.000 claims description 4
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims description 4
- 229910052913 potassium silicate Inorganic materials 0.000 claims description 4
- 235000019353 potassium silicate Nutrition 0.000 claims description 4
- 239000008107 starch Substances 0.000 claims description 4
- 235000019698 starch Nutrition 0.000 claims description 4
- 239000005720 sucrose Substances 0.000 claims description 4
- 229920002527 Glycogen Polymers 0.000 claims description 3
- 229940096919 glycogen Drugs 0.000 claims description 3
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 3
- 229920000447 polyanionic polymer Polymers 0.000 claims description 3
- 239000001294 propane Substances 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 3
- 229940043237 diethanolamine Drugs 0.000 claims 2
- 150000003839 salts Chemical class 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 28
- 239000003921 oil Substances 0.000 abstract description 25
- 230000008569 process Effects 0.000 abstract description 23
- 230000002633 protecting effect Effects 0.000 abstract description 21
- 230000006378 damage Effects 0.000 abstract description 19
- 238000010276 construction Methods 0.000 abstract description 14
- 239000004576 sand Substances 0.000 abstract description 14
- 231100000045 chemical toxicity Toxicity 0.000 abstract description 12
- 239000009096 changqing Substances 0.000 abstract description 11
- 230000000903 blocking effect Effects 0.000 abstract description 9
- 230000000087 stabilizing effect Effects 0.000 abstract description 9
- 239000002002 slurry Substances 0.000 abstract description 6
- 239000000654 additive Substances 0.000 abstract description 4
- 230000000996 additive effect Effects 0.000 abstract description 4
- 230000000694 effects Effects 0.000 description 19
- 230000007613 environmental effect Effects 0.000 description 12
- 238000011084 recovery Methods 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- 238000011156 evaluation Methods 0.000 description 9
- 238000005461 lubrication Methods 0.000 description 9
- 230000009286 beneficial effect Effects 0.000 description 7
- 230000001050 lubricating effect Effects 0.000 description 7
- 230000009467 reduction Effects 0.000 description 7
- 239000011435 rock Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 230000005764 inhibitory process Effects 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000007790 solid phase Substances 0.000 description 5
- 238000011161 development Methods 0.000 description 4
- 239000000706 filtrate Substances 0.000 description 4
- 231100000419 toxicity Toxicity 0.000 description 4
- 230000001988 toxicity Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000002734 clay mineral Substances 0.000 description 3
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 3
- 239000012065 filter cake Substances 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229920001222 biopolymer Polymers 0.000 description 2
- 239000013043 chemical agent Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000008398 formation water Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 230000000887 hydrating effect Effects 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 241000894006 Bacteria Species 0.000 description 1
- CNCOEDDPFOAUMB-UHFFFAOYSA-N N-Methylolacrylamide Chemical compound OCNC(=O)C=C CNCOEDDPFOAUMB-UHFFFAOYSA-N 0.000 description 1
- 108091005804 Peptidases Proteins 0.000 description 1
- 239000004365 Protease Substances 0.000 description 1
- 102100037486 Reverse transcriptase/ribonuclease H Human genes 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000006065 biodegradation reaction Methods 0.000 description 1
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
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- 238000007906 compression Methods 0.000 description 1
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- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
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- 230000002829 reductive effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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- 230000035945 sensitivity Effects 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 150000003568 thioethers Chemical class 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
- C09K8/02—Well-drilling compositions
- C09K8/04—Aqueous well-drilling compositions
- C09K8/06—Clay-free compositions
- C09K8/12—Clay-free compositions containing synthetic organic macromolecular compounds or their precursors
-
- 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
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/12—Swell inhibition, i.e. using additives to drilling or well treatment fluids for inhibiting clay or shale swelling or disintegrating
-
- 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
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/18—Bridging agents, i.e. particles for temporarily filling the pores of a formation; Graded salts
-
- 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
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/34—Lubricant additives
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/141—Feedstock
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Lubricants (AREA)
Abstract
The invention provides a naturally-degradable environment-friendly drilling fluid which comprises the following components in parts by weight: 3.0 to 7.0 percent of shale inhibitor, 1.0 to 3.0 percent of natural anti-collapse agent, 1.0 to 5.0 percent of natural blocking agent, 0.3 to 0.5 percent of natural viscosity-raising and cutting agent, 1.5 to 3 percent of natural fluid loss additive, 0.5 to 4.0 percent of lubricant, 0.1 to 0.3 percent of polyhydroxy methyl hydroxyethyl siloxane, 0.02 to 0.07 percent of antioxidant and the balance of water. The invention can be applied to safe drilling and well completion construction of exploration wells, special process wells and horizontal wells in Changqing areas, has six functions of stabilizing well walls, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying well bores, protecting reservoir beds and protecting environment, has no biotoxicity and chemical toxicity, is biodegradable, belongs to environment protection, has strong anti-collapse capability and good blocking effect, can effectively reduce the stratum collapse capability, has a mud cake which is smooth and compact and is similar to a film shape, has good lubricity, has low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy operation of formula and slurry preparation process.
Description
Technical Field
The invention belongs to drilling fluid, and particularly relates to a naturally-degradable environment-friendly drilling fluid.
Background
The Ansai oil field horizontal well is located in the east of the Changqing oil field and is also an environment-friendly highly sensitive area, and oil layers with the group length of 6 and the group length of 8 are efficiently developed and prolonged through well arrangement of the horizontal well, so that the yield of a single well is increased, and the recovery ratio is increased. The well body structure of the horizontal well of the Changqing Ansai oil field is generally a two-opening structure, and the technical problem of series drilling fluid in the drilling construction process needs to be solved through deep research. The method is characterized by comprising the following steps of firstly solving the technical problem of instability of the borehole wall of the long open hole. The stratum at the top of the block straight well group, the block Yan' an group, the block Fuxian group and the block prolonged group has large sections of shale, the well wall has strong water sensitivity, is easy to absorb water to expand, disperse, fall quickly and even collapse, the phenomenon of encountering resistance exists in the construction of the directional well, and the risk of well wall collapse is more prominent and the safe drilling difficulty is large because the two straight well sections, the inclined well section and the horizontal section are all in the open hole well section. The target layer is an oil layer with the extension group length of 6 and the extension group length of 8, the well hole size is 215.9mm, the horizontal section of the horizontal well is 1000-2500 m, the exposed area of the oil layer is large, and the drilling fluid is required to have a good oil layer protection function. The Ansai oil field is located in a red tourism area, the environment protection strength of the area is enhanced by countries and places, particularly after a new environment protection law is implemented, the technical problems are comprehensively solved by fully utilizing favorable factors under the situation that the environment protection, low-cost development and drilling speed increase are increasingly severe, a technical basis is provided for the continuous and efficient development of the oil field, and the key point for solving the problem contradiction is achieved.
Disclosure of Invention
The naturally degradable environment-friendly drilling fluid is suitable for safe drilling and well completion of exploration wells, special process wells and horizontal wells in Changqing areas, has no biotoxicity and chemical toxicity, is biodegradable, belongs to the environment-friendly type, has strong long-time collapse prevention capability and good plugging effect, can effectively reduce the stratum collapse capability, is smooth and compact like a film shape in mud cakes, has good lubricity and low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy implementation formula and process.
The technical scheme of the invention is as follows:
a naturally-degradable environment-friendly drilling fluid comprises the following components in percentage by weight: 3.0 to 7.0 percent of shale inhibitor, 1.0 to 3.0 percent of natural anti-collapse agent, 1.0 to 5.0 percent of natural blocking agent, 0.3 to 0.5 percent of natural viscosity-raising and cutting agent, 1.5 to 3 percent of natural fluid loss additive, 0.5 to 4.0 percent of lubricant, 0.1 to 0.3 percent of polyhydroxy methyl hydroxyethyl siloxane, 0.02 to 0.07 percent of antioxidant and the balance of water.
The shale inhibitor is a mixture of potassium formate and potassium silicate with the modulus of 2.5-3.0 according to the mass ratio of 1: 2.
The natural anti-collapse agent is modified disaccharide; the modified disaccharide is prepared from the following raw materials in percentage by weight: natural disaccharides: 50% -70%, bromoacetic acid: 5-7%, diethanolamine 2.5-3.5%, sodium hydroxide: 2-5%, acetic anhydride: 0.1-0.5%, 0.5-1.5% of N-bromoacetamide, glacial acetic acid: 0.2 to 0.6 percent of the total weight of the composition, and the balance of water.
The natural disaccharide is one or a mixture of sucrose, lactose and maltose.
The natural blocking agent is natural plant resin with the particle size range of 10-50 nm.
The natural viscosity-increasing cutting agent is a modified polysaccharide environment-friendly viscosity-increasing cutting agent; the modified polysaccharide environment-friendly viscosity-increasing cutting agent comprises the following components in percentage by weight:
70 to 80 percent of natural polysaccharide,
3 to 10 percent of ethylene oxide,
2 to 8 percent of propylene oxide,
1.5 to 3.5 percent of N-hydroxymethyl acrylamide,
0.3 to 0.8 percent of lithium aluminum hydride,
1 to 5 percent of 2-dihydroxy-3-propane sodium sulfonate,
2.5 to 5.5 percent of glycol,
0.5 to 2 percent of triethanolamine,
0.15 to 0.55 percent of initiator.
The initiator is one or a mixture of hydrogen peroxide and sodium carbonate perhydrate.
The natural polysaccharide is one or a mixture of more of cellulose, starch and glycogen.
The natural fluid loss agent is low-viscosity polyanion sodium salt or hydroxypropyl starch, and the apparent viscosity of the low-viscosity polyanion sodium salt is not more than 80 mPa.s.
The lubricant is bio-oil extracted from waste edible oil.
The invention has the beneficial effects that:
the drilling fluid adopts the effects of a natural anti-collapse agent, a shale inhibitor, a natural plugging agent, formation clay minerals and formation water to quickly form a colloidal aggregate with a three-dimensional grid structure on a near well wall, prevents filtrate from further immersing into the formation through adsorption, inlaying and filling modes, prevents shale from hydrating and expanding, plugs formation pores, roar channels and microcracks, and has a necessary mechanical means, so that the drilling fluid has the effects of stabilizing the well wall, preventing leakage, protecting a reservoir and protecting the environment for a long time in the drilling process of a long-open hole horizontal well and the well completion construction process. The rheological property of the drilling fluid is controlled by adopting the environment-friendly biopolymer, and the sand carrying belt is realized to ensure the purification capability of the well hole. The solid control equipment is used for reducing harmful solid phase, and the bio-oil lubricant is mixed to reduce the frictional resistance between the drilling tool and the well wall, so that the lubrication and the drag reduction are realized. Through the field test of 2 horizontal wells in the Changqing Ansai oil field, the result shows that: the drilling fluid has strong collapse resistance, inhibition and blocking performance, can quickly form a tough and compact sealing membrane on a near well wall zone to stabilize the well wall, and simultaneously prevents filtrate and a solid phase from further immersing into a reservoir stratum, thereby achieving the effect of effectively protecting the reservoir stratum. The drilling fluid has no biological toxicity, no chemical toxicity and biodegradability, and is very beneficial to environmental protection. The drilling fluid can meet the basic performance requirements of drilling fluid in the large-scale drilling construction process in the Changqing area, can effectively protect the environment, is beneficial to sustainable development of low-permeability oil and gas fields, has good economic and social benefits, and is worthy of popularization and application.
Detailed Description
Example 1:
the naturally degradable environment-friendly drilling fluid is suitable for safe drilling and well completion of exploration wells, special process wells and horizontal wells in Changqing areas, has no biotoxicity and chemical toxicity, is biodegradable, belongs to the environment-friendly type, has strong long-time collapse prevention capability and good plugging effect, can effectively reduce the stratum collapse capability, is smooth and compact like a film shape in mud cakes, has good lubricity and low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy implementation formula and process.
A naturally-degradable environment-friendly drilling fluid comprises the following components in percentage by weight: 3.0% of shale inhibitor, 1.0% of natural anti-collapse agent, 1.0% of natural plugging agent, 0.3% of natural viscosity-raising and cutting agent, 1.5% of natural fluid loss additive, 0.5% of lubricant, 0.1% of polyhydroxy methyl hydroxyethyl siloxane, 0.02% of antioxidant and the balance of water.
The drilling fluid provided by the embodiment can effectively protect the environment and the production zone, has strong anti-collapse capability, good plugging effect and lubrication and resistance reduction effect, stable and regular well in the drilling process, and smooth operations of tripping, casing running and well completion string running. The invention can be applied to safe drilling and well completion construction of exploration wells, special process wells and horizontal wells in Changqing areas, has six functions of stabilizing well walls, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying well bores, protecting reservoir beds and protecting environment, has no biotoxicity and chemical toxicity, is biodegradable, belongs to environment protection, has strong anti-collapse capability and good blocking effect, can effectively reduce the stratum collapse capability, has a mud cake which is smooth and compact and is similar to a film shape, has good lubricity, has low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy operation of formula and slurry preparation process.
Example 2:
the embodiment provides a naturally-degradable environment-friendly drilling fluid which comprises the following components in parts by weight: 7.0% of shale inhibitor, 3.0% of natural anti-collapse agent, 5.0% of natural plugging agent, 0.5% of natural viscosity-raising and cutting agent, 3% of natural fluid loss agent, 4.0% of lubricant, 0.3% of polyhydroxy methyl hydroxyethyl siloxane, 0.07% of antioxidant and the balance of water.
Preferably, the shale inhibitor is a mixture of potassium formate and potassium silicate with a modulus of 2.5-3.0 according to a mass ratio of 1: 2.
Preferably, the natural anti-collapse agent is modified disaccharide; the modified disaccharide is prepared from the following raw materials in percentage by weight: natural disaccharides: 50% -70%, bromoacetic acid: 5-7%, diethanolamine 2.5-3.5%, sodium hydroxide: 2-5%, acetic anhydride: 0.1-0.5%, N-bromoacetamide 0.5-1.5%, glacial acetic acid: 0.2 to 0.6 percent of the total weight of the composition, and the balance of water.
Preferably, the natural disaccharide is one or more of sucrose, lactose and maltose.
The preparation method of the modified disaccharide comprises the following steps: adding a proper amount of water into a closed reaction kettle according to the feeding sequence in proportion, starting stirring, adding natural disaccharide till the natural disaccharide is completely dissolved, introducing pure nitrogen, continuously stirring for 0.5h, slowly and uniformly adding bromoacetic acid and sodium hydroxide in sequence when the temperature of the reaction kettle reaches 80-90 ℃, stirring for reaction for 1h, continuously heating to 120-125 ℃, adding diethanolamine (the addition is finished for about 1 h), stirring for reaction for 1h, then adding acetic anhydride and N-bromoacetamide in sequence, stirring for reaction for 3h, stopping heating, adding glacial acetic acid, and adjusting the pH value to 8-9. Cooling, drying at 100-110 deg.C, and pulverizing. Thus obtaining the natural anti-sloughing agent for drilling fluid.
Preferably, the natural blocking agent is natural plant resin with the particle size ranging from 10 nm to 50 nm.
Preferably, the natural viscosity-increasing cutting agent is a modified polysaccharide environment-friendly viscosity-increasing cutting agent; the modified polysaccharide environment-friendly viscosity-increasing cutting agent comprises the following components in percentage by weight:
70 to 80 percent of natural polysaccharide,
3 to 10 percent of ethylene oxide,
2 to 8 percent of propylene oxide,
1.5 to 3.5 percent of N-hydroxymethyl acrylamide,
0.3 to 0.8 percent of lithium aluminum hydride,
1 to 5 percent of 2-dihydroxy-3-propane sodium sulfonate,
2.5 to 5.5 percent of glycol,
0.5 to 2 percent of triethanolamine,
0.15 to 0.55 percent of initiator.
In the invention, preferably, the modified polysaccharide environment-friendly viscosity-increasing cutting agent comprises the following components in percentage by weight: 75% of natural starch, 6% of ethylene oxide, 7% of propylene oxide, 2.5% of N-methylolacrylamide, 0.5% of lithium aluminum hydride, 3% of sodium 2-dihydroxy-3-propanesulfonate, 4% of ethylene glycol, 1.5% of triethanolamine and 0.5% of an initiator. The initiator is one or a mixture of hydrogen peroxide and sodium carbonate perhydrate. The natural polysaccharide is one or a mixture of more of cellulose, starch and glycogen.
The preparation method of the modified polysaccharide environment-friendly viscosity-increasing cutting agent comprises the following steps
The method comprises the following steps: air removal
Adding natural polysaccharide into a reaction kettle according to the formula amount, continuously introducing pure nitrogen into an air inlet of the reaction kettle until the air in the reaction kettle is completely discharged from an air outlet, and then starting stirring;
step two: preparation of the first-order intermediate
When the heating temperature of the reaction kettle reaches 70-80 ℃, uniformly adding the lithium aluminum hydride, the ethylene oxide and the propylene oxide with the formula amount while stirring, and stirring for reaction for 55-65 minutes to form a primary intermediate product;
step three: preparation of the second intermediate
Keeping the temperature of the reaction kettle at 70-80 ℃, adding the N-hydroxymethyl acrylamide with the formula amount into the intermediate product prepared in the second step, and stirring for reacting for 25-35 minutes to form a second-level intermediate product;
step four: adding the remaining components
After the third step is finished, sequentially adding the initiator, the 2-dihydroxy-3-sodium propane sulfonate, the ethylene glycol and the triethanolamine in the formula ratio into the reaction kettle, stirring for reacting for 55-65 minutes, and stopping heating;
step five: cooling, drying and pulverizing
And after the fourth step is finished, continuously stirring and cooling, drying the cooled components at 120-130 ℃, and crushing to obtain the modified polysaccharide environment-friendly viscosity-increasing cutting agent.
And 8-10 liters of pure nitrogen is continuously introduced into the step I.
Preferably, the natural fluid loss agent is low-viscosity polyanionic sodium salt or hydroxypropyl starch, and the apparent viscosity of the low-viscosity polyanionic sodium salt is not more than 80 mPa.s.
In the invention, the natural fluid loss agent accounts for 1.5-3% of the weight, the natural fluid loss agent adopts low-viscosity polyanionic sodium sulfonate, the apparent viscosity of the natural fluid loss agent is not more than 50mPa.s when the low-viscosity polyanionic sodium sulfonate accounts for 1.5%, and the apparent viscosity of the natural fluid loss agent is not more than 80mPa.s when the low-viscosity polyanionic sodium sulfonate accounts for 3%.
The lubricant is bio-oil extracted from waste edible oil.
Preferably, the antioxidant is antioxidant 501.
The drilling fluid provided by the embodiment can effectively protect the environment and the production zone, has strong anti-collapse capability, good plugging effect and lubrication and resistance reduction effect, stable and regular well in the drilling process, and smooth operations of tripping, casing running and well completion string running. The invention can be applied to safe drilling and well completion construction of exploration wells, special process wells and horizontal wells in Changqing areas, has six functions of stabilizing well walls, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying well bores, protecting reservoir beds and protecting environment, has no biotoxicity and chemical toxicity, is biodegradable, belongs to environment protection, has strong anti-collapse capability and good blocking effect, can effectively reduce the stratum collapse capability, has a mud cake which is smooth and compact and is similar to a film shape, has good lubricity, has low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy operation of formula and slurry preparation process.
Example 3:
the embodiment provides a naturally-degradable environment-friendly drilling fluid which comprises the following components in parts by weight: 4.0% of shale inhibitor, 2.0% of natural anti-collapse agent, 3.0% of natural plugging agent, 0.4% of natural viscosity-raising and cutting agent, 2.5% of natural fluid loss additive, 2.5% of lubricant, 0.2% of polyhydroxy methyl hydroxyethyl siloxane, 0.04% of antioxidant and the balance of water.
Preferably, the shale inhibitor is a mixture of potassium formate and instant potassium silicate in a ratio of 1: 2.
Preferably, the natural anti-collapse agent is carboxymethyl modified disaccharide, and the disaccharide is one or more of sucrose, lactose and maltose.
Preferably, the natural blocking agent is natural modified plant resin with the particle size ranging from 10 nm to 50 nm.
Preferably, the natural viscosity-increasing cutting agent is an ethylene oxide and propylene oxide modified polysaccharide environment-friendly viscosity-increasing cutting agent.
Preferably, the natural fluid loss agent is low-viscosity polyanionic sodium salt or hydroxypropyl starch.
Preferably, the lubricant is bio-oil extracted from waste edible oil.
Preferably, the antioxidant is antioxidant 501.
The invention can be applied to safe drilling and well completion construction of exploration wells, special process wells and horizontal wells in Changqing areas, has six functions of stabilizing well walls, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying well bores, protecting reservoir beds and protecting environment, has no biotoxicity and chemical toxicity, is biodegradable, belongs to environment protection, has strong anti-collapse capability and good blocking effect, can effectively reduce the stratum collapse capability, has a mud cake which is smooth and compact and is similar to a film shape, has good lubricity, has low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy operation of formula and slurry preparation process. The invention can effectively protect the environment and the production zone, has strong anti-collapse capability, good plugging effect and lubrication and resistance reduction effect, stable and regular well in the drilling process, and smooth operation of tripping, casing running and well completion string running.
Example 4:
in the embodiment, the naturally-degradable environment-friendly drilling fluid is prepared by mixing, by weight, 85.4% of clear water, 5.0% of a shale inhibitor, 1.5% of a natural anti-collapse agent, 2.0% of a natural plugging agent, 0.3% of a natural viscosity-raising cutting agent, 3% of a natural fluid loss agent, 2.5% of a lubricant, 0.25% of polyhydroxymethylhydroxyethyl siloxane and 0.05% of an antioxidant 501.
Environmental protection performance evaluation experiment of naturally-degraded environmental protection drilling fluid
According to the technical requirement for environmental protection of the water-soluble oilfield chemical agent of SY/T6787-2010 in the natural gas industry standard of the people's republic of China, the biotoxicity and the biodegradability of a single treating agent in the drilling fluid in the embodiment 1 are evaluated, wherein a luminescent bacteria method is adopted to test the biotoxicity index EC 50 ，EC 50 Numerical value>20000 mg/L is nontoxic level; the ratio BOD of the chemical oxygen demand to the chemical oxygen demand of the five-day life is adopted 5 /COD cr The biodegradability is evaluated, if the numerical value is more than or equal to 5 percent, the biodegradability belongs to the range of easy biodegradability, and specific test results are shown in table 1.
TABLE 1 evaluation data of biotoxicity and biodegradability of main treatment agent
As can be seen from the data in Table 1, the single treating agent in the drilling fluid of the embodiment has no biotoxicity, belongs to the range of easy biodegradation, and provides basic conditions for researching naturally degradable environment-friendly drilling fluid.
The natural degradation degree of the drilling fluid in the embodiment was evaluated by using the viscosity attenuation value and the natural degradation rate. The specific method comprises the following steps: at room temperature of 25 ℃, 0.5% of microorganism or biological protease is introduced into the drilling fluid of the embodiment, the funnel viscosity FV and the apparent viscosity AV and the natural degradation rate of the drilling fluid are observed, and the test results are shown in table 2.
Table 2 drilling fluid viscosity decay experimental data
As can be seen from the data in Table 2, after the drilling fluid is placed for 7 days, the funnel viscosity FV and the apparent viscosity AV are greatly reduced, the performance after natural degradation is equivalent to that of clear water, the subsequent treatment of the waste drilling fluid is facilitated, the natural degradation rate reaches 100%, and the environmental protection is facilitated.
Chemical toxicity, biodegradability and biological toxicity of the drilling fluid are evaluated according to the technical requirement for environmental protection of water-soluble oilfield chemical agents in natural gas industry standard SY/T6787-.
TABLE 3 environmental Performance parameters of drilling fluids
As can be seen from Table 3, the drilling fluid has heavy metal content, volatile phenol, sulfide, biotoxicity and biodegradability which meet the requirements of the relevant national environmental standards.
Second, evaluation experiment of collapse prevention inhibition performance of naturally-degraded environment-friendly drilling fluid
The test represents the strength of the collapse resistance inhibition of the drilling fluid by testing the shale debris recovery rate of the drilling fluid, namely 50 g of rock debris of a direct-arranged group of an Ansai oil field is added into the drilling fluid in the embodiment, then the drilling fluid is subjected to hot rolling for 16 hours at 120 ℃ of a five-axis heating roller furnace, the primary recovery rate of the shale debris of the drilling fluid is tested, then the collected rock debris is put into tap water and is subjected to hot rolling for 16 hours at 120 ℃ of the five-axis heating roller furnace, the secondary recovery rate of the shale debris is tested, and meanwhile, the primary recovery rate and the secondary recovery rate of the shale debris of clean water are compared. The results are shown in Table 4.
TABLE 4 shale chip recovery data
Remarking: PV is the plastic viscosity and YP is the dynamic shear force.
The data in Table 4 show that the primary recovery rate of shale chips of the drilling fluid is as high as 97.3%, the secondary recovery rate of shale chips of the drilling fluid is 90.1%, the edges and corners of the chips are clear after the drilling fluid fully acts, and the phenomena of hydration, expansion and dispersion do not occur, so that the drilling fluid is proved to be capable of forming a compact plugging film on the surface of the chips, and the film is well maintained once formed even under the action of clear water, thereby effectively preventing the clay minerals of the chips from contacting with water, preventing the hydration and dispersion of shale strata, and further playing a role in inhibiting. The primary recovery rate of the shale reflects that the chemical inhibition of the drilling fluid is strong and weak, the secondary recovery rate reflects the dispersibility of the rock debris soaked by the drilling fluid in clear water, and the smaller the dispersibility is, the stronger the capability of the drilling fluid in resisting the falling and collapse of the shale is, and the more natural and stable the well wall is.
Third, lubricity evaluation experiment of naturally-degraded environment-friendly drilling fluid
The lubricating performance of the drilling fluid of the embodiment is tested by adopting an EP-2A extreme pressure lubrication instrument and an NZ-3 type sliding block friction resistance instrument in the experiment, and the result is shown in Table 5.
TABLE 5 lubricating performance data
As can be seen from Table 5, the extreme pressure lubrication coefficient of the drilling fluid is 0.10, the sliding block friction coefficient is 0.0262, the block drilling engineering design requirements are respectively controlled within 0.20 and 0.07, and the lubricating property is good and meets the field construction requirements.
Fourth, drilling fluid protective reservoir experimental evaluation
According to the SY/T6540-2018 drilling fluid completion fluid damage reservoir indoor evaluation method of the natural gas industry standard of the people's republic of China, the damage evaluation experiment of the drilling fluid system of the embodiment on the rock core of the reservoir of the safety-stoped oil field is carried out, and the rock core damage result is shown in table 6. As is apparent from Table 6, the naturally degradable environment-friendly drilling fluid has little damage to the reservoir, has an average damage rate of 10.14 percent, belongs to low-damage drilling fluid, and can also be used as low-damage completion fluid.
Table 6 evaluation data of drilling fluid core damage
Remarking: the damage pressure difference of the drilling fluid is 3.5MPa, the damage time is 150 minutes, and the temperature is 24-27 ℃;
Ko 1 the core permeability before damage;
Ko 2 the permeability of the damaged core is shown.
Fifthly, basic performance of strong inhibition anti-collapse low-damage drilling fluid
TABLE 7 drilling fluid Performance parameters
| Item | Measured data and Performance |
| Density of(g/cm 3 ) | 1.03-1.35 |
| Ma's funnel viscosity(s) | 40-70 |
| Loss of water (ml) | 2-4 |
| Filter cake (mm) | ＜0.3 |
| Plastic viscosity (mPa.s) | 15-30 |
| Dynamic shear force (Pa) | 8-26 |
| Static shear force (Pa) | 2-8/5-18 |
| pH | 9-10 |
| Natural degradation rate (%) | >90 |
The drilling fluid system described in this example was tested for 2 well applications in an ansa field. The drilling fluid performance parameters in the test process are as follows: viscosity: 45-80s, density: 1.06-1.35g/ml, water loss: 2-4ml, pH: 9-10, YP: 8-25 Pa, PV: 12-33 mPa.s, static shear force: 2 ~ 8/5 ~ 16Pa, embodied good experimental application effect:
1. the well wall is stable and safe in the well. The field test result shows that the drilling fluid system has strong well wall stabilizing capability, well hole purifying capability and crack plugging capability in the field test, ensures the underground safety of unstable stratums such as a direct-coupled unit, an extension unit and the like, has no phenomena of block dropping, hole shrinkage and collapse in the underground, and has no resistance to blocking in the drilling and electrical logging operations. The large-slope horizontal well and the open hole well are positioned at the same time, the well bore is stable, and the average hole diameter expansion rate is 12.6%. Particularly, the drilling cycle of the Y19H1 well is as long as 30 days, no block drop or collapse occurs, and the drilling and completion casing is completed once, so that the smooth operation of exploration operation is ensured.
2. The system has outstanding on-site lubrication and drag reduction effects. The drilling fluid system always keeps excellent lubricating property, harmful solid phase quantity is controlled as far as possible in drilling construction, mud cake quality is improved, a bio-oil lubricant is added according to the conditions of friction resistance and torque, so that a compression-resistant lubricating film is formed on the well wall and the surface of a drilling tool, the friction resistance coefficient of a sliding block is maintained between 0.0262 and 0.0524 in the drilling process, the extreme pressure lubricating coefficient is within the range of 0.05 to 0.10, the torque of the drilling tool is lower than 10kN.m, the friction resistance of tripping-in drilling is lower than 120KN, the resistance is small, and electric measurement and casing tripping are smooth. For example, the L79H2 well is repaired for a plurality of times, and the drilling tool is kept standing in the well for 2 to 5 hours without the complexity of the well.
3. Good oil layer protecting effect
The drilling fluid of the reservoir section on site is sampled, and the indoor core damage evaluation shows that the average damage rate of the cores of the 6-long and 8-long oil layers of the core of the Ansai oilfield is 12.46 percent after the drilling fluid of the embodiment is damaged, and the core belongs to mild damage. After the damaged rock core is taken out from the rock core holder, a thin filter cake is found on the damaged surface, a compact film exists on the surface of the filter cake, and the extreme pressure film of the drilling fluid has high strength, thereby being very beneficial to reducing friction resistance and torque while protecting a reservoir.
4. Is environment-friendly and is beneficial to protecting the environment
After sampling, the drilling fluid is subjected to indoor detection on related parameters of chemical toxicity, biodegradability and biological toxicity, and the results are shown in Table 8. From table 8, it can be seen that the heavy metal content, volatile phenols, sulfides, biotoxicity and biodegradability of the on-site drilling fluid are also within the range of the requirements of the relevant environmental protection standards, and meanwhile, the natural degradation rate is measured to reach 100%, which again indicates that the drilling fluid of the embodiment is environment-friendly.
TABLE 8 field drilling fluid environmental protection testing data
5. The drilling fluid system has the advantages of simple formula, simple and convenient field preparation and maintenance process and strong operability, and provides a technical basis for continuously and efficiently developing an Ansai oilfield in the next step.
The invention can be applied to safe drilling and well completion construction of exploration wells, special process wells and horizontal wells in Changqing areas, has six functions of stabilizing well walls, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying well bores, protecting reservoir beds and protecting environment, has no biotoxicity and chemical toxicity, is biodegradable, belongs to environment protection, has strong anti-collapse capability and good blocking effect, can effectively reduce the stratum collapse capability, has a mud cake which is smooth and compact and is similar to a film shape, has good lubricity, has low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy operation of formula and slurry preparation process.
Example 5:
in the embodiment, the naturally-degradable environment-friendly drilling fluid is prepared by mixing, by weight, 85.43% of clean water, 3.0% of a shale inhibitor, 3.0% of a natural anti-collapse agent, 5.0% of a natural plugging agent, 0.4% of a natural viscosity-raising cutting agent, 1.5% of a natural fluid loss agent, 1.5% of a lubricant, 0.1% of polyhydroxymethylhydroxyethyl siloxane and 0.07% of an antioxidant 501.
The drilling fluid provided by the embodiment can effectively protect the environment and the production zone, has strong anti-collapse capability, good plugging effect and lubrication and resistance reduction effect, stable and regular well in the drilling process, and smooth operations of tripping, casing running and well completion string running.
Example 6:
in the embodiment, the naturally-degradable environment-friendly drilling fluid is prepared by mixing 87.68 wt% of clear water, 7.0 wt% of a shale inhibitor, 1.0 wt% of a natural anti-collapse agent, 1.0 wt% of a natural plugging agent, 0.5 wt% of a natural viscosity-raising cutting agent, 2.0 wt% of a natural fluid loss agent, 0.5 wt% of a lubricant, 0.3 wt% of polyhydroxymethylhydroxyethyl siloxane and 0.02 wt% of an antioxidant 501 according to the weight percentage.
The invention firstly aims at environmental protection, and preferably selects a natural degradation treatment agent to realize multiple functions of the drilling fluid, the drilling fluid adopts the action of a natural anti-collapse agent, a shale inhibitor and a natural plugging agent with formation clay minerals and formation water to quickly form a colloidal aggregate with a three-dimensional grid structure on the near well wall, and through the modes of adsorption, inlaying and filling, the filtrate is prevented from further immersing into the formation, the shale is prevented from hydrating and expanding, the formation pores, roar passages and microcracks are plugged, and necessary mechanical means are adopted, so that the effects of stabilizing the well wall, preventing leakage, protecting the reservoir and protecting the environment of the drilling fluid for a long-time in the process of drilling and well completion construction of a long-open hole horizontal well are realized. The rheological property of the drilling fluid is controlled by adopting the environment-friendly biopolymer, and the sand carrying belt is realized to ensure the purification capability of the well hole. The solid control equipment is used for reducing harmful solid phase, and the bio-oil lubricant is mixed to reduce the frictional resistance between the drilling tool and the well wall, so that the lubrication and the drag reduction are realized. Through the field test of 2 horizontal wells in the Changqing Ansai oil field, the result shows that: the drilling fluid has strong collapse resistance, inhibition and blocking performance, can quickly form a tough and compact sealing membrane on a near well wall zone to stabilize the well wall, and simultaneously prevents filtrate and a solid phase from further immersing into a reservoir stratum, thereby achieving the effect of effectively protecting the reservoir stratum. The drilling fluid has no biological toxicity, no chemical toxicity and biodegradability, and is very beneficial to environmental protection. The drilling fluid can meet the basic performance requirements of drilling fluid in the large-scale drilling construction process in the Changqing area, can effectively protect the environment, is beneficial to sustainable development of low-permeability oil and gas fields, has good economic and social benefits, and is worthy of popularization and application.
The drilling fluid provided by the embodiment can effectively protect the environment and a production zone, has strong anti-collapse capability and good plugging effect and lubricating and drag-reducing effect. The invention can be applied to safe drilling and well completion construction of exploration wells, special process wells and horizontal wells in Changqing areas, has six functions of stabilizing well walls, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying well bores, protecting reservoir beds and protecting environment, has no biotoxicity and chemical toxicity, is biodegradable, belongs to environment protection, has strong anti-collapse capability and good blocking effect, can effectively reduce the stratum collapse capability, has a mud cake which is smooth and compact and is similar to a film shape, has good lubricity, has low damage to low-porosity low-permeability low-abundance oil reservoirs, and has the characteristics of simple and easy operation of formula and slurry preparation process.
The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention. The reagents and the preparation method thereof which are not described in detail in the invention belong to the well-known technology and the common method in the industry, and are not described one by one.
Claims (5)
1. A natural degradation environment-friendly drilling fluid is characterized in that: the components by weight ratio are as follows: 3.0 to 7.0 percent of shale inhibitor, 1.0 to 3.0 percent of natural anti-sloughing agent, 1.0 to 5.0 percent of natural blocking agent, 0.3 to 0.5 percent of natural viscosity-raising and cutting agent, 1.5 to 3 percent of natural fluid loss agent, 0.5 to 4.0 percent of lubricant, 0.1 to 0.3 percent of polyhydroxy methyl hydroxyethyl siloxane, 0.02 to 0.07 percent of antioxidant and the balance of water; the shale inhibitor is a mixture of potassium formate and potassium silicate with the modulus of 2.5-3.0 according to the mass ratio of 1: 2; the lubricant is bio-oil extracted from waste edible oil; the natural anti-collapse agent is modified disaccharide which is prepared from the following raw materials in percentage by weight: natural disaccharides: 50% -70%, bromoacetic acid: 5-7%, diethanolamine 2.5-3.5%, sodium hydroxide: 2-5%, acetic anhydride: 0.1-0.5%, N-bromoacetamide 0.5-1.5%, glacial acetic acid: 0.2 to 0.6 percent of the total weight of the composition, and the balance of water; the natural disaccharide is one or a mixture of sucrose, lactose and maltose; the natural plugging agent is natural plant resin; the natural fluid loss agent is low-viscosity polyanion sodium cellulose salt or hydroxypropyl starch;
The natural viscosity-increasing cutting agent is a modified polysaccharide environment-friendly viscosity-increasing cutting agent; the modified polysaccharide environment-friendly viscosity-increasing cutting agent comprises the following components in percentage by weight:
70 to 80 percent of natural polysaccharide,
3 to 10 percent of ethylene oxide,
2 to 8 percent of propylene oxide,
1.5 to 3.5 percent of N-hydroxymethyl acrylamide,
0.3 to 0.8 percent of lithium aluminum hydride,
1 to 5 percent of 2-dihydroxy-3-propane sodium sulfonate,
2.5 to 5.5 percent of glycol,
0.5 to 2 percent of triethanolamine,
0.15 to 0.55 percent of initiator;
the natural polysaccharide is one or a mixture of more of cellulose, starch and glycogen.
2. The naturally degradable environment-friendly drilling fluid as claimed in claim 1, wherein: the natural blocking agent is natural plant resin with the particle size range of 10-50 nm.
3. The naturally degradable environment-friendly drilling fluid as claimed in claim 1, wherein: the initiator is one or a mixture of hydrogen peroxide and sodium carbonate perhydrate.
4. The naturally degradable environment-friendly drilling fluid as claimed in claim 1, wherein: the low-viscosity polyanionic cellulose sodium salt has an apparent viscosity of no more than 80 mPa.s.
5. The naturally-degradable environment-friendly drilling fluid as claimed in claim 1, wherein: the preparation method of the modified disaccharide comprises the following steps: adding water into a closed reaction kettle according to the formula proportion, starting stirring, adding natural disaccharide until the natural disaccharide is completely dissolved, introducing pure nitrogen, continuously stirring for 0.5h, adding bromoacetic acid and sodium hydroxide when the temperature of the reaction kettle reaches 80-90 ℃, stirring for reaction for 1h, continuously heating to 120-125 ℃, adding diethanol amine, stirring for reaction for 1h, then adding acetic anhydride and N-bromoacetamide sequentially, stirring for reaction for 3h, stopping heating, adding glacial acetic acid to adjust the pH value to 8-9, cooling, drying at 100-110 ℃, and crushing to obtain the modified disaccharide namely the natural anti-collapse agent.
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