CN114426815B - Oil-based drilling fluid suitable for strong water-sensitive and easily-collapsed stratum and preparation method and application thereof - Google Patents
Oil-based drilling fluid suitable for strong water-sensitive and easily-collapsed stratum and preparation method and application thereof Download PDFInfo
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- 238000005553 drilling Methods 0.000 title claims abstract description 152
- 239000012530 fluid Substances 0.000 title claims abstract description 144
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- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- 239000003995 emulsifying agent Substances 0.000 claims abstract description 57
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 41
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000003345 natural gas Substances 0.000 claims abstract description 6
- 239000003209 petroleum derivative Substances 0.000 claims abstract description 6
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 24
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 24
- 238000005917 acylation reaction Methods 0.000 claims description 24
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- CFQZKFWQLAHGSL-FNTYJUCDSA-N (3e,5e,7e,9e,11e,13e,15e,17e)-18-[(3e,5e,7e,9e,11e,13e,15e,17e)-18-[(3e,5e,7e,9e,11e,13e,15e)-octadeca-3,5,7,9,11,13,15,17-octaenoyl]oxyoctadeca-3,5,7,9,11,13,15,17-octaenoyl]oxyoctadeca-3,5,7,9,11,13,15,17-octaenoic acid Chemical compound OC(=O)C\C=C\C=C\C=C\C=C\C=C\C=C\C=C\C=C\OC(=O)C\C=C\C=C\C=C\C=C\C=C\C=C\C=C\C=C\OC(=O)C\C=C\C=C\C=C\C=C\C=C\C=C\C=C\C=C CFQZKFWQLAHGSL-FNTYJUCDSA-N 0.000 claims description 16
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- 239000003054 catalyst Substances 0.000 claims description 13
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 12
- 239000003999 initiator Substances 0.000 claims description 12
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 12
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 12
- CFVWNXQPGQOHRJ-UHFFFAOYSA-N 2-methylpropyl prop-2-enoate Chemical compound CC(C)COC(=O)C=C CFVWNXQPGQOHRJ-UHFFFAOYSA-N 0.000 claims description 11
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 11
- 230000010933 acylation Effects 0.000 claims description 11
- 239000000839 emulsion Substances 0.000 claims description 11
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- 238000006703 hydration reaction Methods 0.000 description 10
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- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical group [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 8
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 8
- 239000010428 baryte Substances 0.000 description 8
- 229910052601 baryte Inorganic materials 0.000 description 8
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 7
- 239000000292 calcium oxide Substances 0.000 description 7
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 7
- 239000006185 dispersion Substances 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 7
- 239000007864 aqueous solution Substances 0.000 description 6
- 239000001110 calcium chloride Substances 0.000 description 6
- 229910001628 calcium chloride Inorganic materials 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
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- 229910000278 bentonite Inorganic materials 0.000 description 5
- 229940092782 bentonite Drugs 0.000 description 5
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 239000002283 diesel fuel Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
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- 229910001870 ammonium persulfate Inorganic materials 0.000 description 4
- 239000002981 blocking agent Substances 0.000 description 4
- ONCZQWJXONKSMM-UHFFFAOYSA-N dialuminum;disodium;oxygen(2-);silicon(4+);hydrate Chemical compound O.[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[Na+].[Na+].[Al+3].[Al+3].[Si+4].[Si+4].[Si+4].[Si+4] ONCZQWJXONKSMM-UHFFFAOYSA-N 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
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- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- 238000004945 emulsification Methods 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
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- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- ADHNUPOJJCKWRT-JLXBFWJWSA-N (2e,4e)-octadeca-2,4-dienoic acid Chemical compound CCCCCCCCCCCCC\C=C\C=C\C(O)=O ADHNUPOJJCKWRT-JLXBFWJWSA-N 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- RZJRJXONCZWCBN-UHFFFAOYSA-N alpha-octadecene Natural products CCCCCCCCCCCCCCCCCC RZJRJXONCZWCBN-UHFFFAOYSA-N 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
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- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000008384 inner phase Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
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- 239000011707 mineral Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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- 229940038384 octadecane Drugs 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/32—Non-aqueous well-drilling compositions, e.g. oil-based
- C09K8/36—Water-in-oil emulsions
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
- C08F212/02—Monomers containing only one unsaturated aliphatic radical
- C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
- C08F212/06—Hydrocarbons
- C08F212/08—Styrene
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/502—Oil-based compositions
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/10—Nanoparticle-containing well treatment fluids
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Polymers & Plastics (AREA)
- Medicinal Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Liquid Carbonaceous Fuels (AREA)
- Colloid Chemistry (AREA)
Abstract
The invention provides an oil-based drilling fluid suitable for a strong water-sensitive and easily-collapsed stratum and a preparation method and application thereof, and belongs to the field of petroleum and natural gas drilling. Comprises the following components: oil phase, water phase, high-efficiency emulsifier, alkalinity regulator, filtrate reducer, nano plugging agent, organic soil and weighting material. The oil-based drilling fluid disclosed by the invention has the characteristics of strong inhibition, strong electric stability, strong plugging performance, low filtration loss and the like, can meet the requirement of strong water-sensitive and easily-collapsed stratum operation on the inhibition capacity of the drilling fluid, effectively prevents the underground complex condition caused by water sensitivity, improves the stability of a well wall, and further prevents the well wall from collapsing.
Description
Technical Field
The invention relates to the technical field of petroleum and natural gas drilling, in particular to an oil-based drilling fluid suitable for a strong water-sensitive and easily-collapsed stratum and a preparation method and application thereof.
Background
With the large-scale exploitation of shale gas, the length of a horizontal section exceeds 800m, the well is drilled in a stratum which is easy to collapse and has strong water sensitivity, and due to the characteristics of the stratum which is extremely developed, easy to break, poor in stability and complex in ground stress, complex accidents such as well wall collapse, water sensitivity damage and water lock damage of a reservoir stratum and the like easily occur, so that the development effect and the development process of the shale gas are seriously influenced. Because the oil-based drilling fluid has low filtration loss and filtrate is oil instead of water, the oil-based drilling fluid has strong inhibition performance and plugging performance, and is widely applied to the development of complex strata such as deep wells at home and abroad, unconventional oil and gas reservoirs, shale gas and the like. The drilling fluid still has certain defects, when drilling in a strong water-sensitive and easily-collapsed shale stratum, the drilling fluid has very excellent plugging capability, and the conventional plugging agent (calcium carbonate) used by the conventional oil-based drilling fluid has larger particle size (0.08-1000 mm), so that effective compact plugging on microcracks is difficult to form. Shale in a strong water-sensitive stratum is extremely easy to break, and even when the oil-based drilling fluid with strong inhibition performance drills, the filtrate enters micro cracks and then destroys the cementation of the shale, so that the hydration expansion and the hydration dispersion of clay minerals are caused, the pore pressure is increased, the shale strength is reduced, and the borehole wall is unstable; meanwhile, the hydration expansion and hydration dispersion of the shale have great influence on the performance of the drilling fluid, and particularly the rheological property thickening is obvious. Therefore, a drilling fluid for use in Jiang Shuimin in a collapsible formation must have excellent chemical inhibition and plugging capabilities.
Disclosure of Invention
In view of the above, the invention aims to provide an oil-based drilling fluid suitable for a strong water-sensitive and easily-collapsed formation, and a preparation method and application thereof. The oil-based drilling fluid provided by the invention is suitable for strong water-sensitive and easily-collapsed strata, and has strong chemical inhibition capability and plugging capability.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides an oil-based drilling fluid suitable for a strong water-sensitive and easily-collapsed stratum, which comprises the following components: the additive comprises an oil phase, a water phase, a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent, organic soil and a weighting material, wherein the volume ratio of the oil phase to the water phase is 80-85: 15-20, wherein the total volume of the oil phase and the water phase is 100mL, the mass of the high-efficiency emulsifier in the oil-based drilling fluid suitable for the stratum with strong water sensitivity and easy collapse is 3.0-4.0 g, the mass of the alkalinity regulator in the oil-based drilling fluid suitable for the stratum with strong water sensitivity and easy collapse is 2.0-3.0 g, the mass of the filtrate reducer in the oil-based drilling fluid suitable for the stratum with strong water sensitivity and easy collapse is 2.0-3.0 g, and the weight of the filtrate reducer in the oil-based drilling fluid suitable for the stratum with strong water sensitivity and easy collapse is suitable for the place with strong water sensitivity and easy collapseThe mass of the nano plugging agent in the oil-based drilling fluid of the layer is 3.0-4.0 g, the mass of the organic soil in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 1.0-2.0 g, and the mass of the weighting material enables the density of the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum to be 1.2-2.4 g/cm 3 ；
The high-efficiency emulsifier is prepared by a method comprising the following steps:
mixing trimer acid, diethanolamine and a basic catalyst to carry out acylation reaction to obtain an acylation product;
and mixing the acylation product, dimer acid and fatty alcohol-polyoxyethylene ether for esterification reaction to obtain the high-efficiency emulsifier.
Preferably, the mass ratio of the trimer acid to the diethanolamine to the basic catalyst is 30-40: 25 to 30:15 to 20.
Preferably, the temperature of the acylation reaction is 180-200 ℃ and the time is 6-8 h.
Preferably, the mass ratio of the trimer acid to the dimer acid to the fatty alcohol-polyoxyethylene ether is 30-40: 10-15: 20 to 30.
Preferably, the temperature of the esterification reaction is 90-120 ℃ and the time is 7-8 h.
Preferably, the nano plugging agent is prepared by a method comprising the following steps:
under the protective atmosphere, mixing styrene, isobutyl acrylate, span80, an initiator, methacrylic acid and water to carry out emulsion aggregation to obtain an emulsion polymer;
and mixing the emulsion polymer with nano silicon dioxide and then drying to obtain the nano plugging agent.
Preferably, the mass ratio of the styrene to the isobutyl acrylate to the Span80 to the water to the initiator to the methacrylic acid is 35-45: 15-20: 5 to 10:100:1 to 2:20 to 25.
Preferably, the temperature of the emulsion aggregation is 60-80 ℃ and the time is 3-4 h.
The invention also provides a preparation method of the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum, which comprises the following steps:
sequentially adding a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent and organic soil into the oil phase to obtain an oil phase mixed solution;
and adding a water phase into the oil phase mixed solution, emulsifying, and then adding a weighting material to obtain the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum.
The invention also provides the application of the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum in the technical scheme or the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum prepared by the preparation method in the technical scheme in the field of petroleum and natural gas drilling of the strong water-sensitive easily-collapsed stratum.
The invention provides an oil-based drilling fluid suitable for a strong water-sensitive and easily-collapsed stratum, which comprises the following components: the additive comprises an oil phase, a water phase, a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent, organic soil and a weighting material, wherein the volume ratio of the oil phase to the water phase is 80-85: 15-20, based on the total volume of the oil phase and the water phase being 100mL, the mass of the high-efficiency emulsifier in the oil-based drilling fluid for the stratum easy to collapse and suitable for the strong water-sensitive stratum is 3.0-4.0 g, the mass of the alkalinity regulator in the oil-based drilling fluid for the stratum easy to collapse and suitable for the strong water-sensitive stratum is 2.0-3.0 g, the mass of the filtrate reducer in the oil-based drilling fluid for the strong water-sensitive stratum easy to collapse and suitable for the strong water-sensitive stratum easy to collapse is 2.0-3.0 g, the mass of the nano plugging agent in the oil-based drilling fluid for the strong water-sensitive stratum easy to collapse is 3.0-4.0 g, the mass of the organic soil in the oil-based drilling fluid for the strong water-sensitive stratum easy to collapse is 1.0-2.0 g, and the mass of the weighting material enables the density of the oil-based drilling fluid for the strong water-sensitive stratum easy to collapse and suitable for the strong water-sensitive stratum easy to collapse to be 1.2-2-2.4 g/cm 3 (ii) a The high-efficiency emulsifier is prepared by a method comprising the following steps: mixing trimer acid, diethanolamine and an alkaline catalyst to carry out an acylation reaction to obtain an acylation product; and mixing the acylation product, dimer acid and fatty alcohol-polyoxyethylene ether for esterification reaction to obtain the high-efficiency emulsifier.
In the invention, the oil phase is used as the continuous phase of the water-in-oil drilling fluid; the water phase is used as the inner phase of the water-in-oil drilling fluid, so that the stability and activity balance of the well wall are ensured; the high-efficiency emulsifier has an emulsifying effect, forms stable water-in-oil drilling fluid, improves the viscosity of the drilling fluid, and enhances the suspending and slag carrying capacity of the drilling fluid, and the high-efficiency emulsifier has good coating performance, can enhance the well wall stability of shale, reduce the entering of the filtrate of the drilling fluid into the shale, prevent the occurrence of water sensitivity, and has a synergistic effect with the synthesized nano plugging agent, so that the well wall stability is improved, and a strong water-sensitive stratum is protected; the organic soil can improve the stability of the drilling fluid and can improve the viscosity and the dynamic shear force of a system; the filtrate reducer is used for reducing the filtrate loss of the drilling fluid; the alkalinity regulator is used for regulating the alkalinity of the drilling fluid; the nano plugging agent improves the inhibition performance of the drilling fluid, plugs micro and nano pores of the shale, and reduces the filtration loss of the drilling fluid. The oil-based drilling fluid provided by the invention has good rheological property under high density.
Compared with the prior art, the invention has the beneficial effects that:
the oil-based drilling fluid has a high demulsification voltage value and high electric stability, the high-efficiency emulsifier maintains the electric stability of the oil-based drilling fluid, the higher the demulsification voltage is, the higher the stability is, the higher the demulsification voltage is, the high-efficiency emulsifier has strong hydrophilic group amide groups, the adsorption capacity of the high-efficiency emulsifier on an oil-water interface can be enhanced, the high-efficiency emulsifier can be directionally adsorbed on an interface of oil and water phases to form a strong interface film, and the emulsion stability and the electric stability can be improved; the plugging performance is strong, the depth of a sand bed is less than 3cm, and the water loss at high temperature and high pressure is less than 2mL; the oil-based drilling fluid has strong inhibition capacity, the filtrate reducer, namely the asphalt oxide, can reduce the high-temperature and high-pressure filtration loss of the drilling fluid, the nano plugging agent has good adhesion, is adsorbed on the surface of rock, improves the well wall strength, effectively inhibits the hydration expansion of shale, and reduces the phenomena of hole shrinkage or well collapse caused by hydration, expansion, dispersion and slurry making, so that the inhibition performance and the plugging performance of the drilling fluid are improved, and the data of the embodiment shows that the linear expansion rate of the oil-based drilling fluid is below 1.3 percent, and the rolling recovery rate is above 96 percent;
the synergistic effect of the high-efficiency emulsifier, the filtrate reducer and the nano plugging agent can effectively plug micro cracks, prevent the leakage of drilling fluid, and effectively reduce the hydration expansion and hydration dispersion of well walls, thereby avoiding the shrinkage and collapse of the well walls, inhibiting the water sensitivity damage of reservoir water sensitive minerals, and meeting the requirements of strong water sensitivity and easy collapse stratum operation on the drilling fluid;
the oil-based drilling fluid has the advantages of wide application density range, low cost and wide application range.
Detailed Description
The invention provides an oil-based drilling fluid suitable for a strong water-sensitive and easily-collapsed stratum, which comprises the following components: the additive comprises an oil phase, a water phase, a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent, organic soil and a weighting material, wherein the volume ratio of the oil phase to the water phase is 80-85: 15-20, wherein the total volume of the oil phase and the water phase is 100mL, the mass of the efficient emulsifier in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 3.0-4.0 g, the mass of the alkalinity regulator in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 2.0-3.0 g, the mass of the filtrate reducer in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 2.0-3.0 g, the mass of the nano plugging agent in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 3.0-4.0 g, the mass of the organic soil in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 1.0-2.0 g, and the mass of the weighting material enables the density of the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum to be 1.2-2.4 g/cm 3 ；
The high-efficiency emulsifier is prepared by a method comprising the following steps:
mixing trimer acid, diethanolamine and an alkaline catalyst to carry out an acylation reaction to obtain an acylation product;
and mixing the acylation product, dimer acid and fatty alcohol-polyoxyethylene ether for esterification reaction to obtain the high-efficiency emulsifier.
In the present invention, unless otherwise specified, all the raw materials used are commercially available in the art.
In the present invention, the trimer acid refers to an octadecadienoic acid trimer, and the dimer acid refers to a dimer fatty acid (octadecane unsaturated fatty acid dimer).
The mass of the efficient emulsifier in the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsible formation is preferably 3.5g, wherein the total volume of the oil phase and the water phase is 100 mL.
The method mixes the trimer acid, the diethanolamine and the alkaline catalyst to carry out acylation reaction, and obtains an acylation product.
In the present invention, the mass ratio of the trimer acid, diethanolamine and basic catalyst is preferably 30 to 40:25 to 30:15 to 20, more preferably 40:30: 20. 30:25:18 or 35:28:15. in the present invention, the basic catalyst is preferably sodium hydroxide.
In the present invention, the temperature of the acylation reaction is preferably 180 to 200 ℃, more preferably 190 ℃, and the time is preferably 6 to 8 hours, more preferably 7 hours.
After obtaining the acylation product, mixing the acylation product, dimer acid and fatty alcohol-polyoxyethylene ether for esterification reaction to obtain the high-efficiency emulsifier.
In the invention, the mass ratio of the trimer acid, the dimer acid and the fatty alcohol-polyoxyethylene ether is preferably 30-40: 10 to 15:20 to 30, more preferably 40:10: 20. 30:15:30 or 35:12:25.
in the present invention, the temperature of the esterification reaction is preferably 90 to 120 ℃, more preferably 100 to 110 ℃.
According to the invention, the trimer acid, the diethanolamine and the alkaline catalyst are preferably added into a three-neck flask, the temperature is raised to the temperature of the acylation reaction for the acylation reaction, then the dimer acid is added after the temperature is reduced, the dimer acid is uniformly mixed, the fatty alcohol-polyoxyethylene ether is dropwise added for the esterification reaction, and the high-efficiency emulsifier is obtained.
In the present invention, the oil phase preferably includes one or more of a gasoline, 3# white oil, 0# diesel oil and 5# white oil.
In the present invention, the aqueous phase is preferably an aqueous calcium chloride solution, and the mass fraction of the aqueous calcium chloride solution is preferably 20 to 25%, and more preferably 25%.
The mass of the alkalinity regulator in the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum is preferably 2.5g, wherein the total volume of the oil phase and the water phase is 100 mL.
In the present invention, the alkalinity regulator preferably includes calcium oxide and/or calcium hydroxide.
The mass of the fluid loss additive in the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsible formation is preferably 2.5g, wherein the total volume of the oil phase and the water phase is 100 mL.
In the invention, the fluid loss additive is preferably oxidized asphalt, the softening point of the oxidized asphalt is preferably 120-220 ℃, more preferably 150-180 ℃, and the asphaltene content of the oxidized asphalt is preferably more than 85wt%.
The mass of the nano blocking agent in the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum is preferably 3.5g by taking the total volume of the oil phase and the water phase as 100 mL.
In the present invention, the nano blocking agent is preferably prepared by a method comprising the following steps:
under the protective atmosphere, mixing styrene, isobutyl acrylate, span80, an initiator, methacrylic acid and water to carry out emulsion aggregation to obtain an emulsion polymer;
and mixing the emulsion polymer with nano silicon dioxide and then drying to obtain the nano plugging agent.
In the invention, under the protective atmosphere, styrene, isobutyl acrylate, span80, an initiator, methacrylic acid and water are mixed for emulsion aggregation to obtain the emulsion polymer.
In the present invention, the protective atmosphere is preferably nitrogen.
In the present invention, the mass ratio of styrene, isobutyl acrylate, span80, water, initiator and methacrylic acid is preferably 35 to 45:15 to 20:5 to 10:100:1 to 2:20 to 25, more preferably 35:15:10:100:1: 25. 45, and (2) 45:18:7:100:2:20 or 40:20:5:100:2:23.
in the present invention, the initiator is preferably ammonium persulfate.
The mixing method of the present invention is not particularly limited, and may be any method known to those skilled in the art, such as stirring.
In the invention, the styrene, the isobutyl acrylate, the Span80 and the water are preferably added into a three-neck flask, nitrogen is introduced, and after the mixture is uniformly stirred, the initiator and the methacrylic acid are dropwise added. The dropping rate is not particularly limited in the present invention.
In the present invention, the temperature of the emulsion aggregation is preferably 60 to 80 ℃ and the time is preferably 3 to 4 hours.
After the emulsion polymer is obtained, the emulsion polymer and the nano silicon dioxide are mixed and dried to obtain the nano plugging agent.
In the present invention, the mass ratio of styrene to nano silica is preferably 35 to 45:10 to 15, more preferably 35: 15. 45, and (2) 45:10 or 40:12.
in the present invention, the particle size of the nano silica is preferably 8 to 100nm.
In the present invention, the drying is preferably spray drying, and the specific manner of the spray drying is not particularly limited in the present invention, and may be any manner known to those skilled in the art.
The mass of the organic soil in the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum is preferably 1.5g, wherein the total volume of the oil phase and the water phase is 100 mL.
In the present invention, the organic soil is preferably commercially available organic bentonite.
In the present invention, the weight material is preferably barite, and the density of the barite is preferably 4.2 to 4.4g/cm 3 (ii) a The dosage of the weighting material is not specially limited, and the density of the oil-based drilling fluid can be ensured to be 1.2-2.4 g/cm 3 And (4) finishing.
In the invention, the density of the oil-based drilling fluid is preferably 1.6-2.0 g/cm 3 And (4) finishing.
The invention also provides a preparation method of the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum, which comprises the following steps:
sequentially adding a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent and organic soil into the oil phase to obtain an oil phase mixed solution;
and adding a water phase into the oil phase mixed solution, emulsifying, and then adding a weighting material to obtain the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum.
The invention adds high-efficiency emulsifier, alkalinity regulator, filtrate reducer, nano plugging agent and organic soil into oil phase in turn to obtain oil phase mixed solution.
According to the invention, the high-efficiency emulsifier is preferably added into the oil phase and mixed, the mixing is preferably mechanical stirring, the rotation speed of the mechanical stirring is preferably 10000-12000 r/min, and the time is preferably 20-30 min.
After the high-efficiency emulsifier is added, the alkalinity regulator, the filtrate reducer, the nano plugging agent and the organic soil are sequentially and respectively added under the stirring condition, and the oil phase mixed solution is obtained after the sequential stirring for 20 to 30min.
After the oil phase mixed solution is obtained, the water phase is added into the oil phase mixed solution for emulsification, and then the weighting material is added to obtain the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum.
In the present invention, the emulsification is preferably performed under stirring conditions, wherein the stirring rotation speed is preferably 10000 to 12000r/min, and the time is preferably 30 to 60min.
In the invention, after the weighting material is added, stirring is preferably further included, wherein the rotation speed of stirring is preferably 10000-12000 r/min, and the time is preferably 30-60 min.
The invention also provides the application of the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum in the technical scheme or the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum prepared by the preparation method in the technical scheme in the field of petroleum and natural gas drilling of the strong water-sensitive easily-collapsed stratum. The invention is not particularly limited to the specific manner of use described, as such may be readily adapted by those skilled in the art.
For further illustration of the present invention, the oil-based drilling fluid suitable for strong water-sensitive and easily collapsible formation and the preparation method and application thereof provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
(1) The preparation method of the high-efficiency emulsifier comprises the following steps:
adding 40 parts by weight of trimer acid, 30 parts by weight of diethanolamine and 20 parts by weight of NaOH catalyst into a three-neck flask, heating to 180 ℃ for acylation reaction, reacting at constant temperature for 8 hours, cooling to 90 ℃, continuing adding 10 parts by weight of dimer acid, stirring for 30 minutes, uniformly mixing, dropwise adding 20 parts by weight of fatty alcohol-polyoxyethylene ether, and reacting for 8 hours to obtain the product high-efficiency emulsifier 1.
(2) The preparation method of the nano plugging agent comprises the following steps:
adding 35 parts by weight of styrene, 15 parts by weight of isobutyl acrylate, 10 parts by weight of Span80 and 100 parts by weight of water into a three-neck flask, introducing nitrogen, uniformly stirring, heating to 80 ℃, simultaneously dropwise adding 1 part by weight of ammonium persulfate and 25 parts by weight of methacrylic acid as initiators, stirring for 4 hours to generate emulsion aggregation, continuously adding 15 parts by weight of nano silica at constant temperature, stirring at high speed for 2 hours, and spray-drying to obtain the nano plugging agent 1.
(3) The volume ratio of oil to water is 80:20 oil-based drilling fluid formulation:
oil phase: 320mL of gassy oil;
water phase: 80mL of 25% calcium chloride aqueous solution;
based on the total volume of 100mL of the oil phase and the water phase, the oil-based drilling fluid of the embodiment comprises the following components in percentage by weight:
high-efficiency emulsifier: 3.5g;
alkalinity adjuster (calcium oxide): 2.5g;
fluid loss additive (oxidized asphalt): 2.0g;
nano plugging agent: 3.0g;
organic clay (organobentonite): 1.0g;
weighting material (barite): weighted to 1.2g/cm 3 。
(4) Oil-based drillThe preparation method of the well fluid comprises the following steps: taking 320mL of gas oil, putting the gas oil into a 1000mL high-stirring cup, adding 14.0g of high-efficiency emulsifier at the rotating speed of 12000r/min, and stirring at a high speed for 20min; then adding 10.0g of calcium oxide, and stirring at high speed for 20min; then 8.0g of oxidized asphalt is added, and the mixture is stirred at a high speed for 20min; then adding 12.0g of nano plugging agent, and stirring at high speed for 20min; then adding 4.0g of organic bentonite, and stirring at high speed for 20min; adding 80mL of 25% calcium chloride aqueous solution by mass fraction, and stirring at high speed for 30min; finally adding barite weighted drilling fluid to the density of 1.2g/cm 3 And stirring at a high speed for 60min to prepare the oil-based drilling fluid.
Example 2
(1) The preparation method of the high-efficiency emulsifier comprises the following steps:
adding 30 parts by weight of trimer acid, 25 parts by weight of diethanolamine and 18 parts by weight of NaOH catalyst into a three-neck flask, heating to 200 ℃ for acylation reaction, reacting at constant temperature for 6 hours, cooling to 120 ℃, continuing adding 15 parts by weight of dimer acid, stirring for 20 minutes, uniformly mixing, dropwise adding 30 parts by weight of fatty alcohol-polyoxyethylene ether, and reacting for 7 hours to obtain the product, namely the high-efficiency emulsifier 2.
(2) The preparation method of the nano plugging agent comprises the following steps:
adding 45 parts by weight of styrene, 18 parts by weight of isobutyl acrylate, 7 parts by weight of Span80 and 100 parts by weight of water into a three-neck flask, introducing nitrogen, uniformly stirring, heating to 60 ℃, simultaneously dropwise adding 2 parts by weight of ammonium persulfate and 20 parts by weight of methacrylic acid serving as initiators, stirring for 4 hours to generate emulsion aggregation, continuously adding 10 parts by weight of nano silicon dioxide at constant temperature, stirring at high speed for 2 hours, and spray-drying to obtain the nano blocking agent 2.
(3) The formula of the oil-based drilling fluid with the oil-water volume ratio of 80:
oil phase: 320mL of 3# white oil;
water phase: 80mL of 25% calcium chloride aqueous solution;
the oil-based drilling fluid of the embodiment comprises the following components in percentage by weight based on 100mL of total volume of the oil phase and the water phase:
high-efficiency emulsifier: 3.0g;
alkalinity adjuster (calcium oxide): 3.0g;
fluid loss additive (oxidized asphalt): 2.5g;
nano plugging agent: 3.5g;
organic clay (organobentonite): 2.0g;
weighting material (barite): weighted to 1.6g/cm 3 。
(4) The preparation method of the oil-based drilling fluid comprises the following steps: taking 320mL 3# white oil, putting into a 1000mL high-stirring cup, adding 12.0g of high-efficiency emulsifier at the rotating speed of 12000r/min, and stirring at high speed for 20min; then adding 12.0g of calcium oxide, and stirring at high speed for 20min; then adding 10.0g of oxidized asphalt, and stirring at high speed for 20min; then adding 14.0g of nano plugging agent, and stirring at high speed for 20min; then adding 8.0g of organic bentonite, and stirring at high speed for 20min; adding 80mL of 25% calcium chloride aqueous solution by mass fraction, and stirring at high speed for 30min; finally adding barite to increase the drilling fluid density to 1.6g/cm 3 And stirring at a high speed for 60min to prepare the oil-based drilling fluid.
Example 3
(1) The preparation method of the high-efficiency emulsifier comprises the following steps:
adding 35 parts by weight of trimer acid, 28 parts by weight of diethanolamine and 15 parts by weight of NaOH catalyst into a three-neck flask, heating to 190 ℃ for acylation reaction, reacting at constant temperature for 7 hours, cooling to 100 ℃, continuing adding 12 parts by weight of dimer acid, stirring for 20-30 min, uniformly mixing, dropwise adding 25 parts by weight of fatty alcohol-polyoxyethylene ether, and reacting for 7 hours to obtain the product, namely the high-efficiency emulsifier 3.
(2) The preparation method of the nano plugging agent comprises the following steps:
adding 40 parts by weight of styrene, 20 parts by weight of isobutyl acrylate, 5 parts by weight of Span80 and 100 parts by weight of water into a three-neck flask, introducing nitrogen, uniformly stirring, heating to 70 ℃, simultaneously dropwise adding 2 parts by weight of ammonium persulfate and 23 parts by weight of methacrylic acid as initiators, stirring for 3 hours to generate emulsion aggregation, continuously adding 12 parts by weight of nano silicon dioxide at constant temperature, stirring at high speed for 1.5 hours, and spray-drying to obtain the nano plugging agent 3.
(3) The formula of the oil-based drilling fluid with the oil-water volume ratio of 85:
oil phase: 255mL of 0# diesel oil;
water phase: 45mL of 25% calcium chloride aqueous solution;
based on the total volume of 100mL of the oil phase and the water phase, the oil-based drilling fluid of the embodiment comprises the following components in percentage by weight:
high-efficiency emulsifier: 4.0g;
alkalinity adjuster (calcium oxide): 2.0g;
fluid loss additive (oxidized asphalt): 3.0g;
nano plugging agent: 4.0g;
organic clay (organobentonite): 1.5g;
weighting material (barite): weighting to 2.0g/cm 3 。
(4) The preparation method of the oil-based drilling fluid comprises the following steps: adding 255mL of 0# diesel oil into a 1000mL high-stirring cup, adding 12.0g of high-efficiency emulsifier at the rotating speed of 12000r/min, and stirring at high speed for 20min; then 6.0g of calcium oxide is added and stirred at high speed for 20min; then adding 9.0g of oxidized asphalt, and stirring at high speed for 20min; then adding 12.0g of nano plugging agent, and stirring at high speed for 20min; then adding 4.5g of organic bentonite, and stirring at high speed for 20min; adding 45mL of 25% calcium chloride aqueous solution by mass fraction, and stirring at high speed for 30min; finally adding barite weighted drilling fluid to the density of 2.0g/cm 3 Stirring at high speed for 60 min; and preparing the oil-based drilling fluid.
Example 4 the invention was implemented using the following steps:
(1) The preparation method of the high-efficiency emulsifier is the same as that of example 3.
(2) The preparation of the nano blocking agent is the same as in example 3.
(3) The oil base drilling fluid formulation was the same as in example 3 except that the 0# diesel was changed to 5# white oil and the density was increased to 2.4g/cm 3 。
(4) The oil-based drilling fluid was prepared as in example 3, except that 0# diesel was changed to 5# white oil, and the density was increased to 2.4g/cm 3 。
Application performance testing and results
The invention evaluates the performance of the product according to the following criteria:
(1) The density, plastic viscosity, dynamic shear force, demulsification voltage and high-temperature high-pressure filtration loss of the drilling fluid are measured by adopting a method and an instrument specified in GB/T16783.2-2012 petroleum and natural gas industrial drilling fluid field test part 2 oil-based drilling fluid;
(2) The plugging performance of the drilling fluid is measured by a method and an instrument specified in SY/T5840-2007 drilling fluid bridging plugging material indoor test method part 3 fracture type plugging test, and is characterized by the depth of a sand bed;
(3) The inhibition performance of the drilling fluid is measured by a method and an instrument specified in a shale inhibition evaluation method for SY/T5613-2016 drilling fluid, namely a shale expansion test of the 5 th part and a shale rolling recovery test of the 6 th part, and is characterized by linear expansion rate and rolling recovery rate.
1. Evaluation of coating Performance of high-efficiency emulsifier
The shale rolling recovery experiment is used for evaluating the dispersion characteristic of the shale and evaluating the strength of the drilling fluid for inhibiting the formation dispersion capability, and the coating performance of the high-efficiency emulsifier is characterized by the rolling recovery rate.
The high-efficiency emulsifier 1, the high-efficiency emulsifier 2 and the high-efficiency emulsifier 3 are prepared according to the preparation methods disclosed in the embodiments 1 to 3. Five 350mL 0# diesel oil is taken, blank, 10.5g of Span-80, 10.5g of high-efficiency emulsifier 1, 10.5g of high-efficiency emulsifier 2 and 10.5g of high-efficiency emulsifier 3 are respectively added, high-speed stirring is carried out for 20min at the rotating speed of 12000r/min, the mixture is poured into a high-temperature aging tank, 50g of strong water-sensitive shale debris (5-10 meshes) is respectively added, rolling aging is carried out for 16h at the temperature of 120 ℃, cleaning is carried out, a 40-mesh sieve is used for sieving, and the rolling recovery rate of the shale debris is calculated, and the result is shown in Table 1. As can be seen from the data in Table 1, compared with 0# diesel oil and Span-80, the rolling recovery rate of the high-efficiency emulsifier of the invention is up to more than 95%, and the high-efficiency emulsifier can form a strong coating effect on strong water-sensitive shale, thereby effectively protecting a strong water-sensitive stratum
TABLE 1 evaluation of coating Properties of high-potency emulsifiers
2. Basic properties of oil-based drilling fluids
The oil-based drilling fluid test samples of examples 1 to 4 were poured into a high-temperature aging tank, roll aged at 180 ℃ for 16 hours, and the oil-based drilling fluid was tested for basic properties, linear expansion coefficient, roll recovery rate, and sand bed depth at 50 ℃ with the results shown in table 2. As is clear from the data in Table 2, the concentration of the compound is 1.2 to 2.4g/cm 3 Under the condition of different densities, the oil-based drilling fluid disclosed by the invention can keep good rheological property and electric stability, the linear expansion rate is below 1.3%, the high-temperature and high-pressure filtration loss is less than 2mL, the depth of a sand bed is less than 3.0cm, and the rolling recovery rate is more than 96%; the oil-based drilling fluid disclosed by the invention has good inhibition performance and plugging performance.
TABLE 2 Properties of oil-based drilling fluids
Note: AV is apparent viscosity; PV is plastic viscosity; YP is dynamic shear force; ES is the demulsification voltage value, the electric stability of the oil-based drilling fluid, and the higher the demulsification voltage is, the stronger the stability is; FL HTHP The high-temperature high-pressure filtration loss; linear expansion coefficient: the method is used for evaluating the inhibition performance of the drilling fluid, and the smaller the linear expansion coefficient is, the stronger the inhibition performance is; rolling recovery rate: a method for evaluating the inhibition performance of a drilling fluid, wherein the larger the rolling recovery rate is, the stronger the inhibition performance is; depth of sand bed: the plugging capacity of the drilling fluid is represented, and the smaller the depth of the sand bed is, the better the plugging capacity is represented.
3. Oil-based drilling fluid anti-pollution performance
The oil-based drilling fluid inevitably encounters water invasion and soil invasion in the drilling use process, so that the performance of the drilling fluid is changed, the oil-based drilling fluid has certain anti-pollution capacity, the influence of the water invasion and the soil invasion on the high-density oil-based drilling fluid is obvious, and the oil-based drilling fluid in the embodiment 4 is selected for evaluation of the anti-pollution performance.
Seven parts of oil-based drilling fluid are taken, blank, 5wt% of water, 10wt% of water, 20wt% of water, 5wt% of sodium bentonite, 10wt% of sodium bentonite and 15wt% of sodium bentonite are sequentially added, high-speed stirring is carried out for 20min at the rotating speed of 12000r/min, the mixture is poured into a high-temperature aging tank, rolling aging is carried out for 16h at 180 ℃, the basic performance of the oil-based drilling fluid is tested at 50 ℃, and the result is shown in table 3. As can be seen from Table 3, as the water invasion amount in the drilling fluid gradually increases, the shear force, the viscosity and the high-temperature and high-pressure fluid loss slightly increase, and the demulsification voltage gradually decreases; when the water invasion is 20%, the demulsification voltage is still greater than 400V, and the high-temperature high-pressure filtration loss is only 3mL, which indicates that the system has good water pollution resistance. With the increase of the addition of sodium bentonite in the drilling fluid, the shearing force and the viscosity are gradually increased, the high-temperature and high-pressure filtration loss is slightly changed, and the performance is in a controllable range, which indicates that the oil-based drilling fluid has good soil pollution resistance.
As can be seen from Table 3, the oil-based drilling fluid disclosed by the invention has stronger inhibition performance, can effectively inhibit hydration expansion of shale when drilling into a water-sensitive stratum, can reduce the phenomenon of hole shrinkage or well collapse caused by hydration, expansion, dispersion and slurrying, and is suitable for drilling a water-sensitive easily-collapsed complex stratum.
TABLE 3 evaluation of anti-contamination Capacity of oil-based drilling fluids
4. Evaluation of plugging performance of nano plugging agent
Experiment the speed and amount of pressure transfer of drilling fluid to shale were investigated by a pressure transfer experiment. The shale core is made by pressing 20g of bentonite at 12MPa for 5min, the core is 2.5cm long, the core is saturated by standard brine, the pressure of an upstream container is 4.2MPa (drilling fluid), the pressure of a downstream container is 0.7MPa (standard brine), the pressure difference is 3.5MPa, base slurry is prepared (the same as that of the embodiment 1, the difference is that no nano plugging agent is added), a high-temperature high-pressure well wall stability simulation experiment device is used indoors to perform a shale pressure transmission experiment, the pressure transmission condition on the shale is tested, the plugging capability of the micro-nano plugging agent on the shale is evaluated, and the plugging capability is represented by the speed of the downstream rising pressure. The results are shown in Table 4. Table 4 shows that as the pressurization time increases, the pressure rise downstream of the drilling fluid added with the nano plugging agent is smaller, and the pressure transmission speed in the core is greatly reduced. The nano plugging agent disclosed by the invention can be used for remarkably improving the plugging property of the drilling fluid on the shale and slowing down the pressure transfer speed of the drilling fluid on the shale stratum.
Table 4 evaluation of plugging ability of oil-based drilling fluids
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. It should be noted that modifications and adaptations can be made by those skilled in the art without departing from the principle of the present invention, and should be considered as within the scope of the present invention.
Claims (6)
1. The oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum is characterized by comprising the following components: the additive comprises an oil phase, a water phase, a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent, organic soil and a weighting material, wherein the volume ratio of the oil phase to the water phase is 80-85: 15-20, wherein the total volume of the oil phase and the water phase is 100mL, the mass of the efficient emulsifier in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 3.0-4.0 g, the mass of the alkalinity regulator in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 2.0-3.0 g, the mass of the filtrate reducer in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 2.0-3.0 g, the mass of the nano plugging agent in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 3.0-4.0 g, the mass of the organic soil in the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum is 1.0-2.0 g, and the mass of the weighting material enables the density of the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum to be 1.2-2.4 g/cm 3 ；
The high-efficiency emulsifier is prepared by a method comprising the following steps:
mixing trimer acid, diethanolamine and an alkaline catalyst to carry out an acylation reaction to obtain an acylation product;
mixing the acylation product, dimer acid and fatty alcohol-polyoxyethylene ether for esterification reaction to obtain the high-efficiency emulsifier;
the mass ratio of the trimer acid to the diethanolamine to the alkaline catalyst is 30-40: 25 to 30:15 to 20;
the mass ratio of the trimer acid to the dimer acid to the fatty alcohol-polyoxyethylene ether is 30-40: 10-15: 20 to 30 percent;
the nano plugging agent is prepared by the method comprising the following steps:
under the protective atmosphere, mixing styrene, isobutyl acrylate, span80, an initiator, methacrylic acid and water to carry out emulsion aggregation to obtain an emulsion polymer;
mixing the emulsion polymer with nano silicon dioxide and then drying to obtain the nano plugging agent;
the mass ratio of the styrene to the isobutyl acrylate to the Span80 to the water to the initiator to the methacrylic acid is 35-45: 15-20: 5 to 10:100:1 to 2:20 to 25.
2. The oil-based drilling fluid according to claim 1, wherein the temperature of the acylation reaction is 180-200 ℃ and the time is 6-8 h.
3. The oil-based drilling fluid according to claim 1, wherein the temperature of the esterification reaction is 90 to 120 ℃ and the time is 7 to 8 hours.
4. The oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed formation according to claim 1, wherein the emulsion is aggregated at a temperature of 60-80 ℃ for 3-4 h.
5. The preparation method of the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum as claimed in any one of claims 1 to 4, which is characterized by comprising the following steps of:
sequentially adding a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent and organic soil into the oil phase to obtain an oil phase mixed solution; and adding a water phase into the oil phase mixed solution, emulsifying, and then adding a weighting material to obtain the oil-based drilling fluid suitable for the strong water-sensitive and easily-collapsed stratum.
6. The application of the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum in any one of claims 1 to 4 or the oil-based drilling fluid suitable for the strong water-sensitive easily-collapsed stratum prepared by the preparation method in the field of petroleum and natural gas drilling of the strong water-sensitive easily-collapsed stratum.
Priority Applications (1)
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