Nano-micron deformation blocking agent as well as preparation method and application thereof

Abstract

The invention relates to the field of drilling fluids for petroleum drilling, and discloses a nano-micron deformation blocking agent as well as a preparation method and application thereof. The plugging agent comprises a core and a shell wrapping the core. Wherein the core is an inorganic micron material and an inorganic nano material, the shell is a network polymer, and the network polymer comprises a structural unit provided by a cross-linking agent, a structural unit provided by a hydrophobic monomer and a structural unit provided by an oil-soluble hydrophilic monomer. The nano-micron deformation plugging agent provided by the invention can be deformed under pressure, improves plugging of different sizes of nano-micron apertures of a stratum, reduces invasion of filtrate, and plays an important role in solving borehole wall instability of a long horizontal section broken stratum and improving stratum pressure bearing.

Description

Technical Field

[0001] The present invention relates to the field of drilling fluid for petroleum drilling, and in particular to a composition for preparing a nano-micron deformation plugging agent, a nano-micron deformation plugging agent, a preparation method thereof and an application thereof. Background Art

[0002] Some research has been conducted in China on nano-micron plugging materials for drilling fluids. CN202110708470.3 discloses a high-temperature-resistant modified nano-silica plugging agent and an oil-based drilling fluid. The high-temperature-resistant modified nano-silica plugging agent is synthesized by a step-by-step synthesis method using enamine compounds, diallyl compounds, long-chain alkyl lipid compounds containing olefinic bonds, amino-containing silane coupling agents, and divinylbenzene, a cross-linking agent, through modified silica. The plugging agent has a particle size between 78 and 300 nm and can be used in deep and ultra-deep wells.

[0003] CN201410369887.1 discloses a nano-blocking agent for oil-based drilling fluids and its preparation method. The nano-blocking agent is produced by a polymerization reaction of styrene, methyl methacrylate, and functional cross-linking monomers initiated by a redox initiator under certain conditions, resulting in an emulsion of deformable nano-sized particles with a certain degree of rigidity and toughness. This agent can effectively block nano-scale micro-cracks and address the problem of shale gas well wall collapse.

[0004] CN202110693522.4 discloses a soft-outer-and-hard-inner oil-based drilling fluid nano-plugging agent and oil-based drilling fluid, which are mainly composed of graphene oxide, benzene ring monomers, carbon-carbon double bond-containing olefins and sodium methyl propylene sulfonate, and are prepared by continuous emulsion polymerization. The synthesized soft-outer-and-hard-inner oil-based drilling fluid nano-plugging agent has a particle size distribution between 120-330nm, and can effectively seal nano-sized pores in shale well walls.

[0005] CN202210441434.X discloses an emulsion-stabilized, ultrahigh-temperature-resistant nano-blocking agent for oil-based drilling fluids, as well as its preparation method and application. The agent is primarily prepared by emulsifying styrene, nano-ZrO2 particles, a flexible hydrophobic monomer, a cationic monomer, a high-temperature-resistant hydrophilic monomer, and an emulsifier. This nano-blocking agent can block nanopores in formations and effectively stabilize oil-based drilling fluids.

[0006] CN202010354860.0 discloses a high-temperature-resistant polymer microsphere nanoblocking agent for water-based drilling fluids. The agent is synthesized through micellar polymerization of vinyl monomers, cationic monomers, branching monomers, emulsifiers, styrene, acrylate hydrophobic monomers, and organosilicon monomers. The microsphere nanoblocking agent disperses completely in water, exhibits high temperature resistance, and exhibits excellent blocking effectiveness, making it suitable for plugging deep shale formations.

[0007] In the field of oil exploration, leakage during drilling and wellbore stability have always been technical challenges, especially in deep, brittle, and fractured formations with developed micropores and microcracks. The large intrusion of drilling fluid filtrate can easily cause the formation to absorb water, swell, and disperse, leading to complications such as wellbore instability and block loss. Therefore, it is necessary to strengthen the sealing of nano- and micron-sized pores and fractures by drilling fluids. Currently, there are relatively few nano- and micron-sized sealing materials in drilling fluids, especially in oil-based drilling fluids. This results in poor sealing and anti-collapse effects of oil-based drilling fluids in fractured formations, causing downhole complications. Conventional rigid sealing materials cannot adapt to microcracks of different pore sizes in the formation, which will affect the sealing effect of drilling fluids.

[0008] Therefore, there is an urgent need for a deformable plugging agent that can improve the sealing of nano- and micro-sized pores in the formation and reduce filtrate intrusion. Compared with conventional rigid plugging materials, deformable plugging materials can adapt to micro-cracks of different pore sizes in the formation and improve their plugging ability. Summary of the Invention

[0009] The purpose of the present invention is to overcome the problem that the plugging materials in the prior art cannot adapt to micro-cracks of different pore sizes in the formation. A composition for preparing a nano-micron deformable plugging agent is provided, as well as a nano-micron deformable plugging agent and its preparation method and application. The nano-micron deformable plugging agent has a core-shell structure and can deform under pressure, thereby improving the plugging of nano-micron pores of different scales in the formation and reducing the intrusion of filtrate. It plays an important role in solving the instability of the well wall in the broken formation with long horizontal sections and increasing the bearing capacity of the formation.

[0010] To achieve the above objectives, the present invention provides a composition for preparing a nano-micron deformation plugging agent in a first aspect, wherein the composition comprises: an inorganic micron material, an inorganic nano material, a hydrophobic monomer, an oil-soluble hydrophilic monomer and a cross-linking agent.

[0011] A second aspect of the present invention provides a nano-micron deformation plugging agent, wherein the plugging agent includes a core and a shell coated on the outside of the core; wherein the core includes an inorganic micron material and / or an inorganic nano material, and the shell is a network polymer, and the network polymer includes structural units provided by a cross-linking agent, structural units provided by a hydrophobic monomer, and structural units provided by an oil-soluble hydrophilic monomer.

[0012] A third aspect of the present invention provides a method for preparing a nano-micron deformable plugging agent, wherein the preparation method comprises the following steps: in the presence of a solvent, an inorganic micron material and an inorganic nano material, mixing a hydrophobic monomer, an oil-soluble hydrophilic monomer and a cross-linking agent to carry out a polymerization reaction.

[0013] A fourth aspect of the present invention provides a nano-micron deformation plugging agent prepared by the preparation method provided by the present invention.

[0014] A fifth aspect of the present invention provides a composition for preparing a nano-micron deformation plugging agent provided by the present invention or use of the nano-micron deformation plugging agent provided by the present invention in plugging micro-fractures in formations of different pore sizes.

[0015] Through the above technical solution, the beneficial effects of the present invention include at least:

[0016] The present invention uses inorganic micron materials and inorganic nanomaterials as inorganic core materials, polymer hydrophobic monomers and oil-soluble hydrophilic monomers as shell polymer raw materials, and adopts a heterogeneous polymerization method to prepare the core-shell structure, which simplifies the production process and reduces costs.

[0017] The nano-micron deformation plugging agent of the present invention is used as a functional treatment agent for drilling fluid and is applied to the plugging and collapse prevention of micro-cracks while drilling, which is beneficial to improving the stability of the well wall. It solves the problems of fluorescence affecting well logging, narrow softening temperature, uncontrollable size, etc. to a certain extent, and makes up for the defects and shortcomings of existing micro-crack plugging and collapse prevention agents. It solves the plugging and collapse prevention problems from the aspects of structural design, temperature adaptation, and extended retention.

[0018] In the method for preparing formed core-shell particles, preferably, by adjusting the monomer and crosslinker ratio, concentration, and crosslinking conditions, a core-shell material with a particle size range of 120nm-6μm is prepared, and used as a drilling fluid plugging and anti-collapse agent with a suitable softening temperature. Furthermore, in a preferred embodiment of the present invention, by selecting the appropriate types and ratios of the components, the shell formed by the inorganic micron material, inorganic nanomaterial core, hydrophobic monomer, oil-soluble hydrophilic monomer, and crosslinker can better exert a synergistic effect, thereby further improving the plugging ability and temperature resistance of the nano-micron deformable plugging agent and further regulating the surface properties of the nano-micron deformable plugging agent particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a transmission electron microscope image of the core-shell structure of the nano-micron deformation plugging agent prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] A first aspect of the present invention provides a composition for preparing a nano-micron deformation plugging agent, wherein the composition comprises: an inorganic micron material, an inorganic nano material, a hydrophobic monomer, an oil-soluble hydrophilic monomer and a cross-linking agent.

[0022] In the present invention, inorganic micron materials and inorganic nanomaterials are used as "hard core" nucleating materials; hydrophobic monomers are used as polymer "soft shell" materials to give the plugging agent a certain softening point, compressible deformation, and improve the plugging ability of the nano plugging agent, and are used as the main raw materials; oil-soluble hydrophilic monomers can realize the regulation of particle surface properties, make them more dispersible in the water-based drilling fluid system, and effectively avoid the agglomeration of particles; cross-linking agents can improve the plugging performance and temperature resistance of the shell structure nano-micron deformation plugging agent.

[0023] In order to enable the inorganic micron material, the inorganic nano material core, the shell formed by the hydrophobic monomer, the oil-soluble hydrophilic monomer and the cross-linking agent to better play a synergistic role, thereby further improving the blocking ability of the nano-micron deformation plugging agent and further regulating the surface properties of the nano-micron deformation plugging agent particles, preferably, in the composition, the ratio of the total weight of the inorganic micron material and the inorganic nano material to the total weight of the hydrophobic monomer, the oil-soluble hydrophilic monomer and the cross-linking agent is 1: (20-70), preferably 1: (50-70).

[0024] According to the present invention, preferably, in the composition, the weight ratio of the inorganic micron material to the inorganic nano material is 0.5:(0.1-0.5).

[0025] According to the present invention, preferably, in the composition, the weight ratio of the cross-linking agent, the hydrophobic monomer and the oil-soluble hydrophilic monomer is 1:(750-1000):(250-375).

[0026] In order to disperse the inorganic micron material, inorganic nano material, hydrophobic monomer, oil-soluble hydrophilic monomer and cross-linking agent more evenly and increase the effective content of the system, preferably, the composition also includes a solvent; in the composition, the weight ratio of the inorganic nano material to the solvent is (0.1-0.5):100.

[0027] According to the present invention, preferably, the solvent is water.

[0028] The present invention has no particular limitation on the type of inorganic micron material, and conventional nucleating materials with suitable hardness in the art can be selected. Preferably, the inorganic micron material is selected from at least one of micron molybdenum disulfide, micron calcium carbonate and micro powder graphite.

[0029] The present invention has no particular limitation on the average particle size of the inorganic micron material, as long as the formed nano-micron deformable plugging agent can effectively plug micro-cracks in the formation. In order to further improve the plugging effect of the plugging agent, preferably, the average particle size of the inorganic micron material is 1-5 μm.

[0030] The present invention has no particular limitation on the type of inorganic nanomaterials. Conventional nucleating materials with suitable hardness in the art can be selected. Preferably, the inorganic nanomaterial is selected from at least one of nano-silicon dioxide, nano-titania and nano-zirconium oxide.

[0031] The present invention has no particular limitation on the average particle size of the inorganic nanomaterial, as long as the formed nano-micron deformable plugging agent can effectively plug micro-cracks in the formation. In order to further improve the plugging effect of the plugging agent, preferably, the average particle size of the inorganic nanomaterial is 100-600nm.

[0032] The present invention has no particular limitation on the type of hydrophobic monomer, as long as the formed plugging agent has a suitable softening point and can be compressibly deformed. In order to enable the plugging agent to better adapt to micro-cracks of different pore sizes in the formation and further improve the plugging effect of the plugging agent on micro-cracks of different pore sizes in the formation, preferably, the hydrophobic monomer is selected from at least one of acrylonitrile (AN), methyl methacrylate (MMA), methyl acrylate (MA), butyl acrylate (BA) and glycidyl methacrylate (GMA), preferably acrylonitrile, glycidyl methacrylate and methyl acrylate.

[0033] In order to further control the surface properties of the plugging agent particles, improve their dispersibility in the water-based drilling fluid system, and further avoid particle agglomeration, preferably, the oil-soluble hydrophilic monomer is selected from vinyl acetate (VAc) and / or maleic anhydride (MAH), preferably vinyl acetate.

[0034] In order to further improve the sealing performance and temperature resistance of the shell material, preferably, the cross-linking agent is a multifunctional monomer, preferably selected from divinylbenzene (DVB) and / or ethylene glycol dimethacrylate (EGDMA).

[0035] A second aspect of the present invention provides a nano-micron deformation plugging agent, wherein the plugging agent includes a core and a shell coated on the outside of the core; wherein the core includes an inorganic micron material and / or an inorganic nano material, and the shell is a network polymer, and the network polymer includes structural units provided by a cross-linking agent, structural units provided by a hydrophobic monomer, and structural units provided by an oil-soluble hydrophilic monomer.

[0036] In the nano-micron deformation plugging agent in the second aspect of the present invention, the types of inorganic micron material, inorganic nanomaterial, hydrophobic monomer, oil-soluble hydrophilic monomer and cross-linking agent are the same as those in the composition for preparing the nano-micron deformation plugging agent described in the first aspect of the present invention. In order to avoid repetition, the present invention will not be further described in this second aspect, and those skilled in the art should not understand it as a limitation of the present invention.

[0037] According to the present invention, the particle size of the plugging agent is preferably in the range of 120nm-6μm, with particles below 1μm accounting for 10-20wt% and particles between 1-6μm accounting for 80-90wt%. Micron-sized particles can bridge and plug nano-micron cracks. Nano-micron-sized particles fill and plug the cracks, making the plugging layer denser and improving the plugging effect.

[0038] According to the present invention, preferably, the weight average molecular weight of the network polymer is 10,000-3,000,000 g / mol.

[0039] According to the present invention, preferably, in the plugging agent, the ratio of the total weight of the inorganic micron material and the inorganic nano material to the total weight of the network polymer is 1:(40-121).

[0040] According to the present invention, preferably, in the plugging agent, the weight ratio of the inorganic micron material to the inorganic nano material is 0.5:(0.1-0.5).

[0041] According to the present invention, preferably, in the network polymer, the weight ratio of the structural units provided by the crosslinking agent, the structural units provided by the hydrophobic monomer and the structural units provided by the oil-soluble hydrophilic monomer is 1:

[0042] (750-1000):(250-375).

[0043] A third aspect of the present invention provides a method for preparing a nano-micron deformable plugging agent, wherein the preparation method comprises the following steps: in the presence of a solvent, an inorganic micron material and an inorganic nano material, mixing a hydrophobic monomer, an oil-soluble hydrophilic monomer and a cross-linking agent to carry out a polymerization reaction.

[0044] In the preparation method of the nano-micron deformation plugging agent in the third aspect of the present invention, the types and amounts of the inorganic micron material, inorganic nanomaterial, hydrophobic monomer, oil-soluble hydrophilic monomer and cross-linking agent are the same as those in the composition for preparing the nano-micron deformation plugging agent described in the first aspect of the present invention. In order to avoid repetition, the present invention will not be described in detail in this third aspect, and those skilled in the art should not understand it as a limitation of the present invention.

[0045] The nano-micron deformation plugging agent of the present invention is produced by a soap-free Pickering polymerization method. The process is simple and easy to use. No additional additives other than polymer products such as emulsifiers and dispersants need to be added to the system. Through the interfacial properties of micron and nanoparticles, they are tightly arranged on the oil-water surface and stably react to form micelles or monomer droplets. This can effectively prevent the residual small molecule surfactants in the product from affecting later applications. The effective solid phase content is high, preferably reaching more than 30wt%. The emulsion has good dispersibility and does not contain components such as emulsifiers. It can be directly added and used without post-processing.

[0046] The present invention has no particular restrictions on the conditions of the polymerization reaction, as long as the polymerization reaction can proceed smoothly and form a network polymer outside the inorganic nanomaterial and / or inorganic micromaterial. In order to further improve the performance of the plugging agent, preferably, the polymerization reaction temperature is 50-80°C and the time is 6-10 hours.

[0047] According to the present invention, preferably, the polymerization reaction is carried out in the presence of a protective gas, and the protective gas may be nitrogen, for example.

[0048] The present invention has no particular restrictions on the mixing method and mixing order of the inorganic micron material, inorganic nano material, hydrophobic monomer, oil-soluble hydrophilic monomer and cross-linking agent in the solvent, as long as the components can be fully dispersed. In order to more fully disperse the components and thus make the particle size and structure of the formed plugging agent more suitable, in a preferred embodiment of the present invention, the preparation method includes the following steps:

[0049] S1. Dispersing a certain proportion of inorganic micron materials and inorganic nano materials into a solvent, first performing mechanical stirring dispersion, and then performing ultrasonic dispersion;

[0050] S2. First, monomer A (hydrophobic monomer) and monomer B (oil-soluble hydrophilic monomer) are mixed evenly, and then added to the above dispersion, and shear emulsified using a high-speed shear emulsifier;

[0051] S3. In the presence of protective gas, a cross-linking agent is added to carry out polymerization reaction to obtain an emulsion of the product.

[0052] Preferably, in S1, the stirring speed during mechanical stirring dispersion is 300-400 r / min, and the time is 15-30 min; the time of ultrasonic dispersion is 10-20 min.

[0053] Preferably, in S2, after monomer A and monomer B are added and mixed and the dispersion is added, shear emulsification is performed under stirring conditions of 8000-10000 r / min for 5-15 minutes.

[0054] Preferably, in S3, the polymerization reaction is carried out under stirring at a stirring speed of 800-1200 r / min.

[0055] A fourth aspect of the present invention provides a nano-micron deformation plugging agent prepared by the preparation method provided by the present invention.

[0056] A fifth aspect of the present invention provides a composition for preparing a nano-micron deformation plugging agent provided by the present invention or use of the nano-micron deformation plugging agent provided by the present invention in plugging micro-fractures in formations of different pore sizes.

[0057] The present invention will be described in detail below through examples and comparative examples. In the following examples, unless otherwise specified, conventional methods are used; and the reagents and materials used, unless otherwise specified, can be obtained from commercial sources.

[0058] The following examples are used to illustrate the preparation method of the core-shell nano-micron deformation plugging agent.

[0059] Example 1

[0060] Micronized molybdenum disulfide (average particle size of 5 μm) and nano-silica (average particle size of 600 nm) were dispersed in water, first mechanically stirred (stirring speed of 300 r / min for 20 minutes), then ultrasonically dispersed for 10 minutes. Acrylonitrile and vinyl acetate were mixed uniformly and added to the dispersion. Emulsification and dispersion were performed using a high-speed shear emulsifier at 8000 r / min for 10 minutes. Divinylbenzene was added under nitrogen protection and reacted at 50°C and 1000 r / min for 6 hours. The weight ratio of micronized molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.5:0.1:30:10:0.03:100. This produced a core-shell nano-micron deformation plugging agent 1.

[0061] A laser particle size analyzer was used to measure the particle size of the plugging agent, which was in the range of 800nm-6μm. Thermogravimetric analysis showed that the ratio of the total weight of micron molybdenum disulfide and nano-silica in the plugging agent to the total weight of the network polymer was 1:80. The laser particle size analysis method was used to measure the weight ratio of micron molybdenum disulfide and nano-silica in the plugging agent was 5:1. The mass spectrometry method was used to measure the weight ratio of the structural units derived from divinylbenzene, the structural units derived from acrylonitrile, and the structural units derived from vinyl acetate in the network polymer shell was 1:1000:300. The weight-average molecular weight of the network polymer was 210,000 g / mol as measured by gel chromatography.

[0062] Scanning electron microscopy revealed that in addition to irregularly shaped composite particles, there were also some spherical particles, all of which had relatively smooth surfaces with some protrusions and pits. Combining the sizes of the irregular and spherical particles, a large number of micron-sized composite particles were present, as well as some small submicron-sized particles.

[0063] Example 2

[0064] Micronized calcium carbonate (average particle size of 3 μm) and nano-titanium dioxide (average particle size of 400 nm) were dispersed in water, first mechanically stirred (at 400 rpm for 20 minutes) and then ultrasonically dispersed for 10 minutes. Glycidyl methacrylate and vinyl acetate were mixed uniformly and added to the dispersion. Emulsification and dispersion were performed using a high-speed shear emulsifier at 9000 rpm for 10 minutes. Under nitrogen protection, divinylbenzene was added and reacted at 60°C and 1000 rpm for 8 hours. The weight ratio of micronized calcium carbonate, nano-titanium dioxide, glycidyl methacrylate, vinyl acetate, divinylbenzene, and water was 0.5:0.3:35:12:0.04:100. This produced a core-shell nano-micron deformation plugging agent 2.

[0065] The particle size of the plugging agent is in the range of 500nm-4μm; the ratio of the total weight of micron calcium carbonate and nano titanium dioxide in the plugging agent to the total weight of the network polymer is 1:58; the weight ratio of micron calcium carbonate and nano titanium dioxide in the plugging agent is 1:0.6; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from glycidyl methacrylate, and the structural units derived from vinyl acetate in the network polymer shell is 1:875:300; and the weight-average molecular weight of the network polymer is 550,000 g / mol.

[0066] Scanning electron microscopy revealed that in addition to irregularly shaped composite particles, there were also some spherical particles with some protrusions and pits. Combining the sizes of irregular and spherical particles, there were a large number of micron-sized composite particles, as well as some small submicron-sized particles.

[0067] Example 3

[0068] Micronized calcium carbonate (average particle size of 1 μm) and nano-silica (average particle size of 100 nm) were dispersed in water, first mechanically stirred (stirring speed of 350 r / min for 20 minutes), and then ultrasonically dispersed for 10 minutes. Methyl acrylate and vinyl acetate were mixed evenly with a solvent and added to the dispersion. Emulsification and dispersion were performed using a high-speed shear emulsifier at 10,000 r / min for 10 minutes. Divinylbenzene was added under nitrogen protection and reacted at 80°C and 1,000 r / min for 10 hours. The weight ratio of micronized calcium carbonate, nano-silica, methyl acrylate, vinyl acetate, divinylbenzene, and water was 0.5:0.5:40:15:0.04:100. This produced a core-shell nano-micron deformation plugging agent 3.

[0069] The particle size of the plugging agent is within the range of 120nm-1.5μm; the ratio of the total weight of micron calcium carbonate and nano-silica in the plugging agent to the total weight of the network polymer is 1:55; the weight ratio of micron calcium carbonate and nano-silica in the plugging agent is 1:1; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from methyl acrylate, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:370; and the weight-average molecular weight of the network polymer is 840,000 g / mol.

[0070] Figure 1 The transmission electron microscope image of the core-shell structure of some core-shell nano-micron deformation plugging agents 3 is shown in Figure 1. Figure 1 It can be seen that the particle size of the composite particles is about 800nm, and the composite structure of the dark nano-SiO2 hard core and the light-colored polymer soft shell is very clear and universal; it can be clearly seen that the size of the core is about 600nm, and the polymer shell wall is slightly uneven, with a thickness (the distance from the core boundary to the particle boundary) ranging from 50-100nm.

[0071] Example 4

[0072] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 1, except that inorganic nanomaterials and inorganic micromaterials of different sizes were used. Specifically, "micron molybdenum disulfide (average particle size of 5 μm) and nano-silicon dioxide (average particle size of 600 nm)" were replaced with "micron molybdenum disulfide (average particle size of 10 μm) and nano-silicon dioxide (average particle size of 800 nm)." Core-shell nano-micron deformation plugging agent 4 was obtained.

[0073] The particle size of the plugging agent is in the range of 950nm-13μm; the ratio of the total weight of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent to the total weight of the network polymer is 1:80; the weight ratio of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent is 5:1; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from acrylonitrile, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:300; and the weight-average molecular weight of the network polymer is 280,000 g / mol.

[0074] Example 5

[0075] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 1, except that the weight ratio of the inorganic nanomaterial to the inorganic micromaterial was different. Specifically, the weight ratio of micron molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.5:0.1:30:10:0.03:100, replaced by "the weight ratio of micron molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.2:0.4:30:10:0.03:100." This produced a core-shell nano-micron deformation plugging agent 5.

[0076] The particle size of the plugging agent is in the range of 650nm-5.5μm; the ratio of the total weight of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent to the total weight of the network polymer is 1:80; the weight ratio of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent is 1:2; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from acrylonitrile, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:300; and the weight-average molecular weight of the network polymer is 225,000 g / mol.

[0077] Example 6

[0078] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 1, except that the weight ratios of the composition used to prepare the core and the composition used to prepare the shell were different. Specifically, the weight ratio of micron molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.5:0.1:30:10:0.03:100, replaced by "the weight ratio of micron molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.5:0.1:15:5:0.015:100." A core-shell nano-micron deformation plugging agent 6 was obtained.

[0079] The particle size of the plugging agent is in the range of 750nm-5.5μm; the ratio of the total weight of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent to the total weight of the network polymer is 1:80; the weight ratio of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent is 5:1; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from acrylonitrile, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:330; and the weight-average molecular weight of the network polymer is 180,000 g / mol.

[0080] Example 7

[0081] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 1, except that the weight ratios of the crosslinking agent, hydrophobic monomer, and oil-soluble hydrophilic monomer were different. Specifically, the weight ratio of micron molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.5:0.1:30:10:0.03:100, replaced by "the weight ratio of micron molybdenum disulfide, nano-silica, acrylonitrile, vinyl acetate, divinylbenzene, and water was 0.5:0.1:20:20:0.03:100." This produced a core-shell nano-micron deformation plugging agent 7.

[0082] The particle size of the plugging agent is in the range of 780nm-5.8μm; the ratio of the total weight of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent to the total weight of the network polymer is 1:80; the weight ratio of micron molybdenum disulfide and nano-silicon dioxide in the plugging agent is 5:1; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from acrylonitrile, and the structural units derived from vinyl acetate in the network polymer shell is 1:660:660; and the weight-average molecular weight of the network polymer is 200,000 g / mol.

[0083] Example 8

[0084] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 2, except that different types of hydrophobic monomers and oil-soluble hydrophilic monomers were used. Specifically, an equal weight of glycidyl methacrylate was replaced with styrene, and an equal weight of vinyl acetate was replaced with maleic anhydride. This resulted in a core-shell nano-micron deformation plugging agent 8.

[0085] The particle size of the plugging agent is within the range of 450nm-3.8μm; the ratio of the total weight of micron calcium carbonate and nano titanium dioxide in the plugging agent to the total weight of the network polymer is 1:58; the weight ratio of micron calcium carbonate and nano titanium dioxide in the plugging agent is 1:0.6; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from styrene, and the structural units derived from maleic anhydride in the network polymer shell is 1:875:300; and the weight-average molecular weight of the network polymer is 500,000 g / mol.

[0086] Example 9

[0087] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 2, except that the weight ratio of micron calcium carbonate, nano-titanium dioxide, butyl acrylate, acrylamide, divinylbenzene, and water was replaced by the weight ratio of 0.5:0.3:35:12:0.04:100. The core-shell nano-micron deformation plugging agent 9 was obtained.

[0088] The particle size of the plugging agent is in the range of 450nm-3.5μm; the ratio of the total weight of micron calcium carbonate and nano titanium dioxide in the plugging agent to the total weight of the network polymer is 1:58; the weight ratio of micron calcium carbonate and nano titanium dioxide in the plugging agent is 1:0.6; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from butyl acrylate, and the structural units derived from acrylamide in the network polymer shell is 1:870:500; and the weight-average molecular weight of the network polymer is 560,000 g / mol.

[0089] Example 10

[0090] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 3, except that a different crosslinking agent was used. Specifically, dicumyl peroxide was used instead of an equal weight of divinylbenzene. This produced a core-shell nano-micron deformation plugging agent 10.

[0091] The particle size of the plugging agent is in the range of 110nm-1.2μm; the ratio of the total weight of micron calcium carbonate and nano-silica in the plugging agent to the total weight of the network polymer is 1:55; the weight ratio of micron calcium carbonate and nano-silica in the plugging agent is 1:1; the weight ratio of the structural units derived from dicumyl peroxide, the structural units derived from methyl acrylate, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:370; and the weight-average molecular weight of the network polymer is 740,000 g / mol.

[0092] Example 11

[0093] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 3, except that a different type of inorganic micron material was used. Specifically, micron barite (average particle size of 1 μm) was used instead of an equal weight of micron calcium carbonate. This produced a core-shell nano-micron deformation plugging agent 11.

[0094] The particle size of the plugging agent is in the range of 115nm-1.4μm; the ratio of the total weight of micron barite and nano-silica in the plugging agent to the total weight of the network polymer is 1:55; the weight ratio of micron barite and nano-silica in the plugging agent is 1:1; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from methyl acrylate, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:370; and the weight-average molecular weight of the network polymer is 800,000 g / mol.

[0095] Comparative Example 1

[0096] A core-shell nano-micron deformation plugging agent was prepared according to the method of Example 3, except that nano-alumina (average particle size of 200 nm) was used instead of an equal weight of micron calcium carbonate to obtain a core-shell nano-micron deformation plugging agent 12.

[0097] The particle size of the plugging agent is within the range of 250nm-300nm; the ratio of the total weight of nano-aluminum oxide and nano-silicon dioxide in the plugging agent to the total weight of the network polymer is 1:55; the weight ratio of nano-aluminum oxide and nano-silicon dioxide in the plugging agent is 1:1; the weight ratio of the structural units derived from divinylbenzene, the structural units derived from methyl acrylate, and the structural units derived from vinyl acetate in the network polymer shell is 1:1000:370; and the weight-average molecular weight of the network polymer is 700,000 g / mol.

[0098] Test Case

[0099] The base slurry formulas of oil-based drilling fluid and water-based drilling fluid are as follows:

[0100] Oil-based drilling fluid base slurry formula (by weight): 100 parts of base oil (No. 3 white oil), 25 parts of 25% mass concentration of calcium chloride aqueous solution, 5 parts of fatty acid amide emulsifier, 5 parts of calcium oxide, and 4 parts of organic soil.

[0101] Water-based drilling fluid base slurry formula (by weight): 100 parts of clean water, 2 parts of evaluation soil, 1 part of low-viscosity polyanionic cellulose (Shandong Deshunyuan Petroleum Technology Co., Ltd.), 3 parts of lignite resin (Shandong Deshunyuan Petroleum Technology Co., Ltd.), 3 parts of sulfomethyl phenolic resin (Zhengzhou Oriental Additive Co., Ltd.), and 0.5 parts of sodium hydroxide.

[0102] The preparation method of drilling fluid base slurry is as follows:

[0103] Preparation of oil-based drilling fluid slurry: put the base oil for oil-based drilling fluid into the mixing cup, add the emulsifier under strong stirring, and stir at high speed for 10 minutes; then add the calcium chloride aqueous solution and stir at high speed for 20 minutes; then add organic soil and calcium oxide to the mixed system in sequence, stir vigorously for 10 minutes after adding each material, and stir vigorously for another 20 minutes after all materials are added to obtain the oil-based drilling fluid slurry.

[0104] Preparation of water-based drilling fluid base slurry: put clean water in a mixing cup, add the evaluation soil under strong stirring, and stir at high speed for 10 minutes; then add low-viscosity polyanionic cellulose and stir at high speed for 10 minutes; then add lignite resin, sulfomethyl phenolic resin and sodium hydroxide to the mixed system in sequence, stir vigorously for 10 minutes after adding each material, and stir vigorously for another 10 minutes after all materials are added to obtain the water-based drilling fluid base slurry.

[0105] The properties of the drilling fluid system were determined with reference to GB / T 16783.1 and GB / T 16783.2. The test results of the oil-based drilling fluid system and the water-based drilling fluid system are shown in Table 1 and Table 2, respectively.

[0106] Table 1

[0107]

[0108]

[0109] Note: Base slurry refers to oil-based drilling fluid base slurry

[0110] Table 2

[0111]

[0112]

[0113] Note: Base slurry refers to water-based drilling fluid base slurry

[0114] It can be seen from the data in Table 1 and Table 2 that the nano-deformation plugging agent provided by the present invention is suitable for water-based and oil-based drilling fluid systems. In the oil-based drilling fluid system, the addition of the core-shell nano-micron deformable plugging agent prepared in Example 1-3 has little effect on the demulsification voltage and rheological properties of the drilling fluid before and after aging at 180°C. Analysis of the API and high-temperature and high-pressure filtration loss data after aging shows an excellent filtration loss reduction effect. The addition of the core-shell nano-micron deformable plugging agent prepared in Example 4-11 has little effect on the performance of the drilling fluid. Compared with the drilling fluid to which the core-shell nano-micron deformable plugging agent prepared in Example 1-3 is added, the demulsification voltage is slightly reduced, and the filtration loss reduction effect is reduced. Inorganic micron materials were not added when preparing the plugging agent in Comparative Example 1. After the plugging agent was added, the dispersion effect of the drilling fluid sample was not good. After the plugging agent prepared in Comparative Example 1 was added, demulsification occurred after aging, and the filtration loss increased, indicating that the plugging agent prepared in Comparative Example 1 is not compatible with the oil-based drilling fluid.

[0115] In a water-based drilling fluid system, the addition of the core-shell nano-micron deformable plugging agent prepared in Examples 1-3 has little effect on the rheological properties of the drilling fluid. The API and high-temperature and high-pressure filtration losses after aging are lower than those of the base slurry, demonstrating an excellent filtration loss reduction effect. The addition of the core-shell nano-micron deformable plugging agent prepared in Examples 4-11 slightly reduces the demulsification voltage and reduces the filtration loss reduction effect compared to the drilling fluid to which the core-shell nano-micron deformable plugging agent prepared in Examples 1-3 is added. The plugging agent prepared in Comparative Example 1 has a poor dispersion effect in the base slurry, and after aging, the shear force decreases and the filtration loss increases, indicating that the plugging agent prepared in Comparative Example 1 is not suitable for water-based base slurry.

[0116] This shows that when the size and weight ratio of the inorganic nanomaterial and the inorganic micromaterial, the weight ratio of the composition used to prepare the core and the composition used to prepare the shell, the weight ratio of the crosslinker, the hydrophobic monomer and the oil-soluble hydrophilic monomer, and the types of the inorganic micromaterial, the inorganic nanomaterial, the hydrophobic monomer, the oil-soluble hydrophilic monomer and the crosslinker meet the preferred conditions, the compatibility of the plugging agent with water-based and oil-based drilling fluids can be further improved, and the filtration loss reduction effect can be further improved.

[0117] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A composition for preparing a nano-micron deformation plugging agent, characterized in that: The composition comprises: inorganic micron material, inorganic nano material, hydrophobic monomer, oil-soluble hydrophilic monomer and cross-linking agent.

2. The composition according to claim 1, characterized in that In the composition, the ratio of the total weight of the inorganic micron material and the inorganic nano material to the total weight of the hydrophobic monomer, the oil-soluble hydrophilic monomer and the cross-linking agent is 1:(20-70), preferably 1:(50-70); Preferably, in the composition, the weight ratio of the inorganic micron material to the inorganic nano material is 0.5:(0.1-0.5); Preferably, in the composition, the weight ratio of the cross-linking agent, the hydrophobic monomer and the oil-soluble hydrophilic monomer is 1:(750-1000):(250-375); Preferably, the composition further comprises a solvent; in the composition, the weight ratio of the inorganic nanomaterial to the solvent is (0.1-0.5):100; Preferably, the solvent is water.

3. The composition according to claim 1 or 2, characterized in that The inorganic micron material is selected from at least one of micron molybdenum disulfide, micron calcium carbonate and micro powder graphite; Preferably, the average particle size of the inorganic micron material is 1-5 μm.

4. The composition according to any one of claims 1 to 3, characterized in that The inorganic nanomaterial is selected from at least one of nano-silicon dioxide, nano-titanium dioxide and nano-zirconium oxide; Preferably, the average particle size of the inorganic nanomaterial is 100-600 nm.

5. The composition according to any one of claims 1 to 4, characterized in that The hydrophobic monomer is selected from at least one of acrylonitrile, methyl methacrylate, methyl acrylate, butyl acrylate and glycidyl methacrylate, preferably acrylonitrile, glycidyl methacrylate and methyl acrylate; and / or, the oil-soluble hydrophilic monomer is selected from vinyl acetate and / or maleic anhydride, preferably vinyl acetate; And / or, the cross-linking agent is a multifunctional monomer, preferably selected from divinylbenzene and / or ethylene glycol dimethacrylate.

6. A nano-micron deformation plugging agent, characterized in that: The plugging agent comprises a core and a shell coated on the outside of the core; wherein the core comprises an inorganic micron material and / or an inorganic nano material, and the shell is a network polymer, and the network polymer comprises structural units provided by a cross-linking agent, structural units provided by a hydrophobic monomer, and structural units provided by an oil-soluble hydrophilic monomer; Preferably, the particle size of the plugging agent is in the range of 120 nm to 6 μm; Preferably, the weight average molecular weight of the network polymer is 10,000-3,000,000 g / mol.

7. The plugging agent according to claim 6, characterized in that: In the plugging agent, the ratio of the total weight of the inorganic micron material and the inorganic nano material to the total weight of the network polymer is 1: (40-121)； Preferably, in the plugging agent, the weight ratio of the inorganic micron material to the inorganic nano material is 0.5:(0.1-0.5); Preferably, in the network polymer, the weight ratio of the structural units provided by the cross-linking agent, the structural units provided by the hydrophobic monomer and the structural units provided by the oil-soluble hydrophilic monomer is 1:(750-1000):(250-375).

8. A method for preparing a nano-micron deformation plugging agent, characterized in that: The preparation method comprises the following steps: in the presence of a solvent, an inorganic micron material and an inorganic nano material, mixing a hydrophobic monomer, an oil-soluble hydrophilic monomer and a cross-linking agent to carry out a polymerization reaction; Preferably, the polymerization reaction temperature is 50-80° C. and the time is 6-10 h.

9. A nano-micron deformation plugging agent prepared by the preparation method according to claim 8.

10. Use of the composition for preparing a nano-micron deformation plugging agent according to any one of claims 1 to 5 or the nano-micron deformation plugging agent according to any one of claims 6, 7, and 9 in plugging micro-fractures in formations of different pore sizes.

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