Anti-collapse agent as well as preparation method and application thereof

Abstract

The invention relates to an anti-collapse agent as well as a preparation method and application thereof. The anti-collapse agent is prepared by in-situ self-crosslinking of POSS monomers on the surfaces of nanoparticles; wherein the mass of the POSS monomer is 5%-15% of the mass of the nano particles. According to the preparation method disclosed by the invention, inorganic nanoparticles are subjected to organic modification by adopting POSS, so that the POSS self-crosslinking nano anti-collapse agent is formed. The POSS self-crosslinking network structure forms a rigid positive-electricity inner core and a low-surface-energy shell on the surface of the nano-particle, so that the particle dispersity can be improved, and the super-hydrophobic performance is endowed; and moreover, the viscosity is not obviously increased under a low-temperature condition, micro-nano pore plugging and surface hydrophobization can be realized under a high-temperature and high-pressure condition, and hydration of the hydrophilic shale is inhibited, so that the problem of borehole wall instability caused by rapid hydration of the deep-water hydrophilic shale is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of deepwater drilling, and in particular relates to an anti-collapse agent and a preparation method and application thereof. Background Art

[0002] Deepwater oil and gas, with its enormous resource potential, has become a strategic frontier for current and future exploration and development. Therefore, in-depth research on deepwater drilling technology is urgently needed to improve exploration and development efficiency and ensure operational safety.

[0003] Drilling fluid, often called the "blood of drilling," directly determines the safety and efficiency of deepwater drilling. Deepwater environments have extremely wide temperature gradients: the annular temperature near the seafloor mudline can drop to 0-4°C or even lower, causing a rapid increase in drilling fluid viscosity and yield stress, equivalent circulating density, and pumping pressure, thereby exacerbating the risk of well collapse and lost circulation. As drilling depth increases, downhole temperatures can exceed 200°C, causing the drilling fluid to partially lose its performance. Under these conditions, conventional additives often struggle to meet demand, and maintaining wellbore stability in complex deepwater formations becomes a major challenge. Seawater displacing the formation causes the overburden to become undercompacted, with low cementation and high clay content, making it susceptible to hydration, expansion, and dispersion. Simultaneously, a large number of nanoscale pores, under the action of pressure differentials, continuously absorb filtrate, further weakening the formation and inducing well collapse and lost circulation.

[0004] Anti-slump agents are commonly added to drilling fluids to maintain wellbore stability during deepwater operations. Inorganic salts (such as KCl, NaCl, and CaCl2) can inhibit clay hydration, but they require high concentrations to be effective, resulting in increased costs and fluid loss, and their effectiveness in inhibiting hydration in hydrophilic shales is limited. Plugging agents (such as nanosilica, asphalt, and calcium carbonate) physically block formation pores and fractures; however, these materials require a precise match between particle size and pore size to effectively seal the pores and fail to fundamentally prevent clay swelling. Chinese patent document CN202111362703.5 discloses a cationic anti-slump agent, which reacts acrylamide with a cationic monomer to form a polymer that can adsorb onto rock surfaces or intercalate between clay layers to inhibit hydration-induced swelling. However, under low-temperature, deepwater conditions, these agents significantly increase drilling fluid viscosity, reduce rheological properties, and their anti-slump effectiveness remains limited.

[0005] Therefore, existing anti-collapse agents are not adaptable enough in deepwater environments and are difficult to meet the strict requirements for wellbore stability in deepwater drilling. Summary of the Invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide an anti-collapse agent and its preparation method and application. The anti-collapse agent provided by the present invention is prepared by in-situ self-crosslinking of POSS monomers on the surface of nanoparticles to form a POSS self-crosslinked nano anti-collapse agent. The POSS self-crosslinked network structure forms a rigid positive core and a low surface energy shell on the surface of the nanoparticles, which can improve the dispersibility of the particles and impart super-hydrophobic properties; moreover, it does not significantly increase viscosity under low temperature conditions, and can achieve micro-nano pore blocking and surface hydrophobization under high temperature and high pressure conditions, while inhibiting the hydration of hydrophilic shale, thereby solving the problem of well wall instability caused by rapid hydration of deep-water hydrophilic shale.

[0007] To achieve the above objectives, the first aspect of the present invention provides an anti-collapse agent, which is prepared by in-situ self-crosslinking of POSS monomers on the surface of nanoparticles; wherein the mass of the POSS monomers is 5% to 15% of the mass of the nanoparticles.

[0008] In the present invention, POSS consumption is limited to 5%~15% of nanoparticle quality, because: when POSS consumption is lower than 5%, the surface still retains naked hydroxyl group, and spot-shaped breach appears in hydrophobic film, and blocking layer is also not dense. On the contrary, when POSS consumption exceeds 15%, free non-adsorbed POSS molecules begin to appear in the system, and these molecules can continue self-polymerization condensation to generate silicone micelles under alkaline conditions, not only increase filtrate viscosity, but also may bridge between particles, cause particle agglomeration sedimentation; Excess POSS also can lift low-temperature viscosity after entering drilling fluid, causes pump pressure to rise. Therefore, POSS consumption is limited to 5%~15% of nanoparticle quality, can ensure that particle surface continuous coverage, blocking and hydrophobic effect are sufficient, again avoid reunion and rheological deterioration that excessive POSS brings.

[0009] In some preferred embodiments, the mass of the POSS monomer is 10%, 12%, or 12.5% ​​of the mass of the nanoparticles.

[0010] In some embodiments, the POSS monomer includes one or more of aminopropyl-isooctyl POSS, aminopropyl-isodecyl POSS, aminoethyl-isooctyl POSS, and diethylaminopropyl-phenyl POSS.

[0011] In some embodiments, the nanoparticles include one or more of nano-silicon dioxide, nano-zinc oxide, and nano-calcium carbonate.

[0012] In some embodiments, the particle size of the nanoparticles is 20-50 nm.

[0013] In the present invention, nanoparticles with a particle size of 20 to 50 nm are used. This particle size range is the optimal interval determined by comprehensive pore throat scale matching, surface chemical activity, and dispersion-rheological properties. First, the diameter of the micro-nano pore throats that dominate deepwater hydrophilic shales is about 60 to 150 nm. According to the commonly used "1 / 3 pore throat" bridging principle, 20 to 50 nm particles can not only achieve multi-particle bridging at the pore mouth, but also continue to fill in the fine pores, thereby forming a gradient sealing layer; if the particle size is greater than 50 nm, it can only stay at the pore mouth and is easily circulated and washed, and the sealing depth is insufficient; if it is less than 20 nm, it must rely on agglomeration to bridge, and the sealing integrity is poor. Secondly, the specific surface area of ​​20 to 50 nm particles is about 70 to 200 m 2 / g, the surface hydroxyl density is high, sufficient for full condensation with POSS / silane and forming a complete hydrophobic layer. However, particles <20 nm have a large specific surface area, requiring more modifier and prone to self-gelation. Particles >50 nm contain insufficient hydroxyl groups, leading to gaps in the hydrophobic film. Furthermore, Brownian motion dominates in this particle size range, allowing long-term suspension without significantly increasing drilling fluid viscosity (ΔAV ≈ 2 mPa·s at 4°C). Particles <20 nm aggregate due to van der Waals attraction, increasing viscosity, while particles >50 nm experience increased sedimentation, requiring additional high shear to maintain suspension.

[0014] The second aspect of the present invention provides a method for preparing the anti-collapse agent according to the first aspect of the present invention, characterized in that the preparation method comprises the following steps: S1, adding nanoparticles to deionized water, stirring and ultrasonicating, and adjusting the pH of the system with alkaline solution to prepare a uniform suspension; S2, in a protective gas atmosphere, under stirring conditions, adding the POSS solution dropwise to the suspension for reaction; after the reaction is completed, centrifuging and collecting the product; S3, post-processing the product to obtain the anti-collapse agent.

[0015] In some embodiments, the ratio of the mass of the nanoparticles to the volume of the deionized water is 0.04-0.1 g:1 mL.

[0016] In the present invention, the nanoparticles are mixed with deionized water to a concentration of 0.04-0.10 g·mL -1 The solid-to-liquid ratio is because: if it is lower than 0.04 g·mL -1 If the solid content of the system is too low, the methanol and heat generated during the hydrolysis and condensation of the POSS solution will be difficult to be adsorbed and dissipated by the particles in a timely manner, resulting in a decrease in reaction efficiency. At the same time, excessive water content will significantly prolong the dehydration time during the centrifugation and drying stages, resulting in a low yield. If the solid content is higher than 0.10 g·mL -1The viscosity of the slurry rises rapidly, and stirring at 200-450 rpm can no longer maintain uniform dispersion. Particles will bridge and wrap unhydrolyzed POSS in the local dense area, resulting in uneven shell layer, agglomeration and sedimentation, and causing blockage in subsequent centrifugal separation.

[0017] In some preferred embodiments, the ratio of the mass of the nanoparticles to the volume of the deionized water is 0.04 g:1 mL or 0.05 g:1 mL.

[0018] In some embodiments, the alkali solution includes one or more of ammonia water, potassium hydroxide solution, sodium hydroxide solution, sodium bicarbonate solution or triethanolamine solution, preferably ammonia water.

[0019] In the present invention, the hydrolysis-condensation reaction on the surface of the nanoparticles requires a weak to moderate alkaline environment, preferably provided by ammonia. This is because ammonia is highly volatile and escapes along with water and trace amounts of methanol during the drying phase after the reaction is complete, leaving no metal ions in the product.

[0020] In some embodiments, the method for preparing the POSS solution comprises: dissolving a POSS monomer in an organic solvent to prepare the POSS solution; Wherein, the ratio of the mass of the POSS monomer to the volume of the organic solvent is 0.025-0.03 g:1 mL; and / or the organic solvent comprises anhydrous ethanol.

[0021] In the present invention, POSS monomer is prepared into 0.025~0.03 g·mL -1 ethanol solution, because: if the concentration exceeds 0.03 g mL -1 The solution will produce mist crystals at room temperature, and when added to the alkaline aqueous phase, it is more likely to instantly aggregate into flocs, resulting in uneven coating on the particle surface. On the contrary, below 0.025 g·mL -1 Although clarity can be maintained during addition, achieving the same surface coverage requires increasing the amount of solvent and the duration of the addition. This significantly increases the amount of ethanol that needs to be evaporated during the subsequent centrifugation and drying stages, increasing energy consumption and time costs. Within this range, the POSS solution remains transparent and stable, while maintaining a viscosity that facilitates constant-rate addition. Furthermore, upon completion of the addition, the surface of 20-50 nm particles can be covered with a monolayer, with a hydrolysis-condensation conversion rate exceeding 80%, without increasing the post-processing load.

[0022] In some embodiments, in step S1, the stirring speed is 200-450 rpm, and the stirring time is 20-30 min; and / or, in step S2, the stirring speed is 250-500 rpm.

[0023] In the present invention, in step S1, stirring is performed at a speed of 200-450 rpm for 20-30 minutes to fully disperse solid particles sized 20-50 nm without forming vortices. When the speed is below 200 rpm, Brownian diffusion is insufficient to overcome the van der Waals attraction between the particles, causing rapid sedimentation and small agglomerations. When the speed is above 450 rpm, a significant central vortex and numerous bubbles are generated. The entrained air not only affects the stability of the subsequent hydrolysis-condensation reaction but also forms a foam layer during centrifugation, reducing the efficiency of solid-liquid separation. Furthermore, a stirring time of 20-30 minutes allows the nanoparticles to completely disaggregate, stabilizing the transmittance of the suspension.

[0024] In the present invention, during step S2, when the POSS solution is added dropwise and the hydrolysis-condensation reaction proceeds, the stirring speed is increased to 250-500 rpm. This is because the solids content and viscosity of the system increase simultaneously at this point, requiring higher shear to maintain a uniform slurry and to promptly remove locally generated methanol and heat from the reaction interface. Speeds below 250 rpm result in localized high-concentration areas, leading to uneven POSS coating on the particle surface; speeds exceeding 500 rpm can disrupt the initially formed organosilicon network due to excessive shear. Under stirring conditions of 250-500 rpm, the combination of 10-30 minutes of dropwise addition and a subsequent 2-4 hours of condensation reaction simultaneously meets the requirements of mass transfer, heat release, and mechanical stability, ultimately yielding a modified powder with a dense shell, a narrow particle size distribution, and the absence of large agglomerates.

[0025] In some embodiments, the pH of the system is adjusted to 8-11.

[0026] In this invention, the system pH is controlled between 8 and 11 to balance the dual requirements of the hydrolysis-condensation rate of silane / POSS and the dispersion stability of the nanoparticles. Below pH 8, the Si-OR bond hydrolysis is too slow, making it difficult to form a complete organosilicon shell within one or two hours, resulting in low modification efficiency. Above pH 11, the condensation rate is too rapid, resulting in the formation of polysiloxane gel locally and encapsulating the particles, causing agglomeration and sedimentation, and reducing subsequent dispersion and filling performance. Within the system pH range of 8-11, the reaction completes over 80% of the Si-O-Si structure, while maintaining a zeta potential of the modified particles above +35 mV and maintaining long-term suspension after aging at 200°C.

[0027] In some embodiments, the dripping time is 15 to 40 minutes.

[0028] In the present invention, the POSS solution is added dropwise rather than poured into the suspension all at once to allow the reaction to proceed uniformly and controllably throughout the system. Upon entering the alkaline aqueous phase, the POSS molecules immediately hydrolyze and release methanol, while simultaneously condensing with the -OH groups on the particle surfaces to form a Si-O-Si network. If a high concentration of POSS is added instantaneously, the local hydrolysis-condensation rate is too fast, easily forming colloidal masses or polysiloxane flocs around the particles, causing the nanoparticles to adhere to each other and settle, ultimately failing to obtain a dense and uniform hydrophobic shell. Constant-rate addition disperses the POSS solution in thin streams, maintaining a low and stable concentration within the reactor, allowing hydrolysis-condensation to proceed gradually only on the particle surfaces. Simultaneously, the generated methanol and heat can be promptly removed, avoiding local temperature rise or bubble aggregation. The protective gas further reduces the entry of CO2 and O2 from the air into the system, preventing carbonation or oxidation side reactions. Through the sustained-release method of "drip addition + stirring", the particles always remain well dispersed, and finally a modified product with uniform shell, stable particle size and no agglomeration is obtained.

[0029] In some embodiments, the reaction temperature is 20-60° C., and the reaction time is 2-4 h.

[0030] In the present invention, the inventors have found that the hydrolysis rate is too slow below 20°C, and it is difficult to form a continuous shell within 4 hours; above 60°C, the condensation is too fast, local gelation is likely to occur, and particles may agglomerate.

[0031] In some embodiments, the protective gas is nitrogen or argon.

[0032] In some embodiments, the centrifugation speed is 8000-10000 rpm and the centrifugation time is 10-30 min. The above centrifugation conditions can make all particles settle and avoid excessive collisions between particles that damage the formed organic shell.

[0033] In some embodiments, the post-treatment includes rinsing, drying and grinding; wherein the drying temperature is 50-80° C., and the drying time is 8-12 h.

[0034] In the present invention, the drying conditions are controlled to remove water and ethanol.

[0035] The third aspect of the present invention provides an application of the anti-collapse agent as described in the first aspect of the present invention or the anti-collapse agent prepared by the method described in the second aspect of the present invention in marine oil and gas drilling, wherein the drilling fluid prepared by mixing the anti-collapse agent with base slurry is used for marine oil and gas drilling, and the amount of the anti-collapse agent added is 1% to 4% of the mass of the base slurry.

[0036] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses POSS to organically modify inorganic nanoparticles. The multifunctional groups in the POSS molecules self-crosslink in situ on the nanoparticle surface through a hydrolysis-condensation reaction under alkaline conditions, forming a dense coating. This creates a stable and dense organic shell on the nanoparticle surface (POSS monomers react with hydroxyl groups on the nanoparticle surface to form a stable siloxane network). This shell structure imparts a high positive charge to the nanoparticles and enables microscopic deformation under pressure differentials, adaptively filling micro- and nano-pores. Simultaneously, a dense hydrophobic membrane forms on the exterior of the shell (formed by the spontaneous arrangement of the hydrophobic functional groups on the POSS monomers in the aqueous phase). This membrane actively adsorbs onto the negatively charged shale pore walls and achieves in-situ membrane sealing. Once the particles enter the pore throats, they bridge, stack, and interfill, rapidly establishing a high-strength micro- and nanoscale blocking barrier. This effectively blocks filtrate channels at the source, effectively preventing shale hydration, expansion, and dispersion. This addresses the problem of wellbore instability caused by rapid hydration of deepwater hydrophilic shales.

[0037] The anti-collapse agent prepared by this invention fully matches the micro- and nano-scale pore throat dimensions commonly found in deepwater formations. It achieves initial bridging at the pore opening and gradually fills and self-assembles within the deep pores to form a continuous membrane. The resulting plugging layer is dense, uniform, and resilient, providing long-term resistance to cyclic erosion and pressure fluctuations, significantly improving wellbore stability.

[0038] The anti-collapse agent prepared by this invention does not contain a long-chain polymer backbone, resulting in small particles and a uniform surface charge, which minimizes the viscosity, yield value, and fluid loss of water-based drilling fluids. Long hydrophobic chains (hydrophobic functional groups in the POSS monomer) are firmly anchored to the nanoparticle surface, preventing interchain entanglement at low temperatures. This ensures both fluidity in deepwater, low-temperature conditions and temperature resistance in high-temperature well sections, broadening the applicable window of the drilling fluid over a wide temperature range.

[0039] The organic modifier used in this invention possesses a stable, heat-resistant, and salt-resistant cage-type siloxane backbone structure and exhibits excellent compatibility with conventional water-based drilling fluid systems. Even a minimal addition can achieve a triple synergistic effect of plugging, adsorption, and hydrophobicity, avoiding the adverse environmental and cost impacts of high salt and polymer concentrations, thus meeting the requirements of green offshore drilling and cost-effective development.

[0040] When used in deep-water marine oil and gas drilling, the anti-collapse agent prepared by the present invention can effectively seal the micro-nano pores in the formation while forming a dense hydrophobic film, inhibiting shale hydration expansion, improving the compressive strength of shale, and ultimately stabilizing the well wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 This is the SEM image (200 nm) of the shale slice after aging with deionized water (200℃ / 16h); Figure 2 This is the SEM image (200 nm) of a shale slice after aging treatment (200°C / 16h) with the anti-collapse agent of Example 1 added; Figure 3 This is the SEM image (20 μm) of the shale slice after aging with deionized water (200℃ / 16h); Figure 4 This is the SEM image (20 μm) of a shale slice after aging treatment (200°C / 16h) with the anti-collapse agent of Example 1 added; Figure 5 AFM image (2D) of shale slice after aging with deionized water (200℃ / 16h); Figure 6 This is an AFM image (2D) of a shale slice after aging treatment (200°C / 16h) with the anti-collapse agent of Example 1 added; Figure 7 AFM image (3D) of shale slices after aging with deionized water (200°C / 16h); Figure 8 This is an AFM image (3D) of a shale slice after aging treatment (200°C / 16h) with the anti-collapse agent of Example 1 added. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are all commercially available, the instruments and equipment used are all conventional instruments and equipment in the field, and the operating methods used are all conventional methods in the field.

[0045] Example Example 1 The preparation method of the anti-collapse agent provided in this embodiment comprises the following steps: S1, disperse 5 g of nano-SiO2 particles (particle size of 50 nm) in 100 mL of deionized water, stir at 300 rpm for 30 min to fully disperse the particles, adjust the pH of the suspension to 10 with ammonia water, and continue stirring for 5 min to prepare a uniform SiO2 suspension; S2, dissolving 0.5 g of aminopropyl-isooctyl POSS in 20 mL of anhydrous ethanol to prepare a POSS solution; S3, in a nitrogen atmosphere, under stirring conditions of 500 rpm, the POSS solution was slowly added dropwise to the SiO2 suspension for 30 min. After the addition was completed, the mixture was stirred at 60 °C for 2 h to carry out the self-crosslinking reaction; S4, after the reaction is completed, the reaction mixture is centrifuged at 8000 rpm for 10 min, the supernatant is discarded, and the precipitate (product) is collected; S5, rinse the precipitate with deionized water three times to remove unreacted residual substances; place the obtained solid in a vacuum drying oven at 60°C and dry it for 12 h; grind the dried product into powder to prepare an anti-collapse agent (aminopropyl-isooctyl POSS modified nano-SiO2 powder).

[0046] Example 2 The preparation method of the anti-collapse agent provided in this embodiment comprises the following steps: S1, disperse 5 g of nano-CaCO3 particles (particle size 50 nm) in 100 mL of deionized water and stir at 400 rpm for 20 min to fully disperse the particles. Adjust the pH of the suspension to 9 with ammonia water and continue stirring for 5 min to obtain a uniform CaCO3 suspension. S2, dissolving 0.5 g of aminopropyl-isodecyl POSS in 20 mL of anhydrous ethanol to prepare a POSS solution; S3, under nitrogen atmosphere and stirring at 500 rpm, the POSS solution was slowly added dropwise to the CaCO3 suspension for 20 min. After the addition was completed, the mixture was stirred at 55 °C for 2.5 h to carry out the self-crosslinking reaction; S4, after the reaction is completed, the reaction mixture is centrifuged at 10,000 rpm for 10 min, the supernatant is discarded, and the precipitate (product) is collected; S5, rinse the precipitate three times with deionized water to remove unreacted residual substances; place the obtained solid in a vacuum drying oven at 60°C and dry it for 12 h; grind the dried product into powder to prepare an anti-collapse agent (aminopropyl-isodecyl POSS modified nano-CaCO3 powder).

[0047] Example 3 The preparation method of the anti-collapse agent provided in this embodiment comprises the following steps: S1, disperse 4 g of nano-SiO2 particles (particle size of 30 nm) in 100 mL of deionized water and stir at 350 rpm for 30 min to fully disperse the particles. Adjust the pH of the suspension to 11 with ammonia water and continue stirring for 5 min to obtain a uniform SiO2 suspension. S2, dissolving 0.5 g of aminoethyl-isooctyl POSS in 20 mL of anhydrous ethanol to prepare a POSS solution; S3, in a nitrogen atmosphere, under stirring conditions of 300 rpm, the POSS solution was slowly added dropwise to the SiO2 suspension for 40 min. After the addition was completed, the mixture was stirred at 60 °C for 3 h to carry out the self-crosslinking reaction; S4, after the reaction is completed, the reaction mixture is centrifuged at 8000 rpm for 15 min, the supernatant is discarded, and the precipitate (product) is collected; S5, rinse the precipitate with deionized water three times to remove unreacted residual substances; place the obtained solid in a vacuum drying oven at 60°C and dry it for 12 h; grind the dried product into powder to prepare an anti-collapse agent (aminoethyl-isooctyl POSS modified nano-SiO2 powder).

[0048] Example 4 The preparation method of the anti-collapse agent provided in this embodiment comprises the following steps: S1, disperse 5 g of nano-SiO2 particles (particle size of 40 nm) in 100 mL of deionized water, stir at 450 rpm for 20 min to fully disperse the particles, adjust the pH of the suspension to 8 with ammonia water, and continue stirring for 5 min to obtain a uniform SiO2 suspension; S2, dissolving 0.6 g of diethylaminopropyl-phenyl POSS in 20 mL of anhydrous ethanol to prepare a POSS solution; S3, in a nitrogen atmosphere, under stirring conditions of 300 rpm, the POSS solution was slowly added dropwise to the SiO2 suspension for 15 min. After the addition was completed, the mixture was stirred at 50 °C for 3.5 h to carry out the self-crosslinking reaction; S4, after the reaction is completed, the reaction mixture is centrifuged at 10,000 rpm for 15 min, the supernatant is discarded, and the precipitate (product) is collected; S5, rinse the precipitate with deionized water three times to remove unreacted residual substances; place the obtained solid in a vacuum drying oven at 60°C and dry it for 12 h; grind the dried product into powder to prepare an anti-collapse agent (diethylaminopropyl-phenyl POSS modified nano-SiO2 powder).

[0049] Example 5 The preparation method of the anti-collapse agent provided in this embodiment comprises the following steps: S1, disperse 5 g of nano-SiO2 particles (particle size of 50 nm) in 100 mL of deionized water, stir at 300 rpm for 30 min to fully disperse the particles, adjust the pH of the suspension to 10 with ammonia water, and continue stirring for 5 min to prepare a uniform SiO2 suspension; S2, dissolving 0.25 g of aminopropyl-isooctyl POSS in 10 mL of anhydrous ethanol to prepare a POSS solution; S3, in a nitrogen atmosphere, under stirring conditions of 500 rpm, the POSS solution was slowly added dropwise to the SiO2 suspension for 30 min. After the addition was completed, the mixture was stirred at 20 °C for 2 h to carry out the self-crosslinking reaction; S4, after the reaction is completed, the reaction mixture is centrifuged at 8000 rpm for 30 min, the supernatant is discarded, and the precipitate (product) is collected; S5, rinse the precipitate with deionized water three times to remove unreacted residual substances; place the obtained solid in a vacuum drying oven at 60°C and dry it for 12 h; grind the dried product into powder to prepare an anti-collapse agent (aminopropyl-isooctyl POSS modified nano-SiO2 powder).

[0050] Comparative Example 1 The preparation method of the anti-collapse agent provided in this comparative example is the same as that in Example 1, except that no POSS monomer is added for modification, that is, steps S2-S5 of Example 1 are omitted, and the suspension prepared in step S1 is directly used as the anti-collapse agent.

[0051] Comparative Example 2 The preparation method of the anti-collapse agent provided in this comparative example is the same as that of Example 1, except that no nano-silicon dioxide is added, that is, step S1 of Example 1 is omitted, and the POSS solution is directly reacted in step S3.

[0052] Comparative Example 3 The preparation method of the anti-collapse agent provided in this comparative example is the same as that of Example 1, except that no ammonia solution is used to adjust the pH of the system for reaction.

[0053] Comparative Example 4 A 5% KCl aqueous solution was prepared using deionized water and potassium chloride. This solution was used directly in subsequent performance evaluations and as a comparison sample for inorganic salt anti-collapse agents.

[0054] Comparative Example 5 A 1% polyamine aqueous solution was prepared using deionized water and a polyamine inhibitor. This solution was used directly in subsequent performance evaluations and as a comparison sample for an organic polyamine anti-slump agent.

[0055] Comparative Example 6 A 1% (mass fraction) PAM aqueous solution was prepared using deionized water and polyacrylamide. This solution was used directly in subsequent performance evaluations and as a comparison sample for the polymer anti-collapse agent.

[0056] Comparative Example 7 The preparation method of the anti-collapse agent provided in this comparative example is the same as that in Example 1, except that the POSS monomer is replaced by octadecyltrimethylammonium chloride; the remaining raw material amounts, stirring rate, ultrasonic time, pH adjustment, reaction temperature and post-processing steps are kept consistent.

[0057] Comparative Example 8 The preparation method of the anti-collapse agent provided in this comparative example is the same as that in Example 1, except that "0.5 g aminopropyl-isooctyl POSS" is replaced by "0.2 g aminopropyl-isooctyl POSS", and the remaining raw material amounts, stirring rate, ultrasonic time, pH adjustment, reaction temperature and post-treatment steps are kept consistent.

[0058] Comparative Example 9 The preparation method of the anti-collapse agent provided in this comparative example is the same as that in Example 1, except that "0.5 g aminopropyl-isooctyl POSS" is replaced by "0.9 g aminopropyl-isooctyl POSS", and the remaining raw material amounts, stirring rate, ultrasonic time, pH adjustment, reaction temperature and post-treatment steps are kept consistent.

[0059] Test Example 1 Preparation of base slurry: 16 g of bentonite was slowly added to 400 mL of distilled water while stirring (600 r / min). After stirring for 20 min, the mixture was sealed and allowed to stand at room temperature for 24 h to obtain a 4% bentonite base slurry.

[0060] Preparation of drilling fluid samples: Take 400 mL of base slurry, add 4 g of the anti-collapse agent to be tested, stir at high speed (8000 r / min) for 20 min, and vacuum degassing to obtain a drilling fluid sample with an anti-collapse agent mass fraction of 1% for subsequent testing.

[0061] Drilling fluid compatibility was evaluated in accordance with the national standard GB / T 16783.1-2014, "Petroleum and Natural Gas Industry—Field Testing of Drilling Fluids, Part 1: Water-Based Drilling Fluids." The samples were tested for their effects on the rheological and fluid loss properties of the base fluid under high and low temperature conditions, as well as at ambient temperature and pressure, and high and high temperature and pressure. The high-temperature aging temperature was set at 200°C, representing the high-temperature bottomhole environment of deepwater wells. The low-temperature test temperature was 4°C, corresponding to the typical shallow temperature near the seafloor mudline. This allowed for a comprehensive assessment of the sample's impact on the rheological and fluid loss properties of the drilling fluid under deepwater conditions. The experimental results are shown in Table 1.

[0062] Table 1 Rheological filtration test results

[0063] As shown in Table 1, after aging at 200°C for 16 h, the apparent viscosity (AV), plastic viscosity (PV), and yield value (YP) of the base slurry further decreased from 7 mPa·s, 5 mPa·s, and 2 Pa, respectively, while the high-temperature, high-pressure (HTHP) fluid loss (FL) increased to 30 mL. After adding 1% of Example 1-5, the AV increased only slightly by 1–3 mPa·s and the YP increased by 0–1 Pa at 4°C. The base slurry still maintained good low-temperature rheological properties and controllable pumping resistance. The API fluid loss also decreased slightly to 13–15 mL, and even to 25–28 mL at 200°C / 3.5 MPa HTHP, demonstrating its considerable fluid loss reduction performance. Comparative Example 1 lacks POSS monomer modification, resulting in minimal rheological impact and a particle size mismatch with the API filter paper pore size, resulting in limited improvement in API and HTHP fluid loss. Comparative Example 3, in which the system pH is not adjusted, has low surface modification efficiency and performance close to that of the base slurry. Comparative Example 6 significantly increases low-temperature viscosity, with the low-temperature YP increasing from 3 Pa to 5 Pa, accompanied by a PV increase from 7 mPa·s to 20 mPa·s, leading to a significant increase in pump pressure for startup and maintenance cycles. In Comparative Example 7, cationic surfactants inhibit bentonite dispersion, increasing API fluid loss to 22 mL and HTHP fluid loss to 40 mL. Comparative Example 8 reduces the POSS addition to 4% of the nanoparticle mass, resulting in insufficient surface coverage and limited improvement in fluid loss. Comparative Example 9 increases the POSS addition to 18% of the nanoparticle mass, resulting in the appearance of free particles and a sudden increase in viscosity, which increases both pump pressure and fluid loss.

[0064] In summary, the anti-collapse agent of the present invention has limited effect on the rheological filtration properties of the base slurry, indicating that it has good compatibility with the drilling fluid.

[0065] Test Example 2 Nanopore plugging performance was tested according to the API ambient temperature fluid loss procedure outlined in the "Filtrate Determination" section of GB / T 16783.1-2014, "Petroleum and Natural Gas Industries—Field Testing of Drilling Fluids, Part 1: Water-Based Drilling Fluids." However, the conventional filter paper was replaced with polytetrafluoroethylene (PTFE) microporous membranes (47 mm diameter, 75% porosity) with nominal pore sizes of 100 nm, 200 nm, and 450 nm to simulate the nanoscale pore throats of deep cemented shales. The specific steps were as follows: 350 mL of the test solution (1 wt% by mass) was poured into the SD6A API fluid loss tester cup and filtered for 7.5 minutes at 0.7 MPa nitrogen pressure and (22 ± 2)°C. The volume of the filtrate that flowed out was measured, and the resulting value was the fluid loss for the membrane with the specified pore size.

[0066] Microporous membranes with pore sizes of 100 nm, 200 nm, and 450 nm were used to simulate nano-scale pore development formations, and the plugging performance of the examples and comparative examples was tested. The results are shown in Table 2.

[0067] Table 2 Microporous membrane blocking test results

[0068] As shown in Table 2, deionized water leaked completely through 100 nm, 200 nm, and 450 nm microporous membranes within a short time (over ten seconds). After adding 1% sample, the filtration losses of Examples 1-5 dropped to 65 / 45 / 72 mL, 78 / 52 / 76 mL, 80 / 55 / 78 mL, 62 / 40 / 70 mL, and 94 / 66 / 85 mL, respectively. This represents a reduction of over 70% compared to deionized water, demonstrating excellent nanoscale plugging performance. In contrast, the filtration losses of Comparative Example 1 on the three membranes remained high at 138 / 112 / 130 mL. While the filtration losses of Comparative Example 3 (which did not adjust the system pH and had low modification efficiency) decreased somewhat, they remained at 110 / 95 / 121 mL. Comparative Example 8, which reduced the POSS addition to 4% of the nanoparticle mass, exhibited insufficient surface coverage, resulting in filtration losses of 105 / 80 / 108 mL for the three pore sizes. While this was a slight improvement over deionized water, it was still significantly inferior to any of the examples. In comparative example 9, the amount of POSS added was increased to 18% of the mass of the nanoparticles, resulting in agglomeration of free colloid particles and particles, and the filtration loss increased to 128 / 97 / 132 mL, with the worst plugging effect.

[0069] In summary, the anti-collapse agent of the present invention has significant nanopore blocking ability.

[0070] Test Example 3 The evaluation of high-temperature, high-pressure plugging with ceramic sand discs was conducted in accordance with the "High-temperature, High-pressure Fluid Loss Determination" section of GB / T 16783.1-2014, "Petroleum and Natural Gas Industries—Field Testing of Drilling Fluids, Part 1: Water-Based Drilling Fluids," and combined with the supplementary provisions for pressure differential and sand disc materials in SY / T 6865-2021, "Calibration Method for Drilling Fluid Fluid Loss Testers." The test used 25 mm × 3.5 mm α-Al2O3 ceramic sand discs with pore sizes of 1 μm and 3 μm, respectively, and a porosity of 30% ± 5%.

[0071] Prepared drilling fluid samples were placed in a rolling aging tank and statically aged at 200°C for 16 hours. After cooling to room temperature, the samples were thoroughly stirred and immediately placed in the filter cup of an HTD-50 high-temperature, high-pressure filter loss instrument. A pre-dried ceramic sand tray was placed, and the sealing ring was installed and tightened. The filter loss instrument was placed in a heating furnace and heated to 200°C. Once the instrument temperature stabilized, a nitrogen pressure of 3.5 MPa (508 psi) was applied to the filter cup, while a backpressure of 0.69 MPa (100 psi) was simultaneously applied to the backpressure chamber to ensure that the filtrate passed through the sand tray at 200°C and a net pressure differential of 2.81 MPa. The filtrate volume was collected and read using a graduated cylinder after 30 minutes. This was the HTHP filter loss value, which was used to characterize the plugging effectiveness at 1 μm or 3 μm pore sizes.

[0072] Ceramic sand discs were used to simulate the micron-scale pore development environment of deepwater shale. Ceramic sand discs with different pore sizes were used to evaluate the plugging capacity of samples under high temperature and high pressure (200°C / 16h aging, 200°C / 3.5 MPa). The results are shown in Table 3.

[0073] Table 3 Ceramic sand disk plugging test results

[0074] As shown in Table 3, after adding 1% sample, the high-temperature, high-pressure fluid loss of Examples 1-5 on 1 µm and 3 µm sand discs decreased to 69-88 mL and 125-143 mL, respectively, significantly outperforming the base slurry (126 mL and 175 mL). In contrast, the fluid loss of Comparative Examples 1 and 3 at the same pore size only decreased to 101 / 157 mL and 96 / 150 mL, respectively, indicating limited plugging effectiveness. In Comparative Example 8, due to insufficient POSS (4%), surface coverage gaps appeared, resulting in fluid loss of 90 / 148 mL. In Comparative Example 9, due to excessive POSS (18%), free particles were generated and particle agglomeration was promoted, resulting in fluid loss of 110 / 160 mL.

[0075] In summary, the anti-collapse agent of the present invention has significant micron pore blocking ability.

[0076] Through the analysis of Experimental Examples 2 and 3, it can be found that POSS self-crosslinking modification can construct an organosiloxane network shell layer with both positive charge and hydrophobicity on the surface of the nanoparticles, so that the modified nanoparticles maintain excellent dispersion stability in water-based drilling fluid; the shell layer can be microscopically deformed and self-assembled to fill micro-nano pores under the action of pressure difference and shear, and quickly form a tight sealing layer; when POSS modification is not performed or the pH is not adjusted, the surface of the nanoparticles lacks a cross-linked network or has insufficient charge, the dispersibility is poor, the improvement in filtration loss is limited, and the sealing effect is significantly worse than that of the embodiment.

[0077] Test Example 4 Linear expansion tests were conducted according to the "Linear Expansion Rate Determination" section of NB / T 10121-2018, "Evaluation Method for Shale Inhibitory Properties of Drilling Fluids and Shale Inhibitor Performance." 10 g of bentonite was placed in a 25 mm diameter hydraulic die and pressed at 10 MPa for 5 minutes to produce a cylindrical specimen approximately 1 cm high. The specimen was then loaded into the measurement chamber of a CPZ-2 dual-channel linear dilatometer. After zero calibration, equal volumes of sample were then injected. Displacement sensor readings were continuously recorded for 24 hours at (25 ± 1)°C.

[0078] The 24-h linear expansion rate of bentonite was tested using a dual-channel linear expansion instrument to quantitatively evaluate the sample’s inhibitory effect on shale hydration expansion. The results are shown in Table 4.

[0079] Table 4 Linear expansion test results

[0080] As shown in Table 4, all examples can significantly inhibit the hydration expansion of bentonite: the linear expansion rate of 24 h is reduced to 32.80%~38.75%, which is about 40%~50% lower than the benchmark deionized water (67.23%). In comparison, the inhibitory effects of the comparative examples are significantly weaker: the expansion rates of comparative example 1 without adding POSS monomer, comparative example 2 without adding nano-silica, and comparative example 3 without adjusting the pH are still as high as 41.66%~58.60%; although 5% KCl (comparative example 4) and 1% commercial polyamine (comparative example 5) can reduce the expansion to a certain extent, they are still significantly higher than the embodiments; the expansion rate of the PAM system (comparative example 6) that mainly relies on adsorption is maintained at 57.8%, and the inhibitory effect is also limited. The modification with a long hydrophobic chain cationic surfactant (comparative example 7) has a general effect, with an expansion rate of 49.8%; when the amount of POSS is insufficient (comparative example 8), the surface coverage is incomplete, and the expansion rate is still 44.80%; and when POSS is excessive (comparative example 9), the inhibitory effect drops to 47.35% because the free colloids promote particle agglomeration.

[0081] In summary, the anti-collapse agent of the present invention exhibits excellent shale hydration expansion inhibition performance.

[0082] Test Example 5 To quantitatively evaluate the effectiveness of the samples in inhibiting shale hydration and dispersion, a rock chip rolling recovery experiment was conducted. 20 g of shale chips with a particle size of 6-10 mesh (approximately 2-3 mm) were weighed and injected into an aging tank with 350 mL of pre-prepared sample. After adding the chips, the sample was rolled and aged at 200°C for 16 h. After aging, the chips were removed, separated through a 40-mesh sieve, and dried in an oven to constant weight. Finally, by comparing the mass of the dried chips with the initial mass, the rolling recovery rate was calculated to evaluate the ability of each sample to inhibit shale dispersion. The results are shown in Table 5. The rock chip rolling recovery rate was calculated as follows:

[0083] Where R is the cuttings rolling recovery rate (%), m1 is the initial cuttings mass (g), and m2 is the cuttings mass after drying (g).

[0084] Table 5 Rolling recovery test results

[0085] As shown in Table 5, after adding 1% of Examples 1-5, the rock cuttings rolling recovery rate was maintained above 64%, which was significantly better than the comparative examples (19.70%~55.64%). Specifically, in Comparative Example 1, no POSS monomer was used for modification, and the recovery rate was only 27.85%; in Comparative Example 2, only POSS monomer self-crosslinking was relied upon, and the recovery rate dropped to 36.45%; in Comparative Example 3, the pH of the system was not adjusted, the degree of modification was insufficient, and the recovery rate was 45.68%; in Comparative Example 4, only cationic inhibition was provided, and the recovery rate was the lowest (19.70%); in Comparative Example 5, 1% polyamine solution was used, which could inhibit hydration dispersion to a certain extent, and the recovery rate was 55.64%, which was still lower than that of the embodiment; in Comparative Example 6, 1% PAM solution was used, and only the adsorption effect of amide groups was relied upon, and the recovery rate was only 40.35%; in Comparative Example 7, a long hydrophobic chain cationic surfactant was used for modification, and the recovery rate was only 50.23%; in Comparative Example 8, the amount of POSS was too low, the surface coverage was incomplete, the inhibition effect was limited, and the recovery rate was only 48.10%; in Comparative Example 9, POSS was excessive, free colloids were generated, and particle agglomeration was promoted, and the recovery rate further decreased to 47.25%.

[0086] In summary, the anti-collapse agent of the present invention exhibits excellent performance in inhibiting shale hydration and dispersion.

[0087] Test Example 6 The wetting properties of hydrophilic shale treated with various sample solutions were evaluated using the hanging drop method on an optical contact angle meter. Shale discs with a diameter of 2.5 cm were placed in a 350 mL aging jar and aged in an oven at 200°C for 16 hours. After cooling to room temperature and drying, the contact angles of each disc were recorded. The results are shown in Table 6.

[0088] The microscopic morphology of the shale slices after aging with deionized water and the sample with the anti-collapse agent of Example 1 was characterized by scanning electron microscopy and British atomic force microscopy, respectively. The results are as follows: Figures 1-8 shown.

[0089] Figure 1 This is a SEM image of a shale slice aged with deionized water at a magnification of 200 nm. Figure 1 It can be seen that the shale layers are slightly tilted along the bedding, and small pore throats and peeling cracks appear between the layers, which suggests that the pore size of the original rock is mainly concentrated in tens to hundreds of nanometers, and the natural surface is relatively rough. Figure 2 The following is an SEM image of a shale slice after aging treatment using the anti-collapse agent of Example 1 at the same magnification and the same sampling location. Figure 2 It can be seen that the originally clear interlayer gaps are filled with granular coatings, the pore throats are blocked by nanoparticles, and only a small amount of micropores remain, proving that the anti-collapse agent of the present invention can enter the nanoscale pores and form a sealing film in situ.

[0090] Figure 3 This is a SEM image of a shale slice aged with deionized water at a magnification of 20 µm. Figure 3 It can be seen that the shale bedding fissures, microcracks and pores of several microns in size are exposed and visible, and the overall surface presents a typical rough clastic texture. Figure 4 The following is an SEM image of a shale slice after aging treatment using the anti-collapse agent of Example 1 at the same magnification and the same sampling location. Figure 4 It can be seen that most cracks and holes are covered by continuous film, the interlayer interface is "bridged" by the film, and the overall surface changes from uneven to relatively dense and smooth, proving that the anti-collapse agent of the present invention can fill not only nano-pore throats but also micron-scale cracks.

[0091] Figure 5 This is a 2D AFM image of a shale slice after aging with deionized water. Figure 5 It can be seen that the color span is large, the peaks and valleys are obvious, and the Ra roughness is high, reflecting the high undulations and active water absorption sites of the unblocked surface. Figure 6 This is a 2D AFM image of a shale slice after aging treatment using the anti-collapse agent of Example 1 added to the same sampling location. Figure 6 It can be seen that the overall color distribution tends to be uniform, the peak-to-valley contrast is weakened, and the Ra value is significantly reduced, indicating that the anti-collapse agent of the present invention fills the surface defects at the nanometer level.

[0092] Figure 7 This is a 3D AFM image of a shale slice after aging with deionized water. Figure 7As can be seen in the figure, sharp peaks and deep valleys are visible, with the maximum peak-valley gap being tens of nanometers; these protrusions and pores together provide the shale with hydrophilic and easily swellable surface conditions. Figure 8 This is the 3D AFM image of the shale slice after aging treatment with the sample of the anti-collapse agent of Example 1 added at the same sampling location. Figure 8 It can be seen that the valleys are filled, the peaks are passivated, the peak-valley difference is reduced, the surface presents a step-like smooth platform, and the quantitative roughness is reduced by ≈40%, proving that the anti-collapse agent of the present invention can still maintain dense coverage after high-temperature aging.

[0093] Table 6 Contact angle test results

[0094] As shown in Table 6, after adding 1% of the anti-collapse agent of Examples 1-5, the shale water contact angle increased to more than 130°, with the highest reaching 142.25°, which is significantly better than the comparative examples (21.56°~101.42°). Comparative Example 1 does not introduce POSS monomer, and the contact angle is only 21.56°; Comparative Example 2 relies solely on POSS monomer and lacks nano-skeleton support, and the contact angle rises to 82.56°, still in the neutral wetting zone; Comparative Example 3 does not adjust the system pH, and the degree of modification is insufficient, with a contact angle of 93.28°, barely reaching the hydrophobic lower limit; Comparative Example 7 uses a long hydrophobic chain cationic surfactant for modification, with a contact angle of 95.27° and a general hydrophobic effect; Comparative Example 8 has an insufficient amount of POSS (4%) and incomplete surface coverage, with a contact angle of only 93.18°, still significantly lower than the examples; Comparative Example 9 has an excess of POSS (18%), generating free particles and promoting particle agglomeration, with a contact angle of 101.42°. It can be seen that the embodiments of the present invention are significantly effective in enhancing the hydrophobicity of the shale surface, while the performance of the comparative examples is significantly inferior to that of the embodiments due to the lack of a synergistic mechanism or incomplete modification.

[0095] At the nanoscale (200 nm), Figure 1 、 Figure 2 As shown in the figure, the shale surface after deionized water treatment still retains a layered exfoliation structure with obvious pores; however, after the sample treated with 1% of the anti-collapse agent of Example 1, these areas are filled with a particle coating and the pores are partially blocked. When the field of view is magnified to the micrometer scale (20 µm), as shown in the figure, Figure 3 、 Figure 4 As shown in Figure 2, most of the microcracks and micropores are also covered, and the surface tends to be dense. AFM height maps further quantify the roughness changes: deionized water treated samples (such as Figure 5 、 Figure 7 The surface peaks and valleys are obviously undulating; after the sample containing 1% anti-collapse agent of Example 1 is treated (as shown in FIG. Figure 6 、 Figure 8As shown in the figure, the peak-to-valley difference is reduced and the overall flatness is significantly improved, indicating that the anti-collapse agent of the present invention effectively plays an anti-collapse role through the synergistic effect of "blocking-adsorption-hydrophobicity".

[0096] Test Example 7 A shale cylindrical core with a length of 5 cm and a diameter of 2.5 cm was placed in an aging tank, and deionized water, each example solution, and comparative example solution were added, and aged at 200°C for 72 h. After the aging, a rock triaxial testing machine was used to test the core at a speed of 0.00125 mm·s -1 The uniaxial compression properties of the core were measured by loading with an axial displacement rate of 1.5 Å. The test results are listed in Table 7.

[0097] Table 7 Test results of uniaxial compressive strength of shale

[0098] As shown in Table 7, after adding 1% of Examples 1-5, the core uniaxial compressive strength remained at 90.28-98.35 MPa, and the overall compressive strength was basically maintained. In contrast, the strength of the comparative examples was only 52.36-80.45 MPa, which was significantly lower than that of the examples. Comparative Example 1 did not introduce POSS monomer and could not play a hydrophobic role. It relied solely on the blocking effect, and the strength dropped to 52.36 MPa; Comparative Example 2 only contained POSS monomer and lacked nano-skeleton support. It relied solely on the hydrophobic effect, and the strength was 60.32 MPa; Comparative Example 3 did not adjust the pH of the system, and the modification was insufficient, with a strength of 78.25 MPa; Comparative Example 7 was modified with a long hydrophobic chain cationic surfactant, with a strength of 80.13 MPa, and the shale strength remained average; In Comparative Example 8, the amount of POSS was insufficient, the surface was covered with gaps, and the strength was 80.45 MPa; In Comparative Example 9, there was an excess of POSS, and the free colloid particles caused the particles to agglomerate and produce brittle voids, and the strength dropped to 78.14 MPa.

[0099] In summary, the anti-collapse agent of the present invention exhibits excellent performance in maintaining the compressive strength of shale.

[0100] In summary, the POSS self-crosslinking nano anti-collapse agent prepared by organically modifying inorganic nanoparticles using POSS in the present invention has good compatibility with drilling fluid, significant micro-nano pore blocking ability, excellent shale hydration expansion inhibition performance and shale hydration dispersion inhibition performance, excellent hydrophobicity and excellent shale compressive strength, and can thus effectively solve the problem of well wall instability caused by rapid hydration of deepwater hydrophilic shale.

[0101] Application Example 1 The method for using the anti-slump agents prepared in Examples 1-5 in marine oil and gas drilling is as follows: the anti-slump agents are mixed with base slurry to prepare the drilling fluid used in marine oil and gas drilling. Preparation of base slurry: 16 g of bentonite was slowly added to 400 mL of distilled water while stirring (600 r / min). After stirring for 20 min, the mixture was sealed and allowed to stand at room temperature for 24 h to obtain a 4% bentonite base slurry.

[0102] Preparation of the anti-collapse drilling fluid system: take 400 mL of base slurry, add 4 g of anti-collapse agent, stir at high speed (8000 r / min) for 20 min, and obtain an anti-collapse drilling fluid system with an anti-collapse agent mass fraction of 1% after vacuum degassing.

[0103] The anti-collapse agent drilling fluid system prepared by the present invention is used in marine oil and gas drilling, which can effectively solve the problem of well wall instability caused by rapid hydration of deep-water hydrophilic shale.

[0104] Application Example 2 The method for using the anti-slump agents prepared in Examples 1-5 in marine oil and gas drilling is as follows: the anti-slump agents are mixed with base slurry to prepare the drilling fluid used in marine oil and gas drilling. Preparation of base slurry: 16 g of bentonite was slowly added to 400 mL of distilled water while stirring (600 r / min). After stirring for 20 min, the mixture was sealed and allowed to stand at room temperature for 24 h to obtain a 4% bentonite base slurry.

[0105] Preparation of the anti-collapse drilling fluid system: 400 mL of base slurry was added with 16 g of anti-collapse agent, stirred at high speed (8000 r / min) for 20 min, and vacuum degassed to obtain an anti-collapse drilling fluid system with an anti-collapse agent mass fraction of 4%.

[0106] The anti-collapse agent drilling fluid system prepared by the present invention is used in marine oil and gas drilling, which can effectively solve the problem of well wall instability caused by rapid hydration of deep-water hydrophilic shale.

[0107] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0108] It should be noted that, in the present application, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly specified.

[0109] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. An anti-collapse agent, characterized in that: It is prepared by in-situ self-crosslinking of POSS monomers on the surface of nanoparticles; wherein the mass of the POSS monomers is 5% to 15% of the mass of the nanoparticles; The POSS monomer includes one or more of aminopropyl-isooctyl POSS, aminopropyl-isodecyl POSS, aminoethyl-isooctyl POSS and diethylaminopropyl-phenyl POSS; The nanoparticles include one or more of nano-silicon dioxide, nano-zinc oxide and nano-calcium carbonate.

2. The anti-collapse agent according to claim 1, characterized in that The particle size of the nanoparticles is 20-50 nm.

3. A method for preparing the anti-collapse agent according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: S1, adding the nanoparticles to deionized water, stirring and ultrasonicating, and adjusting the pH of the system with an alkaline solution to prepare a uniform suspension; the alkaline solution includes one or more of ammonia water, potassium hydroxide solution, sodium hydroxide solution, sodium bicarbonate solution or triethanolamine solution; S2, in a protective gas atmosphere, under stirring conditions, adding the POSS solution dropwise to the suspension for reaction; after the reaction is completed, centrifuging and collecting the product; S3, post-processing the product to obtain the anti-collapse agent; the post-processing includes rinsing, drying and grinding; wherein the drying temperature is 50-80° C., and the drying time is 8-12 hours.

4. The method for preparing the anti-collapse agent according to claim 3, wherein: The ratio of the mass of the nanoparticles to the volume of the deionized water is 0.04-0.1 g:1 mL.

5. The method for preparing the anti-collapse agent according to claim 3, wherein: The preparation method of the POSS solution comprises: dissolving POSS monomer in an organic solvent to prepare the POSS solution; Wherein, the ratio of the mass of the POSS monomer to the volume of the organic solvent is 0.025-0.03 g:1 mL; and / or the organic solvent comprises anhydrous ethanol.

6. The method for preparing the anti-collapse agent according to claim 3, wherein: In step S1, the stirring speed is 200-450 rpm, and the stirring time is 20-30 min; and / or, in step S2, the stirring speed is 250-500 rpm.

7. The method for preparing the anti-collapse agent according to claim 3, wherein: Adjust the system pH to 8~11.

8. The method for preparing the anti-collapse agent according to claim 3, wherein: The time of the dropwise addition is 15 to 40 minutes.

9. The method for preparing the anti-collapse agent according to claim 3, wherein: The reaction temperature is 20-60° C., and the reaction time is 2-4 h.

10. The method for preparing the anti-collapse agent according to claim 3, wherein: The centrifugal speed is 8000-10000 rpm, and the centrifugal time is 10-30 min.

11. Use of the anti-collapse agent according to claim 1 or 2 or the anti-collapse agent prepared by the method according to any one of claims 3 to 10 in marine oil and gas drilling, characterized in that: The anti-collapse agent is mixed with base slurry to prepare a drilling fluid for marine oil and gas drilling, and the amount of the anti-collapse agent added is 1% to 4% of the mass of the base slurry.

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