Upy supermolecular grafted nano-liquid silicon anti-gas channeling agent, preparation method and application thereof

Abstract

This invention relates to the field of oilfield drilling admixtures technology, and proposes a supramolecular graft-modified nano-liquid silica anti-gas channeling agent, its preparation method, and its application. The anti-gas channeling agent is prepared by anchoring a UPy functionalized silane coupling agent onto the surface of nano-silica through a covalent grafting reaction using alkaline nano-silica sol as the matrix. The UPy functionalized silane coupling agent is prepared by reacting 2-amino-4-hydroxy-6-methylpyrimidine with γ-isocyanate propyltriethoxysilane in a molar ratio of 1:(1~1.05). The amount of Py functionalized silane coupling agent added is 5% to 20% of the dry silica mass in alkaline nano-silica sol; the solid content of the anti-gas channeling agent is 20% to 40%. This anti-gas channeling agent achieves functional modification of nano-liquid silicon through the dynamic reversible quadruple hydrogen bond characteristics and covalent grafting of the UPy group, realizing multi-dimensional and full-cycle anti-gas channeling effect in oil and gas wells, taking into account both the pumpability of cement slurry and the anti-gas channeling performance, while improving high-temperature stability and interfacial bonding strength, and adapting to the anti-gas channeling requirements of cementing under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of oilfield drilling admixtures technology, and more specifically, to UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent, its preparation method, and its application. Background Technology

[0002] In oil and gas field cementing operations, gas channeling is a core problem affecting cementing quality, leading to decreased oil and gas well productivity, and even well abandonment. As exploration and development extend to deeper, medium- and high-temperature wells, downhole conditions are becoming increasingly complex. The risk of gas channeling caused by weight loss of cement slurry during the cementing waiting stage is further aggravated, placing higher demands on anti-gas channeling admixtures.

[0003] Among the commonly used anti-gas channeling agents in oil well cement, nano-liquid silica has become a research hotspot in recent years due to its nanoscale effect and high pozzolanic activity. It can narrow the gas channeling risk window by filling pores and accelerating hydration. However, ordinary nano-liquid silica has significant drawbacks: it is prone to agglomeration and deactivation at high temperatures, its hydration activity is uncontrollable and can easily lead to flash setting of cement slurry, it can only achieve pore filling and cannot suppress interfacial micro-annulus, and it has poor compatibility with admixtures, making it difficult to adapt to the needs of deep wells.

[0004] In the existing technology, CN107129796A physically combines nano-liquid silicon with styrene-butadiene latex, but the two are prone to separation, and styrene-butadiene latex is prone to demulsification at high temperatures, making it unsuitable for high-temperature working conditions; CN111704389A uses a silane coupling agent to hydrophobically modify nano-silicon, but the modified layer has weak bonding force and is prone to falling off at high temperatures, still failing to overcome the core contradiction between low-viscosity pumping and high-viscosity anti-channeling, resulting in insufficient long-term anti-channeling capability.

[0005] To address the aforementioned shortcomings, the development of nano-liquid silica anti-gas channeling agents that combine pumpability and anti-channeling properties with high-temperature stability has become an urgent need for cementing in medium- and high-temperature deep wells. Summary of the Invention

[0006] In view of this, the present invention provides an UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent, its preparation method and application. This anti-gas channeling agent achieves functional modification of nano-liquid silicon through the dynamic reversible quadruple hydrogen bond characteristics of the UPy group and covalent grafting, realizing multi-dimensional and full-cycle anti-gas channeling effect in oil and gas wells, taking into account both cement slurry pumping workability and anti-gas channeling performance, while improving high-temperature stability and interfacial bonding strength, and adapting to the anti-gas channeling requirements of cementing under complex working conditions.

[0007] The technical solution of this invention is as follows: In a first aspect, the present invention provides an UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent, wherein the anti-gas channeling agent is prepared by anchoring UPy functionalized silane coupling agent on the surface of nano-silica through a covalent grafting reaction using alkaline nano-silica sol as the matrix. The UPy functionalized silane coupling agent was prepared by reacting 2-amino-4-hydroxy-6-methylpyrimidine with γ-isocyanate propyltriethoxysilane in a molar ratio of 1:(1~1.05). The amount of the UPy functionalized silane coupling agent added is 5% to 20% of the dry silica mass in the alkaline nano silica sol; The solid content of the anti-gas channeling agent is 20%~40%.

[0008] Furthermore, the alkaline nano-silica sol has a solid content of 20%~30%, an average particle size of 5~20nm, a pH value of 9~11, and a silica purity of ≥99%.

[0009] Furthermore, the preparation method of the UPy functionalized silane coupling agent is specifically as follows: Under anhydrous and oxygen-free conditions and nitrogen protection, the 2-amino-4-hydroxy-6-methylpyrimidine was dissolved in an anhydrous organic solvent, heated to the reaction temperature, stirred until completely dissolved, and γ-isocyanate propyltriethoxysilane and catalyst were slowly added dropwise to the system. After the addition was completed, the reaction was carried out at a constant temperature, and the UPy functionalized silane coupling agent was obtained through post-treatment.

[0010] Furthermore, the reaction temperature is 70~90℃, and the isothermal reaction time is 4~8h; The post-processing specifically involves: pouring the reaction solution after the isothermal reaction into an excess of ice-cold petroleum ether to precipitate the precipitate, followed by filtration, washing, and vacuum drying to obtain the UPy functionalized silane coupling agent.

[0011] Furthermore, the anhydrous organic solvent includes at least one of anhydrous N,N-dimethylformamide and anhydrous dimethyl sulfoxide; The amount of anhydrous organic solvent used is 8 to 15 times the mass of the 2-amino-4-hydroxy-6-methylpyrimidine.

[0012] Furthermore, the catalyst is dibutyltin dilaurate, and its addition amount is 0.05% to 0.2% of the total mass of the 2-amino-4-hydroxy-6-methylpyrimidine and the γ-isocyanate propyltriethoxysilane.

[0013] Secondly, based on the same inventive concept, this invention provides a method for preparing the UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent as described in any of the first aspects, comprising the following steps: The alkaline nano-silica sol was mixed with anhydrous ethanol, and the pH was adjusted to 10-11 to obtain a nano-silica sol dispersion. The air in the system was purged with nitrogen, and the temperature was raised to the grafting reaction temperature. The UPy functionalized silane coupling agent was dissolved in anhydrous ethanol and slowly added dropwise to the nano-silica sol dispersion. The reaction was carried out under constant temperature and stirring. Unreacted small molecules were removed by dialysis purification, and deionized water was added to adjust the solid content to obtain the anti-gas channeling agent.

[0014] Furthermore, the mass ratio of the alkaline nano-silica sol to the anhydrous ethanol is 1:(0.8~1.5); the pH adjustment is performed using at least one of triethylamine, ammonia, and sodium hydroxide solution; The nitrogen purging time is 20-30 minutes.

[0015] Furthermore, the grafting reaction temperature is 50~70℃, the constant temperature stirring reaction time is 6~12h, and the slow dropwise addition time is 0.5~2h; The dialysis purification process uses dialysis bags with a molecular weight cutoff of 8000~12000 Da, with a dialysis time of 12~36 h and deionized water as the dialysis medium.

[0016] Thirdly, based on the same inventive concept, this invention provides the application of the UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent described in the first aspect or the UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent prepared by the preparation method described in the second aspect in oil well cementing anti-gas channeling operations.

[0017] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. This invention utilizes UPy groups grafted onto the surface of nanoparticles to form a dynamic intermolecular cross-linking network in cement slurry through self-complementary quadruple hydrogen bonds, endowing the system with excellent shear response characteristics. Under pumping shear, the hydrogen bonds break reversibly, the system viscosity decreases rapidly, the initial consistency of the cement slurry is low, and the pumpability is excellent. During the annular static setting stage, the hydrogen bonds are rapidly rebuilt, forming a stable three-dimensional network that strongly binds free water and inhibits weight loss in the cement slurry. At the same time, combined with the pore-filling effect of the nano-core, it blocks gas channeling at the source, completely solving the contradiction that ordinary nano-liquid silica thickening inevitably compromises pumpability.

[0018] 2. This invention precisely controls the exposure rate of hydration active sites on the surface of nano-silica by utilizing the steric hindrance effect of the UPy group, avoiding the problem of significantly shortened cement slurry flash setting and thickening time caused by the high activity of ordinary nano-liquid silica; at the same time, the nano-core can still stably provide nucleation sites for cement hydration, significantly shortening the transition time of static cementitious strength of cement slurry, narrowing the gas channeling risk window to within 20 minutes, and the SPN anti-channeling coefficient can be as low as below 0.3.

[0019] 3. This invention utilizes the thermally reversible properties of UPy quadruple hydrogen bonds. Under high-temperature conditions, hydrogen bonds can undergo reversible breakage and reconstruction, achieving self-repair of the network structure and avoiding high-temperature agglomeration and deactivation of nanoparticles. At the same time, it offsets the viscosity loss and hydration performance degradation of cement slurry under high temperatures. Under high-temperature conditions, the product can still maintain a monodisperse state, and the cement slurry thickening time is stable, without high-temperature thickening or flash-setting problems.

[0020] 4. This invention achieves multi-dimensional gas channeling prevention through four mechanisms: nanoparticle pore filling, supramolecular network binding of free water, hydration regulation to narrow the gas channeling window, and interface bridging to inhibit micro-annular gaps. The UPy-grafted nanoparticles can bridge cement hydration products with the casing / formation rock surface, significantly improving the bonding strength of the first and second interfaces, inhibiting the formation of microcracks and micro-annular gaps caused by cement stone hydration shrinkage and temperature stress, and fundamentally solving the long-term problem of annular gas channeling.

[0021] 5. The product of this invention is a water-dispersible system, which has excellent compatibility with conventional AMPS-type fluid loss reducers, sulfonated dispersants, organophosphorus retarder and other oil well cement admixtures, and has no flocculation or stratification problems; the preparation process is simple and does not require special high-temperature and high-pressure equipment, and has strong industrialization feasibility and market competitiveness. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The thickening curve of the cement slurry in Test 4 of this invention at 80℃ × 46.5MPa is shown. Figure 2 The thickening curve of the cement slurry in Test 4 of this invention at 120℃ × 73.9MPa is shown. Figure 3 This is a thickening curve of the cement slurry in Test 4 of the present invention at 150℃ × 94.4MPa. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0026] To address the problems existing in the prior art, according to one aspect of the present disclosure, a supramolecular grafted modified nano-liquid silica anti-gas channeling agent is provided, which is prepared by anchoring UPy functionalized silane coupling agent on the surface of nano-silica through a covalent grafting reaction using alkaline nano-silica sol as the matrix. UPy functionalized silane coupling agent is prepared by reacting 2-amino-4-hydroxy-6-methylpyrimidine with γ-isocyanate propyltriethoxysilane in a molar ratio of 1:(1~1.05); The amount of UPy functionalized silane coupling agent added is 5% to 20% of the dry silica mass in the alkaline nano silica sol; The solid content of the anti-gas channeling agent is 20%~40%.

[0027] It should be noted that this invention uses nano-liquid silica as a matrix and anchors a silane coupling agent containing ureidopyrimidinone (UPy) quadruple hydrogen bond functional groups onto the surface of nano-silica through covalent grafting. The modified anti-gas channeling agent prepared by this method has UPy groups grafted onto the surface of nanoparticles that can form a dynamic intermolecular cross-linking network in cement slurry through self-complementary quadruple hydrogen bonds. This network has excellent shear response characteristics: under high-shear pumping conditions, hydrogen bonds break reversibly, and the viscosity of the system decreases rapidly, ensuring the pumpability of the cement slurry; under low-shear conditions of static setting in the annulus, hydrogen bonds are rapidly rebuilt, forming a stable three-dimensional network that strongly binds free water and inhibits the weight loss of the cement slurry. At the same time, in conjunction with the pore-filling effect of the nano-core, it blocks gas channeling channels from the source, solving the core contradiction that the thickening of ordinary nano-liquid silica inevitably compromises pumpability.

[0028] Meanwhile, the steric hindrance effect of the UPy group can precisely control the exposure rate of hydration active sites on the surface of nano silica, avoiding the problem of flash setting and significantly shortened thickening time of cement slurry caused by the high activity of ordinary nano liquid silica; and the thermally reversible properties of the UPy quadruple hydrogen bond can realize the self-repair of the network structure under high temperature environment, avoid the high temperature agglomeration and inactivation of nanoparticles, and ensure the performance stability of the product under medium and high temperature environment.

[0029] In some examples, the molar ratio of 2-amino-4-hydroxy-6-methylpyrimidine to γ-isocyanate propyltriethoxysilane can be selected from any value between 1 and (1 to 1.05); The solid content of the anti-gas channeling agent can be any value between 20% and 40%.

[0030] For example, the molar ratio of 2-amino-4-hydroxy-6-methylpyrimidine to γ-isocyanate propyltriethoxysilane includes, but is not limited to, 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04 or 1:1.05; The solid content of the anti-gas channeling agent includes, but is not limited to, 20%, 21%, 25%, 30%, 33%, 35%, 38% or 40%.

[0031] In some examples, the alkaline nano silica sol has a solid content of 20% to 30%, an average particle size of 5 to 20 nm, a pH value of 9 to 11, and a silica purity of ≥99%.

[0032] In some examples, the preparation method of UPy functionalized silane coupling agents is as follows: Under anhydrous and oxygen-free conditions and nitrogen protection, 2-amino-4-hydroxy-6-methylpyrimidine was dissolved in an anhydrous organic solvent, heated to the reaction temperature, and stirred until completely dissolved. γ-isocyanate propyltriethoxysilane and a catalyst were slowly added dropwise to the system. After the addition was completed, the reaction was carried out at a constant temperature, and the UPy functionalized silane coupling agent was obtained through post-treatment.

[0033] In some examples, the reaction temperature is 70~90℃, and the isothermal reaction time is 4~8h; The post-processing is as follows: the reaction solution after constant temperature reaction is poured into an excess of ice-cold petroleum ether to precipitate the precipitate, which is then filtered, washed, and vacuum dried to obtain UPy functionalized silane coupling agent.

[0034] In some examples, the anhydrous organic solvent includes at least one of anhydrous N,N-dimethylformamide and anhydrous dimethyl sulfoxide; The amount of anhydrous organic solvent used is 8 to 15 times the mass of 2-amino-4-hydroxy-6-methylpyrimidine.

[0035] In some examples, the catalyst is dibutyltin dilaurate, which is added at a rate of 0.05% to 0.2% of the total mass of 2-amino-4-hydroxy-6-methylpyrimidine and γ-isocyanate propyltriethoxysilane.

[0036] According to another aspect of the embodiments of this application, a method for preparing UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent is also provided, comprising the following steps: Alkaline nano-silica sol was mixed with anhydrous ethanol, and the pH was adjusted to 10-11 to obtain a nano-silica sol dispersion. The system was purged with nitrogen to remove air, and the temperature was raised to the grafting reaction temperature. UPy functionalized silane coupling agent was dissolved in anhydrous ethanol and slowly added dropwise to the nano-silica sol dispersion. The reaction was carried out under constant temperature and stirring. Unreacted small molecules were removed by dialysis purification, and deionized water was added to adjust the solid content to obtain an anti-gas channeling agent.

[0037] It should be noted that the raw materials used in this invention, such as 2-amino-4-hydroxy-6-methylpyrimidine (CAS No. 3977-29-5), γ-isocyanate propyltriethoxysilane (CAS No. 24801-88-5), and alkaline nano silica sol, are all commercially available industrial-grade products. Their preparation or synthesis methods have been disclosed in the prior art, and the products obtained by different preparation or synthesis methods can all be applied to the technical solution of this invention. The different preparation or synthesis methods will not affect the technical effect of this invention. Those skilled in the art can refer to the prior art to select a suitable method or purchase commercially available finished products for use without any creative effort. No limitation is made here.

[0038] In some examples, the mass ratio of alkaline nano-silica sol to anhydrous ethanol is 1:(0.8~1.5); The pH is adjusted using at least one of triethylamine, ammonia, or sodium hydroxide solution; the nitrogen purging time is 20-30 minutes.

[0039] Preferably, triethylamine is used to adjust the pH to avoid the introduction of strong electrolytes into the system, which could lead to the aggregation of nanoparticles.

[0040] In some examples, the grafting reaction temperature is 50~70℃, the constant temperature stirring reaction time is 6~12h, and the slow dropwise addition time is 0.5~2h; Dialysis purification was performed using dialysis bags with a molecular weight cutoff of 8000~12000 Da, with a dialysis time of 12~36 h and deionized water as the dialysis medium.

[0041] According to another aspect of the embodiments of this application, the application of the UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent as described in any one of the first aspects or the UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent prepared by the preparation method described in any one of the second aspects in oil well cementing anti-gas channeling operations is also provided.

[0042] In some examples, the anti-gas channeling agent is added to the oil well cement slurry at a rate of 0.5% to 1.5% of the total mass of the oil well cement slurry, and then injected into medium-high temperature deep wells with a bottom circulation temperature of 80 to 150°C for cementing anti-gas channeling operations.

[0043] In some examples, when the amount of anti-gas channeling agent added to the oil well cement slurry is 1%, the SPN anti-channeling coefficient of the oil well cement slurry is ≤0.32 and the static gel strength transition time is ≤18min under the conditions of 80℃ and 46.5MPa.

[0044] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0045] Example 1 This embodiment 1 provides a UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent and its preparation method. The preparation method includes the following steps: 2-Amino-4-hydroxy-6-methylpyrimidine (AHMP) was dried in a vacuum drying oven at 60°C for 12 h to remove water of crystallization. A four-necked flask was purged with nitrogen for 30 min to remove air and moisture. 100 mL of anhydrous N,N-dimethylformamide and 12.5 g of dried AHMP were added to the four-necked flask. The mixture was heated to 80°C and stirred until completely dissolved. 24.7 g of γ-isocyanate propyltriethoxysilane (IPTS) was slowly added dropwise over 30 min, along with 0.05 g of dibutyltin dilaurate catalyst. The mixture was stirred at 80°C for 6 h under nitrogen protection. After the reaction was completed, the reaction solution was cooled to room temperature and slowly poured into 500 mL of ice-cold petroleum ether. A white precipitate was formed. After filtration, the precipitate was washed three times with petroleum ether and dried under vacuum at 40°C for 12 h to obtain a white powdery UPy functionalized silane coupling agent.

[0046] Add 100g of alkaline nano-silica sol (30% solid content, 15nm average particle size, pH=9.5) and 100mL of anhydrous ethanol to a four-necked flask, stir well, add triethylamine to adjust the pH of the system to 10.5, purge with nitrogen for 20min, and heat to 60℃; dissolve 10g of the above-prepared UPy functionalized silane coupling agent in 50mL of anhydrous ethanol, and slowly add it dropwise to the nano-silica sol dispersion over 1h, and stir at 60℃ for 8h; after the reaction is complete, dialyze for 24h using a dialysis bag with a molecular weight cutoff of 10000Da to remove unreacted small molecules, add deionized water to adjust the solid content to 30%, and the UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent product is obtained.

[0047] Example 2 This embodiment 2 provides a UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent and its preparation method. The preparation method includes the following steps: 2-Amino-4-hydroxy-6-methylpyrimidine (AHMP) was dried in a vacuum drying oven at 60°C for 12 h to remove water of crystallization. A four-necked flask was purged with nitrogen for 30 min to remove air and moisture. 100 mL of anhydrous N,N-dimethylformamide and 12.5 g of dried AHMP were added to the four-necked flask. The mixture was heated to 80°C and stirred until completely dissolved. 24.7 g of γ-isocyanate propyltriethoxysilane (IPTS) was slowly added dropwise over 30 min, along with 0.05 g of dibutyltin dilaurate catalyst. The mixture was stirred at 80°C for 6 h under nitrogen protection. After the reaction was completed, the reaction solution was cooled to room temperature and slowly poured into 500 mL of ice-cold petroleum ether. A white precipitate was formed. After filtration, the precipitate was washed three times with petroleum ether and dried under vacuum at 40°C for 12 h to obtain a white powdery UPy functionalized silane coupling agent.

[0048] Add 100g of alkaline nano-silica sol (30% solid content, 15nm average particle size, pH=9.5) and 100mL of anhydrous ethanol to a four-necked flask, stir well, add triethylamine to adjust the pH of the system to 10.5, purge with nitrogen for 20min, and heat to 60℃; dissolve 5g of the above-prepared UPy functionalized silane coupling agent in 50mL of anhydrous ethanol, and slowly add it dropwise to the nano-silica sol dispersion over 1h, and stir at 60℃ for 8h; after the reaction is complete, dialyze for 24h using a dialysis bag with a molecular weight cutoff of 10000Da to remove unreacted small molecules, add deionized water to adjust the solid content to 30%, and the UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent product is obtained.

[0049] Example 3 This embodiment 3 provides an UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent and its preparation method. The preparation method includes the following steps: 2-Amino-4-hydroxy-6-methylpyrimidine (AHMP) was dried in a vacuum drying oven at 60°C for 12 h to remove water of crystallization. A four-necked flask was purged with nitrogen for 30 min to remove air and moisture. 100 mL of anhydrous N,N-dimethylformamide and 12.5 g of dried AHMP were added to the four-necked flask. The mixture was heated to 80°C and stirred until completely dissolved. 24.7 g of γ-isocyanate propyltriethoxysilane (IPTS) was slowly added dropwise over 30 min, along with 0.05 g of dibutyltin dilaurate catalyst. The mixture was stirred at 80°C for 6 h under nitrogen protection. After the reaction was completed, the reaction solution was cooled to room temperature and slowly poured into 500 mL of ice-cold petroleum ether. A white precipitate was formed. After filtration, the precipitate was washed three times with petroleum ether and dried under vacuum at 40°C for 12 h to obtain a white powdery UPy functionalized silane coupling agent.

[0050] Add 100g of alkaline nano-silica sol (30% solid content, 15nm average particle size, pH=9.5) and 100mL of anhydrous ethanol to a four-necked flask, stir well, add triethylamine to adjust the pH of the system to 10.5, purge with nitrogen for 20min, and heat to 60℃; dissolve 15g of the above-prepared UPy functionalized silane coupling agent in 50mL of anhydrous ethanol, and slowly add it dropwise to the nano-silica sol dispersion over 1h, and stir at 60℃ for 8h; after the reaction is complete, dialyze for 24h using a dialysis bag with a molecular weight cutoff of 10000Da to remove unreacted small molecules, add deionized water to adjust the solid content to 30%, and the UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent product is obtained.

[0051] Comparative Example 1 Comparative Example 1 provides an anti-gas channeling agent and its preparation method, which are basically the same as those in Example 1, except that the alkaline nano-silica sol from the same batch as in Example 1 is used without any modification treatment. The solid content is 30%, the average particle size is 15 nm, and the pH is 9.5, in order to verify the effect of the unmodified condition on the technical effect of the present invention.

[0052] Comparative Example 2 Comparative Example 2 provides an anti-gas channeling agent and its preparation method, which is basically the same as Example 1, except that an equal amount of UPy functionalized silane coupling agent hydrolysis product and alkaline nano silica sol are physically mixed and stirred evenly, with a solid content of 30%, and no covalent grafting reaction is performed, in order to verify the effect of the non-grafting condition on the technical effect of the present invention.

[0053] To better understand the present invention, the following performance evaluation tests of the anti-gas channeling agent were performed on the embodiments and comparative examples.

[0054] Test 1 Test 1 is a cement slurry performance test. According to the methods specified in GB / T 19139-2012 "Test Methods for Oil Well Cement" and SY / T6544-2017 "Performance Requirements for Oil Well Cement Slurry", cement slurry was prepared according to the formula. UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent (1% by mass) from the example and the anti-gas channeling agent from the comparative example were added respectively. A blank control group (cement slurry base slurry) was also set up. The experiment was conducted at a temperature of 80℃ and a pressure of 46.5MPa to test the performance of the cement slurry. The results are shown in Table 1.

[0055] The cement slurry sample formula is as follows: 800g Jiahua G-grade high-strength cement, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 1% anti-gas channeling agent, 2% AMPS copolymer water loss reducer, 0.1% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0056] The cement slurry base formula is: 800g Jiahua G-grade high-strength cement, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 2% AMPS copolymer water loss reducer, 0.1% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0057] Among them, microsilicon is a commercially available standard product with no special requirements.

[0058] Table 1 Comparison of Cement Grout Performance As shown in Table 1, the embodiments of the present invention, without shortening the cement slurry thickening time or affecting the construction window, exhibit significantly better anti-gas channeling performance than Comparative Example 1 (unmodified nano-liquid silicon) and Comparative Example 2 (physical blend system). Furthermore, the interfacial bonding strength is greatly improved, indicating that covalently grafted UPy groups can significantly enhance the anti-gas channeling performance of nano-liquid silicon. Only by anchoring the UPy groups to the surface of the nanoparticles through covalent bonds can the advantages of supramolecular dynamic cross-linking be stably utilized. Comparative examples also reveal that Example 1 exhibits the best overall performance, indicating that the amount of UPy functionalized silane coupling agent added also has a slight impact on product performance. Too little addition fails to form an effective supramolecular network, while too much addition leads to excessive steric hindrance of the nanoparticles, resulting in excessive shielding of hydration active sites and a slight decrease in performance.

[0059] Test 2 Test 2 is a performance test of the anti-gas channeling agent under different dosages. According to the methods specified in GB / T 19139-2012 "Test Methods for Cement in Oil Wells" and SY / T 6544-2017 "Performance Requirements for Cement Slurry in Oil Wells", cement slurry was prepared according to the formula, and UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent of Example 1 was added with a mass fraction of 0%, 0.5%, 1%, 1.5%, and 2% respectively. The experiment was conducted under the conditions of 80℃ and 46.5MPa to test its performance under different dosages. The results are shown in Table 2.

[0060] The cement slurry formula is as follows: 800g Jiahua G-grade high-strength cement, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, X% anti-gas channeling agent, 2% AMPS copolymer water loss reducer, 0.1% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0061] Among them, microsilicon is a commercially available standard product with no special requirements.

[0062] Table 2 Comparison of cement paste performance under different dosages As shown in Table 2, the anti-gas channeling agent prepared in Example 1 of this invention can effectively improve the anti-gas channeling performance of cement slurry within the dosage range of 0.5% to 2.0%. When the dosage is ≥0.5%, the SPN anti-gas channeling coefficient can be ≤1, meeting the industry standard requirements; when the dosage is ≥1.5%, the SPN anti-gas channeling coefficient can be lower than 0.3; and when the dosage exceeds 2%, the initial consistency of the cement slurry exceeds 30 Bc, which does not meet the requirements for on-site construction. This indicates that the optimal dosage range for the anti-gas channeling agent of this invention is 0.5% to 1.5%. Within this range, excellent anti-gas channeling effect can be achieved without causing the initial consistency of the cement slurry to exceed the standard or the thickening time to be excessively shortened, thus balancing workability and anti-gas channeling performance.

[0063] Test 3 Test 3 was the apparent viscosity test of the cement slurry. According to the methods specified in GB / T 19139-2012 "Test Methods for Oil Well Cement" and SY / T 6544-2017 "Performance Requirements for Oil Well Cement Slurry", the cement slurry was prepared according to the formula. 1% by mass of the UPy supramolecular grafted modified nano-liquid silica anti-gas channeling agent from Example 1 and the anti-gas channeling agent from Comparative Example 1 were added. A blank control group (cement slurry base slurry) was also set up. The apparent viscosity of the cement slurry at different shear rates was tested using a six-speed rotational viscometer at a temperature of 80℃. The results are shown in Table 3.

[0064] The cement slurry sample formula is as follows: 800g Jiahua G-grade high-strength cement, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 1% anti-gas channeling agent, 2% AMPS copolymer water loss reducer, 0.1% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0065] The cement slurry base formula is: 800g Jiahua G-grade high-strength cement, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 2% AMPS copolymer water loss reducer, 0.1% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0066] Among them, microsilicon is a commercially available standard product with no special requirements.

[0067] Table 3 Comparison of apparent viscosity of cement slurry at different shear rates (unit: mPa) s) As shown in Table 3, the anti-gas channeling agent prepared in Example 1 of this invention exhibits a significantly lower apparent viscosity than the ordinary nano-liquid silica of Comparative Example 1 at a high shear rate of 600 rpm (simulated pumping conditions), resulting in excellent cement slurry fluidity and low pumping resistance. At a low shear rate of 3 rpm (simulated annular static curing conditions), its apparent viscosity rapidly increases, becoming significantly higher than that of the ordinary nano-liquid silica of Comparative Example 1. This demonstrates that the present invention, by grafting UPy groups and leveraging the dynamic reversible nature of their quadruple hydrogen bonds, resolves the contradiction between pumpability and anti-gas channeling properties, achieving a balance between pumpability and static curing anti-gas channeling, thus addressing the pain point of ordinary nano-liquid silica where "viscosity increase inevitably compromises pumpability."

[0068] Test 4 Test 4 of this paper tests the core anti-channeling performance of cement slurry at different temperatures. According to the methods specified in GB / T 19139-2012 "Test Methods for Cement in Oil Wells" and SY / T 6544-2017 "Performance Requirements for Cement Slurry in Oil Wells", cement slurry was prepared according to the formula. The UPy supramolecular grafted modified nano-liquid silica anti-channeling agent of Example 1 was selected for the experiment. At the same time, a blank control group (the cement slurry formula does not contain anti-channeling agent) was set up. The experiment was conducted at temperatures of 80℃, 120℃ and 150℃ respectively to test the performance of the cement slurry. The results are shown in Table 4.

[0069] The 80℃ cement slurry formula is as follows: 800g Jiahua G-grade high-strength cement, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 1% anti-gas channeling agent, 2% AMPS copolymer water loss reducer, 0.1% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0070] The 120℃ cement slurry formula is as follows: 600g Jiahua G-grade high-strength cement, 35% silica fume, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 1.2% anti-gas channeling agent, 2.5% AMPS copolymer water loss reducer, 0.6% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0071] The 150℃ cement slurry formula is as follows: 600g Jiahua G-grade high-strength cement, 35% silica fume, 2% microsilica, 0.5% sulfonated ketone aldehyde condensate drag reducer, 1.5% anti-gas channeling agent, 3% AMPS copolymer water loss reducer, 1.2% polycarboxylate retarder, 0.2% polyether defoamer, and fresh water, with a density of 1.90g / cm³. 3 .

[0072] Among them, silicon powder and microsilicon are both commercially available conventional products with no special requirements.

[0073] Table 4 Comparison of core anti-channeling performance of cement slurry at different temperatures Please refer to Figure 1-3 As can be seen from the data in Figure 1 and Table 4, the anti-gas channeling agent prepared in Example 1 of this invention combines pumpability and anti-gas channeling properties, has no retarding side effects, and, thanks to the thermally reversible self-healing properties of its UPy quadruple hydrogen bonds, can maintain excellent dispersion stability and construction performance even at high temperatures, while maintaining excellent anti-gas channeling effects. As can be seen from the attached figures, after adding the anti-gas channeling agent prepared in Example 1, the cement slurry thickening curve is generally stable, without any abnormalities such as "bulging" or rapid decrease in consistency, indicating that Example 1 provided by this invention has good temperature resistance, good compatibility with oil well cement additives such as retarders, has basically no impact on the cement slurry thickening process, and has a wider temperature application range, which can meet the cementing needs under medium and high temperature conditions.

[0074] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0075] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. 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 invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A UPy supramolecular grafted nanofluidic silica anti-gas channeling agent, characterized in that, The gas channeling prevention agent is prepared by anchoring UPy functionalized silane coupling agent onto the surface of nano-silica through a covalent grafting reaction using alkaline nano-silica sol as the matrix. The UPy functionalized silane coupling agent was prepared by reacting 2-amino-4-hydroxy-6-methylpyrimidine with γ-isocyanate propyltriethoxysilane in a molar ratio of 1:(1~1.05). The amount of the UPy functionalized silane coupling agent added is 5% to 20% of the dry silica mass in the alkaline nano silica sol; The solid content of the anti-gas channeling agent is 20%~40%.

2. The gas channeling preventive agent according to claim 1, characterized by The alkaline nano-silica sol has a solid content of 20%~30%, an average particle size of 5~20nm, a pH value of 9~11, and a silica purity of ≥99%.

3. The gas channeling preventive agent according to claim 1, wherein The specific preparation method of the UPy functionalized silane coupling agent is as follows: Under anhydrous and oxygen-free conditions and nitrogen protection, the 2-amino-4-hydroxy-6-methylpyrimidine was dissolved in an anhydrous organic solvent, heated to the reaction temperature, stirred until completely dissolved, and γ-isocyanate propyltriethoxysilane and catalyst were slowly added dropwise to the system. After the addition was completed, the reaction was carried out at a constant temperature, and the UPy functionalized silane coupling agent was obtained through post-treatment.

4. The gas channeling preventive agent according to claim 3, characterized by The reaction temperature is 70~90℃, and the isothermal reaction time is 4~8h; The post-processing specifically involves: pouring the reaction solution after the isothermal reaction into an excess of ice-cold petroleum ether to precipitate the precipitate, followed by filtration, washing, and vacuum drying to obtain the UPy functionalized silane coupling agent.

5. The gas channeling preventive agent according to claim 3, characterized by The anhydrous organic solvent includes at least one of anhydrous N,N-dimethylformamide and anhydrous dimethyl sulfoxide; The amount of anhydrous organic solvent used is 8 to 15 times the mass of the 2-amino-4-hydroxy-6-methylpyrimidine.

6. The gas channeling preventive agent according to claim 3, wherein The catalyst is dibutyltin dilaurate, and its addition amount is 0.05% to 0.2% of the total mass of the 2-amino-4-hydroxy-6-methylpyrimidine and the γ-isocyanate propyltriethoxysilane.

7. A method of preparing the UPy supramolecular grafted nanofluidic silica anti-gas channeling agent of any one of claims 1-6, characterized in that, Includes the following steps: The alkaline nano-silica sol was mixed with anhydrous ethanol, and the pH was adjusted to 10-11 to obtain a nano-silica sol dispersion. The air in the system was purged with nitrogen, and the temperature was raised to the grafting reaction temperature. The UPy functionalized silane coupling agent was dissolved in anhydrous ethanol and slowly added dropwise to the nano-silica sol dispersion. The reaction was carried out under constant temperature and stirring. Unreacted small molecules were removed by dialysis purification, and deionized water was added to adjust the solid content to obtain the anti-gas channeling agent.

8. The method according to claim 7, characterized in that, The mass ratio of the alkaline nano-silica sol to the anhydrous ethanol is 1:(0.8~1.5); The pH adjustment is performed using at least one of triethylamine, ammonia, and sodium hydroxide solution. The nitrogen purging time is 20-30 minutes.

9. The method according to claim 7, characterized in that, The grafting reaction temperature is 50~70℃, the constant temperature stirring reaction time is 6~12h, and the slow dropwise addition time is 0.5~2h; The dialysis purification process uses dialysis bags with a molecular weight cutoff of 8000~12000 Da, with a dialysis time of 12~36 h and deionized water as the dialysis medium.

10. The application of any one of the UPy supramolecular grafted modified nano-liquid silicon anti-gas channeling agent according to claims 1-6 in oil well cementing anti-gas channeling operations.

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