A water lock preventive for drilling fluid, a preparation method thereof, a water-based drilling fluid containing the same, and application thereof in oil and gas exploitation

Abstract

This invention discloses a waterproofing lockant for drilling fluids, its preparation method, a water-based drilling fluid containing the lockant, and its application in oil and gas extraction. The preparation method of the waterproofing lockant includes: in the presence of a catalyst, reacting dialdehyde starch with a terminal alkyne compound via a nucleophilic addition reaction to obtain an intermediate product M, followed by an alkoxylation reaction and impurity removal treatment to obtain the waterproofing lockant. The waterproofing lockant's molecular chain contains polyoxyethylene and / or polyoxypropylene groups, which, through the synergistic effect of hydration film shielding, steric hindrance, and induction, endow the product with excellent temperature resistance. Simultaneously, it does not possess the amphiphilic structure of traditional surfactants, fully extending and hydrating in aqueous solutions, exhibiting non-foaming or low-foaming properties. This invention also provides a water-based drilling fluid containing the waterproofing lockant and its application in oil and gas extraction, particularly suitable for high-temperature reservoir drilling operations in deep and ultra-deep unconventional oil and gas resources. The waterproofing lockant has the following structure:

Description

Technical Field

[0001] This invention relates to the field of petroleum engineering technology, specifically to the field of oilfield chemistry, and particularly to a waterproof locking agent for drilling fluid, its preparation method, a water-based drilling fluid containing the agent, and its application in oil and gas extraction. Background Technology

[0002] In drilling operations, when the working fluid comes into contact with reservoir rocks and fluids, the "water-locking effect" often leads to a severe decrease in reservoir permeability, which greatly restricts the economic and efficient development of oil and gas fields.

[0003] The physicochemical essence of the water-locking effect lies in the capillary action of porous media. When external aqueous fluids invade reservoir pores, they form menisci at the pore throats, generating significant capillary resistance. For low-permeability and ultra-low-permeability reservoirs, the pore throat radius is generally in the micrometer to nanometer range, and the capillary pressure can reach several megapascals or even tens of megapascals, far exceeding the reservoir's own driving pressure gradient. This causes formation water or bound water to be locked in the pores, hindering the migration of oil and gas into the wellbore. This phenomenon is particularly prominent in unconventional resources such as shale gas, tight oil, and coalbed methane, because these reservoirs not only have small pore throats but also often have well-developed natural fractures, resulting in more severe water-locking damage. In addition, water-based drilling fluids are often used during drilling and completion. The intrusion of their filtrate, the blockage of solid particles, and the hydration expansion of water-sensitive clay minerals all couple with the water-locking effect, exacerbating reservoir damage.

[0004] The mechanism of action of waterproofing lockers is designed to address the aforementioned problems, and their molecular structure is essentially the same as that of surfactants. These surfactants primarily reduce capillary resistance by lowering the interfacial tension between oil and water or the surface tension between gas and water, thereby altering the wettability of the rock surface. An ideal waterproofing locker should be able to transform the rock surface from a hydrophilic to a hydrophobic or neutral wettable state, reducing the retention capacity of the aqueous phase at the pore throat, while simultaneously enhancing the effective permeability of the oil or gas phase. From a molecular structure perspective, waterproofing lockers are typically composed of hydrophobic carbon chains and hydrophilic groups. Depending on reservoir temperature, salinity, fluid properties, and other conditions, nonionic, anionic, cationic, or amphoteric surfactants are selected, or synergistic effects are achieved through compounding. In terms of technological development, early waterproofing treatments mainly relied on conventional surfactants and alcohol-based additives. While these had some effect, they suffered from poor temperature and salt resistance, short action time, and poor compatibility with drilling fluid systems.

[0005] In recent years, with unconventional low-permeability oil and gas becoming the main focus of exploration and development, water-locking agents have been developing towards multifunctionality and high performance. In particular, fluorocarbon-based compound water-locking agents, primarily composed of fluorocarbon surfactants, have become a research focus. For example, the article "Experimental Study on Water-Locking Agents for Low-Permeability Gas Reservoirs in Jilin Oilfield," published in the 2014 issue of *Journal of Petroleum and Natural Gas* (Vol. 36, No. 6), reported a water-locking agent composed of KCl, fluorocarbon surfactant FC-3B, and methanol, which significantly mitigated the self-absorption of water in the core. In 2019, the article "Research and Application of New Water-Locking Agents for Low-Permeability Reservoirs," published in the 2019 issue of *Fault-Block Oil and Gas Fields* (Vol. 26, No. 4), reported a novel water-locking agent, DF-FSS02, which is also a compound fluorocarbon water-locking agent. When its mass fraction was 0.1%, the surface and interfacial tension decreased by 56.92% and 86.52%, respectively, demonstrating a good effect in reducing water-locking damage. However, fluorocarbon-based waterproofing sealants have a strong foaming effect, which can easily cause significant fluctuations in drilling fluid density and poor environmental compatibility. Therefore, it is necessary to develop fluorine-free waterproofing sealants to meet the actual technical requirements of on-site construction.

[0006] In 2023, the article "Development and Performance Evaluation of a Novel Waterproofing Agent for Low-Permeability Reservoirs" in Volume 42, Issue 12 of *Petrochemical Applications* only introduced a fluorine-free surfactant prepared from higher fatty acids and diethanolamine, which was then compounded with a cationic surfactant (YB-1) and an organosilicon defoamer (Desiel) to obtain a novel fluorine-free waterproofing agent. Test results showed that this agent could reduce the gas-liquid surface tension to below 15 mN / m and exhibited good temperature and salt resistance, but its environmental performance was not evaluated. In the same year, the article "An Environmentally Friendly Foam-Free Waterproofing Agent" in Volume 40, Issue 4 of *Drilling Fluids and Completion Fluids* reported a naturally modified waterproofing agent, SMFS-1, which has a temperature resistance up to 120℃, almost no foaming effect, and excellent environmental performance.

[0007] In summary, although significant progress has been made in the research of existing waterproofing agents, key performance shortcomings still exist in the face of increasingly harsh high-temperature and high-pressure conditions in the development of deep and ultra-deep unconventional oil and gas resources. Therefore, for ultra-deep high-temperature reservoirs, there is an urgent need to develop new waterproofing agents that combine excellent high-temperature resistance, non-foaming properties, and environmental friendliness to ensure reservoir protection effectiveness and the safe and efficient implementation of drilling operations under complex conditions. Summary of the Invention

[0008] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the invention.

[0009] The purpose of this invention is to solve the problems of weak temperature resistance, strong foaming effect and poor environmental compatibility of existing waterproofing agents, and to provide a natural modified starch-based waterproofing agent. This invention also provides a method for preparing and applying the natural modified starch-based waterproofing agent.

[0010] To solve the above-mentioned technical problems, one of the objectives of this invention is to provide a waterproof locking agent for drilling fluids, having a structure as shown in Formula I: ; Formula I Among them, R0 is selected from C3 to C4. 16 Alkyl groups, C3-C6 cycloalkyl groups, phenyl groups, C7-C6 cycloalkyl groups 12 Benzyl or C7-C 12 Alkylphenyl groups, preferably C3-C8 alkyl groups; And / or, R 11 R 12 and R 13 They are respectively or One of them.

[0011] Where m is the polyoxyethylene chain length, i.e. the degree of polymerization of polyoxyethylene; n represents the polyoxypropylene chain length, i.e., the degree of polymerization of polyoxypropylene.

[0012] In the specific molecular structure, m is any integer from 1 to 16, and n is any integer from 1 to 12.

[0013] According to one embodiment of the present invention, due to R in each waterproofing molecule 11 R 12 and R 13 Since the lengths of the polyethylene oxide chain and the polypropylene oxide chain are different, this invention provides m′ and n′ as the average lengths of the polyethylene oxide chain or the polypropylene oxide chain in the waterproofing agent molecular chain, respectively, which are respectively used as the number-average degree of polymerization of each corresponding polyether group in the waterproofing agent molecule.

[0014] Understandably, m′ represents the average length of the polyethylene oxide chain in the waterproofing agent molecule, i.e., the average degree of polymerization of the polyethylene oxide chain or the number-average degree of polymerization of the polyethylene oxide chain. n′ represents the average length of the polypropylene oxide chain in the waterproofing agent molecule, i.e., the average degree of polymerization of the polypropylene oxide chain or the number-average degree of polymerization of the polypropylene oxide chain.

[0015] According to one embodiment of the present invention, m′ is an integer or decimal of 1 to 8, and n′ is an integer or decimal of 1 to 6.

[0016] According to one embodiment of the present invention, in a strict molecular structural formula, the subscript indicating the number of repeating units must be an integer, such as m or n. If the number of repeating units is indicated by a decimal, it indicates that the chemical formula represents an average composition, rather than the precise molecular formula of a single compound. In the present invention, m′ represents the average number of polyoxyethylene chain groups in each grafted structural unit of the waterproofing molecule, instead of the specific number of polyoxyethylene chain groups in each grafted structural unit of the waterproofing molecule chain, i.e., the value of m; n′ represents the average number of polyoxypropylene chain groups in each grafted structural unit of the waterproofing molecule, instead of the specific number of polyoxypropylene chain groups in each grafted structural unit of the waterproofing molecule chain, i.e., the value of n;

[0017] Specifically, the formula for calculating m′ is: ; Where m′ is the average degree of polymerization of the polyoxyethylene chain; M n This is the number-average molecular weight of the waterproofing agent, which is the arithmetic mean of the molecular weights of all molecules. M 端基，EO The molecular weight of the end group, i.e. The sum of the molecular weights of H atoms at the ends of the polyoxyethylene chain.

[0018] M EO This represents the molecular weight of the polyoxyethylene structural unit.

[0019] The formula for calculating n′ is: ; Where n′ is the average degree of polymerization of the polyoxypropylene chain; M n′ This is the number-average molecular weight of the waterproofing agent, which is the arithmetic mean of the molecular weights of all molecules. M 端基，PO The molecular weight of the end group, i.e. The sum of the molecular weights of H atoms at the ends of the polyoxypropylene chain.

[0020] M PO is the molecular weight of the polyoxypropylene structural unit.

[0021] The second objective of this invention is to provide a method for preparing the waterproofing agent, comprising the following steps:

[0022] The preparation method includes reacting dialdehyde starch with a terminal alkyne compound of formula i via nucleophilic addition in the presence of catalyst A to obtain intermediate product M, followed by alkoxylation reaction and impurity removal to obtain a waterproofing lock-in agent.

[0023] ; Formula i.

[0024] According to one embodiment of the present invention, the degree of aldehyde of the dialdehyde starch used in the preparation method provided by the present invention is 60% to 97.5%.

[0025] According to one embodiment of the present invention, the number-average molecular weight (Mn) of the dialdehyde starch used in the preparation method provided by the present invention is 2000-12000 g / mol.

[0026] The molecular chain of the dialdehyde starch used in the preparation method provided by this invention has a molecular weight of 162.14 g / mol for the unoxidized unit (protostarch glucose unit) and 160.12 g / mol for the oxidized unit (dialdehyde structural unit).

[0027] According to one embodiment of the present invention, the number-average molar mass of the dialdehyde starch used in the preparation method provided by the present invention is defined as the value obtained by dividing the mass of the dialdehyde starch by its number-average molecular weight.

[0028] According to one embodiment of the present invention, the raw material used to prepare dialdehyde starch is one of cassava starch, corn starch, potato starch, yam starch or wheat starch.

[0029] According to one embodiment of the present invention, the catalyst used in the preparation method provided by the present invention is selected based on the following criteria: it can promote the deprotonation of terminal alkynes to generate alkyne carbanions, thereby realizing the nucleophilic addition reaction of alkyne anions to dialdehyde starch.

[0030] According to one embodiment of the present invention, the catalyst A is selected from at least one of KOH, NaNH2, potassium isobutoxide, potassium tert-butoxide, butyllithium, phenyllithium, and ethyl magnesium bromide.

[0031] The reaction of this invention is a reaction that uses terminal alkyne compounds and dialdehyde starch to prepare corresponding alkyne alcohol compounds. It is a nucleophilic addition reaction, namely the Favorskii reaction.

[0032] According to a specific embodiment of the present invention, the reaction method of the terminal alkyne compound and the dialdehyde starch includes: adding catalyst A to solvent A, controlling the temperature to the reaction temperature, adding the terminal alkyne compound under an inert atmosphere, adding dialdehyde starch under stirring conditions, raising the temperature, and continuing the nucleophilic addition reaction.

[0033] According to one embodiment of the present invention, the nucleophilic addition reaction includes the following steps: Step 1: Mix catalyst A with solvent A to obtain reaction solution I; Step 2: Control the temperature to T1, introduce N2, add the terminal alkyne compound to the reaction solution I, stir for a certain time t1, add dialdehyde starch, raise the temperature to the reaction temperature T2, and continue the reaction under stirring for a period of time t2 to obtain the intermediate product M, and the reaction ends.

[0034] According to one embodiment of the present invention, in the first step, the catalyst A is selected from at least one of KOH, NaNH2, potassium isobutoxide, potassium tert-butoxide, butyllithium, phenyllithium, and ethyl magnesium bromide.

[0035] According to one embodiment of the present invention, in the first step, the solvent A is selected from at least one of tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and 1,2-dimethoxyethane (DME).

[0036] According to one embodiment of the present invention, in the second step, the reaction temperature T1 is -15℃ to 0℃.

[0037] According to one embodiment of the present invention, in the second step, the mass percentage concentration of the terminal alkyne compound in reaction solution I is 1% to 20%, preferably 4% to 8%.

[0038] According to one embodiment of the present invention, in the first and second steps, the molar ratio of the terminal alkyne compound to catalyst A is 1:(0.1 to 0.3).

[0039] According to one embodiment of the present invention, in the second step, the time t1 is 0.5 to 1.5 h.

[0040] According to one embodiment of the present invention, in the second step, the reaction temperature T2 is 10℃~45℃.

[0041] According to one embodiment of the present invention, in the second step, the ratio of the number-average molar amount of the dialdehyde starch to the molar amount of the terminal alkyne compound is 1:(18-72).

[0042] According to one embodiment of the present invention, in the second step, the time t2 is 6 to 36 hours, preferably 12 to 24 hours.

[0043] According to one embodiment of the present invention, after the reaction is completed, a quenching reaction is also performed.

[0044] According to one embodiment of the present invention, the quenching reaction includes the following operations: Step 1: Add 0°C water to the reaction solution after the second step reaction is completed, and stir continuously for a certain time t3.

[0045] Step 2: Under stirring conditions, add an acidic solution to adjust the pH value of the reaction solution.

[0046] According to one embodiment of the present invention, in step 1, the volume of the water is 1 to 3 times that of solvent A.

[0047] According to one embodiment of the present invention, in step 1, the time t3 is 0.5 to 1 hour.

[0048] According to one embodiment of the present invention, in step 2, the acidic solution is selected from at least one of 2% to 5% dilute hydrochloric acid, 2% to 5% dilute sulfuric acid, saturated NH4Cl aqueous solution, saturated (NH4)2SO4 aqueous solution, saturated NaH2PO4 aqueous solution, 10% to 30% acetic acid aqueous solution, and saturated citric acid aqueous solution.

[0049] According to one embodiment of the present invention, in step 2, the pH value is in the range of 7 to 8.

[0050] To obtain a high-purity intermediate product M, the preparation method of intermediate product M provided by the present invention further includes a deep purification operation, namely, recrystallization to remove impurities from the product obtained by the synthesis reaction.

[0051] According to one embodiment of the present invention, the operation steps of the recrystallization and impurity removal operation are as follows: first, the solvent is removed by vacuum distillation, and then the product is rinsed with water to obtain the crude product of intermediate product M; then, the crude product is dissolved in ethanol at 60°C to prepare a solution with a mass percentage concentration of 50%, and the temperature is lowered to -25°C to -10°C, at which point a solid precipitates out. After filtration, the product is rinsed with ethanol and acetone respectively, and then vacuum dried to constant weight to obtain the purified intermediate product M.

[0052] According to one embodiment of the present invention, the alkoxylation reaction includes the following steps:

[0053] Intermediate product M was dissolved in solution A, catalyst B was added, and the mixture was stirred at a constant temperature for a certain time t4 under inert gas protection. The temperature was then raised to the reaction temperature T3, and epoxide was continuously introduced into the reaction solution while controlling the pressure. The reaction was continued under stirring. After a period of time t5, the mixture was cooled to room temperature and distilled under reduced pressure to remove the solvent. The obtained solid was prepared into a 30% aqueous solution, neutralized with a neutralizing agent, and then activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at temperature T4 for a certain time t6, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant.

[0054] According to one embodiment of the present invention, solution A is selected from ethanol solution.

[0055] Preferably, a 20wt% to 40wt% aqueous ethanol solution is used.

[0056] According to one embodiment of the present invention, the intermediate product M has a mass percentage concentration of 8% to 16% in solution A.

[0057] According to one embodiment of the present invention, the catalyst B is one of NaOH, KOH, triethylamine, boron trifluoride diethyl ether complex, p-toluenesulfonic acid, sulfuric acid, or trifluoromethanesulfonic acid.

[0058] According to a preferred embodiment of the present invention, the mass percentage concentration of catalyst B in solution A is 1.5% to 3%.

[0059] According to a preferred embodiment of the present invention, the time t4 is 2 to 4 hours.

[0060] According to a preferred embodiment of the present invention, the inert gas is N2 or Ar.

[0061] According to a preferred embodiment of the present invention, the reaction temperature T3 is 50–80°C.

[0062] According to one embodiment of the present invention, when catalyst B is NaOH, KOH or triethylamine, the epoxide is ethylene oxide; when catalyst B is boron trifluoride diethyl ether complex, p-toluenesulfonic acid, sulfuric acid or trifluoromethanesulfonic acid, the epoxide is propylene oxide.

[0063] According to one embodiment of the present invention, the controlled pressure is 0.2 to 0.6 MPa.

[0064] According to one embodiment of the present invention, the reaction time t5 is 6 to 12 hours.

[0065] According to one embodiment of the present invention, when catalyst B is NaOH, KOH or triethylamine, the neutralizing agent is one of 20%–30% acetic acid solution, 2%–5% hydrochloric acid or 2%–5% sulfuric acid; when catalyst B is boron trifluoride diethyl ether complex, p-toluenesulfonic acid, sulfuric acid or trifluoromethanesulfonic acid, the neutralizing agent is one of 5%–10% NaOH solution or 5%–10% KOH solution.

[0066] According to one embodiment of the present invention, the neutralization is to neutralize to pH 7-8.

[0067] According to one embodiment of the present invention, the mass of the activated carbon is 1% to 3% of the mass of the intermediate product M.

[0068] According to one embodiment of the present invention, the temperature T4 is 40 to 60°C.

[0069] According to one embodiment of the present invention, the time t6 is 4 to 8 hours.

[0070] A third objective of this invention is to provide an application of a waterproofing agent prepared by a method described in one objective of this invention or a method described in another objective of this invention in oil and gas extraction, preferably in the drilling process of oil and gas extraction; more preferably, in the application as a waterproofing agent for drilling fluid during the drilling process of oil and gas extraction.

[0071] This invention provides the application of the above-mentioned waterproofing agent in the field of petroleum engineering, preferably by adding the waterproofing agent to water-based drilling fluid.

[0072] The fourth objective of this invention is to provide a drilling fluid comprising the waterproofing agent described in the first objective of this invention, or the waterproofing agent prepared by the method described in the second objective of this invention.

[0073] In this invention, there is no particular limitation on the amount of the waterproofing agent added to the water-based drilling fluid. It can be appropriately adjusted according to the formation conditions, drilling fluid performance, drilling site requirements, etc. For example, the amount of the waterproofing agent can be 0.2wt% to 2.0wt% based on the total amount of the water-based drilling fluid.

[0074] In this invention, there are no particular limitations on the type of water-based drilling fluid. Types of water-based drilling fluids well-known to those skilled in the art can be used, including but not limited to bentonite drilling fluid systems, potassium amine-based drilling fluid systems, polymer anti-collapse drilling fluid systems, sulfonated drilling fluid systems, polysulfonated drilling fluid systems, KCl drilling fluid systems, brine drilling fluid systems, amine-polysulfonated drilling fluid systems, silicate drilling fluid systems, and oil-in-water drilling fluid systems. Further details are omitted here. Specific operations are listed in this document and should not be construed as limitations on the invention.

[0075] In this invention, there are no particular limitations on the pH range, rheological properties, inhibition properties, lubrication properties, and plugging properties of the water-based drilling fluid to which the waterproofing lock agent is applicable. The pH range, rheological properties, inhibition properties, lubrication properties, and plugging properties of the water-based drilling fluid can be adjusted according to the actual drilling conditions before adding the waterproofing lock agent. For example, the pH of the water-based drilling fluid can be adjusted to 9-11 before adding the waterproofing lock agent.

[0076] The substances and parameters not limited in this invention can be selected according to existing technology, which is a conventional technical means in this field.

[0077] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0078] Compared with the prior art, the present invention has achieved the following beneficial effects: Firstly, it exhibits excellent temperature resistance. The waterproofing agent provided by this invention is a natural modified starch-based treatment agent. Its polyether groups in the molecular chain possess extremely strong negative charge and hydration capabilities, enabling them to bind a large amount of free water through hydrogen bonding and electrostatic adsorption, forming a dense and thick hydration film around the starch molecular chain. This hydration film remains stable at high temperatures, acting as a physical shield to isolate the direct attack of high temperatures on glycosidic bonds and prevent the molecular chain from breaking due to intense thermal motion. Simultaneously, the introduced large-volume side chains generate a steric hindrance effect, hindering the high-temperature degradation of glycosidic bonds; the polyether groups, as weak electron-withdrawing groups, stabilize adjacent carbon atoms through an inductive effect, improving the molecular chain's resistance to free radical attack and thermal degradation. These synergistic effects enable the waterproofing agent of this invention to maintain a core permeability recovery rate of over 80% even at 140℃, significantly superior to existing products.

[0079] Secondly, it exhibits no or low foaming characteristics. The waterproofing agent of this invention does not possess the typical structure of traditional surfactants with a "hydrophilic head + hydrophobic tail." In aqueous solutions, it tends to fully extend and hydrate rather than be directionally adsorbed at the gas-liquid interface. Due to the lack of hydrophobic segments that are stably anchored at the interface, its ability to reduce surface tension is limited, making it difficult to form an elastic film that can stably encapsulate air bubbles. Furthermore, unlike low-molecular-weight surfactants that can tightly arrange themselves at the gas-liquid interface, the large molecular chains of the waterproofing agent of this invention have low coverage efficiency at the interface, resulting in an uneven and defective interfacial film that cannot effectively resist the thinning process of liquid film drainage, making air bubbles prone to coalescence or rupture. Experiments show that the initial foam volume of the product of this invention is less than 5 mL, and after standing for 5 minutes, there is virtually no foam, avoiding engineering problems such as drilling fluid density fluctuations caused by foaming.

[0080] Thirdly, it exhibits excellent environmental friendliness. The waterproofing agent of this invention is a naturally modified starch product. The molecular backbone remains unchanged before and after modification, preserving the α-glycosidic bonds that are easily hydrolyzed by amylases secreted by microorganisms, ensuring a smooth degradation pathway. The introduction of polyether groups further enhances the water solubility of the waterproofing agent, resulting in an extended random coil conformation in water. This highly hydrated and dispersed state increases the contact area and affinity between the molecules and extracellular enzymes secreted by microorganisms, improving enzyme accessibility and accelerating the degradation process. Testing shows that most products of this invention have an EC (ecological efficiency) of [missing value]. 50 With a value exceeding 30,000 mg / L, meeting the emission standards recommended by the U.S. Environmental Protection Agency (EPA), and a biochemical oxygen demand to chemical oxygen demand ratio (Y) greater than 25%, it is a readily biodegradable material with excellent environmental performance. Attached Figure Description

[0081] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit the present invention. Wherein: Figure 1 M1 obtained in Embodiment 1 of the present invention 1 H NMR spectrum; Figure 2 The infrared spectrum of S1 obtained in Embodiment 1 of the present invention; Figure 3 M2 obtained in Embodiment 2 of the present invention 1 H NMR spectrum; Figure 4 The infrared spectrum of S2 obtained in Example 2 of the present invention is shown. Detailed Implementation

[0082] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0083] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0084] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0085] Unless otherwise specified, the instruments, equipment, and chemical reagents used in the embodiments of this invention are all commercially available products.

[0086] Unless otherwise specified, the methods for determining number-average molecular weight and number-average degree of polymerization in the embodiments of this invention are conventional methods.

[0087] Example 1

[0088] 15.37 g (0.24 mol) butyllithium and 1860 mL (2046 g) DMSO were added to the reactor and stirred until homogeneous. The temperature was then controlled at -10 °C, and N2 was introduced. 115.41 g (1.2 mol) 5-methyl-1-hexyne was added, and the mixture was stirred for 1 h. Then, 80 g (0.02 mol) dialdehyde corn starch (Mn=4000 g / mol, degree of aldehydeization 85%) was added, and the temperature was raised to 30 °C. The reaction was continued for 16 h under stirring.

[0089] Add 2800 mL of water at 0℃ to the above reaction solution, stir continuously for 0.75 h, then add a saturated (NH4)2SO4 aqueous solution to adjust the pH of the reaction solution to 7.5. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% solution. Cool to -18℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M1.

[0090] The chemical reaction formula is shown below:

[0091]

[0092] Figure 1 The nuclear magnetic resonance spectrum of the intermediate product M1 prepared in this embodiment is shown. 1 H NMR).

[0093] Depend on Figure 1 It can be seen that the intermediate product M1 obtained in Example 1 was characterized by nuclear magnetic resonance [(CD3)2SO, 25℃], and the nuclear magnetic resonance spectrum ( 1 The H NMR analysis results are consistent with the molecular structure of the target product.

[0094] 50g of intermediate product M1 was dissolved in 500mL of 30wt% ethanol aqueous solution, and 10g of triethylamine was added. The mixture was stirred at a constant temperature for 3h under N2 protection, and the temperature was raised to 60℃. Ethylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.45MPa. The reaction was continued for 10h under stirring, then cooled to room temperature and distilled under reduced pressure to remove the solvent. The obtained solid was prepared into a 30% aqueous solution, and 4% sulfuric acid was added to neutralize the pH to 7.5. Then, 1g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 50℃ for 6h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant, denoted as S1, with a number-average degree of polymerization of 5.38 for the polyoxyethylene chains.

[0095] The Fourier Transmission Infrared (FT-IR) spectra of S1 are shown below. Figure 2 As shown in Table 1, the spectral analysis is presented. The Fourier Transform Infrared (FT-IR) spectrum contains the characteristic absorption peak of S1, indicating that the molecular structure of the target product conforms to the molecular design.

[0096] Table 1: .

[0097] Example 2

[0098] 48.47 g (0.432 mol) of potassium isobutoxide and 2050 mL (1824.5 g) of THF were added to the reactor and stirred until homogeneous. The temperature was then controlled at -15 °C, and N2 was introduced. 158.69 g (1.44 mol) of 1-octyne was added, and the mixture was stirred for 1.5 h. Then, 120 g (0.02 mol) of dialdehyde cassava starch (Mn = 12000 g / mol, degree of aldehydeization 97.5%) was added, and the temperature was raised to 45 °C. The reaction was continued for 20 h under stirring.

[0099] Add 6150 mL of water at 0℃ to the above reaction solution, stir continuously for 1 hour, then add 5% (w / w) dilute sulfuric acid to adjust the pH of the reaction solution to 8. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% (w / w) solution. Cool to -10℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M2.

[0100] The chemical reaction formula is shown below:

[0101]

[0102] Figure 3 The nuclear magnetic resonance spectrum of the intermediate product M2 prepared in this embodiment is shown. 1 H NMR).

[0103] Depend on Figure 3 It can be seen that the intermediate product M2 obtained in Example 2 was characterized by nuclear magnetic resonance [(CD3)2SO, 25℃], and the nuclear magnetic resonance spectrum ( 1 The H NMR analysis results are consistent with the molecular structure of the target product.

[0104] 41.17 g of intermediate product M2 was dissolved in 500 mL of 40 wt% ethanol aqueous solution, and 7.21 g of trifluoromethanesulfonic acid was added. The mixture was stirred at a constant temperature for 4 h under Ar protection, and the temperature was raised to 75 °C. Propylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.4 MPa. The reaction was continued for 12 h under stirring, then cooled to room temperature, and the solvent was removed by vacuum distillation. The obtained solid was prepared into a 30% aqueous solution, and the pH was neutralized to 8 by adding 10% KOH solution. Then, 0.8 g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 40 °C for 8 h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lock agent, denoted as S2, with a number-average degree of polymerization of 4.73 for the polyoxyethylene chains.

[0105] The Fourier Transmission Infrared (FT-IR) spectra of S2 are shown below. Figure 4 As shown in Table 2, the spectral analysis is presented. The Fourier Transform Infrared (FT-IR) spectrum contains the characteristic absorption peak of S2, indicating that the molecular structure of the target product conforms to the molecular design.

[0106] Table 2: .

[0107] Example 3

[0108] 14.03 g (0.25 mol) KOH and 1885 mL (1634.3 g) DME were added to the reactor and stirred until homogeneous. The temperature was then controlled at -5 °C, and N2 was introduced. 68.12 g (1 mol) 1-pentyne was added, and the mixture was stirred for 0.5 h. Then, 150 g (0.02 mol) dialdehyde wheat starch (Mn=7500 g / mol, degree of aldehydeization 80%) was added, and the temperature was raised to 10 °C. The reaction was continued for 12 h under stirring.

[0109] Add 1885 mL of water at 0℃ to the above reaction solution, stir continuously for 0.5 h, then add a saturated citric acid aqueous solution to adjust the pH of the reaction solution to 7. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% solution. Cool to -25℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M3.

[0110] The chemical reaction formula is shown below:

[0111]

[0112] 92.28 g of intermediate product M3 was dissolved in 500 mL of 20 wt% ethanol aqueous solution, and 14.98 g of KOH was added. The mixture was stirred at a constant temperature for 3.5 h under Ar protection, and the temperature was raised to 75 °C. Ethylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.2 MPa. The reaction was continued under stirring for 8 h, then cooled to room temperature, and the solvent was removed by vacuum distillation. The obtained solid was prepared into a 30% aqueous solution, and the pH was neutralized to 8 by adding 20% ​​acetic acid solution. Then, 2.76 g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 60 °C for 4 h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant, denoted as S3, with a number-average degree of polymerization of 7.85 for the polyoxyethylene chains.

[0113] Example 4

[0114] 4.8 g (0.036 mol) of ethyl magnesium bromide and 620 mL (682 g) of DMSO were added to the reactor and stirred until homogeneous. The temperature was then controlled at -6 °C, and N2 was introduced. 49.77 g (0.36 mol) of 5,5-dimethyl-1-octyne was added, and the mixture was stirred for 1 h. Then, 200 g (0.02 mol) of dialdehyde yam starch (Mn=10000 g / mol, degree of aldehydeization 60%) was added, and the temperature was raised to 25 °C. The reaction was continued for 24 h under stirring.

[0115] Add 1200 mL of water at 0℃ to the above reaction solution, stir continuously for 1 h, then add a saturated NaH2PO4 aqueous solution to adjust the pH of the reaction solution to 7.5. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% solution. Cool to -15℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M4.

[0116] The chemical reaction formula is shown below:

[0117]

[0118] 53.4 g of intermediate product M4 was dissolved in 500 mL of 25 wt% ethanol aqueous solution, and 8.81 g of p-toluenesulfonic acid was added. The mixture was stirred at a constant temperature for 2 h under Ar protection, and the temperature was raised to 80 °C. Propylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.6 MPa. The reaction was continued for 6 h under stirring, then cooled to room temperature, and the solvent was removed by vacuum distillation. The obtained solid was prepared into a 30% aqueous solution, and the pH was neutralized to 8 by adding 10% NaOH solution. Then, 0.54 g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 55 °C for 7.5 h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant, denoted as S4, with a number-average degree of polymerization of 4 for the polyoxyethylene chains.

[0119] Example 5

[0120] 5.62 g (0.144 mol) NaNH2 and 1380 mL (1196.46 g) DME were added to the reactor and stirred until homogeneous. The temperature was then controlled at -8 °C, and N2 was introduced. 89.44 g (0.72 mol) 5-ethyl-1-heptyne was added, and the mixture was stirred for 0.5 h. Then, 40 g (0.02 mol) dialdehyde potato starch (Mn=2000 g / mol, degree of aldehydeization 82.5%) was added, and the temperature was raised to 12 °C. The reaction was continued for 15 h under stirring.

[0121] Add 2400 mL of water at 0℃ to the above reaction solution, stir continuously for 0.5 h, then add a saturated NH4Cl aqueous solution to adjust the pH of the reaction solution to 7.5. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% solution. Cool to -20℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M5.

[0122] The chemical reaction formula is shown below:

[0123]

[0124] 64.8 g of intermediate product M5 was dissolved in 500 mL of 35 wt% ethanol aqueous solution, and 9.5 g of NaOH was added. The mixture was stirred at a constant temperature for 4 h under N2 protection, and the temperature was raised to 70 °C. Ethylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.35 MPa. The reaction was continued for 10 h under stirring, then cooled to room temperature and distilled under reduced pressure to remove the solvent. The obtained solid was prepared into a 30% aqueous solution, and 5% hydrochloric acid was added to neutralize the pH to 7. Then, 1.8 g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 45 °C for 5 h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant, denoted as S5, with a number-average degree of polymerization of 6.25 polyoxyethylene chains.

[0125] Example 6

[0126] 13.67 g (0.12 mol) potassium tert-butoxide and 1000 mL (1100 g) DMSO were added to the reactor and stirred until homogeneous. The temperature was then controlled at -12 °C, and N2 was introduced. 65.72 g (0.8 mol) 3,3-dimethyl-1-butyne was added, and the mixture was stirred for 0.75 h. Then, 163.2 g (0.02 mol) dialdehyde corn starch (Mn=8160 g / mol, degree of aldehydeization 76.5%) was added, and the temperature was raised to 28 °C. The reaction was continued for 18 h under stirring.

[0127] Add 1800 mL of water at 0℃ to the above reaction solution, stir continuously for 0.5 h, then add 5% (w / w) dilute hydrochloric acid to adjust the pH of the reaction solution to 8. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% (w / w) solution. Cool to -25℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M6.

[0128] The chemical reaction formula is shown below:

[0129]

[0130] 60g of intermediate product M6 was dissolved in 500mL of 32.5wt% ethanol aqueous solution. 9g of boron trifluoride diethyl ether complex was added, and the mixture was stirred at a constant temperature for 3h under N2 protection. The temperature was raised to 68℃, and propylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.38MPa. The reaction was continued for 10h under stirring, then cooled to room temperature, and the solvent was removed by vacuum distillation. The obtained solid was prepared into a 30% aqueous solution, and the pH was neutralized to 7.5 by adding 5% NaOH solution. Then, 1.2g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 50℃ for 8h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant, denoted as S6, with a number-average degree of polymerization of 3.66 for the polyoxyethylene chains.

[0131] Example 7

[0132] 21.01 g (0.25 mol) of phenyllithium and 1500 mL (1650 g) of DMSO were added to the reactor and stirred until homogeneous. The temperature was then controlled at -10 °C, and N2 was introduced. 124.23 g (1 mol) of 4,5-dimethyl-1-heptyne was added, and the mixture was stirred for 1 h. Then, 144.2 g (0.02 mol) of dialdehyde potato starch (Mn=7210 g / mol, degree of aldehydeization 92.4%) was added, and the temperature was raised to 35 °C. The reaction was continued for 20 h under stirring.

[0133] Add 2000 mL of water at 0℃ to the above reaction solution, stir continuously for 1 hour, then add a 30% (w / w) aqueous acetic acid solution to adjust the pH of the reaction solution to 7. Remove the solvent by vacuum distillation to obtain the crude product. Dissolve the crude product in ethanol at 60℃ to prepare a 50% (w / w) solution. Cool to -15℃, and a solid will precipitate. After filtration, rinse with ethanol and acetone respectively, then vacuum dry to constant weight to obtain intermediate product M, denoted as M7.

[0134] The chemical reaction formula is shown below:

[0135]

[0136] 72g of intermediate product M7 was dissolved in 500mL of 28wt% ethanol aqueous solution, 10g of sulfuric acid was added, and the mixture was stirred at a constant temperature for 4h under N2 protection. The temperature was raised to 66℃, and propylene oxide was continuously introduced into the reaction solution while controlling the pressure to 0.45MPa. The reaction was continued for 12h under stirring, then cooled to room temperature and distilled under reduced pressure to remove the solvent. The obtained solid was prepared into a 30% aqueous solution, and 5% KOH solution was added to neutralize the pH to 7.5. Then, 1.5g of activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at 55℃ for 6h, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant, denoted as S7, with a number-average degree of polymerization of 5.82 for the polyoxyethylene chains.

[0137] Example 8

[0138] The inhibitor was prepared according to the method of Example 1, except that 5-methyl-1-hexyne was replaced with an equimolar amount of cyclohexylacetylene. The final product was designated as S8, with a number-average degree of polymerization of 3.36 for the polyoxyethylene chain.

[0139] Example 9

[0140] The inhibitor was prepared according to the method of Example 1, except that 5-methyl-1-hexyne was replaced with an equimolar amount of phenylacetylene. The final product was designated as S9, with a number-average degree of polymerization of 4.11 for the polyoxyethylene chain.

[0141] Example 10

[0142] The inhibitor was prepared according to the method of Example 1, except that 5-methyl-1-hexyne was replaced with an equimolar amount of 3-phenyl-1-propyne. The final product was designated as S10, with a number-average degree of polymerization of 4.25 for the polyoxyethylene chain.

[0143] Example 11

[0144] The inhibitor was prepared according to the method of Example 1, except that 5-methyl-1-hexyne was replaced with an equimolar amount of 4-methylphenylacetylene. The final product was denoted as S11, and the number-average degree of polymerization of the polyoxyethylene chain was 3.97.

[0145] Test Example 1

[0146] Determination of surface activity

[0147] The waterproofing agents S1-S11 prepared in Examples 1-11, the commercially available silanol waterproofing agent FSS-1, the commercially available fluorocarbon waterproofing agent TF3726, and sodium perfluorononenoxybenzenesulfonate (OBS) were quantitatively dissolved in tap water to prepare a series of solutions with different concentrations (0.1 mol / L, 0.01 mol / L, 0.001 mol / L, 0.0001 mol / L, and 0.00001 mol / L). Under room temperature conditions, the surface tension (γ) was measured using the platinum ring method with a fully automatic surface tension meter. The measurements were performed in triplicate, and the average value was taken. A γ-lgC curve was plotted, and the concentration corresponding to the inflection point of the data curve was the critical micelle concentration (CMC). The surface activity measurement results are shown in Table 3.

[0148] Table 3: .

[0149] As shown in Table 3, the γ of the waterproofing agents S1 to S11 prepared in Examples 1 to 11 is... cmc All of them have relatively small surface tension, and their surface tension is significantly lower than that of FSS-1, TE3726, and OBS. cmc Meanwhile, compared with FSS-1, TE3726, and OBS, the waterproofing lockers S1-S1 prepared in Examples 1-11 have lower CMC, indicating that the waterproofing lockers provided by the present invention have stronger surface activity.

[0150] Test Example 2

[0151] Temperature resistance test

[0152] Different test temperatures were set, and artificial sandstone cores with a permeability of 1.50 mD were placed in distilled water or solutions of waterproofing agents S1-S11, FSS-1, TE3726 and OBS prepared in Examples 1-11 with a concentration of 0.35% for 8 hours. The permeability (K) of the cores was then measured. The formula for calculating the permeability recovery rate (S) is as follows, and the test results are shown in Table 4.

[0153]

[0154] Table 4: .

[0155] As shown in Table 4, the permeability recovery rate of the core gradually decreased with increasing temperature, indicating that the increase in temperature had a negative impact on the permeability recovery rate of the core.

[0156] Furthermore, compared with FSS-1, TE3726, and OBS, the waterproofing agents S1 to S11 prepared in Examples 1 to 11 showed higher permeability recovery rates under various temperature conditions, indicating higher temperature resistance. When the test temperature reached 140℃, the core permeability recovery rate remained at a high level, indicating that the damage caused by water lock in the core could be effectively reduced at 140℃.

[0157] Test Example 3

[0158] Foam performance test

[0159] 200 mL of 0.35% solutions of waterproofing agents S1-S1, FSS-1, TE3726, and OBS prepared in Examples 1-11 were allowed to stand at room temperature for 2 h, then poured into a Waring stirrer and stirred continuously at 8000 r / min for 30 s before being poured into a 2000 mL graduated cylinder. The volume of foam was recorded at the initial stage of standing, after 2.5 min of standing, and after 5.0 min of standing. The test results are shown in Table 5.

[0160] Table 5: .

[0161] As shown in Table 5, the foam volume of each test sample gradually decreased with increasing standing time. Clearly, the foam volumes of the waterproofing agents S1-S11 prepared in Examples 1-11 were significantly smaller, and no foaming effect was observed after 5.0 min of standing time. In contrast, the foam volumes of FSS-1, TE3726, and OBS solutions were significantly larger at any standing time. These test results indicate that the waterproofing agents S1-S11 prepared in Examples 1-11 have no significant foaming effect.

[0162] Test Example 4

[0163] Environmental performance evaluation

[0164] The main testing methods for drilling fluid biotoxicity include: mysid shrimp bioassay, microbial toxicity method, and cumulative biofluorescence method. Among these, the mysid shrimp bioassay is the only method officially approved by the U.S. Environmental Protection Agency (EPA) for evaluating the biotoxicity of drilling fluids. This is based on the EPA's biotoxicity and organic pollutant biodegradability classification standards and testing methods (Biotoxicity Classification Standards: EC...). 50 ≤1, highly toxic; 1 < EC 50 ≤100, highly toxic; 100 < EC 50 ≤1000, moderately toxic; 1000 < EC 50 ≤10000, slightly toxic; 10000 < EC 50 ≤30000, non-toxic; EC 50>30000, recommended emission standard; Biodegradability evaluation index (Y) = (Biochemical oxygen demand (BOD) / Chemical oxygen demand (COD)) × 100, Y≥25.0, easily degradable; 15.0≤Y<25.0, relatively easily degradable; 5≤Y<15.0, degradable; Y<5.0, difficult to degrade). The biotoxicity and biodegradability of the waterproofing lockers S1~S11 prepared in Examples 1~11 were evaluated, and the test results are shown in Table 6.

[0165] Table 6: .

[0166] As shown in Table 6, the EC values ​​of the waterproofing agents S1 to S7 prepared in Examples 1 to 7 are... 50 All values ​​were above 30,000 mg / L, Y > 25.0, meeting the recommended emission standards and being easily biodegradable. The EC values ​​of the waterproofing lockants S8-S11 prepared in Examples 8-11 were... 50 All concentrations were between 10,000 and 30,000 mg / L, and Y was between 5 and 15, indicating that the substances were non-toxic and biodegradable. These test results demonstrate that the waterproofing agents S1 to S7 prepared in Examples 1 to 7 exhibit excellent environmental performance.

[0167] The above description is merely a preferred embodiment of the present invention, showing and describing the basic principles, main features, and advantages of the present invention. It is not intended to limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. In addition to the above embodiments, the present invention may have other implementations without departing from the spirit and scope of the invention. Various changes and modifications to the present invention are possible, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents. Technical features not described in the present invention can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A waterproof locking agent for drilling fluid, characterized in that, It has the structure shown in Equation I: ； Formula I.

2. The waterproofing sealant for drilling fluid according to claim 1, characterized in that, In Formula I, R0 is selected from C3 to C4. 16 Alkyl groups, C3-C6 cycloalkyl groups, phenyl groups, C7-C6 cycloalkyl groups 12 Benzyl or C7-C 12 Alkylphenyl.

3. The waterproofing sealant for drilling fluid according to claim 2, characterized in that, R0 is selected from C3 to C8 alkyl groups.

4. The waterproofing sealant for drilling fluid according to claim 1, characterized in that, In Equation I, R 11 R 12 and R 13 They are respectively or , Where m is the length of the polyethylene oxide chain and n is the length of the polypropylene oxide chain.

5. The waterproofing sealant for drilling fluid according to claim 4, characterized in that, m is any integer from 1 to 16, and n is any integer from 1 to 12.

6. The waterproofing sealant for drilling fluid according to claim 4, characterized in that, The average length of the polyethylene oxide chain in the waterproofing sealant molecular chain is denoted as m′, where m′ is an integer or decimal from 1 to 8; the average length of the polypropylene oxide chain is denoted as n′, where n′ is an integer or decimal from 1 to 6.

7. The waterproofing sealant for drilling fluid according to claim 6, characterized in that, The formula for calculating m′ is: ; Among them, M n It is the arithmetic mean of the molecular weights of all molecules in the waterproofing sealant; M 端基，EO for The sum of the molecular weights of H molecules at the ends of the polyethylene oxide chain; M EO The molecular weight of the polyoxyethylene structural unit; The formula for calculating n′ is: ; Among them, M 端基,PO for The sum of the molecular weights of H atoms at the ends of the polyoxypropylene chain; M PO is the molecular weight of the polyoxypropylene structural unit.

8. A method for preparing a waterproof locking agent for drilling fluid, characterized in that, Includes the following steps: In the presence of catalyst A, dialdehyde starch is reacted with the terminal alkyne compound shown in formula i via a nucleophilic addition reaction to obtain intermediate product M, which is then subjected to alkoxylation reaction and impurity removal treatment to obtain a waterproof lock-in agent. ； Formula i.

9. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The degree of aldehydes in the dialdehyde starch used is 60%–97.5%.

10. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The number-average molar mass of the dialdehyde starch used was 2000–12000 g / mol.

11. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The molar mass of the unoxidized protopylene glucose unit in the molecular chain of the dialdehyde starch used is 162.14 g / mol, and the molar mass of the oxidized dialdehyde structural unit in the molecular chain of the dialdehyde starch is 160.12 g / mol.

12. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The number-average molar mass of the dialdehyde starch used is the value obtained by dividing the mass of the dialdehyde starch by its number-average molar mass.

13. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The raw material used to prepare dialdehyde starch is one of tapioca starch, corn starch, potato starch, yam starch, or wheat starch.

14. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The catalyst used was selected based on the following criteria: it can promote the deprotonation of terminal alkynes to generate alkyne carbanions, thereby enabling the nucleophilic addition reaction of alkyne carbanions to dialdehyde starch.

15. The method for preparing the waterproofing agent for drilling fluid according to claim 14, characterized in that, The catalyst A is selected from at least one of KOH, NaNH2, potassium isobutoxide, potassium tert-butoxide, butyllithium, phenyllithium, or ethyl magnesium bromide.

16. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The nucleophilic addition reaction is a reaction that uses terminal alkyne compounds and dialdehyde starch to prepare corresponding alkyne alcohol compounds.

17. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The reaction method of the terminal alkyne compound and the dialdehyde starch includes: adding catalyst A into solvent A, controlling the temperature to the reaction temperature, adding the terminal alkyne compound under an inert atmosphere, adding dialdehyde starch under stirring conditions, raising the temperature, and continuing the nucleophilic addition reaction.

18. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The nucleophilic addition reaction includes the following steps: Step 1: Mix catalyst A with solvent A to obtain reaction solution I; Step 2: Control the temperature to T1, introduce N2, add the terminal alkyne compound to the reaction solution I, stir for a certain time t1, add dialdehyde starch, raise the temperature to the reaction temperature T2, and continue the reaction under stirring for a period of time t2 to obtain the intermediate product M, and the reaction ends.

19. The method for preparing the waterproofing agent for drilling fluid according to claim 18, characterized in that, In the first step, solvent A is selected from at least one of tetrahydrofuran, dimethyl sulfoxide, or 1,2-dimethoxyethane (DME).

20. The method for preparing the waterproofing agent for drilling fluid according to claim 19, characterized in that, In the second step, the reaction temperature T1 is -15℃ to 0℃, and T2 is 10℃ to 45℃.

21. The method for preparing the waterproofing agent for drilling fluid according to claim 19, characterized in that, In the second step, the mass percentage concentration of the terminal alkyne compound in reaction solution I is 1% to 20%.

22. The method for preparing the waterproofing agent for drilling fluid according to claim 21, characterized in that, In the second step, the mass percentage concentration of the terminal alkyne compound in reaction solution I is 4% to 8%.

23. The method for preparing the waterproofing agent for drilling fluid according to claim 18, characterized in that, In the first and second steps, the molar ratio of the terminal alkyne compound to catalyst A is 1:(0.1 to 0.3).

24. The method for preparing the waterproofing agent for drilling fluid according to claim 18, characterized in that, In the second step, the ratio of the number-average amount of the dialdehyde starch to the amount of the terminal alkyne compound is 1:(18-72).

25. The method for preparing the waterproofing agent for drilling fluid according to claim 18, characterized in that, In the second step, the time t1 is 0.5 to 1.5 hours, and the time t2 is 6 to 36 hours.

26. The method for preparing the waterproofing agent for drilling fluid according to claim 25, characterized in that, In the second step, the time t2 is 12 to 24 hours.

27. The method for preparing the waterproofing agent for drilling fluid according to claim 18, characterized in that, After the second step reaction is completed, a quenching reaction is also performed, which includes the following operations: Step 1: Add 0°C water to the reaction solution after the second step reaction is completed, and stir continuously for a certain time t3; Step 2: Under stirring conditions, add an acidic solution to adjust the pH value of the reaction solution.

28. The method for preparing the waterproofing agent for drilling fluid according to claim 27, characterized in that, In step 1, the volume of water is 1 to 3 times that of solvent A, and the time t3 is 0.5 to 1 hour.

29. The method for preparing the waterproofing agent for drilling fluid according to claim 27, characterized in that, In step 2, the acidic solution is selected from at least one of 2%–5% dilute hydrochloric acid, 2%–5% dilute sulfuric acid, saturated NH4Cl aqueous solution, saturated (NH4)2SO4 aqueous solution, saturated NaH2PO4 aqueous solution, 10%–30% acetic acid aqueous solution, or saturated citric acid aqueous solution, and the pH value ranges from 7 to 8.

30. The method for preparing the waterproofing agent for drilling fluid according to claim 18, characterized in that, After the quenching reaction, the intermediate product M is recrystallized to remove impurities. The steps involved in the recrystallization to remove impurities are as follows: first, the solvent is removed by vacuum distillation, and then the product is rinsed with water to obtain the crude product of intermediate product M; then, the crude product is dissolved in ethanol at 60°C to prepare a 50% (w / w) solution, and the temperature is lowered to -25°C to -10°C, at which point a solid precipitates out. After filtration, the solid is rinsed with ethanol and acetone respectively, and then dried under vacuum to constant weight to obtain the purified intermediate product M.

31. The method for preparing the waterproofing agent for drilling fluid according to claim 8, characterized in that, The alkoxylation reaction includes the following steps: Intermediate product M was dissolved in solution A, catalyst B was added, and the mixture was stirred at a constant temperature for a certain time t4 under inert gas protection. The temperature was raised to the reaction temperature T3, and epoxide was continuously introduced into the reaction solution while controlling the pressure at 0.2–0.6 MPa. The reaction was continued under stirring. After a period of time t5, the mixture was cooled to room temperature and distilled under reduced pressure to remove the solvent. The obtained solid was prepared into a 30% aqueous solution, neutralized with a neutralizing agent, and then activated carbon was added to the neutralized solution for decolorization. The solution was allowed to stand at temperature T4 for a certain time t6, filtered to remove the activated carbon, and the filtrate was dried in a vacuum drying oven to constant weight to obtain the waterproofing lockant.

32. The method for preparing the waterproofing agent for drilling fluid according to claim 31, characterized in that, Solution A is a 20wt% to 40wt% aqueous ethanol solution, and the mass percentage concentration of intermediate product M in solution A is 8% to 16%.

33. The method for preparing the waterproofing agent for drilling fluid according to claim 31, characterized in that, The catalyst B is one of NaOH, KOH, triethylamine, boron trifluoride diethyl ether complex, p-toluenesulfonic acid, sulfuric acid, or trifluoromethanesulfonic acid, and the mass percentage concentration of the catalyst B in solution A is 1.5% to 3%.

34. The method for preparing the waterproofing agent for drilling fluid according to claim 33, characterized in that, When catalyst B is NaOH, KOH, or triethylamine, the epoxide is ethylene oxide; when catalyst B is boron trifluoride diethyl ether complex, p-toluenesulfonic acid, sulfuric acid, or trifluoromethanesulfonic acid, the epoxide is propylene oxide.

35. The method for preparing the waterproofing agent for drilling fluid according to claim 31, characterized in that, The time t4 is 2-4 hours, the reaction time t5 is 6-12 hours, and the time t6 is 4-8 hours. The inert gas is N2 or Ar; The reaction temperature T3 is 50–80°C, and the temperature T4 is 40–60°C.

36. The method for preparing the waterproofing agent for drilling fluid according to claim 31, characterized in that, When catalyst B is NaOH, KOH or triethylamine, the neutralizing agent is one of 20%–30% acetic acid solution, 2%–5% hydrochloric acid or 2%–5% sulfuric acid; When catalyst B is boron trifluoride diethyl ether complex, p-toluenesulfonic acid, sulfuric acid, or trifluoromethanesulfonic acid, the neutralizing agent is one of 5%–10% NaOH solution or 5%–10% KOH solution.

37. The method for preparing the waterproofing agent for drilling fluid according to claim 31, characterized in that, The neutralization is to neutralize to pH 7-8, and the mass of the activated carbon is 1%-3% of the mass of the intermediate product M.

38. The application of a waterproofing sealant in oil and gas extraction, characterized in that, The waterproofing agent is the waterproofing agent according to any one of claims 1 to 7, or the waterproofing agent prepared according to any one of claims 8 to 37.

39. The application of the waterproofing sealant according to claim 38 in oil and gas extraction, characterized in that, The waterproofing lockant is used as a waterproofing lockant for drilling fluids during oil and gas extraction drilling processes.

40. The application of the waterproofing sealant according to claim 38 in oil and gas extraction, characterized in that, The waterproofing agent is added to the water-based drilling fluid used in oil and gas extraction drilling.

41. A water-based drilling fluid, characterized in that, The waterproofing agent comprises any one of claims 1 to 7, or the waterproofing agent prepared according to any one of claims 8 to 37, wherein the amount of the waterproofing agent added is 0.2wt% to 2.0wt% based on the total amount of the water-based drilling fluid.

42. The water-based drilling fluid according to claim 41, characterized in that, The pH of the water-based drilling fluid before the addition of the waterproofing agent is 9-11.

43. The water-based drilling fluid according to claim 41, characterized in that, The water-based drilling fluid is selected from one of the following: bentonite drilling fluid system, potassium amine drilling fluid system, polymer anti-collapse drilling fluid system, sulfonated drilling fluid system, polysulfonated drilling fluid system, KCl drilling fluid system, brine drilling fluid system, amine polysulfonated drilling fluid system, silicate drilling fluid system, or oil-in-water drilling fluid system.

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