A water activity regulator and a preparation method thereof, and a low activity drilling fluid

Abstract

This invention provides a water activity regulator and its preparation method, as well as a low-activity drilling fluid, relating to the field of oilfield drilling technology. The water activity regulator provided by this invention organically combines alkyl glycosides, organic salts, and diol compounds. It not only forms a semi-permeable membrane to effectively control water flow but also effectively controls free water content. These two mechanisms work synergistically to control the intrusion of drilling fluid filtrate into the formation, thereby mitigating shale hydration swelling and stabilizing the wellbore. Experimental results show that the water activity regulator provided by this invention, when used in drilling fluid, can effectively reduce water activity without affecting other properties of the drilling fluid.

Description

Technical Field

[0001] This invention relates to the field of oilfield drilling technology, specifically to a water activity regulator and its preparation method, and a low-activity drilling fluid. Background Technology

[0002] As oil and gas exploration and development extend to deeper and more complex formations, the number of deep, ultra-deep, and complex wells is increasing. Particularly in some shale oil and gas horizontal wells with extended reach, due to the long horizontal sections and complex wellbore trajectories, problems such as lost circulation, well collapse, borehole narrowing, and severe mud-making are prone to occur during drilling, leading to increased downhole complexity. Data shows that 70-90% of wellbore problems are related to the instability of shale and mudstone. Shale and mudstone are highly susceptible to hydration, expansion, and dispersion upon contact with water, causing wellbore collapse. Therefore, it is essential to minimize the intrusion of drilling fluid into the formation to inhibit shale hydration and ensure wellbore stability.

[0003] The water activity of drilling fluid is one of the key factors affecting wellbore stability. When the water activity of the drilling fluid is lower than that of the formation water, the formation water will flow into the wellbore due to the chemical potential difference. This reduces the formation porosity, resulting in a lower collapse pressure than the original collapse pressure, which is beneficial to wellbore stability. Currently, the main way to reduce the water activity of drilling fluid is by adding organic or inorganic salts. However, excessive salt addition can lead to problems such as decreased settling stability and lubricity of the drilling fluid, and may also pollute groundwater during drilling. Therefore, adding organic or inorganic salts can only reduce the water activity of drilling fluid to a limited extent, and existing drilling fluids still have poor effects on reducing activity and inhibiting shale hydration. Summary of the Invention

[0004] In view of this, the present invention provides a water activity regulator and its preparation method, as well as a low-activity drilling fluid. The water activity regulator provided by the present invention uses diol compounds and organic salts to modify alkyl glycosides, which can effectively reduce water activity. Experimental results show that the diol compounds and organic salts in the water activity regulator provided by the present invention have a synergistic effect, which can significantly reduce the activity of drilling fluid and inhibit shale hydration.

[0005] This invention first provides a water activity regulator, which is obtained by reacting alkyl glycosides, catalysts, epoxy compounds, diol compounds and organic salts;

[0006] The molar ratio of the alkyl glycoside, catalyst, diol compound, epoxy compound and organic salt is 1:(0.01-0.1):(0.5-2):(2-5):(0.8-2.5).

[0007] In some specific implementations, the water activity regulator is obtained by reacting the reaction products of alkyl glycosides, catalysts, epoxy compounds, and diol compounds with organic salts.

[0008] In some specific implementations, the alkyl glycoside has ≤8 alkyl carbons; the epoxy compound is selected from at least one of ethylene oxide, propylene oxide, butane oxide, and pentane oxide; and the organic salt is selected from at least one of sodium formate, potassium formate, and sodium acetate.

[0009] In some specific implementations, the diol compound is selected from at least one of ethylene glycol and polyethylene glycol; the polyethylene glycol has a molecular weight of 400 to 800.

[0010] In some specific implementations, the catalyst is an acidic catalyst, which is selected from at least one of organic acids and inorganic acids.

[0011] This invention provides a method for preparing the above-mentioned water activity regulator, comprising:

[0012] a) An etherification reaction is carried out after mixing alkyl glycosides, catalysts, epoxy compounds and diol compounds to obtain alkyl glycoside polyethers;

[0013] b) The alkyl glycoside polyether obtained in step a) is mixed with an organic salt and then subjected to an ionic reaction to obtain a water activity regulator.

[0014] In some specific implementations, the etherification reaction is carried out at a temperature of 80–110°C for a time of 1–5 hours.

[0015] In some specific implementations, the reaction temperature of the ionic reaction is 50–95°C, and the reaction time is 0.5–5 h.

[0016] In some specific implementations, both the etherification reaction and the ionic reaction are carried out under stirring conditions, with the stirring speed being 300–800 r / min.

[0017] The present invention also provides a low-activity drilling fluid, comprising the above-mentioned water activity regulator.

[0018] This invention uses alkyl glycosides, epoxy compounds, diol compounds, and organic salts as raw materials to prepare a series of water activity regulators. The reaction conditions are mild and the process is simple. When applied to drilling fluids, these water activity regulators can effectively regulate the activity of the drilling fluid and inhibit the hydration of shale. They also have minimal impact on the apparent viscosity of the slurry, with a change of ≤3.0 mPa·s, and no significant increase in filtration loss. They exhibit good compatibility and both good inhibitory and compatibility properties. Attached Figure Description

[0019] Figure 1 The infrared spectrum of the water activity regulator prepared in Example 1 of this invention. Detailed Implementation

[0020] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0021] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0022] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0023] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0024] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means an actual value within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0025] This invention first provides a water activity regulator, which is obtained by reacting alkyl glycosides, catalysts, epoxy compounds, diol compounds and organic salts;

[0026] The molar ratio of the alkyl glycoside, catalyst, diol compound, epoxy compound and organic salt is 1:(0.01-0.1):(0.5-2):(2-5):(0.8-2.5).

[0027] Alkyl glycoside derivatives, specifically alkyl glycoside polyethers, contain multiple hydroxyl groups and ether bonds in their molecular structure. They can adsorb onto wellbore rocks and drill cuttings. The alkyl groups, which have a certain degree of oleophilicity, are arranged outwards in a regular pattern. When the dosage reaches a certain level, a strong adsorption semi-permeable membrane can be formed on the wellbore. This membrane can effectively act as a hydrophobic barrier, preventing water molecules from penetrating the wellbore and effectively controlling the migration of drilling fluid filtrate and formation water, thereby achieving the effect of regulating water activity. Meanwhile, organic salts can form hydrogen bonds with water, further forming a network structure within and between water molecules, thus forming low-activity bonded water, effectively reducing the content of free water and achieving the purpose of reducing water activity.

[0028] To address the above issues, this invention first modifies alkyl glycosides into alkyl glycoside polyethers, and then organically combines the alkyl glycoside polyethers with organic salts to develop a water activity regulator product. This product can not only form a semi-permeable membrane to better control the intrusion of drilling fluid filtrate into the formation, but also effectively control the free water content and reduce activity. The two mechanisms of action work synergistically to achieve the effect of reducing water activity, thereby further mitigating shale hydration expansion and stabilizing the wellbore. In some specific implementations of the present invention, the molar ratio of the alkyl glycoside, catalyst, diol compound, epoxy compound and organic salt is 1:(0.01-0.1):(0.5-2):(2-5):(0.8-2.5), preferably 1:(0.01-0.08):(0.7-2):(2-4.5):(1-2.5), and more preferably 1:(0.01-0.06):(0.7-1.8):(2.5-4.5):(1-2.5).

[0029] The alkyl glycoside polyethers described in this invention may have the following structures, but these structures do not cover all alkyl glycoside polyethers provided by this invention, and the scope of protection of this invention is not limited by these structures.

[0030]

[0031] Wherein, n is selected from an integer from 1 to 10, m is selected from an integer from 1 to 20; R is selected from C1 to C8 alkyl groups, and R1 to R6 are independently selected from hydrogen or C1 to C5 alkyl groups; X is selected from halogens or hydrogen. In some specific implementations, R1 to R4 and R6 are independently preferably hydrogen or C1 to C3 alkyl groups, more preferably hydrogen. In some specific implementations, R5 is preferably hydrogen or C1 to C4 alkyl groups, more preferably hydrogen or C3 to C4 alkyl groups.

[0032] Alkyl glycosides with a smaller number of alkyl carbons exhibit better solubility and dispersibility, are easier to modify, and have lower production costs. Therefore, in some specific implementations of this invention, the alkyl glycoside has ≤8 alkyl carbons, i.e., any one of methyl glycoside, ethyl glycoside, propyl glycoside, butyl glycoside, pentyl glycoside, hexyl glycoside, heptayl glycoside, or octyl glycoside, preferably methyl glycoside, ethyl glycoside, propyl glycoside, butyl glycoside, or pentyl glycoside, and more preferably methyl glycoside, ethyl glycoside, or propyl glycoside.

[0033] Epoxides, as starting materials for alkyl glycoside polyethers, significantly influence the chemical structure and properties of the final product. In some specific embodiments of this invention, the epoxy compound is selected from at least one of ethylene oxide, propylene oxide, butane oxide, and pentane oxide, preferably ethylene oxide, propylene oxide, or butane oxide. In some specific embodiments, the organic salt is selected from at least one of sodium formate, potassium formate, and sodium acetate.

[0034] In some specific implementations, the diol compound is selected from at least one of ethylene glycol and polyethylene glycol; the polyethylene glycol has a molecular weight of 400 to 800, preferably polyethylene glycol 400, polyethylene glycol 600 or polyethylene glycol 800, and more preferably polyethylene glycol 400.

[0035] Alkyl glycoside polyethers possess excellent properties, such as low surface tension, good compatibility, and excellent foam stability. Using an acidic catalyst can enhance these properties to some extent, making the product more suitable for various applications. Simultaneously, acidic catalysts typically exhibit good stability and reusability, maintaining catalytic activity for extended periods in industrial production. Therefore, in some specific implementations, the catalyst described in this invention is an acidic catalyst, selected from at least one of organic and inorganic acids. In some specific implementations, the organic acid is selected from at least one of toluenesulfonic acid, dodecylbenzenesulfonic acid, aminosulfonic acid, and tartaric acid, preferably toluenesulfonic acid, aminosulfonic acid, or tartaric acid; the inorganic acid is selected from at least one of sulfuric acid, nitric acid, phosphoric acid, and phosphotungstic acid.

[0036] This invention provides a method for preparing the above-mentioned water activity regulator, comprising:

[0037] a) An etherification reaction is carried out after mixing alkyl glycosides, catalysts, epoxy compounds and diol compounds to obtain alkyl glycoside polyethers;

[0038] b) The alkyl glycoside polyether obtained in step a) is mixed with an organic salt and then subjected to an ionic reaction to obtain a water activity regulator.

[0039] As described above, the present invention first modifies alkyl glycosides into alkyl glycoside polyethers, giving them characteristics such as low surface tension, good compatibility, and excellent foam stability. Then, the obtained alkyl glycoside polyethers are organically combined with organic salts through ionic reactions to obtain a water activity regulator.

[0040] In some specific implementations, the etherification reaction temperature is 80–110°C, preferably 90–110°C, more preferably 95–105°C; the reaction time is 1–5 h, preferably 2–5 h, more preferably 2–4 h. In some specific implementations, the ionic reaction temperature is 50–95°C, preferably 65–95°C, more preferably 70–95°C; the reaction time is 0.5–5 h, preferably 1–5 h, more preferably 2–5 h.

[0041] To ensure a uniform and complete reaction, and considering the characteristics of each reactant, in some specific implementations of this invention, both the etherification reaction and the ionic reaction are carried out under stirring conditions. The stirring speed is 300–800 r / min, preferably 400–800 r / min, and more preferably 600–800 r / min.

[0042] Based on the aforementioned advantages of the water activity regulator, this invention applies it to drilling fluids to obtain a series of low-activity drilling fluids. This invention does not impose any special restrictions on other components of the low-activity drilling fluids. For example, they may include common drilling fluid components such as bentonite, inhibitors, filtration reducers, viscosifiers, plugging agents, lubricants, and weighting agents. Those skilled in the art can add or remove other components according to actual needs, and this invention does not impose any special restrictions in this regard. Furthermore, other components in the low-activity drilling fluid do not affect the scope of protection of this invention.

[0043] The low-activity drilling fluid described in this invention can form a semi-permeable membrane on the wellbore, effectively preventing drilling fluid filtrate from invading the formation. It can also control the free water content in the drilling fluid, reduce the water activity of the drilling fluid, and ultimately inhibit the hydration expansion and dispersion of highly water-sensitive shale formations, thereby stabilizing the wellbore.

[0044] In summary, this invention first modifies alkyl glycosides into alkyl glycoside polyethers, and then organically combines these alkyl glycoside polyethers with organic salts through ionic reactions to obtain a series of water activity regulators, which are then applied to drilling fluids. The water activity regulators provided by this invention, when applied to drilling fluids, can form a robust adsorption semi-permeable membrane on the wellbore. Through their effective hydrophobic effect, they prevent water molecules from penetrating the wellbore, effectively controlling the migration of drilling fluid filtrate and formation water, thereby achieving the effect of regulating water activity. They can also form hydrogen bonds with water, creating a network structure within and between water molecules to form low-activity bonded water, thus effectively reducing the content of free water. These two aspects achieve the goal of reducing water activity. Simultaneously, the water activity regulators provided by this invention have minimal impact on the apparent viscosity of the drilling fluid, with an apparent viscosity change value ≤3.0 mPa·s, and no significant increase in filtration loss, demonstrating excellent compatibility.

[0045] The present invention is further illustrated below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0046] Example 1

[0047] 97g of methyl glycoside, 0.49g of aminosulfonic acid, 44g of ethylene oxide, and 46.5g of ethylene glycol were added to a reaction vessel and stirred until homogeneous at 600 rpm. The mixture was heated to 95°C and reacted for 2 hours, then allowed to cool naturally to room temperature to obtain an alkyl glycoside polyether. 33.6g of potassium formate was added to the above alkyl glycoside polyether, and the mixture was heated to 75°C and reacted for 2 hours to obtain an orange-red transparent liquid, which was the water activity regulator.

[0048] The structure of the water activity regulator obtained in this embodiment was determined by infrared spectroscopy. The results are as follows: Figure 1 As shown. Figure 1 1043cm -1 and 1089cm -1 The double peaks are absorption peaks due to alkyl stretching vibrations, which can identify the alkyl group in alkyl glycosides; 1206 cm⁻¹ -1 The stretching vibration peak of COC confirms the presence of a polyether structure; 613 cm⁻¹ -1 The peak represents the out-of-plane bending vibration of the hydroxyl group, at 3192 cm⁻¹. -1 The peak at 1596 cm⁻¹ represents the stretching vibration of the hydroxyl group, which confirms the presence of a COH structure. -1 The peak represents a carbonyl stretching vibration, confirming the presence of a carbonyl group from the formate. Therefore, it can be concluded that the water activity regulator prepared in this embodiment contains alkyl glycoside polyether and formate.

[0049] Example 2

[0050] 52g of ethyl glycoside, 2.15g of p-toluenesulfonic acid, 43.5g of propylene oxide, and 100g of polyethylene glycol 400 were added to a reaction vessel and stirred until homogeneous at 800r / min. The mixture was then heated to 105℃ and reacted for 3 hours before being allowed to cool naturally to room temperature to obtain alkyl glycoside polyether.

[0051] Add 25.5g of sodium formate to the above alkyl glycoside polyether, heat to 85℃ and react for 5h to obtain an orange-red transparent liquid, which is a water activity regulator.

[0052] Example 3

[0053] 55.5g of propyl glycoside, 1.13g of tartaric acid, 72g of epoxide, and 120g of polyethylene glycol 600 were added to a reaction vessel and stirred until homogeneous at 700r / min. The mixture was then heated to 100℃ and reacted for 4 hours before being allowed to cool naturally to room temperature to obtain alkyl glycoside polyether.

[0054] 41g of sodium acetate was added to the above alkyl glycoside polyether, and the mixture was heated to 92℃ and reacted for 4h to obtain an orange-red transparent liquid, which is a water activity regulator.

[0055] Comparative Example 1

[0056] 97g of methyl glycoside, 0.49g of aminosulfonic acid, 44g of ethylene oxide, and 46.5g of ethylene glycol were added to a reaction vessel and stirred until homogeneous at a stirring speed of 600r / min. The mixture was heated to 95℃ and reacted for 2h, then allowed to cool naturally to room temperature to obtain alkyl glycoside polyether, which was used as the water activity regulator prepared in this comparative example.

[0057] The difference between this comparative example and Example 1 is that no organic salts are added in the preparation steps; only the preparation of alkyl glycoside polyether is completed.

[0058] Comparative Example 2

[0059] 52g of ethyl glycoside, 2.15g of p-toluenesulfonic acid, and 43.5g of propylene oxide were added to a reaction vessel and stirred until homogeneous at 800r / min. The mixture was then heated to 105℃ and reacted for 3 hours before being allowed to cool naturally to room temperature to obtain alkyl glycoside polyether.

[0060] Add 25.5g of sodium formate to the above alkyl glycoside polyether, heat to 85℃ and react for 5h to obtain an orange-red transparent liquid, which is a water activity regulator.

[0061] The difference between this comparative example and Example 2 is that ethylene glycol, a diol compound, is not added in the preparation steps.

[0062] Comparative Example 3

[0063] 97g of methyl glycoside, 0.49g of aminosulfonic acid, 44g of ethylene oxide, and 46.5g of ethylene glycol were added to a reaction vessel and stirred until homogeneous at a stirring speed of 600r / min. The mixture was then heated to 95℃ and reacted for 2 hours before being allowed to cool naturally to room temperature to obtain alkyl glycoside polyether.

[0064] Add 33.6g of potassium formate to the above alkyl glycoside polyether and stir until homogeneous to obtain the water activity regulator.

[0065] The difference between this comparative example and Example 1 is that in step 2, after adding the organic salt, no heating is performed, no ionization reaction occurs, and physical mixing is achieved solely through stirring.

[0066] Experimental Example 1

[0067] The recovery rate of shale from samples prepared by the water activity regulator products of the embodiments and comparative examples of the present invention at a mass concentration of 1.0% was tested; the activity of samples prepared by the water activity regulator products of the embodiments and comparative examples of the present invention at a mass concentration of 10% was tested, and the test results are shown in Table 1.

[0068] The shale recovery rate evaluation method is as follows: Take 400 mL of distilled water, add 4 g of the water activity regulator prepared in the embodiments or comparative examples of this invention, stir at high speed for 20 min, add 20 g of accurately weighed shale rock fragments (4-10 mesh), roll at 180℃ for 16 h, cool down and take out, pass through a 40 mesh sieve to obtain the remaining shale rock fragments, dry and weigh, and record as m1. The formula for calculating the primary shale recovery rate is m1 / 20; add the rock fragments recovered in the primary recovery to 400 mL of water, roll at 180℃ for 16 h, cool down and take out, pass through a 40 mesh sieve to obtain the remaining shale rock fragments, dry and weigh, and record as m2. The formula for calculating the relative recovery rate of rock fragments is m2 / m1.

[0069] The sample activity was tested using a water activity meter. The test method is as follows: Place a 10% (w / w) aqueous solution of the water activity regulator prepared in the embodiments or comparative examples of the present invention into a sample dish. The sample volume should be greater than 60% of the volume of the sample dish. Then place the dish horizontally into the water activity sensor and close the sensor cover. Select the measurement function, press the confirmation button, and the water activity meter will enter the measurement state. Read the water activity value of the sample.

[0070] Table 1. Recovery rate and activity detection results of the water activity regulator prepared in this invention.

[0071]

[0072]

[0073] As shown in Table 1, after aging at 180℃ for 16 hours, the rock cuttings recovery rate of the water activity regulators prepared in Examples 1-3 of this invention was ≥98.13%, and the relative recovery rate of rock cuttings was ≥99.29%; the activity of the 10% water activity regulator was as low as 0.892. In Comparative Examples 1 and 2, when only glycol compounds or organic salts were used for modification, the water activity regulator's effect deteriorated, indicating that glycol compounds and organic salts have a synergistic effect. In Comparative Example 3, because the organic salt and alkyl glycoside polyether were only physically mixed, a semi-permeable membrane that could control water molecule intrusion could not be formed, thus lacking a synergistic effect, and the water activity regulation effect deteriorated.

[0074] Experimental Example 2

[0075] Prepare 6% soil slurry as follows: Add 3.0g of anhydrous sodium carbonate and 60g of sodium bentonite for drilling fluid testing to 1L of water, stir for 20min, and cure at room temperature for 24h to obtain 6% soil slurry.

[0076] Drilling fluid compositions were obtained by adding 1% of the water activity regulators prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention to 6% of the mud mass. The above drilling fluid compositions were then heated at 120°C for 16 hours, and their apparent viscosity and filtration loss were tested according to GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids". The results are listed in Table 2.

[0077] Table 2. Results of apparent viscosity and filtration loss of the water activity regulator prepared in this invention.

[0078]

[0079] Table 2 shows that after aging at 120℃ for 16 hours, the 1.0% water activity modifier had little effect on the apparent viscosity of the 6% soil slurry, with an apparent viscosity change ≤3.0 mPa·s; the 1.0% water activity modifier also had little effect on the filtration loss of the 6% soil slurry, with no significant increase in filtration loss. This indicates that the water activity modifier provided by this invention has no effect on other properties of the drilling fluid while effectively regulating water activity, demonstrating good compatibility.

[0080] In summary, this invention uses alkyl glycosides, catalysts, glycol compounds, epoxy compounds, and organic salts as raw materials to prepare a series of water activity regulators. The reaction conditions are mild, the catalytic reaction energy consumption is low, and there is no wastewater, waste gas, or waste residue emission. When used in drilling fluids, these water activity regulators not only form a strong adsorption semi-permeable membrane on the wellbore, effectively preventing water molecules from penetrating the wellbore through their hydrophobic effect and effectively controlling the migration of drilling fluid filtrate and formation water; they also form hydrogen bonds with water, creating a network structure within and between water molecules to form low-activity bonded water, thereby effectively reducing the content of free water and achieving the purpose of reducing water activity. The water activity regulators provided by this invention can regulate water activity from these two aspects, effectively controlling the free water content, inhibiting shale hydration, and maintaining wellbore stability.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A water activity regulator, characterized in that, It is obtained by reacting alkyl glycosides, catalysts, diols, epoxides, and organic salts; The molar ratio of the alkyl glycoside, catalyst, diol compound, epoxy compound and organic salt is 1:(0.01-0.1):(0.5-2):(2-5):(0.8-2.5).

2. The water activity regulator according to claim 1, characterized in that, It is obtained by reacting the reaction products of alkyl glycosides, catalysts, epoxides and diols with organic salts.

3. The water activity regulator according to claim 1, characterized in that, The alkyl glycoside has ≤8 alkyl carbons; The epoxy compound is selected from at least one of ethylene oxide, propylene oxide, butane oxide, and pentane oxide; The organic salt is selected from at least one of sodium formate, potassium formate, and sodium acetate.

4. The water activity regulator according to claim 1, characterized in that, The diol compound is selected from at least one of ethylene glycol and polyethylene glycol; The molecular weight of the polyethylene glycol is 400-800.

5. The water activity regulator according to claim 1, characterized in that, The catalyst is an acidic catalyst, and the acidic catalyst is selected from at least one of organic acids and inorganic acids.

6. A method for preparing a water activity regulator, characterized in that, include: a) An etherification reaction is carried out after mixing alkyl glycosides, catalysts, epoxy compounds and diol compounds to obtain alkyl glycoside polyethers; b) The alkyl glycoside polyether obtained in step a) is mixed with an organic salt and then subjected to an ionic reaction to obtain a water activity regulator.

7. The preparation method according to claim 6, characterized in that, The etherification reaction is carried out at a temperature of 80–110°C for 1–5 hours.

8. The preparation method according to claim 6, characterized in that, The reaction temperature of the ionic reaction is 50–95°C, and the reaction time is 0.5–5 h.

9. The preparation method according to claim 6, characterized in that, Both the etherification and ionic reactions are carried out under stirring conditions, with the stirring speed being 300–800 r / min.

10. A low-activity drilling fluid, characterized in that, This includes the water activity regulator according to any one of claims 1 to 5 or the water activity regulator prepared by any one of claims 6 to 9.

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