Preparation method of activated attapulgite and application of activated attapulgite in water-based drilling fluid and well cementation cement slurry

Abstract

The invention discloses a preparation method of activated attapulgite and application of the activated attapulgite in water-based drilling fluid and well cementation cement slurry. The preparation method of the activated attapulgite comprises the following steps: carrying out mechanical activation and heat treatment on an attapulgite raw material to obtain a physical activation product; and carrying out alkalization treatment and / or acidification treatment on the physical activation product to realize chemical activation. The specific surface area and the pore volume of the obtained activated attapulgite are improved, and the dispersity is enhanced; when the drilling fluid is used for water-based drilling fluid, filtration loss can be reduced, and rheological stability and well wall sand-carrying capacity can be improved; and when being used for well cementation cement slurry, the additive can improve slurry uniformity, anti-settling performance and construction adaptability.

Description

Technical Field

[0001] This invention relates to the field of materials technology for oil and gas drilling and cementing engineering, and in particular to a method for preparing activated attapulgite and its application in water-based drilling fluids and cementing slurries. Background Technology

[0002] Attapulgite is a natural clay mineral widely used in oil drilling fluids, cementing slurries, and other industrial applications. Due to its excellent adsorption, suspension, and thickening properties, attapulgite is used as a key additive in water-based drilling fluids to reduce filtration loss and improve wellbore strength. During cementing, attapulgite provides better resistance to settling and enhances the stability of the cement slurry, thereby improving cementing effectiveness.

[0003] However, while attapulgite exhibits good performance in many cases as an additive for drilling fluids and cementing slurries, its relatively closed surface characteristics as a natural mineral limit its application in certain situations. Firstly, natural attapulgite has low surface activity, making it difficult to achieve sufficient dispersion in water-based systems, thus affecting its rheological properties in water-based drilling fluids and cementing slurries. Secondly, the large particle size of natural attapulgite makes it prone to agglomeration, resulting in poor stability within the system and impacting the performance stability and service life of drilling fluids and cementing slurries.

[0004] In oil drilling, drilling fluids need to possess good rheological properties, reduced filtration loss, and inhibitory properties to ensure wellbore stability and drilling safety. Cement slurries, on the other hand, need to have suitable thickening time, early strength development, and good impermeability. Traditional modified attapulgite soil is often chemically activated alone (acidification or alkalization), which has problems such as limited increase in specific surface area, insufficient dispersibility, and poor compatibility with drilling fluids or cement slurry systems.

[0005] CN104293328A discloses a high-temperature resistant microfoam drilling fluid, which comprises the following components by weight: 10-15 parts modified attapulgite, 4-6 parts sodium α-olefin sulfonate, 0.5-2 parts nano-titanium dioxide, 1-3 parts tea saponin, 0.2-0.5 parts nano-molybdenum disulfide, 0.4-0.7 parts nano-zirconium dioxide, 3-5 parts filtration loss reducer, 1-2 parts shale inhibitor, and 100-130 parts water. However, it suffers from limited improvement in specific surface area, insufficient dispersibility, and poor compatibility with drilling fluids or cement slurry systems. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is that physical activation can significantly improve the specific surface area and pore volume of attapulgite, but when used alone, the surface charge and chemical environment are still difficult to meet the complex requirements of drilling fluids and cement slurries. If physical activation is carried out in combination with alkalization or acidification, pore structure, surface charge and chemical compatibility can be taken into account.

[0007] To achieve the above objectives, the present invention provides a method for preparing activated attapulgite.

[0008] The first method is: a method for preparing attapulgite soil through physical-alkalization synergistic activation, comprising the following steps:

[0009] (1) Raw material pretreatment: crush and screen the attapulgite ore to a particle size ≤ 2 mm, remove visible impurities, and dry it at 100-110℃ to constant weight.

[0010] (2) Physical activation:

[0011] The above-treated attapulgite clay is added to a ball mill or an air jet mill to obtain powder with a particle size D50 of 5-20 μm;

[0012] The mechanically activated attapulgite clay is placed in a muffle furnace and calcined at 150-350℃ for 1-3 hours with a heating rate of 5-10℃ / min, and then naturally cooled to room temperature.

[0013] The ball mill parameters are as follows: ball ratio 5:1-20:1, grinding media are zirconia balls or stainless steel balls with a diameter of 3-10 mm, and processing time is 0.5-3 h at 200-800 r / min;

[0014] The parameters for the air jet mill are: processing time of 0.5-3 hours at an airflow velocity of 30-80 m / s;

[0015] (3) Alkali treatment: Mix the above-mentioned physically activated attapulgite with an alkaline solution at a solid-liquid ratio of 1g:(5-20)mL; stir at 40-80℃ for 1-3 h; filter and wash until the pH of the filtrate is 9-11; dry at 100-120℃ to constant weight.

[0016] The alkaline solution is at least one of sodium hydroxide aqueous solution and sodium carbonate aqueous solution with a mass fraction of 1-5%.

[0017] Physical activation increases the specific surface area and enhances fiber dispersibility; alkalization generates -ONa and other groups on the surface, increasing hydrophilicity and negative charge density; in water-based drilling fluids, it can form a stable three-dimensional network structure, significantly improving viscosity, yield value and filtration loss reduction performance, and enhancing the inhibition effect on shale.

[0018] This invention also discloses the application of physically-alkalized synergistically activated attapulgite in water-based drilling fluids. Specifically, the physically-alkalized synergistically activated attapulgite is added to the drilling fluid and stirred at 100-500 r / min for 20-40 min until homogeneous.

[0019] The amount of attapulgite soil synergistically activated by physical-alkalization is 1-5% of the total mass of the drilling fluid.

[0020] The second method is: a method for preparing attapulgite soil by physical-acidification synergistic activation, comprising the following steps:

[0021] (1) Raw material pretreatment: crush and screen the attapulgite ore to a particle size ≤ 2 mm, remove visible impurities, and dry it at 100-110℃ to constant weight.

[0022] (2) Physical activation:

[0023] The above-treated attapulgite clay is added to a ball mill or an air jet mill to obtain powder with a particle size D50 of 5-20 μm;

[0024] The mechanically activated attapulgite clay is placed in a muffle furnace and calcined at 150-350℃ for 1-3 hours with a heating rate of 5-10℃ / min, and then naturally cooled to room temperature.

[0025] The ball mill parameters are as follows: ball ratio 5:1-20:1, grinding media are zirconia balls or stainless steel balls with a diameter of 3-10 mm, and processing time is 0.5-3 h at 200-800 r / min;

[0026] The parameters for the air jet mill are: processing time of 0.5-3 hours at an airflow velocity of 30-80 m / s;

[0027] (3) Acidification treatment: Mix the above-mentioned physically activated attapulgite with an acidic solution at a solid-liquid ratio of 1g:(5-20)mL; stir at 30-60℃ for 1-3 h; filter and wash until the pH of the filtrate is 4-6; dry at 100-120℃, and then calcine at 300-450℃ for 1-2 h.

[0028] The acidic solution is 0.5-2 mol / L hydrochloric acid or sulfuric acid.

[0029] Physical activation increases the contact area with cement particles; moderate acidification dissolves some aluminosilicates, which participate in the formation of CSH gel and aluminate hydrates during cement hydration; the porous structure formed after calcination can be used as micro-aggregate to fill the pores of cement stone, improving early strength, impermeability and high temperature resistance.

[0030] This invention also discloses the application of physically-acidified synergistically activated attapulgite in cementing slurry. Specifically, the physically-acidified synergistically activated attapulgite is added to cement, followed by the addition of water and admixtures, and then stirred at 100-500 r / min for 5-15 min until homogeneous.

[0031] The additives mentioned therein include, but are not limited to, at least one of dispersants, retarders, dewatering agents, defoamers, and expanding agents.

[0032] The physical-alkalization synergistic activation significantly improves the dispersibility and rheological regulation of attapulgite in water-based drilling fluids, and has a significant effect on reducing filtration loss; the physical-acidification synergistic activation enables attapulgite to participate in cement hydration reaction, improving the early strength and impermeability of cement stone; a single process can simultaneously prepare two products for different purposes, with low production costs and strong adaptability.

[0033] The preparation methods of physically-alkalized synergistically activated attapulgite and physically-acidified synergistically activated attapulgite also include a step of activating attapulgite with additives; specifically: the physically activated attapulgite obtained in step 2 is added to the treatment liquid and mixed evenly, heated to 50-70℃ for 1-3 hours, and then sheared at high speed of 5000-10000 rpm for 5-20 minutes to obtain a slurry; the slurry obtained above is aged at 30-50℃ for 6-10 hours, filtered, washed, vacuum dried at 80-100℃ for 10-15 hours, and then placed in a muffle furnace and calcined at 200-300℃ for 1-2 hours.

[0034] The solid-liquid ratio of physically activated attapulgite soil to the treatment solution is 1g:(10-15)mL;

[0035] The preparation method of the treatment solution is as follows: the additive is added to a mixed solvent and mixed evenly, then heated to 60-70℃ and stirred for 10-30 minutes to obtain the treatment solution; the mixed solvent is composed of ethanol and water in a volume ratio of 1:(1-3); the amount of additive added is 20-40 wt% of the treatment solution.

[0036] The additive is at least one of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, and caprolactam; preferably, the additive is a mixture of 1-butyl-3-methylimidazolium chloride and caprolactam in a mass ratio of (1-3):(1-2).

[0037] A further preferred method is: a method for preparing attapulgite soil by physical-alkalization synergistic activation, comprising the following steps:

[0038] (1) Raw material pretreatment: crush and screen the attapulgite ore to a particle size ≤ 2 mm, remove visible impurities, and dry it at 100-110℃ to constant weight.

[0039] (2) Physical activation:

[0040] The above-treated attapulgite clay is added to a ball mill or an air jet mill to obtain powder with a particle size D50 of 5-20 μm;

[0041] The mechanically activated attapulgite clay is placed in a muffle furnace and calcined at 150-350℃ for 1-3 hours with a heating rate of 5-10℃ / min, and then naturally cooled to room temperature.

[0042] The ball mill parameters are as follows: ball ratio 5:1-20:1, grinding media are zirconia balls or stainless steel balls with a diameter of 3-10 mm, and processing time is 0.5-3 h at 200-800 r / min;

[0043] The parameters for the air jet mill are: processing time of 0.5-3 hours at an airflow velocity of 30-80 m / s;

[0044] (3) Add the physically activated attapulgite obtained in step (2) to the treatment liquid and mix evenly. Heat to 50-70℃ for 1-3 hours, then shear at 5000-10000 rpm for 5-20 minutes to obtain a slurry. Let the slurry obtained above stand at 30-50℃ for 6-10 hours, filter, wash, vacuum dry at 80-100℃ for 10-15 hours, and then place it in a muffle furnace and calcine at 200-300℃ for 1-2 hours.

[0045] The solid-liquid ratio of physically activated attapulgite soil to the treatment solution is 1g:(10-15)mL;

[0046] The preparation method of the treatment solution is as follows: the additive is added to a mixed solvent and mixed evenly, then heated to 60-70℃ and stirred for 10-30 minutes to obtain the treatment solution; the mixed solvent is composed of ethanol and water in a volume ratio of 1:(1-3); the amount of additive added is 20-40 wt% of the treatment solution.

[0047] The additive is at least one of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, and caprolactam; preferably, the additive is a mixture of 1-butyl-3-methylimidazolium chloride and caprolactam in a mass ratio of (1-3):(1-2).

[0048] (4) Alkali treatment: Mix the above-mentioned attapulgite treated with additives with an alkaline solution at a solid-liquid ratio of 1g:(5-20)mL; stir at 40-80℃ for 1-3 h; filter and wash until the pH of the filtrate is 9-11; dry at 100-120℃ to constant weight.

[0049] The alkaline solution is at least one of sodium hydroxide aqueous solution and sodium carbonate aqueous solution with a mass fraction of 1-5%.

[0050] A further preferred method is a preparation method for attapulgite soil with synergistic physical-acidification activation, comprising the following steps:

[0051] (1) Raw material pretreatment: crush and screen the attapulgite ore to a particle size ≤ 2 mm, remove visible impurities, and dry it at 100-110℃ to constant weight.

[0052] (2) Physical activation:

[0053] The above-treated attapulgite clay is added to a ball mill or an air jet mill to obtain powder with a particle size D50 of 5-20 μm;

[0054] The mechanically activated attapulgite clay is placed in a muffle furnace and calcined at 150-350℃ for 1-3 hours with a heating rate of 5-10℃ / min, and then naturally cooled to room temperature.

[0055] The ball mill parameters are as follows: ball ratio 5:1-20:1, grinding media are zirconia balls or stainless steel balls with a diameter of 3-10 mm, and processing at 200-800 r / min for 0.5-3 h.

[0056] The parameters for the air jet mill are: processing time of 0.5-3 hours at an airflow velocity of 30-80 m / s;

[0057] (3) Add the physically activated attapulgite obtained in step (2) to the treatment liquid and mix evenly. Heat to 50-70℃ for 1-3 hours, then shear at 5000-10000 rpm for 5-20 minutes to obtain a slurry. Let the slurry obtained above stand at 30-50℃ for 6-10 hours, filter, wash, vacuum dry at 80-100℃ for 10-15 hours, and then place it in a muffle furnace and calcine at 200-300℃ for 1-2 hours.

[0058] The solid-liquid ratio of physically activated attapulgite soil to the treatment solution is 1g:(10-15)mL;

[0059] The preparation method of the treatment solution is as follows: the additive is added to a mixed solvent and mixed evenly, then heated to 60-70℃ and stirred for 10-30 minutes to obtain the treatment solution; the mixed solvent is composed of ethanol and water in a volume ratio of 1:(1-3); the amount of additive added is 20-40 wt% of the treatment solution.

[0060] The additive is at least one of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, and caprolactam; preferably, the additive is a mixture of 1-butyl-3-methylimidazolium chloride and caprolactam in a mass ratio of (1-3):(1-2).

[0061] (4) Acidification treatment: Mix the above-mentioned attapulgite treated with additives with an acidic solution at a solid-liquid ratio of 1g:(5-20)mL; stir at 30-60℃ for 1-3 h; filter and wash until the pH of the filtrate is 4-6; dry at 100-120℃, and then calcine at 300-450℃ for 1-2 h.

[0062] The acidic solution is 0.5-2 mol / L hydrochloric acid or sulfuric acid.

[0063] 1-Butyl-3-methylimidazolium chloride and caprolactam work synergistically, on the one hand, the Cl in 1-butyl-3-methylimidazolium chloride... - It can form strong hydrogen bonds with the hydroxyl groups on the surface of attapulgite and adsorbed water, competing with and rearranging the hydrogen bond network between fiber bundles, thus weakening the bonding between fiber bundles. On the other hand, caprolactam, as a polar amide molecule, can establish hydrogen bond associations with Cl⁻ and surface hydroxyl groups through its carbonyl group, amide nitrogen, and surface hydroxyl groups, and can also reduce the viscosity of the system and improve the wetting and penetration ability of mineral surfaces, making it easier for ionic liquids to enter the micropores and gaps between fiber bundles. Thus, the synergistic effect of 1-butyl-3-methylimidazolium chloride and caprolactam is more conducive to fiber bundle dissociation, exfoliation, and dispersion stability under shear dispersion conditions, reducing secondary agglomeration. After washing, displacement, drying, or heat treatment, the outer surface of the particles and the accessible pores are released, resulting in an increase in specific surface area and pore volume.

[0064] The beneficial effects of this invention are:

[0065] Compared with the prior art, the present invention uses physical-acidification synergy or physical-alkalization synergy to activate attapulgite, which improves the specific surface area and pore volume of activated attapulgite soil. After activation, the surface characteristics of particles are improved, the tendency of secondary agglomeration between particles is reduced, and the dispersion is more uniform. This makes the rheological parameters of the system easier to control and reduces the risk of viscosity fluctuation, local flocculation and unstable thickening caused by agglomeration. Detailed Implementation

[0066] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the 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 in this invention.

[0067] The water-based drilling fluid is composed of the following raw materials: 4.5 wt% bentonite, 0.4 wt% PAC filtration reducer, 0.25 wt% hydroxyethyl cellulose, 0.1 wt% xanthan gum, 0.2 wt% sodium carbonate, and the balance is water, with the pH adjusted to 10 using NaOH; wherein the PAC filtration reducer is model PAC-LV, manufactured by Dongying Dayong Petroleum Additives Co., Ltd.

[0068] The G-grade oil well cement slurry is composed of the following raw materials: 100 parts by weight of G-grade oil well cement, 44 parts by weight of water, 0.5 parts by weight of sodium hexametaphosphate, 1 part by weight of polyacrylamide (product number: 1268640, Tianjin Xiens Biochemical Technology Co., Ltd.), 0.3 parts by weight of retarder (prepared by the preparation method of Example 1 in the patent CN 104403056 B of the high-temperature resistant copolymer oil well cement retarder developed by China Petroleum Engineering Technology Research Institute Co., Ltd.), and 0.05 parts by weight of tributyl phosphate; the G-grade oil well cement is commercially available G-grade oil well cement (dry powder) that meets API standards.

[0069] Other raw materials not mentioned are all common raw materials. The above content is only for the purpose of illustrating the present invention and should not be construed as a strict limitation of the present invention. Those skilled in the art can directly purchase the same / similar raw materials from the market or prepare them themselves.

[0070] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] Comparative Example 1

[0072] A method for preparing activated attapulgite includes the following steps: Step 1, Pretreatment: The raw attapulgite ore is crushed to ≤2 mm and dried at 105℃ to constant weight;

[0073] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain activated attapulgite clay.

[0074] The specific method for applying activated attapulgite is as follows: add activated attapulgite to water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of activated attapulgite added is 3% of the total mass of water-based drilling fluid.

[0075] Example 1-1

[0076] A method for preparing attapulgite soil with physical-alkalization synergistic activation includes the following steps:

[0077] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0078] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0079] Step 3, Alkalization treatment: Add the above physically activated attapulgite to a 3% sodium hydroxide aqueous solution, wherein the solid-liquid ratio of the physically activated attapulgite to the sodium hydroxide aqueous solution is 1g:10mL, and then stir at 60℃ for 2 h; after the reaction is completed, filter and wash until pH=10, and dry at 110℃ to constant weight.

[0080] The application of the above-prepared physically-alkalized synergistically activated attapulgite is specifically as follows: add the physically-alkalized synergistically activated attapulgite to the water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of physically-alkalized synergistically activated attapulgite added is 3% of the total mass of the water-based drilling fluid.

[0081] Examples 1-2

[0082] A method for preparing attapulgite soil with physical-alkalization synergistic activation includes the following steps:

[0083] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0084] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0085] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix evenly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix evenly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is composed of 1-butyl-3-methylimidazolium chloride and caprolactam mixed in a mass ratio of 3:2.

[0086] Step 4, Alkalization treatment: Add the above-treated attapulgite with additives to a 3% sodium hydroxide aqueous solution, wherein the solid-liquid ratio of physically activated attapulgite to sodium hydroxide aqueous solution is 1g:10mL, and then stir at 60℃ for 2 h; after the reaction is completed, filter and wash until pH=10, and dry at 110℃ to constant weight.

[0087] The application of the above-prepared physically-alkalized synergistically activated attapulgite is specifically as follows: add the physically-alkalized synergistically activated attapulgite to the water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of physically-alkalized synergistically activated attapulgite added is 3% of the total mass of the water-based drilling fluid.

[0088] Examples 1-3

[0089] A method for preparing attapulgite soil with physical-alkalization synergistic activation includes the following steps:

[0090] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0091] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0092] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix thoroughly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix thoroughly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is 1-butyl-3-methylimidazolium chloride.

[0093] Step 4, Alkalization treatment: Add the above-treated attapulgite with additives to a 3% sodium hydroxide aqueous solution, wherein the solid-liquid ratio of physically activated attapulgite to sodium hydroxide aqueous solution is 1g:10mL, and then stir at 60℃ for 2 h; after the reaction is completed, filter and wash until pH=10, and dry at 110℃ to constant weight.

[0094] The application of the above-prepared physically-alkalized synergistically activated attapulgite is specifically as follows: add the physically-alkalized synergistically activated attapulgite to the water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of physically-alkalized synergistically activated attapulgite added is 3% of the total mass of the water-based drilling fluid.

[0095] Examples 1-4

[0096] A method for preparing attapulgite soil with physical-alkalization synergistic activation includes the following steps:

[0097] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0098] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0099] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1), mix thoroughly, stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution; add the above physically activated attapulgite to the above treatment solution, mix thoroughly, heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL; let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h; wherein the additive is caprolactam;

[0100] Step 4, Alkalization treatment: Add the above-treated attapulgite with additives to a 3% sodium hydroxide aqueous solution, wherein the solid-liquid ratio of physically activated attapulgite to sodium hydroxide aqueous solution is 1g:10mL, and then stir at 60℃ for 2 h; after the reaction is completed, filter and wash until pH=10, and dry at 110℃ to constant weight.

[0101] The application of the above-prepared physically-alkalized synergistically activated attapulgite is specifically as follows: add the physically-alkalized synergistically activated attapulgite to the water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of physically-alkalized synergistically activated attapulgite added is 3% of the total mass of the water-based drilling fluid.

[0102] Examples 1-5

[0103] A method for preparing attapulgite soil with physical-alkalization synergistic activation includes the following steps:

[0104] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0105] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0106] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix evenly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix evenly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is composed of 1-butyl-3-methylimidazolium bromide and caprolactam mixed in a mass ratio of 3:2.

[0107] Step 4, Alkalization treatment: Add the above-treated attapulgite with additives to a 3% sodium hydroxide aqueous solution, wherein the solid-liquid ratio of physically activated attapulgite to sodium hydroxide aqueous solution is 1g:10mL, and then stir at 60℃ for 2 h; after the reaction is completed, filter and wash until pH=10, and dry at 110℃ to constant weight.

[0108] The application of the above-prepared physically-alkalized synergistically activated attapulgite is specifically as follows: add the physically-alkalized synergistically activated attapulgite to the water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of physically-alkalized synergistically activated attapulgite added is 3% of the total mass of the water-based drilling fluid.

[0109] Examples 1-6

[0110] A method for preparing attapulgite soil with physical-alkalization synergistic activation includes the following steps:

[0111] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0112] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0113] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix evenly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix evenly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is composed of 1-ethyl-3-methylimidazolium chloride and caprolactam mixed in a mass ratio of 3:2.

[0114] Step 4, Alkalization treatment: Add the above-treated attapulgite with additives to a 3% sodium hydroxide aqueous solution, wherein the solid-liquid ratio of physically activated attapulgite to sodium hydroxide aqueous solution is 1g:10mL, and then stir at 60℃ for 2 h; after the reaction is completed, filter and wash until pH=10, and dry at 110℃ to constant weight.

[0115] The application of the above-prepared physically-alkalized synergistically activated attapulgite is specifically as follows: add the physically-alkalized synergistically activated attapulgite to the water-based drilling fluid and stir at 500 r / min for 30 min, wherein the amount of physically-alkalized synergistically activated attapulgite added is 3% of the total mass of the water-based drilling fluid.

[0116] Test Example 1

[0117] The filtration loss (FL) of the water-based drilling fluids prepared in each embodiment and comparative example was measured according to GB / T16783.1-2006. API Tests included ( / mL), plastic viscosity, and dynamic shear force.

[0118] Table 1

[0119] Filtration loss / mL Plastic viscosity / mPa.s Dynamic shear force / Pa Example 1-1 8.1 21.6 14.3 Examples 1-2 6.5 26.8 17.5 Examples 1-3 7.0 24.9 16.1 Examples 1-4 7.6 23.1 15.2 Examples 1-5 6.9 25.6 16.7 Examples 1-6 6.7 26.1 17.0 Comparative Example 1 14.0 14.2 5.7

[0120] As shown in Table 1, after the synergistic treatment of physical activation and alkali activation in Example 1-1, the specific surface area of ​​the attapulgite was significantly increased compared to Comparative Example 1. Correspondingly, in terms of water-based drilling fluid performance, API filtration loss decreased by approximately 30%-55%, and both plastic viscosity and dynamic shear strength were improved. The reasonable explanation is that the increased specific surface area enhances the adsorption, entanglement, and structuring ability of particles on the hydration layer and substances in the system, thereby increasing the viscosity and yield characteristics of the system; at the same time, the particles are more likely to form a dense, low-permeability filter cake on the well wall, reducing seepage channels and thus reducing filtration loss.

[0121] A comparison of Examples 1-2, 1-3, and 1-4 shows that Example 1-2 has a higher specific surface area, the lowest filtration loss, and a more significant improvement in plastic viscosity and dynamic shear force, exhibiting overall performance superior to Examples 1-3 and 1-4. The possible reason is: Cl - It readily forms strong hydrogen bonds with hydroxyl groups or adsorbed water on the surface of attapulgite, competing with and rearranging the hydrogen bond network between fiber bundles, thus weakening the bundled structure. Simultaneously, caprolactam improves wetting and penetration through hydrogen bonding association, making it easier for ionic liquids to enter the micropores and gaps between fiber bundles. Under shear dispersion, the above synergistic effect is more conducive to fiber dissociation, exfoliation, and inhibition of secondary aggregation, ultimately resulting in increased specific surface area and pore volume. Furthermore, the more open, accessible surface and pore structure enhance the hydration layer and the adsorption and fixation capacity of substances, strengthen structural viscosity and yield characteristics, and promote a decrease in filter cake porosity.

[0122] Examples 1-2 performed better than Examples 1-5, which can be attributed to Cl. - Compared to Br - With higher charge density and stronger hydrogen bond acceptor capacity, it is more likely to compete with surface hydroxyl groups / adsorbed water, thereby more effectively weakening the hydrogen bond network between fiber bundles and improving the degree of dissociation and stripping. Corresponding to the drilling fluid system, the particles are more fully dispersed and have a larger effective specific surface area, which is more conducive to the formation of a dense filter cake and reduces the permeation channels, thus resulting in better filtration loss control.

[0123] The advantages of Examples 1-2 compared to Examples 1-6 can be understood from the difference in the alkyl chain of the ionic liquid: compared to 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride has a longer alkyl chain, which generally makes it easier to form a certain organic coating and steric hindrance effect on the particle surface, making it less prone to fiber re-bundling after dispersion, and promoting the structural association between particles and system components. Therefore, while maintaining a lower filtration loss, it is more likely to bring slightly higher plastic viscosity and dynamic shear force.

[0124] Comparative Example 2

[0125] A method for preparing activated attapulgite includes the following steps: Step 1, Pretreatment: The raw attapulgite ore is crushed to ≤2 mm and dried at 105℃ to constant weight;

[0126] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain activated attapulgite clay.

[0127] The specific method for applying activated attapulgite is as follows: add activated attapulgite to G-grade oil well cement slurry and stir at 500 r / min for 15 min, wherein the amount of activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0128] Example 2-1

[0129] A method for preparing attapulgite with synergistic physical-acidification activation includes the following steps:

[0130] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0131] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0132] Step 3, acidification treatment: Add the above physically activated attapulgite to 1 mol / L hydrochloric acid, wherein the solid-liquid ratio of physically activated attapulgite to hydrochloric acid is 1 g: 10 mL, and then stir at 40 °C for 2 h; after the reaction is completed, filter and wash until pH=5, and dry at 110 °C to constant weight; then calcine at 350 °C for 1.5 h.

[0133] The application of the above-prepared physically-acidified synergistically activated attapulgite is specifically as follows: the physically-acidified synergistically activated attapulgite is added to G-grade oil well cement slurry and stirred at 500 r / min for 15 min, wherein the amount of physically-acidified synergistically activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0134] Example 2-2

[0135] A method for preparing attapulgite with synergistic physical-acidification activation includes the following steps:

[0136] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0137] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0138] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix evenly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix evenly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is composed of 1-butyl-3-methylimidazolium chloride and caprolactam mixed in a mass ratio of 3:2.

[0139] Step 4, acidification treatment: Add the above-treated attapulgite with additives to 1 mol / L hydrochloric acid, wherein the solid-liquid ratio of physically activated attapulgite to hydrochloric acid is 1 g: 10 mL, and then stir at 40 °C for 2 h; after the reaction is completed, filter and wash until pH=5, dry at 110 °C to constant weight; then calcine at 350 °C for 1.5 h.

[0140] The application of the above-prepared physically-acidified synergistically activated attapulgite is specifically as follows: the physically-acidified synergistically activated attapulgite is added to G-grade oil well cement slurry and stirred at 500 r / min for 15 min, wherein the amount of physically-acidified synergistically activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0141] Example 2-3

[0142] A method for preparing attapulgite with synergistic physical-acidification activation includes the following steps:

[0143] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0144] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0145] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix thoroughly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix thoroughly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is 1-butyl-3-methylimidazolium chloride.

[0146] Step 4, acidification treatment: Add the above-treated attapulgite with additives to 1 mol / L hydrochloric acid, wherein the solid-liquid ratio of physically activated attapulgite to hydrochloric acid is 1 g: 10 mL, and then stir at 40 °C for 2 h; after the reaction is completed, filter and wash until pH=5, dry at 110 °C to constant weight; then calcine at 350 °C for 1.5 h.

[0147] The application of the above-prepared physically-acidified synergistically activated attapulgite is specifically as follows: the physically-acidified synergistically activated attapulgite is added to G-grade oil well cement slurry and stirred at 500 r / min for 15 min, wherein the amount of physically-acidified synergistically activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0148] Examples 2-4

[0149] A method for preparing attapulgite with synergistic physical-acidification activation includes the following steps:

[0150] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0151] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0152] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1), mix thoroughly, stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution; add the above physically activated attapulgite to the above treatment solution, mix thoroughly, heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL; let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h; wherein the additive is caprolactam;

[0153] Step 4, acidification treatment: Add the above-treated attapulgite with additives to 1 mol / L hydrochloric acid, wherein the solid-liquid ratio of physically activated attapulgite to hydrochloric acid is 1 g: 10 mL, and then stir at 40 °C for 2 h; after the reaction is completed, filter and wash until pH=5, dry at 110 °C to constant weight; then calcine at 350 °C for 1.5 h.

[0154] The application of the above-prepared physically-acidified synergistically activated attapulgite is specifically as follows: the physically-acidified synergistically activated attapulgite is added to G-grade oil well cement slurry and stirred at 500 r / min for 15 min, wherein the amount of physically-acidified synergistically activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0155] Examples 2-5

[0156] A method for preparing attapulgite with synergistic physical-acidification activation includes the following steps:

[0157] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0158] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0159] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix evenly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix evenly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is composed of 1-butyl-3-methylimidazolium bromide and caprolactam mixed in a mass ratio of 3:2.

[0160] Step 4, acidification treatment: Add the above-treated attapulgite with additives to 1 mol / L hydrochloric acid, wherein the solid-liquid ratio of physically activated attapulgite to hydrochloric acid is 1 g: 10 mL, and then stir at 40 °C for 2 h; after the reaction is completed, filter and wash until pH=5, dry at 110 °C to constant weight; then calcine at 350 °C for 1.5 h.

[0161] The application of the above-prepared physically-acidified synergistically activated attapulgite is specifically as follows: the physically-acidified synergistically activated attapulgite is added to G-grade oil well cement slurry and stirred at 500 r / min for 15 min, wherein the amount of physically-acidified synergistically activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0162] Examples 2-6

[0163] A method for preparing attapulgite with synergistic physical-acidification activation includes the following steps:

[0164] Step 1: Pretreatment: Crush the attapulgite ore to ≤2 mm and dry it at 105℃ to constant weight;

[0165] Step 2, Physical Activation: The pretreated attapulgite was added to a planetary ball mill, with stainless steel balls of 3 mm diameter added at a ball milling ratio of 10:1. The ball mill speed was 400 r / min, and the milling was carried out for 1.5 h to obtain attapulgite powder with a particle size D50 of 10-12 μm. The obtained attapulgite powder was placed in a muffle furnace and heated from room temperature to 250℃ at a heating rate of 5℃ / min, and calcined at 250℃ for 2 h to obtain physically activated attapulgite clay.

[0166] Step 3: Add the additive to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 1:1) and mix evenly. Stir at 60°C for 20 min to obtain a treatment solution, wherein the amount of additive added is 30 wt% of the treatment solution. Add the above physically activated attapulgite to the above treatment solution and mix evenly. Heat to 60°C for 2 h, then shear at 10000 rpm for 10 min to obtain a slurry, wherein the solid-liquid ratio of physically activated attapulgite to the treatment solution is 1 g: 10 mL. Let the above slurry stand at 40°C for 6 h for aging, filter, wash, vacuum dry at 80°C for 12 h, and then calcine in a muffle furnace at 250°C for 1 h. The additive is composed of 1-ethyl-3-methylimidazolium chloride and caprolactam mixed in a mass ratio of 3:2.

[0167] Step 4, acidification treatment: Add the above-treated attapulgite with additives to 1 mol / L hydrochloric acid, wherein the solid-liquid ratio of physically activated attapulgite to hydrochloric acid is 1 g: 10 mL, and then stir at 40 °C for 2 h; after the reaction is completed, filter and wash until pH=5, dry at 110 °C to constant weight; then calcine at 350 °C for 1.5 h.

[0168] The application of the above-prepared physically-acidified synergistically activated attapulgite is specifically as follows: the physically-acidified synergistically activated attapulgite is added to G-grade oil well cement slurry and stirred at 500 r / min for 15 min, wherein the amount of physically-acidified synergistically activated attapulgite added is 2% of the total mass of G-grade oil well cement slurry.

[0169] Test Example 2

[0170] The cement slurries prepared in the above examples and comparative examples were tested according to GB / T 19139-2012. After the mixed cement slurry was poured into the strength curing mold, it was placed in an oil bath and cured at 130°C for 24 hours. After curing, it was cooled, demolded, and then the compressive strength and permeability were tested.

[0171] Table 2

[0172] 24h compressive strength / MPa Permeability / mD Example 2-1 22.5 0.133 Example 2-2 24.6 0.110 Example 2-3 23.8 0.118 Examples 2-4 23.2 0.125 Examples 2-5 24.0 0.114 Examples 2-6 24.3 0.112 Comparative Example 2 19.8 0.18

[0173] The specific surface area and pore volume of the activated attapulgite prepared in each example and comparative example were tested using the nitrogen adsorption BET method.

[0174] Table 3

[0175] <![CDATA[Specific surface area / m 2 ·g -1 > <![CDATA[Pore volume / cm 3 ·g -1 > Example 1-1 211 0.42 Examples 1-2 260 0.55 Examples 1-3 246 0.51 Examples 1-4 232 0.46 Examples 1-5 257 0.53 Examples 1-6 258 0.53 Comparative Example 1 105 0.21 Example 2-1 204 0.44 Example 2-2 255 0.58 Example 2-3 241 0.52 Examples 2-4 223 0.48 Examples 2-5 249 0.54 Examples 2-6 252 0.56

[0176] As shown in Table 3, compared with the comparative example, Example 2-1 uses ball milling and medium-temperature calcination to obtain physically activated attapulgite, and then performs acid activation treatment. Through mechanical action and heat treatment, the agglomeration of mineral fiber bundles is weakened and some contactable surfaces are released. On the other hand, acidification can dissolve or remove some impurity phases and generate more reactive surface sites, so that the specific surface area and pore volume of the activated sample are significantly higher than those of the insufficiently activated state.

[0177] According to the data in Table 2, compared with Comparative Example 2, Example 2-1 showed a 10-25% increase in compressive strength and a 20-40% decrease in permeability after 24 hours. This indicates that physical and acidic activation can bring about structural densification and reinforcement of the load-bearing skeleton, but the extent of the improvement is still limited by insufficient fiber bundle dissociation and insufficient release of effective pores.

[0178] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing activated attapulgite, characterized in that, Includes the following steps: (1) Pre-treatment of raw attapulgite ore; (2) The pretreated attapulgite soil is mechanically activated and then subjected to heat treatment to obtain physically activated attapulgite soil; (3) The physically activated attapulgite is chemically activated, wherein the chemical activation is at least one of alkalization treatment and acidification treatment, to obtain activated attapulgite.

2. The method for preparing activated attapulgite as described in claim 1, characterized in that, Includes the following steps: (1) Raw material pretreatment: crush and screen the attapulgite ore and dry it to constant weight; (2) Physical activation: The pretreated attapulgite is mechanically activated; and the powder is placed in a muffle furnace for calcination to obtain physically activated attapulgite. (3) Chemical activation treatment: The physically activated attapulgite obtained in step (2) is subjected to chemical activation treatment to obtain activated attapulgite; the chemical activation is at least one of alkalization treatment and acidification treatment; a) Alkaliization treatment: Mix the physically activated attapulgite with an alkaline solution and stir at 40-80℃ for 1-3 h; filter and wash until the pH of the filtrate is 9-11; dry at 100-120℃ to constant weight; b) Acidification treatment: Mix the physically activated attapulgite with an acidic solution and stir at 30-60℃ for 1-3 h; filter and wash until the pH of the filtrate is 4-6; dry at 100-120℃, and then calcine at 300-450℃ for 1-2 h.

3. The method for preparing activated attapulgite as described in claim 2, characterized in that: The mechanical activation is performed using a ball mill with the following parameters: ball ratio 5:1-20:1, grinding media being zirconia balls or stainless steel balls with a diameter of 3-10 mm, and processing at 200-800 r / min for 0.5-3 h.

4. The method for preparing activated attapulgite as described in claim 2, characterized in that: The mechanical activation is performed using an airflow pulverizer with an airflow velocity of 30-80 m / s and a processing time of 0.5-3 h.

5. The method for preparing activated attapulgite as described in claim 2, characterized in that: The calcination temperature in step (2) is 150-350℃, the calcination time is 1-3 h, and the heating rate is 5-10℃ / min.

6. The method for preparing activated attapulgite as described in claim 2, characterized in that: Prior to the chemical activation treatment in step (3), an additive activation treatment step is also included: The physically activated attapulgite obtained in step (2) is added to the treatment liquid and mixed evenly. It is heated to 50-70℃ for 1-3 hours and then sheared at high speed to obtain a slurry. The slurry is then allowed to stand for aging. After filtration and washing, it is vacuum dried and then placed in a muffle furnace for calcination.

7. The method for preparing activated attapulgite as described in claim 6, characterized in that: The treatment solution is prepared by adding the additive to a mixed solvent, mixing thoroughly, heating and stirring to obtain the treatment solution.

8. The method for preparing activated attapulgite as described in claim 6, characterized in that: The additive is at least one of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, and caprolactam.

9. An activated attapulgite soil, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the activated attapulgite as described in claim 9 in water-based drilling fluids and cementing slurries.