Bentonite for compound anti-seepage drilling mud as well as preparation method and application of bentonite

Abstract

The invention provides bentonite for compound anti-seepage drilling mud as well as a preparation method and application thereof, and the method comprises the following steps: respectively airing and coarsely crushing bentonite raw ore and attapulgite raw ore to obtain bentonite coarse ore and attapulgite coarse ore; the bentonite coarse ore and the attapulgite coarse ore are subjected to drying, grinding, impurity removal and sieving respectively, and bentonite ore powder and attapulgite ore powder are obtained; the preparation method comprises the following steps: mixing bentonite mineral powder, attapulgite mineral powder, a tackifier and water in parts by mass, and stirring to obtain compound clay ore pulp; the compound clay ore pulp is subjected to standing curing treatment and heating treatment, and the compound anti-seepage drilling mud is obtained. The bentonite for the compound anti-seepage drilling mud is high in viscosity, low in filter loss and capable of effectively meeting the requirements of the drilling mud after being subjected to high-temperature reaction, and meanwhile the preparation method is simple in process, low in production cost, rich in raw material and easy to produce and use in a large scale.

Description

Technical Field

[0001] The invention relates to the field of preparing functional drilling mud materials from non-metallic mineral raw materials, and in particular to a compound anti-seepage bentonite for drilling mud and a preparation method and application thereof. Background Art

[0002] In drilling operations, a variety of materials are needed to ensure the smooth completion of drilling operations. The preferred material for drilling mud is sodium bentonite, which not only has the function of lubricating and cooling the drill bit, but also can fill the well wall, avoid well wall collapse, and prevent groundwater and other substances from penetrating into the well wall.

[0003] Clay minerals, such as montmorillonite and attapulgite, are a type of non-metallic minerals with large specific surface area and strong adsorption properties. Due to their stability, sealing, adsorption and lubricity, they are widely used in drilling mud lubricants, plugging agents, feed additives, degreasing and decolorizing agents, adhesives and heavy metal adsorbents.

[0004] At present, the existing bentonite and attapulgite are of low grade, and the viscosity and filtration loss of the slurry after high temperature treatment are difficult to meet the standards of bentonite for drilling mud. The bentonite formula for drilling mud on the market uses a single bentonite as the matrix and pure organic matter as an additive, and the viscosity will be greatly reduced after high temperature reaction. At present, the industrial operation of compounding bentonite and attapulgite, using organic and inorganic substances as bentonite additives for drilling mud, to further increase the viscosity of the mud after high temperature reaction and reduce the filtration loss of the mud has not been reported. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present invention is to provide a method for preparing a compound anti-seepage bentonite for drilling mud; a second purpose of the present invention is to provide a compound anti-seepage bentonite for drilling mud; a third purpose of the present invention is to provide an application of a compound anti-seepage bentonite for drilling mud.

[0006] In order to achieve the above object, the present invention provides a method for preparing a composite anti-seepage drilling mud bentonite, the method comprising:

[0007] Drying and roughly crushing the bentonite ore and the attapulgite ore to obtain crude bentonite ore and crude attapulgite ore;

[0008] Drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore to obtain bentonite ore powder and attapulgite ore powder;

[0009] The bentonite powder, the attapulgite powder, the viscosity enhancer and the water are mixed in proportion by mass and stirred to obtain a composite clay slurry;

[0010] The compound clay slurry is subjected to static curing treatment and heating treatment to obtain the compound anti-seepage drilling mud.

[0011] Optionally, the bentonite ore includes at least one of sodium bentonite and transition bentonite; the montmorillonite content in the bentonite ore is ≥40%, and the impurity minerals include quartz, calcite and illite.

[0012] Optionally, the attapulgite ore is sedimentary attapulgite clay, the attapulgite content in the attapulgite ore is ≥40%, and the impurity minerals are mainly montmorillonite, containing a small amount of quartz and dolomite.

[0013] Optionally, the coarse crushing is to crush the raw ore using a crusher;

[0014] The crusher includes one or more of a double-roll crusher, a jaw crusher, a gyratory crusher, and a cone crusher, and the size of the discharge port of the crusher is set to be less than 15 mm.

[0015] Optionally, the drying is to reduce the moisture content of the crude bentonite ore and the crude attapulgite ore to 15-22% by sun drying or air drying in a drying and stacking yard.

[0016] Optionally, the drying is carried out using an industrial kiln, such as a rotary kiln, a fluidized bed drying kiln or an electric heating drying kiln, to reduce the moisture content of the bentonite crude ore and the attapulgite crude ore to 4-8% respectively after drying.

[0017] Alternatively, the grinding is to grind the crude bentonite ore and the crude attapulgite ore into fine powder by conveying with a conveyor belt using a Raymond mill, a jet mill and a cyclone mill to obtain bentonite ore powder and attapulgite ore powder.

[0018] Optionally, the impurity removal is to separate and remove some impurity minerals that are difficult to crush in the original ore by screening or gravity classification during the crushing and grinding process, and the impurity minerals include quartz, feldspar and dolomite.

[0019] Optionally, the particle sizes of the bentonite powder and the attapulgite powder are -100 to -300 meshes, the montmorillonite content in the bentonite powder is 50 to 75%, and the attapulgite content in the attapulgite powder is 50 to 70%.

[0020] Optionally, the mass ratio of the bentonite powder to the attapulgite powder is (6-9):(4-1); after uniform mixing, the composite powder is obtained.

[0021] Optionally, the mass ratio of the composite mineral powder, the viscosity enhancer and the tap water is 100 parts of the composite mineral powder, 1 to 8 parts of the viscosity enhancer and 1555 parts of the tap water.

[0022] Optionally, the viscosity increasing agent includes two or more of magnesium oxide, sodium carboxymethyl cellulose, sodium pyrophosphate, calcium oxide and potassium hydrogen phthalate;

[0023] Optionally, the water includes tap water, industrial water, etc., and the pH value of the water is adjusted to 8-11.

[0024] Optionally, the stirring equipment includes a barrel stirrer, a horizontal stirrer, a vertical stirrer and a top-entry stirrer;

[0025] Optionally, the stirring treatment is to add the composite mineral powder, viscosity enhancer and tap water into a stirring device for high-speed stirring reaction, and the reaction time is 10 to 40 minutes to obtain a composite clay slurry.

[0026] Optionally, the temperature of the static curing treatment is 20-30°C.

[0027] Optionally, the heating treatment is to place the compound clay slurry into a reaction tank and heat it by steam heating, electric heating, flame heating and high-pressure water heating to obtain a compound anti-seepage drilling mud;

[0028] Wherein, the temperature of the heating treatment is 150-220°C and the time is 16 hours.

[0029] Optionally, the bentonite used in the composite anti-seepage drilling mud has a viscosity of 30 to 73 mPa·s and a filtration loss of 10 to 24 mL.

[0030] Another aspect of the present invention provides a composite bentonite for anti-seepage drilling mud.

[0031] The compound anti-seepage drilling mud bentonite can be prepared by the above method.

[0032] In another aspect, the present invention provides an application of compound bentonite for anti-seepage drilling mud, wherein the bentonite can be applied to drilling mud.

[0033] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0034] 1) After high-temperature reaction, the composite anti-seepage drilling mud bentonite prepared by the present invention has high viscosity and low filtration loss, which can effectively meet the requirements of drilling mud.

[0035] 2) The organic and inorganic composite modified montmorillonite anti-seepage drilling mud prepared by the present invention using bentonite can effectively fill the well wall and pores to prevent the well wall from collapsing during the drilling process.

[0036] 3) The composite anti-seepage drilling mud bentonite prepared by the present invention has high viscosity, is conducive to the adsorption of toxic and harmful substances generated by drilling, etc., reduces the processing cost of drilling waste fluid and saves time.

[0037] 4) The raw and auxiliary materials used in the production of the present invention are low in price and excellent in performance, and have good economic and social benefits.

[0038] 5) The preparation method of the present invention has simple process, low production cost, abundant raw materials, and is easy to use for large-scale production. DETAILED DESCRIPTION

[0039] Hereinafter, a composite anti-seepage drilling mud bentonite and a preparation method and application thereof of the present invention will be described in detail in conjunction with exemplary embodiments.

[0040] Exemplary Embodiment 1

[0041] This exemplary embodiment provides a method for preparing a composite anti-seepage drilling mud bentonite, the method comprising the following steps:

[0042] S01. Drying and roughly crushing the bentonite ore and the attapulgite ore to obtain crude bentonite ore and crude attapulgite ore.

[0043] In this embodiment, the bentonite ore includes at least one of sodium bentonite and transitional bentonite; the percentage of montmorillonite in the bentonite ore is ≥40%, for example, 40%, 55%, 60%, etc.; the percentage of attapulgite in the attapulgite ore is ≥40%, for example, 40%, 50%, 60%, etc.

[0044] In this embodiment, the drying is to reduce the moisture content of the crude bentonite ore and the crude attapulgite ore to 15-22%, for example, 15%, 15.5%, 16%, 17.2%, 19%, 21.5%, etc. by sun drying or air drying in a drying and stacking yard.

[0045] Among them, ensuring that the moisture content is within this range can avoid weighing errors, while preventing caking and reducing stirring costs and time costs.

[0046] In this embodiment, the coarse crushing is to crush the raw ore using a crusher;

[0047] The crusher includes one or more of a double-roll crusher, a jaw crusher, a gyratory crusher, and a cone crusher, and the size of the discharge port of the crusher is set to be less than 15 mm.

[0048] The purpose of the coarse crushing is to separate and remove the hard-to-crush impurity minerals such as quartz and feldspar in the bentonite ore by screening and gravity classification during the crushing process to obtain the crude bentonite ore and the crude attapulgite ore.

[0049] S02: Drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore respectively to obtain bentonite ore powder and attapulgite ore powder.

[0050] In this embodiment, the drying is carried out using an industrial kiln, such as a rotary kiln, a fluidized bed drying kiln or an electric drying kiln, to reduce the moisture content of the dried bentonite ore and the attapulgite ore to 4-8%, for example, 4%, 5%, 5.5%, 6.8%, 7.9%, etc.

[0051] Among them, if the coarse ore contains too much moisture, it will waste processing costs and time costs, while if the moisture is too little, the coarse ore is prone to overburning, affecting the quality of the ore powder.

[0052] In this embodiment, the grinding is performed by using a Raymond mill, a jet mill and a cyclone mill to grind the bentonite ore and the attapulgite ore into fine powder.

[0053] In this embodiment, the impurity removal is to separate and remove some impurity minerals that are difficult to crush in the original ore by screening or gravity classification during the crushing and grinding process, and the impurity minerals include quartz, feldspar and dolomite; the particle size of the obtained bentonite ore powder and attapulgite ore powder is -100 to -300 mesh, for example, -100 mesh, -150 mesh, -180 mesh, -220 mesh, -300 mesh, etc.; if the particle size is too small, it is easy to absorb water, which interferes with accurate weighing, thereby reducing the mud mass ratio; if the particle size is too large, it affects the slurry making effect.

[0054] Among them, the montmorillonite content in the bentonite ore powder is 50-75%, such as 55%, 65%, 70%, 75%, etc.; the attapulgite content in the attapulgite ore powder is 50-70%, such as 50%, 55%, 60%, 70%, etc.

[0055] S03: Mix bentonite powder, attapulgite powder, thickener and water in proportion by mass and stir to obtain a composite clay slurry.

[0056] In this embodiment, the mass ratio of the bentonite powder to the attapulgite powder is (6-9):(4-1), for example, 6:4, 6.5:2.5, 8:2, 9:1, etc., and the composite powder is obtained after uniform mixing.

[0057] Among them, too much attapulgite will affect the quality of slurry making. Selecting bentonite powder and attapulgite powder within this range for compounding can effectively play the role of bentonite powder and attapulgite powder, ensure full combination, and effectively improve the viscosity of mud.

[0058] In this embodiment, the viscosity enhancer includes two or more of magnesium oxide, sodium carboxymethyl cellulose, sodium pyrophosphate, calcium oxide and potassium hydrogen phthalate; the pH of the water is regulated to 8-11, specifically, 0.1 mol / L sodium hydroxide solution is added dropwise to the tap water, and tested with a pH test paper; for example, pH=8, pH=9.2, pH=10.9, etc., too high pH is easy to corrode equipment, increase drilling costs, and may cause formation dissolution and corrosion, increasing drilling difficulty; too low pH, H + Ion exchange occurs on the clay surface, which deteriorates the hydration and dispersibility of the clay and affects the viscosity of the drilling mud.

[0059] In this embodiment, the mass ratio of the composite mineral powder, magnesium oxide, sodium carboxymethyl cellulose and tap water is 100 parts of composite mineral powder, 1 to 8 parts of magnesium oxide, 1 to 8 parts of sodium carboxymethyl cellulose, and 1555 parts of tap water; for example, the ratio is (100:2:6:1555), (100:4:4:1555), (100:6:2:1555), etc.

[0060] Among them, if there is too much thickener, residual thickener will exist during the reaction, which will increase the industrial production cost; selecting thickeners within this range and adding them to the mineral powder can effectively disperse the bentonite mineral powder and the attapulgite mineral powder, and can further regulate the surface charge of the attapulgite, which is beneficial to increase the viscosity of the mud, and at the same time can reduce the generation of harmful substances and reduce the cost of treating waste drilling mud.

[0061] In this embodiment, the stirring treatment is to add the composite mineral powder, viscosity enhancer and tap water into a stirring device for high-speed stirring reaction, and the reaction time is 10 to 40 minutes, for example, 10 minutes, 25 minutes, 32 minutes and 39 minutes, etc., to obtain a compound clay slurry.

[0062] Among them, if the reaction time is too short, the thickener is not easy to be dissolved and dispersed, and the thickener is not in sufficient contact with the mineral powder, which affects the slurry making performance; if the reaction time is too long, it will increase the loss of equipment, waste processing costs and production time, and affect the drilling process.

[0063] S04: subjecting the compound clay slurry to static curing treatment and heating treatment to obtain a compound anti-seepage drilling mud.

[0064] In this embodiment, the temperature of the static curing treatment is 20-30°C, for example, 20°C, 23°C, 25°C, 30°C, etc.

[0065] Among them, if the maintenance treatment temperature is too high, the mud will easily clump into agglomerates, reduce the mud viscosity, cause unstable flow of mud in the well, and increase the risk factor of drilling; if the maintenance treatment temperature is too low, the hydration products will form slowly and the structure will be relatively sparse, affecting the mud performance.

[0066] In this embodiment, the heating treatment is to place the compound clay slurry into a reaction tank and heat it by one of steam heating, electric heating, flame heating and high-pressure water heating to obtain a compound anti-seepage drilling mud.

[0067] In this embodiment, the temperature of the heating treatment is 150-220° C., for example, 150° C., 175° C., 180° C., 215° C., etc.

[0068] The operating temperature of drilling mud is mostly around 150-200°C, and high-molecular polymer mud is very sensitive to temperature. If the reaction temperature is too low, it will not meet the drilling mud temperature requirement. Its lubrication and dehydration effects are poor and it is difficult to maintain the stability of the well wall. The scouring effect on the well wall is enhanced, which may lead to well wall instability and increase the risk of well collapse and drill sticking. Its viscosity and cutting force will also be affected, resulting in poor wellbore purification effect, and it cannot effectively carry and suspend rock cuttings, thus affecting the efficiency and safety of drilling operations. It will also cause the rock cuttings to be too fine, affecting the accuracy of logging and interfering with the acquisition of geological data.

[0069] The reaction temperature is too high. High temperature will cause irreversible performance changes of the drilling fluid, such as thickening, gelling, and solidification, which will affect the fluidity and rock-carrying capacity of the drilling fluid. The efficiency and safety of the drilling operation cannot be guaranteed. High temperature will also cause the water loss of the drilling fluid to increase and the mud cake to thicken, further affecting the quality of the drilling operation, reducing the hydration treatment capacity, reducing the thickness of the hydration film, and increasing the pressure on the well wall and the construction pressure.

[0070] In this embodiment, the treatment time is 16 hours.

[0071] Exemplary Embodiment 2

[0072] This embodiment provides a composite bentonite for anti-seepage drilling mud.

[0073] The bentonite can be prepared by the method described in the above exemplary embodiment 1.

[0074] In this embodiment, the viscosity of the compound anti-seepage drilling mud with bentonite after high-temperature reaction can be 30 to 75 mPa·s, for example, 30 mPa·s, 40 mPa·s, 45 mPa·s, 54 mPa·s, 65 mPa·s, 73 mPa·s, etc.; the filtration loss can be 10 to 25 mL, for example: 10 mL, 14 mL, 16 mL, 18 mL, 20 mL, 24 mL, etc.

[0075] Exemplary Embodiment 3

[0076] This exemplary embodiment provides an application of a compound anti-seepage bentonite for drilling mud, wherein the bentonite includes the compound anti-seepage bentonite for drilling mud described in exemplary embodiment 2, which is applied in drilling mud operations to ensure smooth drilling and reduce pollutants.

[0077] In order to further illustrate the present invention, the present invention is further described in detail below with reference to specific examples.

[0078] Example 1

[0079] Bentonite powder with a mesh size of -200 and a purity of 75% was mixed with tap water in a mass ratio of (10:1555) and subjected to high-speed stirring for 20 minutes to obtain bentonite slurry; and after curing in a constant temperature box at 25°C for 16 hours, the slurry was subjected to a high-temperature reaction at 180°C for 16 hours to obtain montmorillonite drilling mud. The high-temperature viscosity and filtration loss of this example sample were tested (the sample number of this example is FN0).

[0080] Example 2

[0081] 1) drying and roughly crushing the bentonite ore and the attapulgite ore to obtain crude bentonite ore and crude attapulgite ore;

[0082] 2) drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore to obtain bentonite ore powder and attapulgite ore powder with a particle size of -200 mesh and a moisture content of 6%;

[0083] 3) Bentonite powder, attapulgite powder and tap water are mixed in a mass ratio of (9:1:1555) and stirred at high speed for 20 minutes to obtain a compound clay slurry; and after curing in a constant temperature box at 25°C for 16 hours, subjected to a high temperature reaction at 180°C for 16 hours, a compound anti-seepage drilling mud is obtained, and the high temperature viscosity and filtration loss of this example sample are tested (the sample number of this example is FN1).

[0084] Example 3

[0085] 1) drying and roughly crushing the bentonite ore and the attapulgite ore to obtain crude bentonite ore and crude attapulgite ore;

[0086] 2) drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore to obtain bentonite ore powder with a purity of 75% and attapulgite ore powder with a purity of 60%, a particle size of -200 mesh, and a moisture content of 6%;

[0087] 3) Bentonite powder, attapulgite powder, magnesium oxide, sodium carboxymethyl cellulose and tap water are mixed in a mass ratio of (9:1:2:6:1555) and stirred at high speed for 20 minutes to obtain a compound clay slurry; and after curing in a constant temperature box at 25°C for 16 hours, subjected to a high temperature reaction at 180°C for 16 hours, a compound anti-seepage drilling mud is obtained, and the high temperature viscosity and filtration loss of this example sample are tested (the sample number of this example is FN2).

[0088] Example 4

[0089] 1) Drying and roughly crushing the bentonite ore and the attapulgite ore to obtain crude bentonite ore and crude attapulgite ore with a particle size of -100 to -300 mesh;

[0090] 2) drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore to obtain bentonite ore powder with a purity of 75% and attapulgite ore powder with a purity of 60%, a particle size of -200 mesh, and a moisture content of 6%;

[0091] 3) Bentonite powder, attapulgite powder, magnesium oxide, sodium carboxymethyl cellulose and tap water are mixed in a mass ratio of (9:1:4:4:1555) and stirred at high speed for 20 minutes to obtain a compound clay slurry; and after curing in a constant temperature box at 25°C for 16 hours, subjected to a high temperature reaction at 180°C for 16 hours, a compound anti-seepage drilling mud is obtained, and the high temperature viscosity and filtration loss of this example sample are tested (the sample number of this example is FN3).

[0092] Example 5

[0093] 1) drying and roughly crushing the bentonite ore and attapulgite ore to obtain crude bentonite ore and crude attapulgite ore with a particle size of -100 to -300 mesh;

[0094] 2) drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore to obtain bentonite ore powder with a purity of 75% and attapulgite ore powder with a purity of 60%, a particle size of -200 mesh, and a moisture content of 6%;

[0095] 3) Bentonite powder, attapulgite powder, magnesium oxide, sodium carboxymethyl cellulose and tap water are mixed in a mass ratio of (9:1:6:2:1555) and stirred at high speed for 20 minutes to obtain a compound clay slurry; and after curing in a constant temperature box at 25°C for 16 hours, subjected to a high temperature reaction at 180°C for 16 hours, a compound anti-seepage drilling mud is obtained, and the high temperature viscosity and filtration loss of this example sample are tested (the sample number of this example is FN4).

[0096] Example 6

[0097] 1) drying and roughly crushing the bentonite ore and attapulgite ore to obtain crude bentonite ore and crude attapulgite ore with a particle size of -100 to -300 mesh;

[0098] 2) drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore to obtain bentonite ore powder with a purity of 75% and attapulgite ore powder with a purity of 60%, a particle size of -200 mesh, and a moisture content of 6%;

[0099] 3) Bentonite powder, attapulgite powder, magnesium oxide, sodium carboxymethyl cellulose and tap water are mixed in the mass proportion of (8:2:4:4:1555) and stirred at high speed for 20 minutes to obtain a compound clay slurry; and after curing in a constant temperature box at 25°C for 16 hours, subjected to a high temperature reaction at 180°C for 16 hours, a compound anti-seepage drilling mud is obtained, and the high temperature viscosity and filtration loss of this example sample are tested (the sample number of this example is FN5).

[0100] Test example

[0101] The composite anti-seepage drilling mud in the above exemplary embodiment was subjected to high temperature viscosity and filtration loss test.

[0102] Experimental data show that compounding bentonite powder and attapulgite powder, and further adding inorganic and organic composite thickeners, can greatly increase the viscosity of the mud and reduce the filtration loss after high temperature reaction. It can be seen that the viscosity of the mud after organic and inorganic compounding is significantly better than that of the original ore, which shows that the preparation process of compounded bentonite for anti-seepage drilling mud is feasible.

[0103] The high temperature viscosity and filtration loss of the series of compound samples exemplified above are shown in Table 1.

[0104] Table 1 High temperature viscosity and filtration loss of a series of compound samples

[0105]

[0106] As shown in Table 1, when bentonite powder and attapulgite powder are simply compounded, their viscosity value and filtration loss after high temperature reaction are worse than those after high temperature reaction of bentonite powder alone. The viscosity value of the series of samples compounded by adding inorganic and organic thickeners at the same time after high temperature reaction is significantly improved, and the filtration loss also meets the requirements of drilling mud (600r / min viscosity value 30~90mpa·s, filtration loss ≤25mL). Therefore, the composite anti-seepage drilling mud bentonite of the present invention can not only effectively increase viscosity, but also cool or lubricate the drill bit, reduce the wear of the drill bit, reduce the use cost and production cost of equipment, and the high-viscosity drilling mud can also control the stability of the well body, prevent well wall collapse and cracks, and reduce the drilling risk factor; and the higher the viscosity, the easier it is to adsorb harmful substances produced by drilling and mud configuration, which is of great significance to environmental protection.

[0107] Although the present invention has been described above in conjunction with exemplary embodiments, it will be apparent to those skilled in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing a composite anti-seepage drilling mud bentonite, characterized in that: The method comprises the following steps: 1) drying and roughly crushing the bentonite ore and the attapulgite ore respectively to obtain a crude bentonite ore and a crude attapulgite ore; 2) drying, grinding, removing impurities and sieving the crude bentonite ore and the crude attapulgite ore respectively to obtain bentonite ore powder and attapulgite ore powder; 3) Mixing bentonite powder, attapulgite powder, a thickener and water in proportion by mass and stirring to obtain a composite clay slurry; 4) The compound clay slurry is subjected to a static curing treatment and a heating treatment to obtain a compound anti-seepage drilling mud.

2. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The bentonite ore in step 1) comprises at least one of sodium bentonite and transition bentonite; the montmorillonite content in the bentonite ore is ≥40%, and the impurity minerals include quartz, calcite, and illite; The attapulgite ore is sedimentary attapulgite clay, the attapulgite content in the attapulgite ore is ≥40%, and the impurity minerals are mainly montmorillonite, containing a small amount of quartz and dolomite.

3. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The coarse crushing in step 1) is performed by using a crusher, and the discharge port size of the crusher is set to be less than 15 mm; The drying includes airing in the sun, which can reduce the moisture content of the crude bentonite ore and the crude attapulgite ore to 15-22%.

4. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The drying in step 2) is carried out by using an industrial kiln, such as a rotary kiln, a fluidized bed drying kiln or an electric drying kiln, to reduce the moisture content of the crude bentonite ore and the crude attapulgite ore after drying to 4-8% respectively; the grinding is carried out by using a Raymond mill, a jet mill and a cyclone mill to grind the crude bentonite ore and the crude attapulgite ore; the impurity removal is to separate and remove the impurity minerals that are difficult to crush in the original ore by screening or gravity classification during the crushing and grinding process, and the impurity minerals include quartz, feldspar and dolomite; The particle sizes of the bentonite powder and the attapulgite powder are -100 to -300 meshes, the content of montmorillonite in the bentonite powder is 50 to 75%, and the content of attapulgite in the attapulgite powder is 50 to 70%.

5. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The mass ratio of the bentonite powder to the attapulgite powder is (6-9):(4-1); after uniform mixing, the composite powder is obtained; The mass ratio of the composite mineral powder, the viscosity enhancer and the water is 100 parts of the composite mineral powder, 1 to 8 parts of the viscosity enhancer and 1555 parts of water.

6. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The viscosity increasing agent comprises two or more of magnesium oxide, sodium carboxymethyl cellulose, sodium pyrophosphate, calcium oxide and potassium hydrogen phthalate; The water includes tap water, industrial water, etc., and the pH of the water is adjusted to 8-11.

7. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The stirring treatment in step 3) is to add the composite mineral powder, viscosity enhancer and water into a stirring device for high-speed stirring reaction, and the reaction time is 10 to 40 minutes; The stirring equipment includes a barrel stirrer, a horizontal stirrer, a vertical stirrer and a top-entry stirrer.

8. The method for preparing the composite anti-seepage drilling mud bentonite according to claim 1, characterized in that: The temperature of the static curing treatment in step 4) is 20-30°C; The heating treatment is to place the composite clay slurry into a reaction tank and heat it by steam heating, electric heating, flame heating and high-pressure water heating; The heating temperature is 150-220° C. and the heating time is 16 hours.

9. A composite bentonite for anti-seepage drilling mud, characterized in that: The compound anti-seepage drilling mud bentonite is prepared by the method according to any one of claims 1 to 8; The viscosity of the composite anti-seepage drilling mud bentonite is 30-73 mPa·s, and the filtration loss is 10-24 mL.

10. Use of the composite bentonite for anti-seepage drilling mud according to claim 9 in anti-seepage of drilling mud.

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