A sepiolite dispersion system and its preparation method and application

Abstract

The present invention provides a sepiolite dispersion system and a preparation method and application thereof, and relates to the technical field of drilling fluids. The sepiolite dispersion system provided by the present invention comprises the following components by mass fraction: 0.1 to 3.6 parts of a cationic surfactant with a polyoxyethylene (EO) chain, 1 to 6 parts of sepiolite particles, and 94 to 99 parts of an oil phase. In the present invention, the sepiolite particles are in the shape of long rods with a large aspect ratio, and are more likely to form a haystack structure when stacked together, and are more likely to form a network structure in oil; the cationic surfactant with a polyoxyethylene (EO) chain can maintain good dispersion stability of sepiolite particles in the oil phase, can regulate the viscosity of the system, and maintain a low temperature dependence of the system in a wide temperature range. The sepiolite dispersion system provided by the present invention has stable rheological properties in a wide temperature range (-25 to 160°C).

Description

Technical Field

[0001] The invention relates to the technical field of drilling fluid, and in particular to a sepiolite dispersion system and a preparation method and application thereof. Background Art

[0002] With the continuous development of oil drilling technology, the exploration and development of oil and gas fields involves complex deep formations and deep sea drilling. The circulating flushing medium used in the drilling process is called drilling fluid. The rheological properties of drilling fluid are the key to the success of drilling operations. In addition to lubricating the drill bit and stabilizing the well wall, the most important thing about drilling fluid is that it needs to have a certain viscosity and shear force to carry the drill cuttings generated during the drilling process. In previous studies, most organic soils were selected as a viscosity-enhancing and shear-enhancing agent.

[0003] Chinese patent CN102660237A discloses a method for thickening an organic solvent by in-situ formation of organic soil. The preparation process is simple, but the organic soil dispersion system prepared in the above patent has a high temperature dependence. U.S. Patent USOO9534162B2 discloses a series of organic soil dispersion systems that help oil-based drilling fluids maintain good fluidity in a wide temperature range, but the preparation method uses water modification and surfactants need to be compounded, the process is relatively complicated, and its application at ultra-low temperatures is not explored.

[0004] In actual drilling operations, various complex extreme conditions are encountered in the formation, such as ultra-low temperature, high temperature, etc. Therefore, it is of great significance to develop a dispersion system that can provide low temperature dependence in a wide temperature range from ultra-low temperature to high temperature. Summary of the invention

[0005] The purpose of the present invention is to provide a sepiolite dispersion system and a preparation method and application thereof. The sepiolite dispersion system provided by the present invention has stable rheological properties within a wide temperature range.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a sepiolite dispersion system, comprising the following components in parts by mass: 0.1 to 3.6 parts of a cationic surfactant with a polyoxyethylene chain, 1 to 6 parts of sepiolite particles, and 94 to 99 parts of an oil phase.

[0008] Preferably, the cation in the cationic surfactant with a polyoxyethylene chain has one or more of the structures shown in Formula I and Formula II:

[0009]

[0010] In the formula I, R 1 and R 3-(CH2-CH2-O) y -H, R 1 and R 3 The y in the structural formula is independently 10 to 15; R 2 C 10 ~C 20 The alkyl chain of R 4 C 10 ~C 20 The alkyl chain of

[0011]

[0012] In the formula II, R 5 and R 7 CH3; R 6 For (CH3) n -O-(CH2-CH2-O) y -C2H4, n is 10 to 20, y is 10 to 20; R 8 C 10 ~C 20 of the alkyl chain.

[0013] Preferably, the anions in the cationic surfactant with a polyoxyethylene chain include one or more of chloride ion, sulfate ion, acetate ion, iodide ion and bromide ion.

[0014] Preferably, the sepiolite particles are rod-shaped particles with a length of 2.0-3.0 μm, a width of 25-35 nm, and a density of 2.000-2.300 g / cm 3 .

[0015] Preferably, the oil phase comprises an alkane solvent.

[0016] Preferably, the alkane solvent includes one or more of decane, kerosene, white oil and gas-to-liquids.

[0017] The present invention provides a method for preparing the sepiolite dispersion system described in the above technical solution, comprising the following steps:

[0018] The cationic surfactant with a polyoxyethylene chain and the oil phase are first mixed, sepiolite particles are added for second mixing, and then ultrasonic treatment is performed to obtain a sepiolite dispersion system.

[0019] Preferably, the first mixing is performed at room temperature; and the second mixing is performed at a temperature of 55-95°C.

[0020] Preferably, the power of the ultrasonic treatment is 200-600W;

[0021] The ultrasonic treatment includes 20 to 40 cycles; each cycle is ultrasonic for 5 seconds with an interval of 5 seconds.

[0022] The present invention provides the use of the sepiolite dispersion system described in the above technical solution or the sepiolite dispersion system prepared by the preparation method described in the above technical solution in oil-based drilling fluid, paint or coating.

[0023] The present invention provides a sepiolite dispersion system, comprising the following components in mass fractions: 0.1 to 3.6 parts of a cationic surfactant with a polyoxyethylene (EO) chain, 1 to 6 parts of sepiolite particles, and 94 to 99 parts of an oil phase. In the present invention, the sepiolite particles are in the shape of long rods with a large aspect ratio. They are easier to form a haystack structure when stacked together, and are easier to form a network structure in oil. Low particle concentration provides high viscosity performance, and has better viscosity-increasing effect and rheological properties than organic soil; the cationic surfactant with a polyoxyethylene (EO) chain can maintain good dispersion stability of sepiolite particles in the oil phase, can regulate the viscosity of the system, and maintain low temperature dependence of the system in a wide temperature range. The sepiolite dispersion system provided by the present invention has stable rheological properties in a wide temperature range (-25 to 160°C).

[0024] The present invention provides a method for preparing the sepiolite dispersion system described in the above technical solution. The preparation method of the present invention is in-situ modification, which is different from the complicated process of organic soil and water modification in the past and is simple to prepare. The sepiolite dispersion system prepared by the present invention has a small change in rheological properties within the range of -25 to 160°C and can be applied to ultra-low temperature and high temperature drilling environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Inverted pictures of samples of the embodiments and comparative examples at different temperatures;

[0026] Figure 2 The graphs of the apparent viscosity of the embodiments and comparative examples as a function of temperature are shown;

[0027] Figure 3 This is a curve showing the change of apparent viscosity of the simulated oil-based drilling fluid system with temperature. DETAILED DESCRIPTION

[0028] The invention provides a sepiolite dispersion system, comprising the following components in parts by weight: 0.1 to 3.6 parts of a cationic surfactant with a polyoxyethylene (EO) chain, 1 to 6 parts of sepiolite particles, and 94 to 99 parts of an oil phase.

[0029] The sepiolite dispersion system provided by the present invention comprises 0.1 to 3.6 parts of a cationic surfactant with a polyoxyethylene chain, preferably 0.54 to 1.5 parts, and more preferably 0.9 to 1.35 parts, in parts by mass.

[0030] In the present invention, the cation in the cationic surfactant with a polyoxyethylene chain preferably has one or more of the structures shown in Formula I and Formula II:

[0031]

[0032] In the formula I, N is nitrogen, R 1 and R 3 -(CH2-CH2-O) y -H, R 1 and R 3 The y in the structural formula is independently 10 to 15; R 2 C 10 ~C 20 The alkyl chain is preferably C 12 ~C 18 The alkyl chain is preferably C 18 ; R 4 C 10 ~C 20 The alkyl chain is preferably C 12 ~C 18 The alkyl chain is preferably C 18 ;

[0033]

[0034] In the formula II, N is nitrogen, R 5 and R 7 CH3; R 6 For (CH3) n -O-(CH2-CH2-O) y -C2H4, n is 10 to 20, preferably 12 to 18, most preferably 18; y is 10 to 20, preferably 17; R 8 C 10 ~C 20 The alkyl chain is preferably C 12 ~C 18 The alkyl chain is preferably C 18 .

[0035] In the present invention, the anions in the cationic surfactant with a polyoxyethylene chain preferably include one or more of chloride ion, sulfate ion, acetate ion, iodide ion and bromide ion.

[0036] As an embodiment of the present invention, the structure of the cationic surfactant with a polyoxyethylene chain is shown in Formula III:

[0037]

[0038] In the formula III, N is nitrogen, R 1 and R 3 -(CH2-CH2-O) y -H, R 1 and R 3 The y in the structural formula is independently 10 to 15; R 2 C 10 ~C 20 The alkyl chain is preferably C 12 ~C 18 The alkyl chain is preferably C 18 ; R 4 C 10 ~C 20 The alkyl chain is preferably C 12 ~C 18 The alkyl chain is preferably C 18 ; X includes one or more of chloride ion, sulfate ion, acetate ion, iodide ion and bromide ion.

[0039] As an embodiment of the present invention, the structure of the cationic surfactant with a polyoxyethylene chain is shown in Formula IV:

[0040]

[0041] In the formula IV, N is nitrogen, R 5 and R 7 CH3; R 6 For (CH3) n -O-(CH2-CH2-O) y -C2H4, n is 10 to 20, preferably 12 to 18, most preferably 18; y is 10 to 20, preferably 17; R 8 C 10 ~C 20 The alkyl chain is preferably C 12 ~C 18 The alkyl chain is preferably C 18 ; X includes one or more of chloride ion, sulfate ion, acetate ion, iodide ion and bromide ion.

[0042] In a specific embodiment of the present invention, the cationic surfactant with a polyoxyethylene chain preferably includes one or more of octadecyl polyoxyethylene octadecyl ammonium chloride and octadecyl alcohol polyoxyethylene ether dimethyl octadecyl ammonium bromide. In the present invention, the alkyl chain carbon number of the octadecyl polyoxyethylene octadecyl ammonium chloride is 36, and the EO number is 10 to 15; the molecular weight of the octadecyl polyoxyethylene octadecyl ammonium chloride is preferably 750. In the present invention, the alkyl chain carbon number of the octadecyl alcohol polyoxyethylene ether dimethyl octadecyl ammonium bromide is 36, and the EO number is 17; the molecular weight of the octadecyl alcohol polyoxyethylene ether dimethyl octadecyl ammonium bromide is preferably 1438.

[0043] Based on the mass fraction of the cationic surfactant with a polyoxyethylene chain, the sepiolite dispersion system provided by the present invention comprises 1 to 6 parts of sepiolite particles, preferably 1.8 to 5 parts, and more preferably 3 to 4 parts.

[0044] In the present invention, the sepiolite particles are rod-shaped particles, preferably 2.0 to 3.0 μm in length, more preferably 2.5 μm; preferably 25 to 35 nm in width, more preferably 30 nm; and preferably 2.000 to 2.300 g / cm 3 , more preferably 2.200 g / cm 3 .

[0045] Based on the mass fraction of the cationic surfactant with a polyoxyethylene chain, the sepiolite dispersion system provided by the present invention comprises 94 to 99 parts of the oil phase, preferably 95 to 97 parts.

[0046] In the present invention, the oil phase preferably includes an alkane solvent. In the present invention, the alkane solvent preferably includes one or more of decane, kerosene, white oil and gas-to-liquid. In the present invention, the gas-to-liquid is preferably Isopar M.

[0047] In the present invention, the viscosity of the sepiolite dispersion system is preferably above 20 mPa·s, more preferably above 25 mPa·s. The sepiolite dispersion system provided by the present invention has stable rheological properties within the range of -25 to 160°C.

[0048] The present invention provides a method for preparing the sepiolite dispersion system described in the above technical solution, comprising the following steps:

[0049] The cationic surfactant with a polyoxyethylene chain and the oil phase are first mixed, sepiolite particles are added for second mixing, and then ultrasonic treatment is performed to obtain a sepiolite dispersion system.

[0050] In the present invention, the first mixing is preferably carried out at room temperature. In the present invention, the first mixing is preferably carried out under stirring conditions; the stirring speed is preferably 300 to 1200 r / min, more preferably 500 to 600 r / min; the stirring time is preferably 5 to 10 min, more preferably 6 to 8 min.

[0051] In the present invention, the temperature of the second mixing is preferably 55 to 95°C, more preferably 80 to 85°C; the second mixing is preferably carried out in a water bath. In the present invention, the second mixing is preferably carried out under stirring conditions; the stirring speed is preferably 500 to 1200 r / min, more preferably 600 to 800 r / min; the stirring time is preferably 20 to 200 min, more preferably 30 min.

[0052] In the present invention, the power of the ultrasonic treatment is preferably 200-600 W, more preferably 400 W. In the present invention, the ultrasonic treatment preferably includes 20-40 cycles; each cycle preferably has 5 seconds of ultrasonic treatment and 5 seconds of interval.

[0053] In the present invention, the obtained system is preferably subjected to aging treatment after the ultrasonic treatment. In the present invention, the temperature of the aging treatment is preferably 160-180°C, more preferably 180°C; the time of the aging treatment is preferably 8-16h, more preferably 12h. The purpose of the aging treatment in the present invention is to make the system have better thermal stability and be able to adapt to the high temperature environment during the drilling process.

[0054] In the present invention, it is preferred that the aging treatment be followed by cooling at room temperature.

[0055] The present invention provides the use of the sepiolite dispersion system described in the above technical solution or the sepiolite dispersion system prepared by the preparation method described in the above technical solution in oil-based drilling fluid, paint or coating.

[0056] In the present invention, the oil-based drilling fluid preferably includes a sepiolite dispersion system, a fatty alcohol polyoxyethylene ether carboxylic acid and barium sulfate particles. In the present invention, the mass ratio of the fatty alcohol polyoxyethylene ether carboxylic acid and the barium sulfate particles is preferably 0.004-0.008:1, more preferably 0.006:1. In the present invention, the mass content of the sepiolite dispersion system in the oil-based drilling fluid is preferably 55-65%, more preferably 60%. In the present invention, the carbon number of the alkyl chain of the fatty alcohol polyoxyethylene ether carboxylic acid is preferably 12, and the EO number is preferably 9; the particle density of the barium sulfate particles is preferably 4.5g / cm 3 , the particle size is preferably 0.5 μm.

[0057] In the present invention, the preparation method of the oil-based drilling fluid preferably comprises: adding barium sulfate particles to the sepiolite dispersion system, performing a first stirring at room temperature, adding fatty alcohol polyoxyethylene ether carboxylic acid, performing a second stirring at room temperature; and then performing ultrasound to obtain the oil-based drilling fluid. In the present invention, the rotation speed of the first stirring is preferably 1200r / min; the time of the first stirring is preferably 30min. In the present invention, the rotation speed of the second stirring is preferably 1000r / min; the time of the second stirring is preferably 30min. In the present invention, the power of the ultrasound is preferably 200-600W, more preferably 400W. In the present invention, the time of the ultrasound is preferably 20-40 cycles; each cycle is preferably ultrasound for 5s, with an interval of 5s.

[0058] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The sepiolite particles used in the examples are rod-shaped particles with a length of 2.5 μm, a width of 30 nm, and a density of 2.200 g / cm 3 .

[0060] Example 1

[0061] The composition of the sepiolite dispersion system is as follows, by weight: 0.9 parts of octadecyl polyoxyethylene octadecyl ammonium chloride (molecular weight 750, EO number 10-15), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0062] The preparation method of the sepiolite dispersion system in this embodiment is as follows: 0.9 parts of octadecyl polyoxyethylene octadecyl ammonium chloride are added to 97 parts of gas-to-oil, and magnetically stirred for 5 minutes at a speed of 500 r / min at room temperature to obtain a surfactant oil dispersion system, and then 3 parts of sepiolite particles are added to the above system, and magnetically stirred for 30 minutes at a speed of 600 r / min at 80°C, and then ultrasonicated 20 times at a power of 400 W (ultrasound for 5 seconds, interval of 5 seconds).

[0063] Example 2

[0064] The composition of the sepiolite dispersion system is as follows, by weight: 0.9 parts of octadecyl polyoxyethylene ether dimethyl octadecyl ammonium bromide (molecular weight 1438, EO number 17), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0065] The preparation method of the sepiolite dispersion system in this embodiment is as follows: 0.9 parts of octadecyl polyoxyethylene ether dimethyl octadecyl ammonium bromide is added to 97 parts of gas-to-oil, and magnetically stirred for 5 minutes at a speed of 500 r / min at room temperature to obtain a surfactant oil dispersion system, and then 3 parts of sepiolite particles are added to the above system, and magnetically stirred for 30 minutes at a speed of 600 r / min at 80°C, and then ultrasonicated 20 times at a power of 400 W (ultrasound for 5 seconds, interval of 5 seconds).

[0066] Example 3

[0067] The composition of the sepiolite dispersion system is as follows, by weight: 0.9 parts of octadecyl polyoxyethylene octadecyl ammonium chloride (molecular weight 750, EO number 10-15), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0068] The preparation method of the sepiolite dispersion system in this embodiment is as follows: 0.9 parts of octadecyl polyoxyethylene octadecyl ammonium chloride is added to 97 parts of gas-to-oil, and magnetically stirred for 5 minutes at a speed of 500 r / min at room temperature to obtain a surfactant oil dispersion system, and then 3 parts of sepiolite particles are added to the above system, and magnetically stirred for 30 minutes at a speed of 600 r / min at 80° C., and then ultrasonicated 20 times at a power of 400 W (ultrasonication for 5 seconds, interval of 5 seconds);

[0069] Then the prepared sepiolite dispersion system was placed in an aging tank and aged at 180° C. for 12 hours. After cooling at room temperature, the system had good fluidity.

[0070] Example 4

[0071] The composition of the sepiolite dispersion system is as follows, by weight: 1.35 parts of octadecyl polyoxyethylene octadecyl ammonium chloride (molecular weight 750, EO number 10-15), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0072] The preparation method of the sepiolite dispersion system in this embodiment is as follows: 1.35 parts of octadecyl polyoxyethylene octadecyl ammonium chloride are added to 97 parts of gas-to-oil, and magnetically stirred for 5 minutes at a speed of 500 r / min at room temperature to obtain a surfactant oil dispersion system, and then 3 parts of sepiolite particles are added to the above system, and magnetically stirred for 30 minutes at a speed of 800 r / min at 80° C., and then ultrasonicated 20 times at a power of 400 W (ultrasound for 5 seconds, interval of 5 seconds);

[0073] Then the prepared sepiolite dispersion system was placed in an aging tank and aged at 180° C. for 12 hours. After cooling at room temperature, the system had good fluidity.

[0074] Example 5

[0075] The composition of the sepiolite dispersion system is as follows, by weight: 0.9 parts of octadecyl polyoxyethylene ether dimethyl octadecyl ammonium bromide (molecular weight 1438, EO number 17), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0076] The preparation method of the sepiolite dispersion system in this embodiment is as follows: 0.9 parts of octadecyl alcohol polyoxyethylene ether dimethyl octadecyl ammonium bromide is added to 97 parts of gas-to-oil, and magnetically stirred at a speed of 500 r / min for 5 minutes at room temperature to obtain a surfactant oil dispersion system, and then 3 parts of sepiolite particles are added to the above system, and magnetically stirred at a speed of 600 r / min for 30 minutes at 80° C., and then ultrasonicated 20 times at a power of 400 W (ultrasonication for 5 seconds, interval of 5 seconds);

[0077] Then the prepared sepiolite dispersion system was placed in an aging tank and aged at 180° C. for 12 hours. After cooling at room temperature, the system had good fluidity.

[0078] Example 6

[0079] The composition of the sepiolite dispersion system is as follows, by weight: 1.5 parts of octadecyl polyoxyethylene octadecyl ammonium chloride (molecular weight 750, EO number 10-15), 5 parts of sepiolite particles, and 95 parts of gas-to-liquid (Isopar M).

[0080] The preparation method of the sepiolite dispersion system in this embodiment is as follows: 1.5 parts of octadecyl polyoxyethylene octadecyl ammonium chloride are added to 95 parts of gas-to-oil, and magnetically stirred at a speed of 600 r / min for 5 minutes at room temperature to obtain a surfactant oil dispersion system, and then 5 parts of sepiolite particles are added to the above system, and magnetically stirred at a speed of 800 r / min for 30 minutes at 80° C., and then ultrasonicated 20 times at a power of 400 W (ultrasonication for 5 seconds, interval of 5 seconds);

[0081] Then the prepared sepiolite dispersion system was placed in an aging tank and aged at 180° C. for 12 hours. After cooling at room temperature, the system had good fluidity.

[0082] Example 7

[0083] The simulated oil-based drilling fluid system is composed of the following components by weight: 0.54 parts of octadecyl polyoxyethylene octadecyl ammonium chloride (molecular weight 750, EO number 10-15), 1.8 parts of sepiolite particles, 0.24 parts of fatty alcohol polyoxyethylene ether carboxylic acid (alkyl chain carbon number 12, EO number 9), and barium sulfate particles (particle density 4.5 g / cm 3, particle size is 0.5μm) 40 parts, gas-based oil (IsoparM) 58.2 parts.

[0084] The preparation method of the simulated oil-based drilling fluid in this embodiment is as follows: 0.54 parts of octadecyl polyoxyethylene octadecyl ammonium chloride is added to 58.2 parts of gas-to-oil, and magnetically stirred for 5 minutes at a speed of 300 r / min at room temperature to obtain a surfactant oil dispersion system, and then 1.8 parts of sepiolite particles are added to the above system, and magnetically stirred for 30 minutes at a speed of 300 r / min at 80° C., and then ultrasonicated 20 times at a power of 400 W (ultrasound for 5 seconds, interval 5 seconds);

[0085] Then add 40 parts of barium sulfate particles to the prepared sepiolite dispersion system, and magnetically stir at a speed of 1200 r / min for 30 minutes at room temperature. Add 0.24 parts of fatty alcohol polyoxyethylene ether carboxylic acid, and magnetically stir at a speed of 1000 r / min for 30 minutes at room temperature; then ultrasonicate 20 times at a power of 400 W (ultrasound 5 seconds, interval 5 seconds).

[0086] Comparative Example 1

[0087] The composition of the sepiolite dispersion system is as follows by weight: 3 parts of sepiolite particles and 97 parts of gas-to-liquid (Isopar M).

[0088] The preparation method of the sepiolite dispersion system in this comparative example is: add 3 parts of sepiolite particles to 97 parts of gas-to-liquid, at 80°C, at a speed of 800r / min, magnetically stir for 30min, and then ultrasonicate 20 times at a power of 400W (ultrasound for 5s, interval of 5s) to obtain an unmodified sepiolite dispersion system, which has poor dispersibility.

[0089] Comparative Example 2

[0090] The composition of the sepiolite dispersion system is as follows, by weight: 0.72 parts of dioctadecyl dimethyl ammonium chloride (molecular weight 586.52), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0091] The preparation method of the sepiolite dispersion system in this comparative example is as follows: 0.72 parts of dioctadecyl dimethyl ammonium chloride are added to 97 parts of gas-to-oil, and the mixture is stirred magnetically for 5 minutes at a speed of 500 r / min at room temperature to obtain a surfactant oil dispersion system, and then 3 parts of sepiolite particles are added to the above system, and the mixture is stirred magnetically for 30 minutes at a speed of 600 r / min at 80°C, and then ultrasonicated 20 times at a power of 400 W (ultrasound for 5 seconds, intervals of 5 seconds). When the system is placed under low temperature conditions, gelation occurs, and its fluidity is poor.

[0092] Comparative Example 3

[0093] The composition of the sepiolite dispersion system is as follows, by weight: 0.72 parts of dioctadecyl dimethyl ammonium chloride (molecular weight 586.52), 3 parts of sepiolite particles, and 97 parts of gas-to-liquid (Isopar M).

[0094] The preparation method of the sepiolite dispersion system in this comparative example is: add 0.72 parts of dioctadecyl dimethyl ammonium chloride to 97 parts of gas-to-oil, and magnetically stir for 5 minutes at a speed of 500 r / min at room temperature to obtain a surfactant oil dispersion system, then add 3 parts of sepiolite particles to the above system, and magnetically stir for 30 minutes at a speed of 600 r / min at 80°C, and then ultrasonicate 20 times at a power of 400 W (ultrasound for 5 seconds, interval of 5 seconds).

[0095] Then the prepared sepiolite dispersion system was placed in an aging tank and aged at 180° C. for 12 hours; after cooling at room temperature, the system as a whole showed gelation and poor fluidity.

[0096] Comparative Example 4

[0097] The simulated oil-based drilling fluid system is composed of the following components by weight: 0.432 parts of dioctadecyl dimethyl ammonium chloride (molecular weight 586.52), 1.8 parts of sepiolite particles, 0.24 parts of fatty alcohol polyoxyethylene ether carboxylic acid (alkyl chain carbon number 12, EO number 9), and barium sulfate particles (particle density 4.5 g / cm 3 , particle size is 0.5μm) 40 parts, gas-based oil (IsoparM) 58.2 parts.

[0098] The preparation method of the simulated oil-based drilling fluid in this comparative example is as follows: 0.432 parts of dioctadecyl dimethyl ammonium chloride are added to 58.2 parts of gas-to-oil, and the mixture is magnetically stirred for 5 minutes at a speed of 200 r / min at room temperature to obtain a surfactant oil dispersion system, and then 1.8 parts of sepiolite particles are added to the above system, and the mixture is magnetically stirred for 30 minutes at a speed of 200 r / min at 80° C., and then ultrasonicated 20 times at a power of 400 W (ultrasound for 5 seconds, with an interval of 5 seconds);

[0099] Then add 40 parts of barium sulfate particles to the prepared sepiolite dispersion system, and magnetically stir at a speed of 1200 r / min for 30 minutes at room temperature. Add 0.24 parts of fatty alcohol polyoxyethylene ether carboxylic acid, and magnetically stir at a speed of 1000 r / min for 30 minutes at room temperature; then ultrasonicate 20 times at a power of 400 W (ultrasound 5 seconds, interval 5 seconds); the system will gel at low temperatures and have poor fluidity.

[0100] Test Case

[0101] The embodiment and the comparative example were prepared at a shear rate of 7.22 s -1 The apparent viscosity at different temperatures is shown in Table 1.

[0102] Table 1 Apparent viscosity of the examples and comparative examples at different temperatures

[0103]

[0104] It can be seen from Table 1 that the viscosity of the sepiolite dispersion system and the simulated oil-based drilling fluid prepared with the cationic surfactant with polyoxyethylene chain at -25°C, 5°C, 75°C and 160°C changes less than that of the sepiolite dispersion system and the simulated oil-based drilling fluid prepared with the cationic surfactant without polyoxyethylene chain, and the system has good fluidity.

[0105] Figure 1 The inverted pictures of the samples of the embodiments and comparative examples at different temperatures are shown in FIG. Figure 1 It can be seen that the sepiolite dispersion system prepared with the cationic surfactant with polyoxyethylene chain and the simulated oil-based drilling fluid have fluidity at -22°C, 5°C, 25°C and 80°C.

[0106] Figure 2 The apparent viscosity of the embodiment and the comparative example varies with temperature, and the shear rate is 7.22s -1 .Depend on Figure 2 It can be seen that the sepiolite dispersion system prepared with a cationic surfactant with a polyoxyethylene chain has a lower temperature dependence at -25 to 160°C.

[0107] Figure 3 To simulate the apparent viscosity of the oil-based drilling fluid system as a function of temperature, the shear rate is 7.22s -1 .Depend on Figure 3 It can be seen that within the range of -25 to 160°C, the viscosity of the simulated oil-based drilling fluid prepared by using sepiolite modified with a cationic surfactant having a polyoxyethylene chain changes little.

[0108] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A sepiolite dispersion system, comprising the following components in parts by weight: 0.1 to 3.6 parts of a cationic surfactant with a polyoxyethylene chain, 1 to 6 parts of sepiolite particles, and 94 to 99 parts of an oil phase; The cation in the cationic surfactant with a polyoxyethylene chain has one or more structures shown in Formula I and Formula II: Formula I; In the formula I, R 1 and R 3 -(CH2-CH2-O) y -H, R 1 and R 3 The y in the structural formula is independently 10~15; R 2 C 10 ~C 20 The alkyl chain of 4 C 10 ~C 20 The alkyl chain of Formula II; In the formula II, R 5 and R 7 CH3; R 6 For (CH3) n -O-(CH2-CH2-O) y -C2H4, n is 10~20, y is 10~20; R 8 C 10 ~C 20 The alkyl chain of The sepiolite particles are rod-shaped particles with a length of 2.0-3.0 μm and a width of 25-35 nm; the density is 2.000-2.300 g / cm 3 .

2. The sepiolite dispersion system according to claim 1, characterized in that: The anions in the cationic surfactant with a polyoxyethylene chain include one or more of chloride ion, sulfate ion, acetate ion, iodide ion and bromide ion.

3. The sepiolite dispersion system according to claim 1, characterized in that: The oil phase includes an alkane solvent.

4. The sepiolite dispersion system according to claim 3, characterized in that: The alkane solvent includes one or more of decane, kerosene, white oil and gas-to-liquid.

5. The method for preparing the sepiolite dispersion system according to any one of claims 1 to 4, comprising the following steps: The cationic surfactant with a polyoxyethylene chain and the oil phase are first mixed, sepiolite particles are added for second mixing, and then ultrasonic treatment is performed to obtain a sepiolite dispersion system.

6. The preparation method according to claim 5, characterized in that: The first mixing is performed at room temperature; the second mixing is performed at a temperature of 55-95°C.

7. The preparation method according to claim 5, characterized in that: The power of the ultrasonic treatment is 200~600W; The ultrasonic treatment includes 20 to 40 cycles; each cycle is ultrasonic for 5 seconds with an interval of 5 seconds.

8. Use of the sepiolite dispersion system according to any one of claims 1 to 4 or the sepiolite dispersion system prepared by the preparation method according to any one of claims 5 to 7 in oil-based drilling fluids, paints or coatings.

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