Organic soil and method for its preparation and use

Abstract

The application provides organic soil and a preparation method and application thereof. The preparation method of the organic soil comprises the following steps: modifying bentonite by surface activation with a strong oxidizing solution to obtain a first reaction intermediate; performing a first contact reaction of the first reaction intermediate and a silane coupling agent containing long-chain alkyl in an alkaline water-alcohol mixed solution to obtain a second reaction intermediate; wherein the long-chain alkyl contained in the silane coupling agent containing long-chain alkyl is C3+ alkyl; and performing a second contact reaction of the second reaction intermediate and a quaternary ammonium salt surfactant to obtain the organic soil. The organic soil has excellent stability in a super-high-temperature environment of a deep well or an ultra-deep well, can effectively improve the structural force, apparent viscosity, dynamic shear force and low shear rate viscosity of a water-in-oil emulsified drilling fluid system, and can improve the rheological stability and sedimentation stability of the water-in-oil emulsified drilling fluid system under a super-high-temperature condition.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oilfield exploitation, and relates to an organic clay for water-in-oil emulsified drilling fluid resistant to ultrahigh temperature as well as a preparation method and application thereof. BACKGROUND

[0002] With the continuous exploration and development of petroleum to deep and ultra-deep reservoirs, the drilling process will face increasingly high formation temperature, pressure and increasingly complex geological conditions. Since oil-based drilling fluid has better inhibition, lubricity and high-temperature stability than water-based drilling fluid, it has become the first choice for drilling deep and ultra-deep wells. Of course, as the bottom hole temperature continues to rise, especially when the temperature is higher than 180 DEG C, higher requirements are put forward for the emulsion stability, rheological stability and sedimentation stability of the drilling fluid.

[0003] During the drilling process of deep and ultra-deep wells, high-temperature and high-density oil-based drilling fluid is needed to ensure the flowability of the drilling fluid during the drilling process, and at the same time, the high-density drilling fluid forms a high hydrostatic pressure so as to effectively balance the high pressure of the formation. The high-density drilling fluid needs to be realized by adding a large amount of weighting material to the drilling fluid, and the more the weighting material, the greater the challenge to the suspension stability of the drilling fluid under high-temperature conditions. Once the weighting material settles, a series of downhole complex accidents will be caused, such as sticking, loss circulation, and difficulty in running casing to the bottom during drilling, resulting in great time and economic losses.

[0004] In view of the above-mentioned complex situation, the rheological stability of the drilling fluid is mainly enhanced by adding organic clay to the oil-based drilling fluid. When the temperature is higher than 180 DEG C, the conventional organic clay is easy to fail, which is mainly due to the fact that this kind of organic clay is prepared by ion exchange and intercalation modification. When the temperature is lower than 180 DEG C, the organic clay can maintain good stability; when the temperature is higher than 180 DEG C, the intercalated surfactant will desorb, so that the organic clay fails, further causing the rheological instability of the oil-based drilling fluid system, the settlement of the drilling fluid weighting material, and the reduction of the cuttings suspension performance. Therefore, how to improve the stability of the organic clay under ultrahigh temperature conditions and improve the rheological stability and sedimentation stability of the high-density oil-based drilling fluid under ultrahigh temperature conditions has become the core of the research on efficient drilling of ultra-deep reservoirs. SUMMARY

[0005] Based on the defects existing in the prior art, the first object of the present application is to provide a preparation method of an organic clay for resisting super-high temperature water-in-oil emulsified drilling fluid; the second object of the present application is to provide the organic clay prepared by the preparation method; and the third object of the present application is to provide the application of the organic clay in water-in-oil emulsified drilling fluid. The organic clay has excellent stability in the super-high temperature environment of deep wells and ultra-deep wells, can effectively improve the structural force, apparent viscosity, dynamic shear force and low shear rate viscosity of the water-in-oil emulsified drilling fluid system, and improve the rheological stability and sedimentation stability of the water-in-oil emulsified drilling fluid system under super-high temperature conditions.

[0006] In order to achieve the above-mentioned objects, the present application provides the following technical solutions.

[0007] In a first aspect, the present application provides a preparation method of an organic clay, comprising the following steps:

[0008] Step one, surface activation modification of bentonite by using a strong oxidizing solution to obtain a first reaction intermediate;

[0009] Step two, first contact reaction of the first reaction intermediate with a silane coupling agent containing long-chain alkyl in an alkaline water-alcohol mixed solution to obtain a second reaction intermediate; wherein the long-chain alkyl contained in the silane coupling agent containing long-chain alkyl is C3+ alkyl;

[0010] Step three, second contact reaction of the second reaction intermediate with a quaternary ammonium salt surfactant to obtain the organic clay.

[0011] In the technical solution of the present application, the surface of bentonite is first activated and modified by a strong oxidizing solution to form more active hydroxyl groups, and at the same time, organic impurities in the bentonite are removed, then the activated bentonite is surface grafted with a silane coupling agent containing long-chain alkyl, and finally the grafted bentonite is intercalated and modified by using a quaternary ammonium salt surfactant, so as to improve the temperature resistance of the organic clay.

[0012] According to a preferred embodiment of the first aspect, the bentonite comprises sodium-based bentonite and / or calcium-based bentonite; in a specific embodiment, the bentonite is sodium-based bentonite.

[0013] According to a preferred embodiment of the first aspect, the strong oxidizing solution comprises hydrogen peroxide and / or strong acid;

[0014] Further, the mass concentration of H2O2 in the hydrogen peroxide is not less than 30% based on 100% of the total mass of the hydrogen peroxide;

[0015] Further, the strong acid comprises one or more than two combinations of concentrated sulfuric acid, concentrated hydrochloric acid and concentrated nitric acid; wherein the concentrated sulfuric acid refers to sulfuric acid with H2SO4 mass concentration not less than 70% (based on the total mass of concentrated sulfuric acid as 100%); the concentrated hydrochloric acid refers to hydrochloric acid with HCl mass concentration not less than 37% (based on the total mass of concentrated hydrochloric acid as 100%); and the concentrated nitric acid refers to nitric acid with HNO3 mass concentration not less than 68% (based on the total mass of concentrated nitric acid as 100%);

[0016] Further, the strong oxidizing solution comprises hydrogen peroxide and a strong acid.

[0017] Further, the use amount ratio of the bentonite, the hydrogen peroxide and the strong acid is 1 kg:(10-45) mL:(50-80) mL, preferably 1 kg:(20-40) mL:(55-70) mL, and more preferably 1 kg:(25-35) mL:(55-65) mL.

[0018] According to the preferred embodiments of the first aspect, the long-chain alkyl contained in the long-chain alkyl-containing silane coupling agent is C3-C18 alkyl; further, the long-chain alkyl contained in the long-chain alkyl-containing silane coupling agent is one of propyl, butyl, hexyl, octyl, cuminyl, dodecyl, hexadecyl and octadecyl; further, the long-chain alkyl-containing silane coupling agent comprises one or more than two combinations of propyl triethoxysilane, butyl triethoxysilane, hexyl triethoxysilane, octyl triethoxysilane, cuminyl triethoxysilane, dodecyl triethoxysilane, hexadecyl triethoxysilane and octadecyl triethoxysilane.

[0019] According to the preferred embodiments of the first aspect, the first contact reaction is carried out at pH value of 7-11; further, the first contact reaction is carried out at pH value of 7-10; and further, the first contact reaction is carried out at pH value of 8-9.

[0020] According to the preferred embodiments of the first aspect, the alkaline reagent used in the alkaline water-alcohol mixed solution comprises one or more than two combinations of ammonia, sodium hydroxide, calcium hydroxide and triethanolamine.

[0021] According to the preferred embodiments of the first aspect, the alcohol comprises one or more than two combinations of methanol, ethanol, n-propanol and isopropanol.

[0022] According to the preferred embodiments of the first aspect, the first contact reaction of the first reaction intermediate and the long-chain alkyl-containing silane coupling agent is carried out in the alkaline water-alcohol mixed solution; the use of the water-alcohol mixed solution can promote the sufficient hydrolysis of the silane coupling agent, and help the grafting reaction of the silane coupling agent and the bentonite.

[0023] According to the preferred embodiment of the first aspect, in step two, the first reaction intermediate is mixed with ethanol and / or water and the silane coupling agent containing long chain alkyl to obtain a first mixture, and then the first mixture is adjusted to be alkaline by using an alkaline reagent to perform the first contact reaction.

[0024] According to the preferred embodiment of the first aspect, the quaternary ammonium salt surfactant is selected from quaternary ammonium salt surfactants containing C8+ long chain alkyl;

[0025] Further, the quaternary ammonium salt surfactant is selected from quaternary ammonium salt surfactants containing C8-C18 long chain alkyl;

[0026] Further, the quaternary ammonium salt surfactant includes quaternary ammonium salt surfactants containing single C8+ long chain alkyl and / or quaternary ammonium salt surfactants containing double C8+ long chain alkyl; further, the quaternary ammonium salt surfactant includes quaternary ammonium salt surfactants containing single C8-C18 long chain alkyl and / or quaternary ammonium salt surfactants containing double C8-C18 long chain alkyl;

[0027] Further, the quaternary ammonium salt surfactant includes one or more than two combinations of octyl trimethyl ammonium chloride, eucalyptus trimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, dioctyl dimethyl ammonium chloride, di-eucalyptus dimethyl ammonium chloride, didodecyl dimethyl ammonium chloride, dihexadecyl dimethyl ammonium chloride, and dioctadecyl dimethyl ammonium chloride.

[0028] According to the preferred embodiment of the first aspect, the use amount ratio of the bentonite, the silane coupling agent containing long chain alkyl, and the quaternary ammonium salt surfactant is 1 kg:(0.010-0.050) mol:(0.02-1) mol; further, the use amount ratio of the bentonite, the silane coupling agent containing long chain alkyl, and the quaternary ammonium salt surfactant is 1 kg:(0.015-0.04) mol:(0.03-0.09) mol; further, the use amount ratio of the bentonite, the silane coupling agent containing long chain alkyl, and the quaternary ammonium salt surfactant is 1 kg:(0.02-0.035) mol:(0.04-0.08) mol. In the present application, the use amount of the bentonite, the silane coupling agent containing long chain alkyl, and the quaternary ammonium salt surfactant can be appropriately adjusted according to the required structure ratio of the organo-clay.

[0029] According to the preferred embodiment of the first aspect, the surface activation modification temperature is 60-100℃; further, the surface activation modification temperature is 70-90℃.

[0030] According to a preferred embodiment of the first aspect, the surface activation modification time is 1-4h; further, the surface activation modification time is 2-3h.

[0031] According to a preferred embodiment of the first aspect, the first contact reaction temperature is 80-100℃; further, the first contact reaction temperature is 85-95℃.

[0032] According to a preferred embodiment of the first aspect, the first contact reaction time is 4-8h; further, the first contact reaction time is 5-6h.

[0033] According to a preferred embodiment of the first aspect, the second contact reaction temperature is 30-70℃; further, the second contact reaction temperature is 40-60℃.

[0034] According to a preferred embodiment of the first aspect, the second contact reaction time is 2-6h; further, the second contact reaction time is 3-4h.

[0035] According to a preferred embodiment of the first aspect, in step two, during the first contact reaction process of the first reaction intermediate and the silane coupling agent containing long-chain alkyl in the alkaline water-alcohol mixed solution, the feeding is carried out under the stirring condition of 250-300r / min, which can make the reaction more sufficient.

[0036] According to a preferred embodiment of the first aspect, in step three, during the second contact reaction process of the second reaction intermediate and the quaternary ammonium salt surfactant, the feeding is carried out under the stirring condition of 350-400r / min, which can make the reaction more sufficient.

[0037] In the second aspect, the present application also provides the organic soil prepared by the above preparation method.

[0038] The organic soil provided by the present application has excellent temperature resistance and can withstand ultra-high temperature of 200-260℃, has excellent stability in the ultra-high temperature environment of deep wells and ultra-deep wells, and can be applied to water-in-oil emulsified drilling fluid to improve the rheological stability and sedimentation stability of the water-in-oil emulsified drilling fluid system under ultra-high temperature conditions.

[0039] In the third aspect, the present application also provides the application of the above organic soil in oil and gas exploitation.

[0040] According to a preferred embodiment of the third aspect, the above organic soil is used in water-in-oil emulsified drilling fluid (i.e. oil-based drilling fluid) in oil and gas exploitation.

[0041] Specifically, the above organic soil can be used for increasing viscosity and cutting of water-in-oil emulsified drilling fluid.

[0042] According to a preferred embodiment of the third aspect, the aging temperature of the water-in-oil emulsified drilling fluid is 260℃.

[0043] According to a fourth aspect, the present application further provides a water-in-oil emulsified drilling fluid, which comprises the organic clay as described above.

[0044] According to a preferred embodiment of the fourth aspect, the content of the organic clay is 2-5% based on the total mass of the water-in-oil emulsified drilling fluid.

[0045] According to a preferred embodiment of the fourth aspect, the oil phase of the water-in-oil emulsified drilling fluid can be provided by the oil phase commonly used in the art; further, the oil phase of the water-in-oil emulsified drilling fluid comprises diesel oil and / or white oil; still further, the white oil comprises 3# white oil (flash point of 220℃, 40℃ kinematic viscosity of 3mm 2 / s, specific gravity of 0.85) and / or 5# white oil (flash point of 220℃, 40℃ kinematic viscosity of 3.5mm 2 / s, specific gravity of 0.85).

[0046] According to a preferred embodiment of the fourth aspect, the water phase of the water-in-oil emulsified drilling fluid is an aqueous solution of CaCl2; further, the mass concentration of CaCl2 in the aqueous solution of CaCl2 is 20-40% based on the total mass of the aqueous solution of CaCl2.

[0047] According to a preferred embodiment of the fourth aspect, the volume ratio of the oil phase to the water phase of the water-in-oil emulsified drilling fluid is 70-90:30-10.

[0048] According to a preferred embodiment of the fourth aspect, the water-in-oil emulsified drilling fluid can further contain other treating agents commonly used in the art, such as one or more of primary emulsifiers, auxiliary emulsifiers, wetting agents, alkalinity adjusting agents, weighting agents, and the like. The above-mentioned treating agents and their amounts can be selected according to the types and amounts commonly used in the art, and the present application does not have a particular limitation in this regard.

[0049] The present application provides technical solutions, which have the following beneficial effects:

[0050] The present application modifies bentonite by using strong oxidizing solution, silane coupling agent and quaternary ammonium salt surfactant to obtain the organic clay resistant to ultra-high temperature. The organic clay resistant to ultra-high temperature of the present application can effectively improve the structural strength of the water-in-oil emulsified drilling fluid under the extreme high temperature environment of 200-260℃, especially improve the apparent viscosity, dynamic shear force and low shear rate viscosity of the drilling fluid system, so that the water-in-oil emulsified drilling fluid system has excellent solid phase suspension capacity, effectively solves the problems of solid phase sedimentation and cuttings suspension of the water-in-oil emulsified drilling fluid system under ultra-high temperature conditions, and meets the actual application requirements of deep wells and ultra-deep wells at present stage. Detailed Implementation

[0051] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0052] Example 1:

[0053] This embodiment provides an organic soil suitable for ultra-high temperature resistance in water-in-oil emulsion drilling fluids, which is prepared by the following method:

[0054] First, a strong oxidizing solution was prepared according to a volume ratio of 30:60 for hydrogen peroxide (with a H2O2 concentration of 30% in the total hydrogen peroxide solution, calculated as 100% of the total hydrogen peroxide mass) and concentrated sulfuric acid (with a H2SO4 concentration of 70% in the concentrated sulfuric acid solution, calculated as 100% of the total concentrated sulfuric acid mass). Then, 1 kg of sodium-based bentonite was dispersed in 100 mL of the strong oxidizing solution, and the temperature was raised to 80 °C and the reaction was continued for 2 h to activate the surface of the sodium-based bentonite. After washing, filtering, and drying, the surface-activated sodium-based bentonite (i.e., the first reaction intermediate) was obtained.

[0055] A mixed solution of ethanol and water was prepared at a volume ratio of 30:70. Then, surface-activated sodium bentonite was added to 10 L of the ethanol and water mixture, and 0.03 mol of n-octyltriethoxysilane was added to obtain the first mixture. The first mixture was then added to a three-necked flask, and the pH was adjusted to 8-9 using ammonia water (the mass concentration of NH3 in the ammonia water was 25% based on the total mass of ammonia water being 100%). The temperature was raised to 90 °C, and the rotation speed was adjusted to 250 r / min. The reaction was continued for 5 h. After the reaction was completed, the temperature was lowered to room temperature to obtain the second reaction intermediate.

[0056] Add 0.06 mol of dioctadecyldimethylammonium chloride to the second reaction intermediate, adjust the temperature to 50 °C, and continue the reaction for 3 h under stirring speed of 350 r / min;

[0057] After the reaction was completed, the reactants were purified to obtain organo-earth AHC-1.

[0058] Example 2:

[0059] This embodiment provides an organic soil suitable for ultra-high temperature resistance in water-in-oil emulsion drilling fluids, which is prepared by the following method:

[0060] First, a strong oxidizing solution is prepared according to a volume ratio of 25:55 of hydrogen peroxide (mass concentration of H2O2 in the hydrogen peroxide is 30% based on the total mass of the hydrogen peroxide) and concentrated sulfuric acid (mass concentration of H2SO4 in the concentrated sulfuric acid is 70% based on the total mass of the concentrated sulfuric acid), then 1 kg of sodium bentonite is dispersed in 100 mL of the strong oxidizing solution, the temperature is raised to 70°C, and the sodium bentonite is surface-activated for 2 h, after which the sodium bentonite is washed, filtered, and dried to obtain surface-activated sodium bentonite (i.e., a first reaction intermediate);

[0061] A mixed solution of ethanol and water is prepared according to a volume ratio of 30:70, then the surface-activated sodium bentonite is added to 10 L of the mixed solution of ethanol and water, and 0.01 moL of n-octyl triethoxysilane is added to obtain a first mixture, then the first mixture is added to a three-necked flask, ammonia water (mass concentration of NH3 in the ammonia water is 25% based on the total mass of the ammonia water) is used to adjust the pH to 8-9, the temperature is raised to 85°C, the rotation speed is adjusted to 250 r / min, and the reaction is continued for 5 h; after the reaction is completed, the temperature is lowered to room temperature to obtain a second reaction intermediate;

[0062] 0.03 moL of dioctadecyl dimethyl ammonium chloride is added to the second reaction intermediate, the temperature is adjusted to 40°C, and the reaction is continued for 3 h under the condition of a stirring rotation speed of 350 r / min;

[0063] After the reaction is completed, the reaction product is purified to obtain the organic soil AHC-2.

[0064] Example 3:

[0065] The present example provides an organic soil suitable for a water-in-oil emulsified drilling fluid that is resistant to ultra-high temperature, which is prepared by the following preparation method:

[0066] First, a strong oxidizing solution is prepared according to a volume ratio of 25:65 of hydrogen peroxide (mass concentration of H2O2 in the hydrogen peroxide is 30% based on the total mass of the hydrogen peroxide) and concentrated sulfuric acid (mass concentration of H2SO4 in the concentrated sulfuric acid is 70% based on the total mass of the concentrated sulfuric acid), then 1 kg of sodium bentonite is dispersed in 100 mL of the strong oxidizing solution, the temperature is raised to 70°C, and the sodium bentonite is surface-activated for 2 h, after which the sodium bentonite is washed, filtered, and dried to obtain surface-activated sodium bentonite (i.e., a first reaction intermediate);

[0067] A mixed solution of ethanol and water was prepared in a volume ratio of 30:70, and then the surface-activated sodium bentonite was added into 10 L of the mixed solution of ethanol and water and 0.02 moL of n-octyl triethoxysilane was added to obtain a first mixture, and then the first mixture was added into a three-necked flask, ammonia water (the mass concentration of NH3 in the ammonia water was 25% based on the total mass of the ammonia water) was used to adjust the pH to 8-9, the temperature was raised to 85°C, the rotating speed was adjusted to 250 r / min, and the reaction was continued for 5 h; after the reaction was completed, the temperature was lowered to room temperature to obtain a second reaction intermediate;

[0068] 0.09 moL of dioctadecyl dimethyl ammonium chloride was added into the second reaction intermediate, the temperature was adjusted to 60°C, and the reaction was continued for 4 h under the stirring rotating speed of 400 r / min;

[0069] After the reaction was completed, the reaction product was purified to obtain the organic clay AHC-3.

[0070] Example 4:

[0071] The present example provides an organic clay suitable for water-in-oil emulsified drilling fluid resistant to ultra-high temperature, which is prepared by the following preparation method:

[0072] First, a strong oxidizing solution was prepared in a volume ratio of 35:65 of hydrogen peroxide (the mass concentration of H2O2 in the hydrogen peroxide was 30% based on the total mass of the hydrogen peroxide) and concentrated sulfuric acid (the mass concentration of H2SO4 in the concentrated sulfuric acid was 70% based on the total mass of the concentrated sulfuric acid), and then 1 kg of sodium bentonite was dispersed in 100 mL of the strong oxidizing solution, the temperature was raised to 90°C, and the sodium bentonite was surface-activated for 3 h, and then the sodium bentonite was washed, filtered, and dried to obtain the surface-activated sodium bentonite (i.e., a first reaction intermediate);

[0073] A mixed solution of ethanol and water was prepared in a volume ratio of 30:70, and then the surface-activated sodium bentonite was added into 10 L of the mixed solution of ethanol and water and 0.04 moL of n-octyl triethoxysilane was added to obtain a first mixture, and then the first mixture was added into a three-necked flask, ammonia water (the mass concentration of NH3 in the ammonia water was 25% based on the total mass of the ammonia water) was used to adjust the pH to 8-9, the temperature was raised to 95°C, the rotating speed was adjusted to 300 r / min, and the reaction was continued for 6 h; after the reaction was completed, the temperature was lowered to room temperature to obtain a second reaction intermediate;

[0074] 0.03 moL of dioctadecyl dimethyl ammonium chloride was added into the second reaction intermediate, the temperature was adjusted to 40°C, and the reaction was continued for 3 h under the stirring rotating speed of 350 r / min;

[0075] After the reaction was completed, the reaction product was purified to obtain the organic clay AHC-4.

[0076] Example 5:

[0077] The present embodiment provides an organic clay suitable for water-in-oil emulsified drilling fluid resistant to ultra-high temperature, which is prepared by the following preparation method:

[0078] First, a strong oxidizing solution is prepared according to a volume ratio of hydrogen peroxide (the mass concentration of H2O2 in the hydrogen peroxide is 30% based on the total mass of the hydrogen peroxide) to concentrated sulfuric acid (the mass concentration of H2SO4 in the concentrated sulfuric acid is 70% based on the total mass of the concentrated sulfuric acid) of 35:65, then 1 kg of sodium-based bentonite is dispersed in 100 mL of the strong oxidizing solution, the temperature is raised to 90°C, and the sodium-based bentonite is surface-activated for 3 hours, then the sodium-based bentonite after surface activation (i.e., the first reaction intermediate) is obtained after washing, filtering, and drying.

[0079] A mixed solution of ethanol and water is prepared according to a volume ratio of 30:70, then the sodium-based bentonite after surface activation is added to 10 L of the mixed solution of ethanol and water, and 0.035 moL of n-octyl triethoxysilane is added to obtain a first mixture, then the first mixture is added to a three-necked flask, ammonia water (the mass concentration of NH3 in the ammonia water is 25% based on the total mass of the ammonia water) is used to adjust the pH to 8-9, the temperature is raised to 95°C, the rotation speed is adjusted to 300 r / min, and the reaction is continued for 6 hours; after the reaction is completed, the temperature is lowered to room temperature, and a second reaction intermediate is obtained.

[0080] 0.08 moL of dioctadecyl dimethyl ammonium chloride is added to the second reaction intermediate, the temperature is adjusted to 60°C, and the reaction is continued for 4 hours under the condition of a stirring rotation speed of 400 r / min.

[0081] After the reaction is completed, the reaction product is purified, and the organic clay AHC-5 is obtained.

[0082] Comparative Example 1:

[0083] The present comparative example provides an organic clay, and the difference between the preparation method of the present comparative example and Example 1 is that the present comparative example does not perform intercalation modification of dioctadecyl dimethyl ammonium chloride, but only performs graft modification of the surface-activated sodium-based bentonite with a long-chain alkane silane coupling agent, and the organic clay provided by the present comparative example is DAHC-1.

[0084] Comparative Example 2:

[0085] The present comparative example provides an organic clay, and the difference between the preparation method of the present comparative example and Example 1 is that the present comparative example does not perform surface activation modification of the sodium-based bentonite and graft modification of the surface-activated sodium-based bentonite with a long-chain alkane silane coupling agent, but only performs intercalation modification of the sodium-based bentonite with dioctadecyl dimethyl ammonium chloride, and the organic clay provided by the present comparative example is DAHC-2.

[0086] Comparative Example 3:

[0087] The present comparative example provides an organic soil, the preparation method of which is only different from that of Example 1 in that the present comparative example does not perform intercalation modification of sodium bentonite with dioctadecyldimethylammonium chloride, but only graft modification of surface-activated sodium bentonite with long-chain alkane silane coupling agent. The organic soil provided by the present comparative example is DAHC-3.

[0088] Comparative Example 4:

[0089] The present comparative example provides an organic soil, the preparation method of which is only different from that of Example 1 in that the present comparative example does not perform surface activation modification of sodium bentonite and graft modification of surface-activated sodium bentonite with long-chain alkane silane coupling agent, but only performs intercalation modification of surface-activated sodium bentonite with dioctadecyldimethylammonium chloride. The organic soil provided by the present comparative example is DAHC-4.

[0090] Comparative Example 5:

[0091] The present comparative example provides an organic soil, the preparation method of which is only different from that of Example 1 in that the present comparative example directly mixes long-chain alkane silane coupling agent and dioctadecyldimethylammonium chloride to graft modify surface-activated sodium bentonite. The organic soil provided by the present comparative example is DAHC-5.

[0092] Comparative Example 6:

[0093] The present comparative example provides an organic soil, the preparation method of which is only different from that of Example 1 in that the present comparative example replaces long-chain alkane silane coupling agent with octakis (trimethylammonium) silsesquioxane to graft modify surface-activated sodium bentonite. The organic soil provided by the present comparative example is DAHC-6.

[0094] Test Example 1:

[0095] The present test example is used to test the colloid rate of the organic soils provided by Examples 1-5 and Comparative Examples 1-6 in oil phase.

[0096] The organic soils provided by Examples 1-5 and Comparative Examples 1-6 are respectively added into oil phase to obtain organic soil dispersion liquid, and the colloid rate thereof is measured before and after high-temperature aging.

[0097] The formula composition of the organic soil dispersion liquid is as follows: 300 mL base oil + 2 g anhydrous ethanol + 6 g organic soil, wherein the base oil is 3# white oil.

[0098] Take 100 mL of each prepared organic soil dispersion and place it in a 100 mL stoppered graduated cylinder; take 100 mL of each prepared organic soil dispersion and place it in an aging tank, age at 260℃ for 16 h, cool to room temperature, open the tank and place it in a 100 mL stoppered graduated cylinder; observe the volume V of the oil phase precipitated in the upper part of the stoppered graduated cylinder after standing for 90 min and 24 h, and then calculate the colloid ratio R according to the following formula:

[0099] R = (100 - V) ÷ V × 100

[0100] The results of the colloidal content test are shown in Table 1.

[0101] Table 1. Changes in colloidal content of organic soil dispersions prepared according to various examples and comparative examples before and after aging.

[0102]

[0103] As shown in Table 1, the organoclays AHC-1 and AHC-5 synthesized in Examples 1 and 5 exhibited the best colloidal content before and after aging at 260℃. The ultra-high temperature resistant organoclays synthesized in Comparative Examples 1 and 2 through only surface silane coupling agent grafting and surfactant intercalation modification showed poor temperature resistance and were difficult to stabilize under high temperature conditions. The organoclays in Comparative Examples 3 and 4, which did not undergo surface activation of bentonite, showed poor performance. The organoclays in Comparative Example 5, which underwent mixed modification, showed poor performance after aging at 260℃. Meanwhile, the organoclay prepared using octamethylamine cage-type silsesquioxane in Comparative Example 6 had poor temperature resistance.

[0104] Test Example 2

[0105] This test case is used to test the viscosity-enhancing and shearing effect of the organic soil provided in Examples 1-5 and Comparative Examples 1-6 on water-in-oil emulsion drilling fluid.

[0106] Oil-in-water emulsion drilling fluids were prepared using the organic soils provided in Examples 1-5 and Comparative Examples 1-6, respectively. Specifically, a first oil-in-water emulsion drilling fluid base and a second oil-in-water emulsion drilling fluid base were prepared according to basic formula 1 and basic formula 2, respectively. Then, 12 parts of the first oil-in-water emulsion drilling fluid base and 12 parts of the second oil-in-water emulsion drilling fluid base were taken, and the organic soils and organic soil HFGEL120 provided in Examples 1-5 and Comparative Examples 1-6 were added to each part of the first oil-in-water emulsion drilling fluid base to prepare 12 parts of the first formula oil-in-water emulsion drilling fluid. The organic soils and organic soil HFGEL120 provided in Examples 1-5 and Comparative Examples 1-6 were added to each part of the second oil-in-water emulsion drilling fluid base to prepare 12 parts of the second formula oil-in-water emulsion drilling fluid.

[0107] The base formula 1 (oil-water ratio 90:10, density 2.5 g / cm 3 ) is composed as follows: 270 mL base oil + 30 mL CaCl2 aqueous solution (CaCl2 concentration 25 wt%) + 12 g main emulsifier + 12 g auxiliary emulsifier + 15 g CaO powder + 5% filtration reducer + 1185 g barite; the base formula 2 (oil-water ratio 85:15, density 1.8 g / cm 3 ) is composed as follows: 255 mL base oil + 45 mL CaCl2 aqueous solution (CaCl2 concentration 25 wt%) + 18 g main emulsifier + 18 g auxiliary emulsifier + 15 g CaO powder + 5% filtration reducer + 500 g barite; wherein the base oil is 3# white oil, purchased from Guangdong Maoming Petrochemical Company; the main emulsifier (alkanolamide DR-CO), the auxiliary emulsifier (fatty acid amide DR-EM) and the filtration reducer (humic acid amide FLRA) are all taken from China Petroleum Engineering & Technical Research Institute Co., Ltd., and the barite (density ≥ 4.2 g / cm 3 ) is taken from Huayao Mineral Product Processing Factory in Lingshou County;

[0108] In the first formula water-in-oil emulsified drilling fluid, the amount of organic clay added is 1.5% based on 100% of the mass of the drilling fluid; in the second formula water-in-oil emulsified drilling fluid, the amount of organic clay added is 3% based on 100% of the mass of the drilling fluid;

[0109] The organic clay HFGEL120 is purchased from Zhejiang Fenghong New Material Co., Ltd.

[0110] The rheological property test is carried out before and after high-temperature aging on the base formula of the water-in-oil emulsified drilling fluid, and the test is compared with the commercially available organic clay.

[0111] The base formula of the water-in-oil emulsified drilling fluid used has two kinds,

[0112] After the prepared first formula water-in-oil emulsified drilling fluid and the second formula water-in-oil emulsified drilling fluid are put into the aging tank, the settling condition of the drilling fluid is probed with a glass rod after being aged at 260℃ for 16h and cooled to room temperature, wherein: hard settling refers to that the barite settles seriously, resulting in that the glass rod cannot touch the bottom of the aging tank; soft settling refers to that there is a density difference in the drilling fluid in the aging tank, and the barite settles weakly, so that the glass rod can slowly touch the bottom of the aging tank; no settling refers to that there is no density difference between the upper and lower parts of the drilling fluid in the aging tank. Then the drilling fluid in the aging tank is stirred at high speed at 12000 rpm for 20 min, and then heated to 65℃, and the scale readings of 600 r / min, 300 r / min, 6 r / min and 3 r / min are tested by using a ZNN-D6 type six-speed rotary viscometer, and the rheological parameters of the drilling fluid are calculated according to the following formula:

[0113] Apparent viscosity: AV = 1 / 2 × 600 r / min (reading) mPa.s

[0114] Plastic viscosity: PV = 600 r / min (reading) - 300 r / min (reading) mPa.s

[0115] Yield point: YP = 1 / 2 x (300 r / min (reading) - PV) Pa

[0116] The test results are shown in Tables 2-4, wherein Table 2 is a comparison of the performance of the first water-in-oil emulsified drilling fluid base fluid and the second water-in-oil emulsified drilling fluid base fluid before and after aging, Table 3 is a comparison of the performance of the second formula water-in-oil emulsified drilling fluid added with organic soil HFGEL120 before and after aging, and Table 4 is a comparison of the performance of the second formula water-in-oil emulsified drilling fluid added with the organic soil of Examples 1-5 and Comparative Examples 1-6 before and after aging at a temperature of 260°C.

[0117] Table 2 Performance of the first water-in-oil emulsified drilling fluid base fluid and the second water-in-oil emulsified drilling fluid base fluid before and after aging

[0118]

[0119] As shown in Table 2, the first water-in-oil emulsified drilling fluid base fluid and the second water-in-oil emulsified drilling fluid base fluid without adding organic soil have low yield point and low shear rate viscosity before aging, and after aging at 260°C, both appear hard sediment, and the yield point and low shear rate viscosity after aging are almost zero, indicating that the rheological property is poor, the system shear force is small, and sufficient structural force is not formed, which makes it difficult to effectively suspend weighting materials.

[0120] Table 3 Performance of the first and second formula water-in-oil emulsified drilling fluid added with organic soil HFGEL120 before and after aging

[0121]

[0122]

[0123] As shown in Table 3, the drilling fluid added with HFGEL120 has significantly increased yield point and low shear rate viscosity before aging, but the viscosity and shear force of the overall system decrease significantly after high-temperature aging at 260°C, and the yield point and low shear rate viscosity after aging are almost zero, indicating that the organic soil HFGEL120 has poor temperature resistance and is difficult to stabilize the rheological property of the system at 260°C.

[0124] Table 4 Performance of the second formula water-in-oil emulsified drilling fluid added with each example and comparative example before and after aging

[0125]

[0126] As shown in Table 4, the organic clay prepared by the examples 1-5 of the present application can effectively improve the yield point and low shear rate viscosity of the drilling fluid system before and after high temperature aging at 260 DEG C, thus can greatly improve the sedimentation stability of the water-in-oil emulsified drilling fluid, indicating that the temperature resistance can reach 260 DEG C, and has great advantage in temperature resistance compared with the commonly used water-in-oil emulsified drilling fluid organic clay.

[0127] The comparative example 1 only grafts the silane coupling agent containing long-chain alkane on the surface, the temperature resistance can be improved, but the rheological property of the system is still unstable after aging at 260 DEG C, and the soft settling phenomenon appears.

[0128] The comparative example 2 only synthesizes the anti-ultra-high temperature organic clay by intercalation modification of the surfactant, although the rheological property of the system can be well improved at normal temperature, but the hard settling phenomenon appears after aging at 260 DEG C, indicating that the organic clay is invalid after aging at 260 DEG C, and is difficult to maintain the suspension stability of the weighting material.

[0129] The comparative example 3 only forms the organic clay by grafting modification of the sodium-based bentonite which is not surface-activated by using the long-chain alkane-containing silane coupling agent, the single silane coupling agent cannot reflect the tackifying and shear-thickening performance of the organic clay, and the hard settling phenomenon appears after aging.

[0130] The comparative example 4 only forms the organic clay by intercalation modification of the sodium-based bentonite which is not activated by using the dioctadecyldimethylammonium chloride, which has good tackifying and shear-thickening effect at normal temperature, but does not have temperature resistance, and the hard settling phenomenon appears after aging.

[0131] The comparative example 5 forms the organic clay by grafting modification of the surface-activated sodium-based bentonite by mixing the long-chain alkane-containing silane coupling agent and the dioctadecyldimethylammonium chloride, which has good tackifying and shear-thickening effect at normal temperature, but is not a step-by-step reaction, cannot produce synergistic effect, and instead forms competitive adsorption, so that the organic clay as a whole does not have temperature resistance, and the hard settling phenomenon appears after aging.

[0132] The comparative example 6 forms the organic clay by using octa-polytetramethylammonium cage-type silsesquioxane to replace the long-chain silane coupling agent, which still has good tackifying and shear-thickening effect at normal temperature, but does not have temperature resistance, and the hard settling phenomenon appears after aging.

[0133] Meanwhile, it is found from the examples 1-5 that the amount of the synthesized organic clay silane coupling agent and the amount of the surfactant have an optimal ratio, but the less or more amount still better maintains the rheological stability of the system to a certain extent.

[0134] In conclusion, the organic soil can be applied to the water-in-oil emulsified drilling fluid system, can effectively improve the structural force of the water-in-oil emulsified drilling fluid system before and after high temperature aging, especially the dynamic shear force and the low shear rate viscosity, and improve the high temperature sedimentation stability of the system, and the temperature resistance can reach 260 DEG C.

[0135] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and belong to the protection scope of the application.

Claims

1. A method for preparing organic soil, comprising the following steps: Step one involves surface-activating and modifying bentonite using a strong oxidizing solution to obtain a first reaction intermediate; wherein the strong oxidizing solution comprises hydrogen peroxide and a strong acid; the strong acid is concentrated sulfuric acid; and the total mass of the hydrogen peroxide is 100%, with the H2O2 mass concentration in the hydrogen peroxide being 30%. Step two, the first reaction intermediate is reacted with a silane coupling agent containing a long-chain alkyl group in an alkaline water-alcohol mixture to obtain a second reaction intermediate; wherein the long-chain alkyl group contained in the silane coupling agent is a C3+ alkyl group. Step 3: The second reaction intermediate is reacted with a quaternary ammonium salt surfactant in a second contact reaction to obtain the organic soil.

2. The preparation method according to claim 1, wherein, The bentonite includes sodium-based bentonite and / or calcium-based bentonite.

3. The preparation method according to claim 1, wherein, The ratio of the amount of bentonite, hydrogen peroxide and strong acid is 1 kg:(10-45) mL:(50-80) mL.

4. The preparation method according to claim 3, wherein, The ratio of the amount of bentonite, hydrogen peroxide and strong acid is 1 kg:(20-40) mL:(55-70) mL.

5. The preparation method according to claim 4, wherein, The ratio of the amount of bentonite, hydrogen peroxide and strong acid is 1 kg: (25-35) mL: (55-65) mL.

6. The preparation method according to claim 1, wherein, The long-chain alkyl group contained in the silane coupling agent is a C3-C18 alkyl group.

7. The preparation method according to claim 6, wherein, The long-chain alkyl group contained in the silane coupling agent is one of propyl, butyl, hexyl, octyl, decyl, dodecyl, hexadecyl, and octadecyl.

8. The preparation method according to claim 7, wherein, The silane coupling agent containing long-chain alkyl groups includes one or more combinations of propyltriethoxysilane, butyltriethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, hexadecyltriethoxysilane, and octadecyltriethoxysilane.

9. The preparation method according to claim 1, wherein, The first contact reaction was carried out at a pH of 7-11.

10. The preparation method according to claim 9, wherein, The first contact reaction was carried out at a pH of 7-10.

11. The preparation method according to claim 10, wherein, The first contact reaction was carried out at a pH of 8-9.

12. The preparation method according to claim 1, wherein, The alkaline reagent used in the alkaline water-alcohol mixture includes one or more of ammonia, sodium hydroxide, calcium hydroxide, and triethanolamine. The alcohol includes one or more of methanol, ethanol, n-propanol and isopropanol; The first reaction intermediate undergoes a first contact reaction with a silane coupling agent containing long-chain alkyl groups in an alkaline aqueous alcohol mixture.

13. The preparation method according to claim 1, wherein, The quaternary ammonium salt surfactant is selected from quaternary ammonium salt surfactants containing C8+ long-chain alkyl groups.

14. The preparation method according to claim 13, wherein, The quaternary ammonium salt surfactant is selected from quaternary ammonium salt surfactants containing C8-C18 long-chain alkyl groups.

15. The preparation method according to claim 13, wherein, The quaternary ammonium salt surfactants include quaternary ammonium salt surfactants containing a single C8+ long-chain alkyl group and / or quaternary ammonium salt surfactants containing two C8+ long-chain alkyl groups.

16. The preparation method according to claim 15, wherein, The quaternary ammonium salt surfactants include quaternary ammonium salt surfactants containing a single C8-C18 long-chain alkyl group and / or quaternary ammonium salt surfactants containing two C8-C18 long-chain alkyl groups.

17. The preparation method according to claim 16, wherein, The quaternary ammonium salt surfactants include one or more of the following: octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dioctyldimethylammonium chloride, didecyldimethylammonium chloride, didodecyldimethylammonium chloride, dihexadecyldimethylammonium chloride, and dioctadecyldimethylammonium chloride.

18. The preparation method according to claim 1, wherein, The ratio of the bentonite, the silane coupling agent containing long-chain alkyl groups, and the quaternary ammonium salt surfactant is 1 kg:(0.010-0.050) mol:(0.02-1) mol.

19. The preparation method according to claim 1, wherein, The ratio of the bentonite, the silane coupling agent containing long-chain alkyl groups, and the quaternary ammonium salt surfactant is 1 kg:(0.015-0.04) mol:(0.03-0.09) mol.

20. The preparation method according to claim 1, wherein, The ratio of the bentonite, the silane coupling agent containing long-chain alkyl groups, and the quaternary ammonium salt surfactant is 1 kg:(0.02-0.035) mol:(0.04-0.08) mol.

21. The preparation method according to claim 1, wherein, The surface activation modification temperature is 60-100℃.

22. The preparation method according to claim 21, wherein, The surface activation modification temperature is 70-90℃.

23. The preparation method according to claim 1, wherein, The temperature of the first contact reaction is 80-100℃.

24. The preparation method according to claim 1, wherein, The temperature of the first contact reaction is 85-95℃.

25. The preparation method according to claim 1, wherein, The temperature of the second contact reaction is 30-70℃.

26. The preparation method according to claim 1, wherein, The temperature of the second contact reaction is 40-60℃.

27. The organic soil prepared by any one of claims 1-26.

28. The application of the organic soil according to claim 27 in oil and gas extraction.

29. The application according to claim 28, wherein, The organic soil of claim 10 is used in oil and gas extraction for water-in-oil emulsion drilling fluid.

30. The application according to claim 28, wherein, The aging temperature of the water-in-oil emulsion drilling fluid is 260℃.

31. A water-in-oil emulsion drilling fluid comprising the organic soil of claim 27.

32. The water-in-oil emulsion drilling fluid according to claim 31, wherein, Based on the total mass of the water-in-oil emulsion drilling fluid as 100%, the content of organic soil is 2-5%.

33. The water-in-oil emulsion drilling fluid according to claim 31, wherein, The oil phase of the water-in-oil emulsion drilling fluid includes diesel oil and / or white oil.

34. The water-in-oil emulsion drilling fluid according to claim 33, wherein, The white oil includes No. 3 white oil and / or No. 5 white oil.

35. The water-in-oil emulsion drilling fluid according to claim 31, wherein, The aqueous phase of the water-in-oil emulsion drilling fluid is an aqueous solution of CaCl2.

36. The water-in-oil emulsion drilling fluid according to claim 35, wherein, With the total mass of the CaCl2 aqueous solution being 100%, the mass concentration of CaCl2 in the CaCl2 aqueous solution is 20-40%.

37. The water-in-oil emulsion drilling fluid according to claim 36, wherein, The volume ratio of the oil phase to the water phase in the oil-in-water emulsion drilling fluid is 70-90:30-10.

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