Anti-ultra-high temperature fluid loss additive, composition and application thereof

Abstract

The present application relates to the technical field of drilling fluid, in particular to an ultra-high temperature resistant fluid loss additive, a composition thereof and application thereof. The ultra-high temperature resistant fluid loss additive is prepared from the following raw materials, the raw materials include C=C containing anhydride monomer, benzene ring containing olefin monomer, long carbon chain olefin monomer, initiator and crosslinking agent; wherein the number of C atoms n in the long carbon chain olefin monomer is greater than or equal to 10, and the crosslinking agent has the following molecular formula: H[O(CH2)b]a{NH(CH2)b}cNH2. The fluid loss additive is resistant to temperature up to 240 DEG C, has excellent fluid loss reduction effect, and has little effect on the rheological property and emulsion stability of the base formula. Further compounding the fluid loss additive with specific inorganic materials, the composition obtained is resistant to temperature up to 260 DEG C.

Description

Technical Field

[0001] This invention relates to the field of drilling fluid technology, specifically to a high-temperature resistant filtration loss reducer, its composition, and its application. Background Technology

[0002] Oil-based drilling fluids possess inherent advantages such as excellent lubricity, inhibition, and high-temperature stability, and have become one of the main technologies for drilling complex wells such as high-temperature deep wells, ultra-deep wells, and shale oil and gas horizontal wells. In recent years, with the continuous deepening of oil and gas resource exploration and development both domestically and internationally, the number of deep and ultra-deep wells has gradually increased, and the upper limit of wellbore temperature is constantly being refreshed, bringing increasingly severe challenges to oil-based drilling fluid technology. Filter loss is a serious problem during drilling operations. Formations typically contain a large number of micropores and fractures, allowing drilling fluid to penetrate the formation through these fractures. Especially under high-temperature and high-pressure conditions, the pressure difference accelerates the flow of fluid through formation fractures, exacerbating the filter loss problem and easily leading to stuck pipe, wellbore instability, and other downhole complications, resulting in economic losses. In recent years, with the continuous deepening of oil and gas resource exploration and development both domestically and internationally, the number of deep and ultra-deep wells has gradually increased, and the upper limit of wellbore temperature is constantly being refreshed, bringing increasingly severe challenges to oil-based drilling fluid technology.

[0003] Filtration reducers are typically added to oil-based drilling fluids to control filtration loss. Currently, the main filtration reducers used in oil-based drilling fluids include asphalt-based, humic acid-based, natural polymer-based, and synthetic polymer-based agents. Asphalt-based filtration reducers reduce filtration loss in the drilling fluid system through their "softening point," while humic acid-based agents primarily improve mud cake quality by forming bridges in the mud cake pores, thereby reducing filtration loss. However, asphalt-based filtration reducers have high-temperature viscosity-increasing effects and environmental pollution problems, while humic acid-based filtration reducers have limited high-temperature resistance. Conventional natural polymer-based agents require large dosages, are resistant to temperature differences, and the performance of modified products is unstable. Synthetic polymer-based agents are relatively new, and there are few reports of high-temperature resistant products in the field. Therefore, asphalt-based and humic acid-based agents are currently the most widely used filtration reducers in drilling fields. However, when drilling ultra-deep wells, especially when the bottom hole temperature exceeds 200°C, the dosage of both is usually above 5%, and high-temperature failure issues may occur.

[0004] Therefore, there is an urgent need in this field to develop high-performance, ultra-high temperature resistant oil-based drilling fluid filtration reducers to provide technical support for high-temperature, high-pressure deep and ultra-deep wells. Summary of the Invention

[0005] This invention provides a filtration loss reducer for oil-based drilling fluids that is resistant to ultra-high temperatures. This filtration loss reducer has good filtration loss reduction and ultra-high temperature resistance, and has little impact on the rheological properties and emulsion stability of the basic formulation, thereby improving the overall performance of ultra-high temperature oil-based drilling fluid systems.

[0006] The present invention also provides a composition of a filtration loss reducer for oil-based drilling fluid that is resistant to ultra-high temperatures, and its high-temperature resistance can be further improved based on the filtration loss reducer used therein.

[0007] This invention provides an oil-based drilling fluid resistant to ultra-high temperatures, which has good high-temperature resistance and reduced filtration loss.

[0008] The present invention achieves the above-mentioned technical objectives through the following technical solutions:

[0009] This invention provides a high-temperature resistant filtration loss reducer, prepared from the following raw materials: an anhydride monomer containing C=C, an olefin monomer containing a benzene ring, a long-chain olefin monomer, an initiator, and a crosslinking agent; wherein, the long-chain olefin monomer has a C atom number n≥10; and the crosslinking agent has the following molecular formula: H[O(CH2)b]a{NH(CH2)b}cNH2, where a=0 or 1, b is 2 or 3, and c is 1 to 4.

[0010] The preparation method includes at least the step of reacting a first product obtained by reacting C=C-containing acid anhydride monomers, benzene ring-containing olefin monomers, and long-chain olefin monomers under the action of an initiator with a crosslinking agent under the protection of an inert gas.

[0011] In the above-mentioned ultra-high temperature filtration loss reducing agent, the molar ratio of the C=C-containing acid anhydride monomer, the benzene ring-containing olefin monomer, the long carbon chain olefin monomer and the crosslinking agent is 1:(0.5-1):(1-2.5):(0.5-2).

[0012] In the above-mentioned ultra-high temperature filtration loss reducing agent, the amount of the initiator added is 0.1-5% of the total mass of the monomer.

[0013] The filtration loss reducing agent with ultra-high temperature resistance described above, wherein the C=C-containing acid anhydride monomer is one or a combination of two of itaconic anhydride and maleic anhydride.

[0014] The filtration loss reducing agent with ultra-high temperature resistance described above, wherein the olefin monomer containing a benzene ring is one or more of styrene, p-hydroxystyrene, and sodium p-styrene sulfonate.

[0015] The filtration loss reducing agent with ultra-high temperature resistance described above, wherein the long carbon chain olefin monomer is one or more of 1-dodecene, 5-dodecene, tert-dodecene, 1-tetrideene, 1-tetradecene, 1-pentadene, 1-hexadecene, 1-heptadecene, 1-heptadecene, 1-octadecene, and 1-eicosene.

[0016] The initiator in the above-mentioned ultra-high temperature resistant filtration loss reducer is one or a combination of two of azobisisobutyronitrile and benzoyl peroxide.

[0017] The reaction temperature of the C=C-containing acid anhydride monomer, the benzene ring-containing olefin monomer, and the long carbon chain olefin monomer in the ultra-high temperature resistant filtration loss agent described above is 70-95℃ under the action of the initiator.

[0018] The temperature at which the first product reacts with the crosslinking agent to reduce filtration loss under ultra-high temperature conditions, as described above, is 30-80°C.

[0019] The above-mentioned ultra-high temperature filtration reduction agent, the reaction system of the C=C acid anhydride monomer, the benzene ring olefin monomer and the long carbon chain olefin monomer under the action of the initiator also contains solvent one.

[0020] The precipitate of the product after the crosslinking reaction between the first product and the crosslinking agent described above is washed with solvent two.

[0021] The solvent in the above-mentioned ultra-high temperature filtration reduction agent is one or more of the following: isoamyl acetate, n-amyl acetate, isopropanol, tert-butanol, dichloromethane, chloromethane, 1,2-dichloroethane, toluene, and xylene.

[0022] The solvent two in the above-mentioned ultra-high temperature resistant filtration loss reducer is anhydrous ethanol.

[0023] The preparation method of the ultra-high temperature resistant filtration loss reducer described above is as follows: Under nitrogen protection, a certain amount of solvent is added to the reaction vessel, the temperature is raised to 40-60℃, and under stirring conditions, acid anhydride monomers containing C=C, olefin monomers containing benzene rings and long carbon chain olefin monomers are added. After stirring evenly, the temperature is raised to 70-95℃, and the initiator is added dropwise slowly and evenly. The reaction is carried out for 2-8 hours to obtain a solution of the first reaction product.

[0024] Add a crosslinking agent dropwise to the solution of the first reaction product, react at 30-80℃ for 0.5-5h to obtain a solution of the second reaction product. Then cool the solution of the second reaction product to room temperature, wash the precipitate with solvent II, separate by suction filtration, dry under vacuum at 40-50℃, and pulverize to obtain the final product.

[0025] The present invention provides a high-temperature resistant filtration loss reduction composition, wherein the composition comprises at least ultrafine calcium carbonate, modified lithium saponite, and the filtration loss reduction agent according to any one of claims 1-7, wherein the ultrafine calcium carbonate has a particle size of 5000 mesh or more, the modified lithium saponite is octyltriethoxysilane modified lithium saponite, and the mass ratio of the filtration loss reduction agent to the ultrafine calcium carbonate and the modified lithium saponite is 8:(2-12):(1-4).

[0026] The ultra-high temperature resistant oil-based drilling fluid provided by the present invention comprises the above-mentioned ultra-high temperature resistant filtration loss reducer or ultra-high temperature resistant filtration loss reducer composition.

[0027] In the above-described ultra-high temperature resistant oil-based drilling fluid, the addition ratio of the ultra-high temperature resistant filtration loss reducer or the composition of the ultra-high temperature resistant filtration loss reducer is 0.5-8% of the total mass of the base fluid.

[0028] The preferred saturation level of the ultra-high temperature resistant oil-based drilling fluid is 2-6%.

[0029] The ultra-high temperature filtration loss reducer provided by this invention enhances its solubility in oil by introducing long carbon chains, improves its high-temperature resistance by introducing benzene rings, and imparts a certain proportion of hydrophilic groups (amino and / or hydroxyl groups) to maintain its hydrophilicity. Hydrogen bonds between these hydrophilic groups strengthen the network structure of the filtration loss reducer, facilitating the formation of a thin and resilient mud cake. Through these synergistic effects, it effectively reduces the high-temperature, high-pressure filtration loss of oil-based drilling fluids without affecting the emulsion stability of the base oil-based drilling fluid. This filtration loss reducer withstands temperatures up to 240℃, exhibits excellent filtration loss reduction, and has minimal impact on the rheological properties and emulsion stability of the base formulation. Furthermore, its low dosage helps reduce overall drilling costs, making it a promising candidate for application.

[0030] The present invention also provides a composition of a filtration loss reducing agent resistant to ultra-high temperature. By introducing a specific inorganic material as a primer on the basis of the above-mentioned filtration loss reducing agent, its high temperature resistance is further improved, reaching 260°C.

[0031] The ultra-high temperature resistant oil-based drilling fluid provided by this invention has excellent high temperature resistance, emulsion stability and filtration loss reduction. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] This invention provides a high-temperature resistant filtration loss reducer, which is prepared from the following raw materials: anhydride monomers containing C=C, olefin monomers containing benzene rings, long-chain olefin monomers, initiators, and crosslinking agents; wherein, the number of C atoms in the long-chain olefin monomers is n≥10, and the crosslinking agent has the following molecular formula: H[O(CH2)b]a{NH(CH2)b}cNH2, where a=0 or 1, b is 2 or 3, and c is 1 to 4.

[0034] The preparation method of the above-mentioned ultra-high temperature resistant filtration loss reducer includes at least the step of reacting the first product obtained by reacting C=C acid anhydride monomers, benzene ring olefin monomers and long carbon chain olefin monomers under the action of an initiator with a crosslinking agent under inert gas protection.

[0035] The ultra-high temperature filtration loss reducer provided by this invention enhances the solubility of the filtration loss reducer composition in oil by introducing long carbon chains, enhances the high temperature resistance of the filtration loss reducer composition by introducing benzene rings, and also has a certain degree of hydrophilicity by introducing a certain proportion of hydrophilic groups (amino and / or hydroxyl groups). Hydrogen bonds formed between the hydrophilic groups enhance the network structure of the filtration loss reducer, which is beneficial for forming a thin and tough mud cake. Through these synergistic effects, it can effectively reduce the high-temperature and high-pressure filtration loss of oil-based drilling fluids, and this filtration loss reducer does not affect the emulsion stability of the base oil-based drilling fluid. This filtration loss reducer has a temperature resistance of up to 240℃, excellent filtration loss reduction effect, and has little impact on the rheological properties and emulsion stability of the base formulation.

[0036] In this invention, the molar ratio of C=C anhydride monomers, benzene ring-containing olefin monomers, long-chain olefin monomers, and crosslinking agents is 1:(0.5-1):(1-2.5):(0.5-2). That is, when the molar amount of C=C anhydride monomers is 1 mol, the amount of benzene ring-containing olefin monomers is 0.5-1 mol, for example, 0.5 mol, 0.6 mol, 0.7 mol, 0.8 mol, 0.9 mol, 1 mol, or any value between any two of the above. The amount of long-chain olefin monomers is 1-2.5 mol, for example, 1 mol, 1.2 mol, 1.4 mol, 1.6 mol, 1.8 mol, 2.0 mol, 2.2 mol, 2.4 mol, 2.5 mol, or any value between any two of the above. The amount of crosslinking agent used is 0.5-2 mol, for example, 0.5 mol, 0.8 mol, 1.0 mol, 1.2 mol, 1.4 mol, 1.6 mol, 1.8 mol, 2.0 mol, and any value between any two of the above can be used.

[0037] The amount of initiator added is 0.1-5% of the total monomer mass, for example, it can be 0.1%, 0.5%, 1.2%, 1.8%, 2%, 2.3%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5%, or any value between two of the above. When the amount of initiator added is 0.5-2% of the total monomer mass, the product quality is better.

[0038] The total mass of monomers mentioned in this invention refers to the sum of the masses of C=C anhydride monomers, benzene ring-containing olefin monomers, and long-chain olefin monomers.

[0039] In some specific embodiments, the C=C anhydride monomers are any one or a combination of two of itaconic anhydride and maleic anhydride; the benzene ring olefin monomers are one or more of styrene, p-hydroxystyrene, and sodium p-styrenesulfonate; the long carbon chain olefin monomers are one or more of 1-dodecene, 5-dodecene, tert-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecanene, 1-hexadecene, 1-heptadecene, 1-heptadecene, 1-octadecene, and 1-eicosene; and the initiator is one or a combination of two of azobisisobutyronitrile and benzoyl peroxide.

[0040] The reaction temperature of C=C anhydride monomers, benzene ring olefin monomers, and long-chain olefin monomers under the action of an initiator is 70-95℃, for example, it can be 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, and any two of the above temperatures.

[0041] The temperature at which the crosslinking agent is added dropwise to the first reaction solution to carry out the crosslinking reaction is 30-80℃, for example, it can be 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or any two of the above temperatures.

[0042] The reaction system of C=C anhydride monomers, benzene ring-containing olefin monomers, and long-chain olefin monomers under the action of an initiator also contains a solvent, which is one or more of isoamyl acetate, n-amyl acetate, isopropanol, tert-butanol, dichloromethane, chloromethane, 1,2-dichloroethane, toluene, and xylene.

[0043] The precipitate formed after the first product crosslinks with the crosslinking agent is washed with solvent two, preferably anhydrous ethanol.

[0044] In some specific embodiments, the above-mentioned ultra-high temperature resistant filtration loss reducing agent composition can be prepared by the following method:

[0045] Under nitrogen protection, a certain amount of solvent is added to the reaction vessel, the temperature is raised to 40-60℃, and under stirring conditions, acid anhydride monomers containing C=C, olefin monomers containing benzene rings and long carbon chain olefin monomers are added. After stirring evenly, the temperature is raised to 70-95℃, and the initiator is added dropwise slowly and evenly. The reaction is carried out for 2-8 hours to obtain a solution of the first reaction product.

[0046] Add a crosslinking agent dropwise to the solution of the first reaction product, react at 30-80℃ for 0.5-5h to obtain a solution of the second reaction product. Then cool the solution of the second reaction product to room temperature, wash the precipitate with solvent II, separate by suction filtration, dry under vacuum at 40-50℃, and pulverize to obtain the final product.

[0047] The present invention also provides a composition of a filtration loss reducing agent resistant to ultra-high temperature, the composition comprising at least ultrafine calcium carbonate, modified lithium saponite and the above-mentioned filtration loss reducing agent, wherein the particle size of ultrafine calcium carbonate is 5000 mesh or above, the modified lithium saponite is octyltriethoxysilane modified lithium saponite, and the mass ratio of filtration loss reducing agent to ultrafine calcium carbonate and modified lithium saponite is 8:(2-12):(1-4), for example, in some specific embodiments, the ratio of the three is 8:(5-7):(1-2).

[0048] In the above method, octyltriethoxysilane-modified lithium saponite refers to the reaction of the silane group in octyltriethoxysilane with lithium saponite. Conventional lithium saponite modification methods can be used, which involve reacting the two under certain conditions; further details will not be elaborated here.

[0049] By adding specific inorganic materials to the above-mentioned filtration loss reducer, its high temperature resistance is further improved, reaching 260℃.

[0050] This invention also provides an ultra-high temperature resistant oil-based drilling fluid, comprising the aforementioned ultra-high temperature resistant filtration loss reducer or a composition of ultra-high temperature resistant filtration loss reducers. The addition ratio of the ultra-high temperature resistant filtration loss reducer or composition is 0.5-8% of the total mass of the base slurry. For example, the addition ratio can be controlled at 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, and any value between these two values. Furthermore, the effect is better when the addition ratio is controlled at 2-6%. This ultra-high temperature resistant oil-based drilling fluid exhibits excellent high-temperature resistance, emulsion stability, and filtration loss reduction properties.

[0051] The oil phase of the aforementioned ultra-high temperature resistant oil-based drilling fluid can be provided by oil phases conventionally used in the art, such as one or more of diesel oil, white oil (e.g., No. 3 white oil, No. 5 white oil), and synthetic base oil. The aqueous phase is typically an aqueous solution of CaCl2 (an aqueous solution with a CaCl2 concentration of 20-40 wt% is preferred), where the volume ratio of the oil phase to the aqueous phase can be 70:30-95:5. The selection and use of the oil and aqueous phases are conventional techniques in the art and will not be described in detail here.

[0052] In addition, the oil-based drilling fluid may also contain other treatment agents commonly used in the art. For example, the water-in-oil emulsion drilling fluid may also contain one or more of the following: primary emulsifier, secondary emulsifier, organobentonite, alkalinity regulator, and weighting agent. The types and amounts of the above-mentioned treatment agents can be selected with reference to the conventional types and amounts used in the art, and the present invention does not have any particular limitations in this regard.

[0053] The following is a detailed description of the composition for reducing filtration loss in response to ultra-high temperatures, using specific embodiments.

[0054] Sources of some raw materials:

[0055] The ultrafine calcium carbonate (3000 mesh and above) involved in the examples was purchased from Lianzhou Xiangfa Powder Co., Ltd.; the modified lithium saponite was lithium saponite modified with a silane coupling agent, specifically lithium saponite modified with octyltriethoxysilane. The specific modification method was as follows: 15 g of lithium saponite was completely dispersed in a mixed solution of ethanol / water in a three-necked flask, and then a certain amount of ammonium hydroxide solution was added to the solution to adjust the pH value of the solution to ≥9; the reaction temperature was raised to 65~75℃, 4.5 g of n-octyltriethoxysilane was added dropwise, the reaction was carried out for 3~5 h, cooled, dried and pulverized to obtain modified lithium saponite.

[0056] The calcium carbonate (1000 mesh and below) used in the comparative examples was purchased from Lianzhou Xiangfa Powder Co., Ltd., and the modified lithium saponite was n-butylamine modified lithium saponite. The specific modification method was the same as that of n-octyltriethoxysilane modified lithium saponite.

[0057] Example 1

[0058] This embodiment provides a high-temperature resistant filtration loss reducer and its composition, which is prepared through the following steps:

[0059] Weigh 20 mL of isoamyl acetate and add it to a three-necked flask. Purge with nitrogen for 20 min while simultaneously heating to 50 °C. Then add 6 g of itaconic anhydride, 3 g of styrene, and 12 g of 1-octadecene. Continue stirring and heating to 85 °C, then slowly add 0.3 g of azobisisobutyronitrile (AIBN), and continue the reaction for 5.5 h. After cooling to room temperature, add dropwise a mixed solution of 6.5 g of diethylenetriamine and 6.5 mL of isoamyl acetate, and stir at 50 °C for 3 h. Allow to cool naturally to room temperature, wash the precipitate with anhydrous ethanol, separate by vacuum filtration, dry and pulverize in a vacuum oven at 50 °C to obtain the filtrate loss reducer A1.

[0060] The filtration loss reducer A1 was thoroughly mixed with ultrafine calcium carbonate and modified lithium saponite (octyltriethoxysilane modified lithium saponite) in a mass ratio of 8:6:1 to obtain ultra-high temperature resistant filtration loss reducer composition B1.

[0061] Example 2

[0062] This embodiment provides a high-temperature resistant filtration loss reducer and its composition, which is prepared through the following steps:

[0063] Weigh 25 mL of isoamyl acetate and add it to a three-necked flask. Purge with nitrogen for 20 min while simultaneously heating to 60 °C. Then add 6 g of itaconic anhydride, 6.5 g of sodium styrene sulfonate, and 13 g of 1-octadecene. Continue stirring and heating to 95 °C, then slowly add 0.46 g of azobisisobutyronitrile (AIBN), and continue the reaction for 3 h. After cooling to room temperature, add dropwise a mixed solution of 5 g of hydroxyethyl ethylenediamine, 3 g of diethylenetriamine, and 8 mL of isoamyl acetate, and stir at 60 °C for 2.5 h. Allow to cool naturally to room temperature, wash the precipitate with anhydrous ethanol, separate by vacuum filtration, dry and pulverize in a vacuum oven at 45 °C to obtain filtrate loss reducer A2.

[0064] The filtration loss reducer A2 was thoroughly mixed with the reaction intermediate product, and then the reaction intermediate product, ultrafine calcium carbonate, and modified lithium saponite were mixed in a mass ratio of 8:5:1 to obtain the ultra-high temperature resistant filtration loss reducer composition B2.

[0065] Example 3

[0066] This embodiment provides a high-temperature resistant filtration loss reducer and its composition, which is prepared through the following steps:

[0067] Weigh 35 mL of xylene and add it to a three-necked flask. Purge with nitrogen gas for 20 min while simultaneously heating to 40 °C. Then add 10 g of maleic anhydride, 6 g of styrene, and 22 g of tetradecene. Continue stirring and heating to 82 °C. Slowly add 0.95 g of benzoyl peroxide and continue the reaction for 5 h. After cooling to 30 °C, add a mixed solution of 10 g of hexamethylenediamine and 10 mL of xylene dropwise. Stir and react at 70 °C for 2 h. Allow to cool naturally to room temperature, wash the precipitate with anhydrous ethanol, separate by vacuum filtration, dry and pulverize in a vacuum oven at 45 °C to obtain the filtrate loss reducer A3.

[0068] The filtration loss reducer A3 was thoroughly mixed with ultrafine calcium carbonate and modified lithium saponite in a mass ratio of 8:4:1 to obtain a filtration loss reducer composition B3 resistant to ultra-high temperature.

[0069] Example 4

[0070] This embodiment provides a high-temperature resistant filtration loss reducer and its composition, which is prepared through the following steps:

[0071] Weigh 35 mL of xylene and add it to a three-necked flask. Purge with nitrogen for 20 min while simultaneously heating to 40 °C. Then add 10 g of maleic anhydride, 10 g of sodium styrene sulfonate, and 25 g of 1-hexadecene. Continue stirring and heating to 80 °C. Slowly add 0.85 g of benzoyl peroxide and continue the reaction for 4 h. After cooling to 30 °C, add dropwise a mixed solution of 6 g of hydroxyethyl ethylenediamine, 4 g of diethylenetriamine, and 10 mL of xylene. Stir the reaction at 50 °C for 2 h. Allow to cool naturally to room temperature. Wash the precipitate with anhydrous ethanol, separate by vacuum filtration, dry and pulverize in a vacuum oven at 45–50 °C to obtain the filtrate loss reducer A4.

[0072] The filtration loss reducer A4 was thoroughly mixed with ultrafine calcium carbonate and modified lithium saponite in a mass ratio of 8:7:2 to obtain a filtration loss reducer composition B4 resistant to ultra-high temperature.

[0073] Example 5

[0074] This embodiment provides a filtration loss reducing agent and its composition that are resistant to ultra-high temperature. The only difference between this embodiment and Example 4 is that the crosslinking agent is 10g of hydroxyethyl ethylenediamine, and the resulting filtration loss reducing agent A5 and filtration loss reducing agent composition B5 are respectively.

[0075] Comparative Example 1

[0076] The filtration loss reducing agent and its composition provided in this comparative example differ from those in Example 1 in that the olefin monomer containing a benzene ring is omitted. The specific method is as follows:

[0077] Weigh 20 mL of isoamyl acetate and add it to a three-necked flask. Purge with nitrogen for 20 min while simultaneously heating to 50 °C. Then add 6 g of itaconic anhydride and 12 g of 1-octadecene, continue stirring, and heat to 85 °C. Slowly add 0.3 g of azobisisobutyronitrile (AIBN), and continue the reaction for 5.5 h. After cooling to room temperature, add dropwise a mixed solution of 6.5 g of diethylenetriamine and 6.5 mL of isoamyl acetate, and stir at 50 °C for 3 h. Allow to cool naturally to room temperature, wash the precipitate with anhydrous ethanol, separate by vacuum filtration, dry in a vacuum oven at 50 °C, and pulverize to obtain the filtrate loss reducer a1.

[0078] The filtration loss reducer a1 was thoroughly mixed with ultrafine calcium carbonate and modified lithium saponite (octyltriethoxysilane modified lithium saponite) in a mass ratio of 8:6:1 to obtain an ultra-high temperature resistant filtration loss reducer composition b1.

[0079] Comparative Example 2

[0080] The filtration loss reducing agent and its composition provided in this comparative example differ from those in Example 1 in that: after obtaining the first reaction solution, stirring was stopped, and the solution was allowed to cool naturally to room temperature. The precipitate was washed with anhydrous ethanol, separated by vacuum filtration, dried in a vacuum oven at 45°C, and pulverized to obtain filtration loss reducing agent a2. Then, the filtration loss reducing agent, ultrafine calcium carbonate, and modified lithium saponite were thoroughly mixed in a mass ratio of 8:6:1 to obtain the filtration loss reducing agent b2 of this comparative example.

[0081] Comparative Example 3

[0082] The filtration loss reducing agent provided in this comparative example is prepared as follows: 35 mL of xylene is weighed and added to a three-necked flask, nitrogen gas is introduced for 20 min, and the temperature is raised to 40 °C. Then, 10 g of maleic anhydride, 6 g of styrene, and 22 g of tetradecene are added, and the mixture is stirred and heated to 82 °C. 0.95 g of benzoyl peroxide is slowly added, and the reaction is continued for 5 h. After naturally cooling to room temperature, the precipitate is washed with anhydrous ethanol, separated by vacuum filtration, dried and pulverized in a vacuum oven at 45 °C to obtain filtration loss reducing agent a3.

[0083] Comparative Example 4

[0084] The filtration loss reducing agent provided in this comparative example differs from that in Example 1 in that: during the preparation of the composition, 1000-mesh calcium carbonate is used to replace the 3000-mesh ultrafine calcium carbonate in Example 1, resulting in filtration loss reducing agent b4.

[0085] Comparative Example 5

[0086] The filtration loss reducer provided in this comparative example differs from that in Example 1 in that, during the preparation of the composition, n-butylamine-modified lithium saponite is used to replace the modified lithium saponite in Example 1, resulting in filtration loss reducer b5.

[0087] Test case

[0088] The ultra-high temperature filtration loss reducer and its composition prepared in the examples and the filtration loss reducer and its composition prepared in the comparative examples were respectively added to the basic formulation of oil-based drilling fluid. Drilling fluid performance tests were conducted before and after high temperature aging, and further compared with commercially available oxidized asphalt filtration loss reducers.

[0089] The basic formulation of the oil-based drilling fluid used (oil-water ratio 90:10, density 1.6 g / cm³) 3 The composition is as follows: 270mL base oil + 30mL CaCl2 aqueous solution (concentration 30wt%) + 9g main emulsifier (DR-EM) + 9g co-emulsifier (DR-CO) + 15g organocarb + 15g CaO + 340g barite. The base oil is 0# diesel oil. The main emulsifier, co-emulsifier, organocarb and barite are all taken from China Petroleum Engineering Technology Research Institute Co., Ltd., and the CaO is analytical grade.

[0090] The prepared oil-based drilling fluid was placed in an aging tank and aged at 240-260℃ for 16 hours. After cooling to room temperature, the drilling fluid in the aging tank was stirred at 12000 rpm for 20 minutes, and then heated to 65℃. The ES (demulsification voltage), AV (apparent viscosity), PV (plastic viscosity), YP (dynamic shear force) values ​​of the test fluid before and after aging, as well as the high-temperature and high-pressure filtration loss (FL) value at 180℃ after high-temperature aging, were evaluated according to the oil-based drilling fluid test procedure (GB / T16783.2-2012). HPHT The thickness of the mud cake was determined. The results are shown in Tables 1, 2, 3, and 4.

[0091] Table 1. Performance Comparison of Basic Formulation Before and After Aging

[0092]

[0093] As shown in Table 1, the demulsification voltage of the basic formula remained basically unchanged after high-temperature aging, indicating that it still had good rheological properties after high-temperature aging. However, the high-temperature and high-pressure filtration loss reached 32 mL and 98 mL after aging at 200℃ and 240℃, respectively. In particular, the cake thickness reached 17 mm after heat treatment at 240℃, indicating that the basic formula had good rheological properties but poor filtration loss reduction.

[0094] Table 2. Performance comparison of the basic formulation before and after aging after adding filtration loss reducers.

[0095]

[0096] The results above show that when 2% of the filtration loss reducer from the present invention is added to the basic formulation, after aging at 240℃ for 16h, the demulsification voltage is above 1000, which still meets the practical application requirements, meaning that it has little impact on the emulsification stability of the basic formulation. After aging at 240℃ for 16h, the decrease in dynamic shear force is significantly smaller than that of the comparative example and the experimental group with oxidized asphalt, indicating that it has little impact on the rheological properties of the basic formulation. However, after aging at 240℃ for 16h, the high-temperature and high-pressure filtration loss is significantly lower than that of the basic formulation (98mL), dropping to below 6mL, and the quality of the mud cake is also significantly improved, with a maximum mud cake thickness of 3mm. This indicates that the filtration loss reducer provided by the present invention has excellent high-temperature resistance and filtration loss reduction properties, with a maximum temperature resistance up to 240℃, and has little impact on the rheological properties and emulsification stability of the basic formulation.

[0097] Adding 2% of the filtration loss reducer provided in Comparative Example 1 to the basic formulation, after aging at 200℃ for 16h, although the demulsification voltage still meets the actual application requirements and the filtration loss is lower than that of the basic formulation, the dynamic shear force decreases significantly. Furthermore, after aging at 240℃ for 16h, the demulsification voltage is only 506V, which does not meet the actual application requirements and the filtration loss also increases significantly. This indicates that although the filtration loss reducer provided in Comparative Example 1 also has a certain filtration loss reduction effect, its high temperature resistance is poor and it has a significant impact on the rheological properties of the basic formulation.

[0098] Adding 2% of the filtration loss reducer provided in Comparative Example 3 to the basic formulation and aging at 200℃ for 16h, although the demulsification voltage can still meet the actual application requirements and the filtration loss is lower than that of the basic formulation, the dynamic shear force decreases significantly and the filtration loss is also significantly higher than that of the example. This indicates that although the filtration loss reducer provided in Comparative Example 3 also has a certain filtration loss reduction effect, the filtration loss reduction effect is far worse than that of the example and has a greater impact on the rheology of the basic formulation.

[0099] Table 2 also shows that after adding 6% of the commonly used field filtration loss reducer oxidized asphalt to the basic formulation, the high-temperature and high-pressure filtration loss after aging at 200℃ / 16h and 240℃ / 16h were 13mL and 15mL, respectively, which were much higher than those in the example and the dynamic shear force decreased significantly. This indicates that although adding oxidized asphalt also has a certain filtration loss reduction effect, the filtration loss reduction effect is much worse than that in the example and has a greater impact on the rheology of the basic formulation.

[0100] In summary, the filtration loss reducer provided in this embodiment of the invention has a lower dosage and better filtration loss reduction effect compared to oxidized asphalt. It can withstand temperatures up to 240℃, and the high-temperature and high-pressure filtration loss does not exceed 6mL. Moreover, it has little impact on the rheological properties and emulsification stability of the basic formulation.

[0101] Table 3

[0102]

[0103] Table 4

[0104]

[0105] As shown in Tables 3 and 4, after adding 4% of the filtration loss reducing agent composition provided in the embodiments of the present invention to the basic formula, the demulsification voltage after aging at 260℃ for 16h is above 1000, which can still meet the actual application requirements, that is, it has little impact on the emulsification stability of the basic formula. After aging at 260℃ for 16h, the decrease in dynamic shear force is significantly smaller than that of the comparative example and the experimental group with oxidized asphalt, indicating that it has little impact on the rheological properties of the basic formula. However, after aging at 260℃ for 16h, the high-temperature and high-pressure filtration loss is significantly lower than that of the basic formula (98mL), dropping to below 5mL, and the quality of the mud cake is also significantly improved, with a maximum mud cake thickness of 3mm. This indicates that the filtration loss reducing agent composition provided in the present invention has excellent high-temperature resistance and filtration loss reduction properties, with a maximum temperature resistance of up to 260℃, and has little impact on the rheological properties and emulsification stability of the basic formula.

[0106] After adding 4% of the filtration loss reducing agent compositions provided by Comparative Examples 1, 2, 4, and 5 of this invention to the basic formulation, and aging at 260°C for 16 hours, although the demulsification voltage can still meet the actual application requirements and the filtration loss is lower than that of the basic formulation, the dynamic shear force decreases significantly and the filtration loss is also significantly higher than that of the examples. This indicates that although the filtration loss reducing agent compositions provided by Comparative Examples 1, 2, 4, and 5 also have a certain filtration loss reducing effect, the filtration loss reducing effect is far worse than that of the examples and has a greater impact on the rheology of the basic formulation.

[0107] Table 3 also shows that after adding 6% of the commonly used field filtration loss reducer oxidized asphalt to the basic formulation, the high-temperature and high-pressure filtration loss after aging at 240℃ / 16h and 260℃ / 16h were 15mL and 32.8mL, respectively, which were much higher than those in the example and the dynamic shear force decreased significantly. This indicates that although adding oxidized asphalt also has a certain filtration loss reduction effect, the filtration loss reduction effect is much worse than that in the example and has a greater impact on the rheology of the basic formulation.

[0108] In summary, the oil-in-water drilling fluid filtration loss reducing agent composition provided in this embodiment of the invention requires a small dosage, has excellent filtration loss reducing effect, can withstand temperatures up to 260℃, and has a high-temperature and high-pressure filtration loss of no more than 5mL, and has little impact on the rheological properties and emulsification stability of the basic formulation.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature resistant filtration loss reducer, characterized in that, It is prepared from the following raw materials, which include C=C anhydride monomers, benzene ring-containing olefin monomers, long-chain olefin monomers, initiators, and crosslinking agents; wherein, the number of C atoms n in the long-chain olefin monomers is ≥10; the crosslinking agent has the following molecular formula: H[O(CH2)b]a{NH(CH2)b}cNH2, a=0 or 1, b is 2 or 3, and c is 1 to 4; The preparation method includes at least the step of reacting a first product obtained by reacting C=C-containing acid anhydride monomers, benzene ring-containing olefin monomers, and long-chain olefin monomers under the action of an initiator with a crosslinking agent under the protection of an inert gas.

2. The filtration loss reducing agent according to claim 1, characterized in that, The molar ratio of the C=C-containing acid anhydride monomer, the benzene ring-containing olefin monomer, the long-chain olefin monomer, and the crosslinking agent is 1:(0.5-1):(1-2.5):(0.5-2); and / or The amount of initiator added is 0.1-5% of the total mass of the monomer.

3. The filtration loss reducing agent according to claim 1 or 2, characterized in that, The C=C-containing anhydride monomer is one or a combination of two of itaconic anhydride and maleic anhydride; and / or The benzene ring-containing olefin monomer is one or more of styrene, p-hydroxystyrene, and sodium p-styrene sulfonate; and / or The long-chain olefin monomer is one or more selected from 1-dodecene, 5-dodecene, tert-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecanene, 1-hexadecene, 1-heptadecene, 1-heptadecene, 1-octadecene, and 1-eicosene; and / or The initiator is one or a combination of two of azobisisobutyronitrile and benzoyl peroxide.

4. The filtration loss reducing agent according to claim 1 or 2, characterized in that, The reaction temperature of the C=C-containing acid anhydride monomer, the benzene ring-containing olefin monomer, and the long-chain olefin monomer under the action of the initiator is 70-95℃; and / or The crosslinking reaction temperature between the first product and the crosslinking agent is 30-80℃.

5. The filtration loss reducing agent according to claim 1 or 2, characterized in that, The reaction system containing the C=C anhydride monomer, the benzene ring-containing olefin monomer, and the long-chain olefin monomer under the action of the initiator also contains solvent I; and / or The precipitate formed after the first product crosslinks with the crosslinking agent is washed with solvent two.

6. The filtration loss reducing agent according to claim 5, characterized in that, Solvent 1 is one or more of the following: isoamyl acetate, n-amyl acetate, isopropanol, tert-butanol, dichloromethane, chloromethane, 1,2-dichloroethane, toluene, and xylene; and / or Solvent 2 is anhydrous ethanol.

7. The filtration loss reducing agent according to claim 6, characterized in that, The preparation method is as follows: Under nitrogen protection, a certain amount of solvent is added to the reaction vessel, the temperature is raised to 40-60℃, and under stirring conditions, acid anhydride monomers containing C=C, olefin monomers containing benzene rings and long carbon chain olefin monomers are added. After stirring evenly, the temperature is raised to 70-95℃, and the initiator is added dropwise slowly and evenly. The reaction is carried out for 2-8 hours to obtain a solution of the first reaction product. Add a crosslinking agent dropwise to the solution of the first reaction product, react at 30-80℃ for 0.5-5h to obtain a solution of the second reaction product. Then cool the solution of the second reaction product to room temperature, wash the precipitate with solvent II, separate by suction filtration, dry under vacuum at 40-50℃, and pulverize to obtain the final product.

8. A composition for reducing filtration loss under ultra-high temperature conditions, characterized in that, The composition comprises at least ultrafine calcium carbonate, modified lithium saponite, and the filtration loss reducing agent according to any one of claims 1-7, wherein the ultrafine calcium carbonate has a particle size of 3000 mesh or more, the modified lithium saponite is octyltriethoxysilane modified lithium saponite, and the mass ratio of the filtration loss reducing agent to the ultrafine calcium carbonate and the modified lithium saponite is 8:(2-12):(1-4).

9. A high-temperature resistant oil-based drilling fluid, characterized in that, The composition comprises the ultra-high temperature resistant filtration loss reducing agent as described in any one of claims 1-7 or the ultra-high temperature resistant filtration loss reducing agent composition as described in claim 8.

10. The ultra-high temperature resistant oil-based drilling fluid according to claim 9, characterized in that, The addition ratio of the ultra-high temperature resistant filtration loss reducer or the composition of the ultra-high temperature resistant filtration loss reducer is 0.5-8% of the total mass of the base slurry; The preferred ratio is 2-6%.

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