Ultrahigh-temperature plugging filtrate reducer for water-based drilling fluid and preparation method of ultrahigh-temperature plugging filtrate reducer

Abstract

The invention provides an ultrahigh-temperature plugging filtrate reducer for water-based drilling fluid and a preparation method thereof, the filtrate reducer comprises a core layer and a shell layer, the core layer is a functional compound, and the shell layer is a sulfonic polymer. The ultrahigh-temperature plugging filtrate reducer cannot be degraded and damaged at high temperature, effectively controls the filter loss of drilling fluid before and after ultrahigh-temperature action, has excellent filter loss control performance, and can effectively control the filtrate reducer of water-based drilling fluid.

Description

Technical Field

[0001] The invention belongs to the field of oilfield chemistry and relates to a fluid loss agent, in particular to an ultra-high temperature plugging fluid loss agent for water-based drilling fluid and a preparation method thereof. Background Art

[0002] Compared with traditional hydrothermal geothermal resources, hot dry rock geothermal resources have the advantages of large energy, wide distribution, renewable, safe, clean and pollution-free, and not restricted by seasons and day and night. They are an important goal of geothermal energy development. Due to the complex situation of extremely high bottom hole temperature, hot dry rock resources have high requirements for the high temperature resistance of drilling fluid loss reducers. However, the existing drilling fluid loss reducers are difficult to meet the needs of hot dry rock drilling. The plugging type loss reducers currently used are mainly asphalt (powder), super calcium carbonate (powder) and various nanomaterials. The use of asphalt (powder) type loss reducers is significantly restricted by the softening point temperature, which generally does not exceed 150°C. Super calcium carbonate (powder) raw materials are widely available, but have poor deformation ability in the formation, limited ability to plug microcracks, and the formed filter cake has poor density. At present, there are still few plugging type loss reducers that can be used in high-temperature drilling fluids. CN 111499790 A proposes a high temperature resistant polymer microsphere nano plugging agent for water-based drilling fluid and a preparation method thereof. By adopting a rheological stabilizer, the drilling fluid can be resistant to a temperature of up to 260°C. This technology can well inhibit the decomposition of the drilling fluid treatment agent under ultra-high temperature conditions, but does not consider the problem of thickening of the drilling fluid under ultra-high temperature conditions; CN103160259 A proposes a water-based drilling fluid resistant to ultra-high temperature of 255°C and a construction process thereof. This technology can well solve the problem of regulating the performance of the drilling fluid under ultra-high temperature conditions, but the temperature resistance is less than 260°C, and the performance of the water-based drilling fluid under ultra-high temperature conditions is not considered. Therefore, the research on a water-based drilling fluid resistant to ultra-high temperature and efficient rock-carrying and a preparation method thereof has important practical significance.

[0003] Therefore, it is necessary to develop ultra-high temperature plugging and filtration loss reducer. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides an ultra-high temperature plugging and loss reducer for water-based drilling fluid and a preparation method thereof. The ultra-high temperature plugging and loss reducer will not degrade and be destroyed at high temperatures, effectively controls the loss of drilling fluid before and after ultra-high temperature action, and has excellent loss control performance, and can effectively control the loss reducer of water-based drilling fluid.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] One of the purposes of the present invention is to provide an ultra-high temperature plugging and fluid loss reducer for water-based drilling fluid, wherein the fluid loss reducer comprises a core layer and a shell layer, wherein the core layer is a functional compound and the shell layer is a sulfonic acid polymer.

[0007] As a preferred technical solution of the present invention, the functional compound includes any one of montmorillonite, hydrotalcite or graphene, or a combination of at least two of them.

[0008] As a preferred technical solution of the present invention, the sulfonic acid polymer is acrylamide, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid copolymer.

[0009] As a preferred technical solution of the present invention, the molar ratio of the sulfonic acid polymer is acrylamide, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid is (5-9):(4-8):(1-4), such as 5:4:1, 6:5:1.5, 7:6:2, 8:7:3 or 9:8:4, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0010] The second object of the present invention is to provide a method for preparing the ultra-high temperature plugging and filtration reducer for water-based drilling fluid as described in the first object, the preparation method comprising:

[0011] mixing the oil phase substance with the emulsifier to obtain an oil phase system;

[0012] After mixing the sulfonic acid polymer monomer with water, adjusting the pH, adding a cross-linking agent and a modified intermediate, and obtaining an aqueous phase system;

[0013] The water phase system is added to the oil phase system, an initiator is added to carry out polymerization reaction, and the ultra-high temperature plugging and filtration reducer for water-based drilling fluid is obtained after separation treatment.

[0014] As a preferred technical solution of the present invention, the preparation method of the modified intermediate comprises: dispersing the intermediate in water, adding a modifier, and heating the reaction to obtain the modified intermediate.

[0015] As a preferred technical solution of the present invention, the modifier includes hexadecyltrimethylammonium bromide and / or 2-aminoethyl methacrylate hydrochloride.

[0016] As a preferred technical solution of the present invention, the volumes of the water phase and the oil phase are (1-2):(2-3), such as 1:2, 1.1:2.1, 1.2:2.2, 1.3:2.3, 1.4:2.4, 1.5:2.5, 1.6:2.6, 1.7:2.7, 1.8:2.8, 1.9:2.9 or 2:3, etc., but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] As a preferred technical solution of the present invention, the polymerization reaction temperature is 50-80°C and the time is 5-10h. The temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, and the time can be 5h, 6h, 7h, 8h, 9h or 10h, but is not limited to the listed values. Other values ​​not listed within the above ranges are also applicable.

[0018] The third object of the present invention is to provide a water-based drilling fluid, wherein the water-based drilling fluid includes the ultra-high temperature plugging and filtration reducer for water-based drilling fluid described in the first object.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] (1) The present invention provides an ultra-high temperature plugging and loss reducing agent for water-based drilling fluid, which will not degrade and be damaged at high temperatures, has a temperature resistance of up to 240°C, and can effectively control the loss of drilling fluid before and after ultra-high temperature action, with a loss reduction rate of up to 60%;

[0021] (2) The present invention provides an ultra-high temperature plugging and filtration reducer for water-based drilling fluid. Compared with traditional filtration reducers, the ultra-high temperature core-shell microsphere plugging and filtration reducer for water-based drilling fluid provided by the present invention has a wide range of raw materials and low cost;

[0022] (3) The present invention provides a method for preparing an ultra-high temperature plugging and filtration reducer for water-based drilling fluid, and the preparation process is simple and suitable for industrial production. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0024] A specific embodiment of the present invention provides an ultra-high temperature plugging and fluid loss reducer for water-based drilling fluid. The fluid loss reducer comprises a core layer and a shell layer. The core layer is a functional compound, and the shell layer is a sulfonic acid polymer.

[0025] In a specific embodiment of the present invention, the fluid loss reducer is a core-shell microsphere structure, the shell layer is a sulfonic acid polymer, specifically acrylamide, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid copolymer, which can improve the high temperature resistance of the fluid loss reducer because when the core layer functional compound structure dispersion size reaches the nanometer level, the specific surface area of ​​the core layer functional compound increases sharply, enhancing the interaction with the polymer, thereby limiting the thermal motion of the polymer chain at high temperature. At the same time, the core layer functional compound sheet is a good thermal insulator, and its excellent barrier property reduces the heat transfer in the polymer matrix, so that the thermal stability of the fluid loss reducer is improved.

[0026] The specific embodiment of the present invention provides a method for preparing an ultra-high temperature plugging and filtration reducer for water-based drilling fluid, the preparation method comprising:

[0027] mixing the oil phase substance with the emulsifier to obtain an oil phase system;

[0028] After mixing the sulfonic acid polymer monomer with water, adjusting the pH, adding a cross-linking agent and a modified intermediate, and obtaining an aqueous phase system;

[0029] The water phase system is added to the oil phase system, an initiator is added to carry out polymerization reaction, and the ultra-high temperature plugging and filtration reducer for water-based drilling fluid is obtained after separation treatment.

[0030] In the present invention, the purpose of modifying the intermediate is to improve the compatibility of the core layer functional compound in the polymer material while expanding the interlayer spacing of the core layer functional compound, increasing the contact area with the subsequent polymer monomer and enhancing the interaction.

[0031] In a specific embodiment of the present invention, the oil phase substance can be any one of aromatic compounds such as benzene or cycloalkanes such as cyclobutane or cyclohexane, or a combination of at least two of them.

[0032] In one embodiment of the present invention, the emulsifier may be Span 80 and / or Tween 80.

[0033] In a specific embodiment of the present invention, the amount of emulsifier added is 2-5% of the mass of the oil phase substance, such as 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In one embodiment of the present invention, the intermediate refers to a functional compound of the core layer.

[0035] In a specific embodiment of the present invention, the molar ratio of the modifier to the intermediate is (0.5-3): (0.5-2), preferably (1-2): (0.5-1), such as 0.5:0.5, 1:0.8, 1.5:1, 2:1.2, 2.5:1.5 or 3:2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In a specific embodiment of the present invention, the temperature of the heating reaction of the intermediate modification can be 50-80°C, and the time can be 5-10h, such as the temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, and the time can be 5h, 6h, 7h, 8h, 9h or 10h, but it is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable. Preferably, the temperature can be 60-70°C, and the time can be 5-7h.

[0037] In a specific embodiment of the present invention, the amount of sulfonic acid polymer monomer added is 30-70% of the water mass, preferably 40-60%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In one embodiment of the present invention, the pH is adjusted to 6 to 9, preferably 7. The pH adjuster used for pH adjustment can be any one of sodium carbonate, sodium hydroxide or sodium bicarbonate, or a combination of at least two of them.

[0039] In one embodiment of the present invention, the crosslinking agent can be any one of divinylbenzene, diisocyanate or N,N-methylenebisacrylamide or a combination of at least two thereof, preferably N,N-methylenebisacrylamide. The amount of the crosslinking agent added is 1-3% of the mass of the sulfonic acid polymer monomer.

[0040] In a specific embodiment of the present invention, the amount of the modified intermediate added is 30-60% of the mass of water, preferably 40-50%, such as 30%, 35%, 40%, 45%, 50%, 55% or 60%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In a specific embodiment of the present invention, when preparing the water phase system and the oil phase system, the preparation temperature can be 20-40°C, preferably 25-30°C.

[0042] In one embodiment of the present invention, the initiator can be any one of azobisisobutyronitrile, dodecyl peroxide, hydrogen peroxide or potassium persulfate, or a combination of at least two thereof, preferably potassium persulfate. The amount of the initiator added is 1-2% of the mass of the sulfonic acid polymer monomer.

[0043] In one embodiment of the present invention, the polymerization reaction is carried out in a conventional reaction vessel in the art. Preferably, the polymerization reaction is carried out in a reaction vessel with airtight conditions, such as a polytetrafluoroethylene sealed tank.

[0044] In one embodiment of the present invention, the volume ratio of the liquid in the reactor to the volume of the reaction vessel is greater than or equal to 50%, preferably greater than or equal to 80%. That is, when the volume of the reaction vessel is 100 mL, the volume of the added suspension should be greater than or equal to 80 mL.

[0045] In a specific embodiment of the present invention, the separation treatment comprises adding acetone and ethanol to the reaction product of the polymerization reaction to demulsify and precipitate, followed by washing, drying and crushing.

[0046] In one embodiment of the present invention, the drying temperature in the separation process may be 60-100°C.

[0047] A specific embodiment of the present invention provides a water-based drilling fluid, wherein the water-based drilling fluid includes the ultra-high temperature plugging and filtration reducer for water-based drilling fluid.

[0048] In a specific embodiment of the present invention, the amount of the ultra-high temperature plugging and filtration reducer for the base drilling fluid in the water-based drilling fluid is 0.1 to 5 wt%, preferably 1 to 4 wt%, such as 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt% or 5 wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] In a specific embodiment of the present invention, the water-based drilling fluid comprises sodium hydroxide, zwitterionic polymer coating agent, plugging inhibitor, white oil and sulfonate copolymer fluid loss reducer. Based on the total weight of the water-based drilling fluid, the content of sodium hydroxide is 0.1-0.3%, the content of zwitterionic polymer coating agent is 0.1-0.5%, the content of sulfonate copolymer fluid loss reducer is 0.1-0.5%, the content of plugging inhibitor is 1-3%, and the content of white oil is 1-3%.

[0050] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0051] Example 1

[0052] This embodiment provides an ultra-high temperature plugging and filtration reducer for water-based drilling fluid, and a preparation method thereof comprises the following steps:

[0053] (1) Preparation of oil phase system: Add 50 mL of cyclohexane (CHY) to a 100 mL flask at 30°C, slowly add 1.0 g of Span 80 under stirring at 100-200 r / min, and stir for 30 min to obtain an oil phase reaction system for use;

[0054] (2) Intermediate modification: Weigh 0.5 g of montmorillonite and disperse it in 100 mL of deionized water. Dissolve 0.5 g of hexadecyltrimethylammonium bromide modifier (CTAB) in an appropriate amount of deionized water. After it is completely dissolved, add it to the montmorillonite aqueous solution, deoxygenate at 60-70 ° C, and react for 6 h to obtain CTAB-MMT product.

[0055] (3) Preparation of aqueous phase system: under room temperature, add 30.0 mL of water into a beaker, add 6 g of acrylamide (AM) monomer, 4.8 g of acrylic acid (AA) monomer, and 1.2 g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer under stirring at 70-100 r / min, and form a reaction solution system after mixing and stirring for 30 min. Use sodium carbonate to adjust the pH value to close to 7.0, then add 1.2 g of cross-linking agent N,N-methylenebisacrylamide (MBA), stir for 30-60 min, add 15 g of modified intermediate, and obtain an aqueous phase reaction system for use;

[0056] (4) The aqueous phase reaction system is slowly added to the oil phase system, and then the condensed water and the agitator are turned on, the speed is adjusted to 200-300 r / min, stirred for 30 min, deoxygenated with N2 for 20 min, heated to 65°C, and the speed is adjusted to 400-600 r / min, 1.2 g of initiator (KPS) is added, and the reaction is continued for 5 h to obtain the product system. Thereafter, acetone and ethanol are added to the product system, and the product system is subjected to demulsification precipitation, filtration and drying processes to obtain the desired ultra-high temperature core-shell microsphere plugging and filtration reducer FF-1.

[0057] Example 2

[0058] This embodiment provides an ultra-high temperature plugging and filtration reducer for water-based drilling fluid, and a preparation method thereof comprises the following steps:

[0059] (1) Preparation of the oil phase system: at 30°C, add 50 mL of cyclohexane (CHY) into a 100 mL flask, slowly add 2.5 g of Span 80 under stirring at 100-200 r / min, and stir for 30 min to obtain an oil phase reaction system for use;

[0060] (2) Intermediate modification: Weigh 1 g of hydrotalcite and disperse it in 100 mL of deionized water. Dissolve 2 g of hexadecyltrimethylammonium bromide (CTAB) in an appropriate amount of deionized water. After it is completely dissolved, add it to the hydrotalcite aqueous solution, deoxygenate at 60-70°C with N2, and react for 5-7 hours to obtain a CTAB-hydrotalcite product.

[0061] (3) Preparation of aqueous phase system: under room temperature, add 30.0 mL of water into a beaker, add 6 g of acrylamide (AM) monomer, 4.8 g of acrylic acid (AA) monomer, and 1.2 g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer under stirring at 70-100 r / min, and form a reaction solution system after mixing and stirring for 30 min. Use sodium carbonate to adjust the pH value to close to 7.0, then add 1.2 g of cross-linking agent N,N-methylenebisacrylamide (MBA), stir for 30-60 min, add 15 g of modified intermediate, and obtain an aqueous phase reaction system for use;

[0062] (4) The aqueous phase reaction system is slowly added to the oil phase system, and then the condensed water and the agitator are turned on, the speed is adjusted to 200-300 r / min, stirred for 30 min, deoxygenated with N2 for 20 min, heated to 65°C, and the speed is adjusted to 400-600 r / min, 1.2 g of initiator (KPS) is added, and the reaction is continued for 4-6 h to obtain a product system, after which acetone and ethanol are added to the product system to undergo demulsification precipitation, filtration and drying processes to obtain the desired ultra-high temperature core-shell microsphere plugging and filtration reducer FF-2.

[0063] Example 3

[0064] This embodiment provides an ultra-high temperature plugging and filtration reducer for water-based drilling fluid, and a preparation method thereof comprises the following steps:

[0065] (1) Preparation of the oil phase system: at 30°C, add 50 mL of cyclohexane (CHY) into a 100 mL flask, slowly add 2.5 g of Tween 80 under stirring at 100-200 r / min, and stir for 30 min to obtain an oil phase reaction system for use;

[0066] (2) Intermediate modification: Weigh 2 g of graphene and disperse it in 100 mL of deionized water. Dissolve 2 g of hexadecyltrimethylammonium bromide modifier (CTAB) in an appropriate amount of deionized water. After it is completely dissolved, add it to the graphene aqueous solution, deoxygenate at 60-70° C., and react for 5-7 h to obtain a CTAB-graphene product.

[0067] (3) Preparation of aqueous phase system: under room temperature, add 30.0 mL of water into a beaker, add 6 g of acrylamide (AM) monomer, 4.8 g of acrylic acid (AA) monomer, and 1.2 g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer under stirring at 70-100 r / min, and form a reaction solution system after mixing and stirring for 30 min. Use sodium carbonate to adjust the pH value to close to 7.0, then add 1.2 g of cross-linking agent N,N-methylenebisacrylamide (MBA), stir for 30-60 min, add 15 g of modified intermediate, and obtain an aqueous phase reaction system for use;

[0068] (4) The aqueous phase reaction system is slowly added to the oil phase system, and then the condensed water and the agitator are turned on, the speed is adjusted to 200-300 r / min, stirred for 30 min, deoxygenated with N2 for 20 min, heated to 65°C, and the speed is adjusted to 400-600 r / min, 1.2 g of initiator (KPS) is added, and the reaction is continued for 4-6 h to obtain a product system, after which acetone and ethanol are added to the product system to undergo demulsification precipitation, filtration and drying processes to obtain the desired ultra-high temperature core-shell microsphere plugging and filtration reducer FF-3.

[0069] Comparative Example 1

[0070] This comparative example provides a water-based drilling fluid fluid loss reducer, and its preparation method comprises the following steps:

[0071] (1) Preparation of the oil phase system: Add 50 mL of cyclobutane into a 100 mL flask at 30°C and stir for 30 min at 100-200 r / min to obtain an oil phase reaction system for use;

[0072] (2) Intermediate modification: Weigh 1 g of montmorillonite and disperse it in 100 mL of deionized water. Dissolve 2 g of 2-aminoethyl methacrylate hydrochloride in an appropriate amount of deionized water. After it is completely dissolved, add it to the hydrotalcite aqueous solution, deoxygenate at 60-70° C. with N2, and react for 5-7 hours to obtain a modified intermediate product.

[0073] (3) Preparation of aqueous phase system: under normal temperature, add 30.0 mL of water into a beaker, add 13.8 g of acrylamide (AM) monomer and 1.2 g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer under stirring at 70-100 r / min, and form a reaction solution system after mixing and stirring for 30 min. Use sodium carbonate to adjust the pH value to close to 7.0, then add 1.2 g of cross-linking agent N,N-methylenebisacrylamide (MBA), stir for 30-60 min, add 15 g of modified intermediate, and obtain an aqueous phase reaction system for use;

[0074] (4) The aqueous phase reaction system is slowly added to the oil phase system, and then the condensed water and the agitator are turned on, the speed is adjusted to 200-300 r / min, stirred for 30 min, deoxygenated with N2 for 20 min, heated to 65°C, and the speed is adjusted to 400-600 r / min, 1.2 g of initiator (KPS) is added, and the reaction is continued for 4-6 h to obtain a product system, after which acetone and ethanol are added to the product system to undergo demulsification precipitation, filtration and drying processes to obtain the desired ultra-high temperature core-shell microsphere plugging and filtration reducer FF-4.

[0075] Comparative Example 2

[0076] This comparative example provides a water-based drilling fluid fluid loss reducer, and its preparation method comprises the following steps:

[0077] (1) Preparation of the oil phase system: Add 50 mL of cyclobutane into a 100 mL flask at 30°C and stir for 30 min at 100-200 r / min to obtain an oil phase reaction system for use;

[0078] (2) Intermediate modification: Weigh 2 g of hydrotalcite and disperse it in 100 mL of deionized water. Weigh 2 g of 2-aminoethyl methacrylate hydrochloride and dissolve it in an appropriate amount of deionized water. After it is completely dissolved, add it to the hydrotalcite aqueous solution, deoxygenate at 60-70° C. with N2, and react for 5-7 hours to obtain a modified intermediate product.

[0079] (3) Preparation of aqueous phase system: under normal temperature, add 30.0 mL of water into a beaker, add 12.8 g of acrylic acid (AA) monomer and 1.2 g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer under stirring at 70-100 r / min, mix and stir for 30 min to form a reaction solution system, adjust its pH value to close to 7.0 with sodium carbonate, then add 1.2 g of cross-linking agent N,N-methylenebisacrylamide (MBA), stir for 30-60 min, add 15 g of modified intermediate, and obtain an aqueous phase reaction system for use;

[0080] (4) The aqueous phase reaction system is slowly added to the oil phase system, and then the condensed water and the agitator are turned on, the speed is adjusted to 200-300 r / min, stirred for 30 min, deoxygenated with N2 for 20 min, heated to 65°C, and the speed is adjusted to 400-600 r / min, 1.2 g of initiator (KPS) is added, and the reaction is continued for 4-6 h to obtain a product system, after which acetone and ethanol are added to the product system to undergo demulsification precipitation, filtration and drying processes to obtain the desired ultra-high temperature core-shell microsphere plugging and filtration reducer FF-5.

[0081] API Filtration Test:

[0082] Preparation of bentonite-based slurry: 16 g of sodium-based bentonite for drilling fluid (Huawei Bentonite Co., Ltd.) was added to 400 mL of tap water, stirred at 10,000 r / min for 30 min, and then sealed and allowed to stand for 24 h to obtain a prehydrated 4% bentonite-based slurry.

[0083] 4 g of the fluid loss reducers prepared in Examples 1-3 and Comparative Examples 1-3 and Driscal-D were added to 400 mL of bentonite-based slurry, respectively. After stirring at 10,000 r / min for 20 min, the API fluid loss of the slurry was tested.

[0084] The slurry was transferred to an aging tank, which was placed in a high-temperature roller heating furnace, heated at 220°C for 16 hours, cooled to room temperature, stirred at 10,000 r / min for 20 minutes, and then the API filtration loss of the slurry was tested and the filtration loss reduction rate was calculated. The results are shown in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] From the test results in Table 1, it can be seen that before hot rolling at 240°C, after adding the fluid loss reducer prepared in Examples 1-3 of the present invention to the 4% bentonite-based slurry, the fluid loss reduction rate of the experimental slurry reached 30%, while after adding the traditional high-temperature fluid loss reducer Driscal-D, the fluid loss reduction rate of the experimental slurry was less than 30%. After hot rolling at 240°C, when the fluid loss reducer prepared in Examples 1-3 of the present invention was used, the fluid loss reduction rate of the experimental slurry was greater than 60%, which was significantly higher than that of Comparative Examples 1-2 and Driscal-D. This shows that the performance of the fluid loss reducer for water-based drilling fluid prepared in Examples 1-3 of the present invention in controlling the fluid loss of bentonite-based slurry after hot rolling is significantly better than that of Comparative Examples 1-2 and Driscal-D.

[0089] Bentonite-based slurry was prepared according to the API fluid loss test method, and then 1.2 g NaOH, 0.6 g zwitterionic polymer coating agent, 2 g sulfonate copolymer fluid loss reducer, 8 g plugging inhibitor, and 12 g white oil were added to 400 mL of bentonite-based slurry to prepare drilling fluid base slurry Z1.

[0090] 4 g of the fluid loss reducers prepared in Examples 1-3 and Comparative Examples 1-2 and Driscal-D were added to the drilling fluid Z1, respectively, and after stirring at 10000 r / min for 20 min, the rheological properties of the drilling fluid were tested;

[0091] The drilling fluid was placed in an aging tank, and the aging tank was placed in a high-temperature roller heating furnace. It was heated at 240°C for 16 hours, cooled to room temperature, stirred at 10,000 r / min for 10 minutes, and the API filtration loss of the drilling fluid was tested. The results are shown in Table 2.

[0092] Table 2

[0093]

[0094] It can be seen from the test results in Table 2 that after adding different types of fluid loss reducers to the drilling fluid Z1 and hot rolling at 240°C for 16 hours, the fluid loss reducers for water-based drilling fluids prepared in Examples 1-3 of the present invention have a fluid loss reduction rate of more than 32% on the drilling fluid Z1, with the highest reaching 45%, and the fluid loss control ability is better than that of Comparative Examples 1-2 and Driscal-D. This shows that the fluid loss reducers for water-based drilling fluids prepared in Examples 1-3 of the present invention have good performance in controlling the fluid loss of drilling fluids at high temperatures.

[0095] In the above API fluid loss test, the test method of GB / T 29170-2012 is used to test the parameters of apparent viscosity and API fluid loss.

[0096] API fluid loss reduction rate is calculated by the following formula:

[0097]

[0098] Among them, η is the API filtration loss reduction rate, FL1 is the API filtration loss of the test slurry without adding micro-nano composite materials, and FL2 is the API filtration loss of the test slurry with the addition of ultra-high temperature core-shell microsphere plugging and filtration reducer.

[0099] In the above API filtration loss test, sodium hydroxide was provided by Sinopharm Shanghai Testing Group with a purity of more than 99%; zwitterionic polymer coating agent was provided by Minquan Dongxing Mud Material Co., Ltd.; sulfonate copolymer filtration reducer was provided by Shandong Deshunyuan Petroleum Technology Co., Ltd.; plugging inhibitor was provided by China National Petroleum Corporation Engineering and Technology Research Institute Co., Ltd.; white oil was provided by Nanjing Rongji Chemical Co., Ltd.

[0100] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An ultra-high temperature plugging and filtration reducer for water-based drilling fluid, characterized in that: The fluid loss reducer comprises a core layer and a shell layer, wherein the core layer is a functional compound and the shell layer is a sulfonic acid polymer.

2. The fluid loss reducer according to claim 1, characterized in that: The functional compound includes any one of montmorillonite, hydrotalcite or graphene, or a combination of at least two of them.

3. The fluid loss reducer according to claim 1 or 2, characterized in that: The sulfonic acid polymer is acrylamide, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid copolymer.

4. The fluid loss reducer according to claim 3, characterized in that: The sulfonic acid polymer is acrylamide, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of (5-9):(4-8):(1-4).

5. A method for preparing the ultra-high temperature plugging and filtration reducer for water-based drilling fluid according to any one of claims 1 to 4, characterized in that: The preparation method comprises: mixing the oil phase substance with the emulsifier to obtain an oil phase system; After mixing the sulfonic acid polymer monomer with water, adjusting the pH, adding a cross-linking agent and a modified intermediate, and obtaining an aqueous phase system; The water phase system is added to the oil phase system, an initiator is added to carry out polymerization reaction, and the ultra-high temperature plugging and filtration reducer for water-based drilling fluid is obtained after separation treatment.

6. The preparation method according to claim 5, characterized in that: The preparation method of the modified intermediate comprises: dispersing the intermediate in water, adding a modifier, and heating the intermediate to react to obtain the modified intermediate.

7. The preparation method according to claim 6, characterized in that: The modifier includes hexadecyltrimethylammonium bromide and / or 2-aminoethyl methacrylate hydrochloride.

8. The preparation method according to claim 5, characterized in that: The volumes of the water phase and the oil phase are (1-2):(2-3).

9. The preparation method according to claim 5, characterized in that: The polymerization reaction temperature is 50-80° C. and the reaction time is 5-10 hours.

10. A water-based drilling fluid, characterized in that: The water-based drilling fluid comprises the ultra-high temperature plugging and filtration reducer for water-based drilling fluid according to any one of claims 1 to 4.

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