An ultra-high temperature plugging fluid loss additive for water-based drilling fluid and a preparation method thereof

Abstract

The application provides an ultra-high-temperature plugging fluid loss additive for water-based drilling fluid and a preparation method thereof. The fluid loss additive comprises a core layer and a shell layer. The core layer is a functional compound, and the shell layer is a sulfonic acid-based polymer. The ultra-high-temperature plugging fluid loss additive cannot be degraded and destroyed at high temperature, effectively controls the fluid loss amount of drilling fluid before and after the action of ultra-high temperature, has excellent fluid loss amount control performance, and can effectively control the fluid loss additive of water-based drilling fluid.

Description

TECHNICAL FIELD

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

[0002] Compared with traditional water-thermal geothermal resources, hot dry rock geothermal resources have the advantages of large energy, wide distribution, renewable, safety, cleanliness, no pollution, and no restriction by seasons and day and night, and are an important target for geothermal energy development. Due to the extremely high bottom hole temperature of hot dry rock resources, the high temperature resistance of the drilling fluid fluid loss additive is very high. However, the existing drilling fluid fluid loss additive cannot meet the needs of hot dry rock drilling. The currently used plugging type fluid loss additives mainly include asphalt (powder), super calcium carbonate (powder), and various nanomaterials. However, the use of asphalt (powder) type fluid loss additive is obviously restricted by the softening point temperature, which is generally not higher than 150 DEG C. The super calcium carbonate (powder) type raw material has a wide source, but has poor deformation ability in the formation, limited plugging ability for micro cracks, and poor compactness of the filter cake. At present, there are still few plugging type fluid loss additives that can be used in high temperature drilling fluid. CN 111499790 A proposes a water-based drilling fluid anti-high temperature polymer microsphere nanometer plugging agent and a preparation method thereof. By using a rheological stabilizer, the drilling fluid can resist a temperature of 260 DEG C. This technology can well inhibit the decomposition of drilling fluid treatment agents under ultra-high temperature conditions, but does not consider the problem of thickening of the water-based drilling fluid under ultra-high temperature conditions. CN103160259 A proposes a water-based drilling fluid resistant to 255 DEG C ultra-high temperature and a construction process. This technology can well solve the problem of performance control of drilling fluid under ultra-high temperature conditions, but cannot resist a temperature of 260 DEG C or above, and does not consider the performance of water-based drilling fluid under ultra-high temperature conditions. Therefore, it is of great practical significance to study an anti-ultra-high temperature and efficient cuttings carrying water-based drilling fluid and a preparation method thereof.

[0003] Therefore, it is necessary to develop an ultra-high temperature plugging fluid loss additive. SUMMARY

[0004] To solve the above technical problems, the present application provides an ultra-high temperature plugging fluid loss additive for water-based drilling fluid and a preparation method thereof. The ultra-high temperature plugging fluid loss additive will not be degraded and destroyed under high temperature, effectively controls the fluid loss amount before and after the ultra-high temperature effect of the drilling fluid, and has excellent fluid loss amount control performance, which can effectively control the fluid loss additive of the water-based drilling fluid.

[0005] To achieve the above technical effects, the present application adopts the following technical solutions:

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

[0007] As a preferred technical scheme of the present application, the functional compound comprises any one or a combination of at least two of montmorillonite, hydrotalcite or graphene.

[0008] As a preferred technical scheme of the present application, the sulfonic acid-based polymer is a copolymer of acrylamide, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid.

[0009] As a preferred technical scheme of the present application, the molar ratio of 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 not limited to the listed values, and other values not listed in the range are also applicable.

[0010] The second object of the present application is to provide a preparation method of the ultra-high temperature plugging and fluid loss reducer for water-based drilling fluid, comprising:

[0011] Mixing the oil phase material with the emulsifier to obtain an oil phase system;

[0012] Mixing the sulfonic acid-based polymer monomer with water, adjusting the pH, adding a crosslinking agent and a modified intermediate to obtain an aqueous phase system;

[0013] Adding the aqueous phase system to the oil phase system, adding an initiator for polymerization, and separating and processing to obtain the ultra-high temperature plugging and fluid loss reducer for water-based drilling fluid.

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

[0015] As a preferred technical scheme of the present application, the modifier comprises cetyltrimethylammonium bromide and / or 2-aminoethyl methacrylate hydrochloride.

[0016] As a preferred technical scheme of the present application, the volume ratio of the aqueous phase to the oil phase is (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, but not limited to the listed values, and other values not listed in the range are also applicable.

[0017] As a preferred technical scheme of the present application, the temperature of the polymerization reaction is 50-80℃, and the time is 5-10h. Among them, the temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, etc., and the time can be 5h, 6h, 7h, 8h, 9h or 10h, etc., but it is not limited to the listed values, and other values not listed in the above range are also applicable.

[0018] A third object of the present application is to provide a water-based drilling fluid comprising the super-high-temperature plugging fluid loss additive for water-based drilling fluid according to any one of the preceding objects.

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

[0020] (1) The present application provides a super-high-temperature plugging fluid loss additive for water-based drilling fluid, which will not be degraded and destroyed at high temperatures, and the temperature resistance can reach 240℃, and the fluid loss amount of the drilling fluid before and after the super-high-temperature effect can be effectively controlled, and the reduction rate of the fluid loss amount can be as high as 60%;

[0021] (2) The present application provides a super-high-temperature plugging fluid loss additive for water-based drilling fluid, and compared with the conventional fluid loss additive, the raw materials used in the super-high-temperature core-shell microsphere plugging fluid loss additive for water-based drilling fluid provided in the present application are widely sourced, and the cost is low;

[0022] (3) The present application provides a preparation method of a super-high-temperature plugging fluid loss additive for water-based drilling fluid, which has a simple preparation process and is suitable for industrial production. DETAILED DESCRIPTION

[0023] The technical scheme of the present application will be further described below through specific embodiments.

[0024] The present application provides a super-high-temperature plugging fluid loss additive for water-based drilling fluid, which comprises a core layer and a shell layer, the core layer is a functional compound, and the shell layer is a sulfonic acid-based polymer.

[0025] In one specific embodiment of the present application, the fluid loss additive is a core-shell microsphere structure, the shell layer is a sulfonic acid-based polymer, specifically an acrylamide, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid copolymer, which can improve the high-temperature resistance of the fluid loss additive. The reason for this is that when the structure of the core layer functional compound reaches the nanoscale, the specific surface area of the core layer functional compound increases sharply, enhancing the interaction with the polymer and thereby limiting the thermal motion of the polymer chain at high temperatures. At the same time, the core layer functional compound layer is a good thermal insulator, which reduces the heat transfer in the polymer matrix due to its excellent barrier property, thereby improving the thermal stability of the fluid loss additive.

[0026] The embodiment of the present application provides a preparation method of the ultra-high temperature plugging and fluid loss additive for water-based drilling fluid, and the preparation method comprises the following steps:

[0027] The oil phase material is mixed with the emulsifier to obtain an oil phase system;

[0028] After the sulfonic acid group polymer monomer is mixed with water, the pH is adjusted, the crosslinking agent and the modified intermediate are added to obtain a water phase system;

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

[0030] In the present application, the purpose of modifying the intermediate is to improve the compatibility of the core layer functional compound in the polymer material, expand the interlayer spacing of the core layer functional compound, increase the contact area with the subsequent polymer monomer and enhance the interaction.

[0031] In one embodiment of the present application, the oil phase material can be any one or a combination of at least two of benzene, an aromatic compound, or cyclobutane or cyclohexane, a cycloalkane.

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

[0033] In one embodiment of the present application, the addition amount of the emulsifier is 2-5% of the mass of the oil phase material, such as 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

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

[0035] In one embodiment of the present application, 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 values not listed in the value range are also applicable.

[0036] In one embodiment of the present application, the temperature of the heating reaction for modifying the intermediate can be 50-80 DEG C, and the time can be 5-10 h, such as 50 DEG C, 55 DEG C, 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C or 80 DEG C, and the time can be 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, but is not limited to the listed values, and other values not listed in the above value range are also applicable. Preferably, the temperature can be 60-70 DEG C, and the time can be 5-7 h.

[0037] In one embodiment of the present application, the amount of the sulfonic acid group-containing polymer monomer is 30-70% by mass of the water, preferably 40-60%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%, but not limited to the listed values, and other values not listed within the range are also applicable.

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

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

[0040] In one embodiment of the present application, the amount of the modified intermediate is 30-60% by mass of the water, preferably 40-50%, such as 30%, 35%, 40%, 45%, 50%, 55% or 60%, but not limited to the listed values, and other values not listed within the range are also applicable.

[0041] In one embodiment of the present application, the temperature for preparing the aqueous phase system and the oil phase system can be 20-40°C, preferably 25-30°C.

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

[0043] In one embodiment of the present application, the polymerization reaction is carried out in a reaction vessel commonly used in the art. Preferably, the polymerization reaction is carried out in a reaction vessel with airtight condition, such as a polytetrafluoroethylene airtight tank.

[0044] In one embodiment of the present application, the ratio of the volume 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 suspension added should be greater than or equal to 80 mL.

[0045] In one embodiment of the present application, the separation treatment includes adding acetone and ethanol to the reaction product of the polymerization reaction to perform demulsification precipitation, and then washing, drying and crushing.

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

[0047] The present application provides a water-based drilling fluid, which comprises the above-mentioned super-high-temperature plugging fluid loss reducer for water-based drilling fluid.

[0048] In one embodiment of the present application, the amount of the super-high-temperature plugging fluid loss reducer for water-based drilling fluid in the water-based drilling fluid is 0.1-5 wt%, preferably 1-4 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%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0049] In one embodiment of the present application, 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] In order to facilitate the understanding of the present application, the present application lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0051] Example 1

[0052] The present embodiment provides a super-high-temperature plugging fluid loss reducer for water-based drilling fluid, and the preparation method thereof comprises the following steps:

[0053] (1) Oil phase system preparation: 30°C, 100 mL flask, 50 mL cyclohexane (CHY), 100-200 r / min stirring, slowly add 1.0 g Span 80, stir for 30 min, and obtain the oil phase reaction system for standby;

[0054] (2) Intermediate modification: weigh 0.5 g of montmorillonite and disperse in 100 mL of deionized water, and dissolve 0.5 g of cetyltrimethylammonium bromide modifier (CTAB) in an appropriate amount of deionized water. After complete dissolution, add it to the montmorillonite aqueous solution, 60-70°C, N2deoxidation, and react for 6 h to obtain the CTAB-MMT product;

[0055] (3) water phase system preparation: under normal temperature conditions, 30.0 mL of water was added in a beaker, 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 were added under stirring at 70-100 r / min, and after mixing and stirring for 30 min, a reaction solution system was formed, sodium carbonate was used to adjust the pH value to about 7.0, then 1.2 g of crosslinking agent N,N-methylenebisacrylamide (MBA) was added, stirring for 30-60 min, and 15 g of modified intermediate was added to obtain a water phase reaction system for standby;

[0056] (4) The water phase reaction system was slowly added to the oil phase system, then the condensate water and stirrer were started, the speed was adjusted to 200-300 r / min, stirring for 30 min, N2deoxidation for 20 min, the temperature was increased to 65°C, the speed was adjusted to 400-600 r / min again, 1.2 g of initiator (KPS) was added, and the reaction was continued for 5 h to obtain the product system, then acetone and ethanol were added to the product system to precipitate and filter, and the product was dried to obtain the desired ultra-high temperature core-shell microsphere plugging and fluid loss reducer FF-1.

[0057] Example 2

[0058] The present embodiment provides an ultra-high temperature plugging and fluid loss reducer for water-based drilling fluid, and the preparation method comprises the following steps:

[0059] (1) Oil phase system preparation: 50 mL of cyclohexane (CHY) was added in a 100 mL flask under 30°C, 2.5 g of Span 80 was slowly added under stirring at 100-200 r / min, and stirring was continued for 30 min to obtain an oil phase reaction system for standby;

[0060] (2) Intermediate modification: 1 g of hydrotalcite was dispersed in 100 mL of deionized water, 2 g of cetyltrimethylammonium bromide modifier (CTAB) was dissolved in an appropriate amount of deionized water, after complete dissolution, it was added to the hydrotalcite aqueous solution, deoxidized under N2at 60-70°C, and the reaction was continued for 5-7 h to obtain CTAB-hydrotalcite product;

[0061] (3) Water phase system preparation: under normal temperature conditions, 30.0 mL of water was added in a beaker, 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 were added under stirring at 70-100 r / min, and after mixing and stirring for 30 min, a reaction solution system was formed, sodium carbonate was used to adjust the pH value to about 7.0, then 1.2 g of crosslinking agent N,N-methylenebisacrylamide (MBA) was added, stirring for 30-60 min, and 15 g of modified intermediate was added to obtain a water phase reaction system for standby;

[0062] (4) Slowly add the water phase reaction system to the oil phase system, then turn on the condenser water and the stirrer, adjust the speed to 200-300 r / min, stir for 30 min, N2deoxidation for 20 min, increase the temperature to 65°C, adjust the speed to 400-600 r / min again, add 1.2 g of initiator (KPS), and react for another 4-6 h to obtain the product system. Then, add acetone and ethanol to the product system, precipitate by demulsification, and perform the processes of suction filtration and drying to obtain the desired super-high-temperature core-shell microsphere plugging fluid loss additive FF-2.

[0063] Example 3

[0064] The present example provides a super-high-temperature plugging fluid loss additive for water-based drilling fluid, and a preparation method thereof, which comprises the following steps:

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

[0066] (2) Modification of intermediate: weigh 2 g of graphene and disperse it in 100 mL of deionized water, weigh 2 g of cetyltrimethylammonium bromide modifier (CTAB) and dissolve it in an appropriate amount of deionized water, add it to the graphene aqueous solution after complete dissolution, deoxidize under N2at 60-70°C, and react for 5-7 h to obtain a CTAB-graphene product;

[0067] (3) Water phase system preparation: under the condition of 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 the condition of stirring at 70-100 r / min, mix and stir for 30 min to form a reaction solution system, adjust the pH value of the reaction solution system to be close to 7.0 using sodium carbonate, then add 1.2 g of crosslinking agent N,N-methylenebisacrylamide (MBA), stir for 30-60 min, and add 15 g of the modified intermediate to obtain a water phase reaction system for standby use;

[0068] (4) Slowly add the water phase reaction system to the oil phase system, then turn on the condenser water and the stirrer, adjust the speed to 200-300 r / min, stir for 30 min, N2deoxidation for 20 min, increase the temperature to 65°C, adjust the speed to 400-600 r / min again, add 1.2 g of initiator (KPS), and react for another 4-6 h to obtain the product system. Then, add acetone and ethanol to the product system, precipitate by demulsification, and perform the processes of suction filtration and drying to obtain the desired super-high-temperature core-shell microsphere plugging fluid loss additive FF-3.

[0069] Comparative Example 1

[0070] The present comparative example provides a kind of water-based drilling fluid fluid loss additive, its preparation method includes the following steps:

[0071] (1) oil phase system preparation: 30 ℃, in 100 mL flask, add cyclobutane 50 mL, under the condition of 100-200 r / min stirring, stir 30 min, obtain oil phase reaction system standby;

[0072] (2) intermediate modification: 1g montmorillonite is weighed and dispersed in 100 mL deionized water, 2g of 2-aminoethyl methacrylate hydrochloride is dissolved in appropriate amount of deionized water, after complete dissolution, add to hydrotalcite aqueous solution, 60-70 ℃, N2 oxygen removal, reaction 5-7h, obtain modified intermediate product;

[0073] (3) water phase system preparation: under normal temperature condition, in beaker, add 30.0 mL water, under the condition of 70-100 r / min stirring, add 13.8g acrylamide (AM) monomer, 1.2g 2-acrylamide-2-methylpropane sulfonic acid (AMPS) monomer, after mixing and stirring 30 min, form reaction solution system, use sodium carbonate to adjust its pH value close to 7.0, then, 1.2g crosslinking agent N,N-methylene bisacrylamide (MBA) is added, stir 30-60 min, add 15g modified intermediate, obtain water phase reaction system standby;

[0074] (4) the water phase reaction system is slowly added to the oil phase system, then open the condensate water and stirrer, speed is adjusted to 200-300 r / min, stir 30 min, N2 oxygen removal 20 min, temperature is raised to 65 ℃, speed is adjusted to 400-600 r / min again, add 1.2g initiator (KPS), then react for 4-6h to obtain product system, then, add acetone and ethanol to the product system, carry out demulsification precipitation and filtration and drying process, to obtain the required ultra-high temperature core-shell microsphere plugging fluid loss additive FF-4.

[0075] Comparative Example 2

[0076] The present comparative example provides a kind of water-based drilling fluid fluid loss additive, its preparation method includes the following steps:

[0077] (1) oil phase system preparation: 30 ℃, in 100 mL flask, add cyclobutane 50 mL, under the condition of 100-200 r / min stirring, stir 30 min, obtain oil phase reaction system standby;

[0078] (2) Intermediate modification: 2 g of water-sliding stone was weighed and dispersed in 100 mL of deionized water, 2 g of 2-aminoethyl methacrylate hydrochloride was weighed and dissolved in a suitable amount of deionized water, and after complete dissolution, it was added to the water-sliding stone aqueous solution, 60-70℃, N2oxygen removal, reaction for 5-7h, to obtain the modified intermediate product;

[0079] (3) Water phase system preparation: under normal temperature conditions, 30.0 mL of water was added to a beaker, 12.8 g of acrylic acid (AA) monomer, 1.2 g of 2-acrylamide-2-methylpropane sulfonic acid (AMPS) monomer was added under the condition of 70-100 r / min stirring, after mixing and stirring for 30 min, the reaction solution system was formed, sodium carbonate was used to adjust the pH value to about 7.0, then 1.2 g of crosslinking agent N,N-methylene bisacrylamide (MBA) was added, stirring for 30-60 min, 15 g of modified intermediate was added, to obtain the water phase reaction system for standby;

[0080] (4) The water phase reaction system was slowly added to the oil phase system, then the condensate water and stirrer were started, the speed was adjusted to 200-300 r / min, stirring for 30 min, N2oxygen removal for 20 min, the temperature was raised to 65℃, the speed was adjusted to 400-600 r / min again, 1.2 g of initiator (KPS) was added, and the reaction was carried out for 4-6 h to obtain the product system, then acetone and ethanol were added to the product system to precipitate and filter, and the desired ultra-high temperature core-shell microspherical plugging fluid reducing loss agent FF-5 was prepared.

[0081] API fluid loss test:

[0082] Preparation of bentonite-based slurry: 16 g of sodium-based bentonite for drilling fluid (Huaiwei bentonite Co., Ltd.) was added to 400 mL of tap water, stirred at 10000 r / min for 30 min, and then sealed and placed for 24 h to obtain a pre-hydrated 4% bentonite-based slurry.

[0083] 4 g of the fluid loss agent prepared in the above examples 1-3 and comparative examples 1-3 and Driscal-D was added to 400 mL of the bentonite-based slurry, respectively, and stirred at 10000 r / min for 20 min, then 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℃ for 16 h, cooled to room temperature, stirred at 10000 r / min for 20 min, then the API fluid loss of the slurry was tested, and the fluid loss reduction rate was calculated. The results are shown in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] From the test results of Table 1, it can be seen that before hot rolling at 240℃, the filtration loss reduction rate of the experimental slurry reaches 30% after adding the filtrate reducer prepared by the present application examples 1-3 in the 4% bentonite-based slurry, while the filtration loss reduction rate of the experimental slurry is less than 30% after adding the traditional high-temperature filtrate reducer Driscal-D. After hot rolling at 240℃, when the filtrate reducer prepared by the present application examples 1-3 is used, the filtration loss reduction rate of the experimental slurry is greater than 60%, which is significantly higher than that of the comparative examples 1-2 and Driscal-D. It shows that the performance of the filtrate reducer prepared by the present application examples 1-3 for controlling the filtration loss of bentonite-based slurry after hot rolling is significantly better than that of the comparative examples 1-2 and Driscal-D.

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

[0090] 4g of the filtrate reducer prepared by the above examples 1-3 and comparative examples 1-2 and Driscal-D were added into the drilling fluid Z1 respectively, and after stirring at 10000r / min for 20min, 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 rolling heating furnace, and hot rolling was carried out at 240℃ for 16h, and then cooled to room temperature, and stirred at 10000r / min for 10min, and the API filtration of the drilling fluid was tested, and the results are shown in Table 2.

[0092] Table 2

[0093]

[0094] From the test results of Table 2, it can be seen that after adding different kinds of filtrate reducers into the drilling fluid Z1, the filtration loss reduction rate of the drilling fluid Z1 is greater than 32% after hot rolling at 240℃ for 16h, and the highest reaches 45%, and the filtration loss control ability is better than that of the comparative examples 1-2 and Driscal-D. It shows that the water-based drilling fluid filtrate reducer prepared by the present application examples 1-3 has good performance in controlling the filtration loss of drilling fluid at high temperature.

[0095] In the above API filtration test, the apparent viscosity and API filtration were tested according to the test method of GB / T 29170-2012.

[0096] The API filtration reduction rate was calculated by the following formula:

[0097]

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

[0099] In the above API filtration loss test, the sodium hydroxide is provided by the National Medicine Shanghai Test Group, and the purity is more than 99%; the amphoteric ion polymer coating agent is provided by Minquan Dongxing Mud Material Co., Ltd.; the sulfonate copolymer filtration loss reducer is provided by Shandong Deshengyuan Petroleum Technology Co., Ltd.; the plugging inhibitor is provided by China Petroleum Engineering Technology Research Institute Co., Ltd.; and the white oil is provided by Nanjing Rongji Chemical Co., Ltd.

[0100] The applicant declares that the detailed process equipment and process flow of the present application are illustrated by the above embodiments, but the present application is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present application must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing an ultra-high temperature plugging and filtration loss reducing agent for water-based drilling fluids, characterized in that, The preparation method includes: An oil phase system is obtained by mixing the oil phase substance with an emulsifier; After mixing sulfonic acid polymer monomers with water, adjusting the pH, adding crosslinking agents and modified intermediates, an aqueous phase system is obtained. The aqueous phase system is added to the oil phase system, an initiator is added to carry out a polymerization reaction, and after separation treatment, the ultra-high temperature plugging and filtration reduction agent for water-based drilling fluid is obtained. The filtration reduction agent 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; The method for preparing the modified intermediate includes: dispersing the intermediate in water, adding a modifier, and heating to react to obtain the modified intermediate; the intermediate refers to a core layer functional compound; the modifier includes hexadecyltrimethylammonium bromide; The functional compound includes any one or a combination of at least two of montmorillonite, hydrotalcite, or graphene; The sulfonic acid polymer is an acrylamide, acrylic acid, and a copolymer of 2-acrylamide-2-methylpropanesulfonic acid.

2. The preparation method according to claim 1, 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).

3. The preparation method according to claim 1, characterized in that, The volume ratio of the aqueous phase to the oil phase is (1-2):(2-3).

4. The preparation method according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 50-80℃ for 5-10 hours.

5. A water-based drilling fluid, characterized in that, The water-based drilling fluid includes the ultra-high temperature plugging and filtration reduction agent for water-based drilling fluid prepared by the preparation method according to any one of claims 1-4.

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