High-temperature-resistant filtrate reducer based on molecular simulation mechanism and preparation method of high-temperature-resistant filtrate reducer

Abstract

The invention relates to a high-temperature-resistant filtrate reducer based on a molecular simulation mechanism and a preparation method of the high-temperature-resistant filtrate reducer, and belongs to the technical field of filtrate loss reduction of drilling fluid. The high-temperature-resistant filtrate reducer is prepared from the following raw materials in parts by mass: 50 to 100 parts of a temperature-resistant monomer, 10 to 30 parts of a hydrophilic monomer, 2 to 10 parts of a heterocyclic monomer, 0.01 to 0.05 part of an initiator, 25 to 35 parts of a pH (Potential of Hydrogen) regulator and 100 to 500 parts of deionized water. The invention also provides a preparation method of the high-temperature-resistant filtrate reducer and application of the high-temperature-resistant filtrate reducer in preparation of drilling fluid. The filter loss of the high-temperature-resistant filtrate reducer based on the molecular simulation mechanism is only 6.4 mL after the high-temperature-resistant filtrate reducer is aged for 16 h at the temperature of 200 DEG C, the filter loss of the high-temperature-resistant filtrate reducer is only 8.4 mL after the high-temperature-resistant filtrate reducer is aged for 16 h at the temperature of 230 DEG C, and the high-temperature-resistant filtrate reducer has good temperature resistance and can effectively regulate and control the rheological property of drilling fluid and improve the filtrate reduction performance so as to guarantee safe operation of deep wells and ultra-deep wells.

Description

TECHNICAL FIELD

[0001] The application relates to a high-temperature-resistant filtrate reducer based on a molecular simulation mechanism and a preparation method thereof, and belongs to the technical field of drilling fluid filtrate reduction. BACKGROUND

[0002] In the drilling process, water in the drilling fluid inevitably leaks into the formation through the well wall due to the pressure difference, causing the drilling fluid to lose water. As water enters the formation, clay particles in the drilling fluid adhere to the well wall to form a "filter cake", forming a filter cake well wall. Since the filter cake well wall is much denser than the original well wall, it prevents further water loss of the drilling fluid and protects the well wall. However, excessive filtration of the drilling fluid can cause shale swelling and collapse, resulting in an unstable well wall. In addition, the increase in filtration increases the thickness of the filter cake, reducing the well diameter and causing a large torque on the rotating drilling tool, causing pumping and pressure fluctuations during tripping, which can cause differential sticking. Therefore, a filtrate reducer needs to be added to the drilling fluid to control the amount of filtration of the drilling fluid.

[0003] In recent years, the development of deep and ultra-deep oil and gas resources has become one of the main targets of China's oil industry. Drilling fluid, known as the "blood of drilling engineering", is one of the key technologies to ensure drilling safety. High temperature and high pressure in deep and ultra-deep formations can cause drilling fluid failure, leading to collapse, leakage, spraying, and sticking. As the depth of the formation increases, the temperature underground increases. In the western Sichuan Basin, Tarim Basin and Junggar Basin, the temperature of deep and ultra-deep wells above 8000 meters reaches more than 200℃, while in the eastern Bohai Bay depression and Biyang depression, the temperature exceeds 200℃ at 6000 meters, such as Shengke 1 well, which has a drilling depth of 7026 meters and a bottom hole temperature of 236℃; Bishen 1 well has a drilling depth of 6005 meters and a bottom hole temperature of 241℃; The reservoir temperature in Yinggehai DF13 area also reaches nearly 220℃. Therefore, in order to ensure the safety of drilling engineering, it is urgent to develop a filtrate reducer with excellent temperature resistance to improve the high-temperature stability of drilling fluid and improve the temperature resistance of drilling fluid to ensure drilling safety. The temperature resistance and filtrate reduction effect of the filtrate reducer not only depend on the temperature resistance of the main chain of the treatment agent, but also are closely related to the temperature resistance, hydrophilicity and adsorption of the functional groups.

[0004] The Chinese patent document CN119331165A provides a drilling fluid tackifying high-temperature fluid loss additive, mainly dissolving raw materials N-vinyl pyrrolidone, 2-acrylamide-2-methylpropane sulfonic acid (AMPS) and allyl glyceryl ether in water to form an aqueous solution in a mass ratio of (1-3):(5-7):(1-4), adjusting the pH value of the aqueous solution, adding a crosslinking agent and an initiator, and obtaining the tackifying fluid loss additive through crosslinking copolymerization. However, the patent does not sufficiently study the interaction principle of the fluid loss additive with water and clay, and fails to study the functional group type combination and reaction process of the fluid loss additive, and the temperature resistance of the fluid loss additive can only reach 200 DEG C, which still cannot meet the temperature resistance requirement of the fluid loss additive for oil and gas drilling at present and in the future.

[0005] Therefore, it is of great significance to study a drilling fluid fluid loss additive with higher temperature resistance, stronger adsorption and better fluid loss reduction effect, which is of great significance to the safe and efficient development of deep oil and gas resources. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a high-temperature resistant fluid loss additive based on molecular simulation mechanism and a preparation method thereof.

[0007] The technical scheme of the present application is as follows: A high-temperature resistant fluid loss additive based on molecular simulation mechanism comprises the following raw materials in mass fraction: temperature-resistant monomer 50-100 parts, hydrophilic monomer 10-30 parts, heterocyclic monomer 2-10 parts, initiator 0.01-0.05 parts, pH adjuster 25-35 parts and deionized water 100-500 parts.

[0008] According to the present application, the temperature-resistant monomer is one or a combination of sodium p-styrenesulfonate, maleimide, dimethyldiallylammonium chloride and 1,7-diphenylsulfonic acid octane.

[0009] Further preferably, the temperature-resistant monomer is one or a combination of sodium p-styrenesulfonate and dimethyldiallylammonium chloride.

[0010] According to the present application, the hydrophilic monomer is one or a combination of acrylic acid, acrylamide, ethylene glycol, 1,2,6,7-tetracarboxy-heptane and 1,7-dimethylamino-octane.

[0011] Further preferably, the hydrophilic monomer is acrylamide.

[0012] According to the present application, the heterocyclic monomer is one or a combination of N-vinyl caprolactam and N-vinyl pyrrolidone.

[0013] Further preferably, the heterocyclic monomer is N-vinyl caprolactam.

[0014] According to the application, the initiator is preferably one or more of azobisisobutyronitrile, ammonium persulfate, potassium persulfate.

[0015] Further preferably, the initiator is one or more of azobisisobutyronitrile, ammonium persulfate, potassium persulfate.

[0016] According to the application, the pH regulator is preferably NaOH.

[0017] Most preferably, the anti-high-temperature fluid loss additive based on the molecular simulation mechanism comprises the following raw materials in mass fraction: 50 parts of sodium p-styrenesulfonate, 15 parts of acrylamide, 10 parts of N-vinyl caprolactam, 10 parts of dimethyl diallyl ammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0018] The preparation method of the anti-high-temperature fluid loss additive based on the molecular simulation mechanism comprises the following steps: A pH regulator solution with a mass fraction of 25-35% is prepared using a pH regulator; According to the proportion, part of the temperature-resistant monomer and the hydrophilic monomer are added to the deionized water at room temperature, and after stirring to dissolve completely, the pH regulator solution is added to adjust the pH value to 6-7, while nitrogen is introduced and stirred for 8-12 min, then the temperature is raised to 45-55℃, and the reaction is carried out under nitrogen for 1.5-2.5 h; according to the proportion, the remaining temperature-resistant monomer, heterocyclic monomer and initiator are continuously added, and the temperature is raised to 60-70℃, and the reaction is carried out under nitrogen for 1.5-2.5 h; the temperature is continuously raised to 75-85℃, and the reaction is continuously carried out under nitrogen for 1.5-2.5 h, to obtain a gel solution; the gel solution is sealed and dried at 100-110℃, to obtain the anti-high-temperature fluid loss additive based on the molecular simulation mechanism.

[0019] According to the application, the anti-high-temperature fluid loss additive based on the molecular simulation mechanism is used in the preparation of a drilling fluid.

[0020] Beneficial effects: 1. The anti-high-temperature fluid loss additive provided by the application is based on a molecular simulation mechanism, wherein the temperature-resistant monomer used has a sulfonic acid group, the S=O bond energy of the sulfonic acid group is high, the overall thermal stability of the sulfonic acid group is better than that of a carboxyl group or a hydroxyl group, the sulfonic acid group can maintain structural stability at high temperatures, is more resistant to hydrolysis than an ester group or an amide group, and is suitable for a high-temperature and high-salt environment. Moreover, the sulfonic acid group can be combined with high-valence metal ions such as Ca2+ and Mg2+ to reduce gelation caused by ion crosslinking at high temperatures. At the same time, the sulfonic acid group is often combined with a rigid structure such as a benzene ring and a heterocycle (for example, N-vinyl caprolactam) to jointly improve the rigidity of a polymer chain through steric hindrance and charge effects and inhibit deformation at high temperatures. The hydrophilic monomer has an amide group, can form a hydrogen bond with water molecules, and enables the polymer to have good hydrophilicity. In particular, the cationic group of dimethyldiallylammonium chloride can not only strengthen the adsorption capacity of the additive on the surface of clay (the clay particles are negatively charged), but also can synergistically enhance the temperature resistance of the sulfonic acid group with the five-membered nitrogen heterocycle, and the temperature resistance can be above 230 DEG C.

[0021] 2. The anti-high-temperature fluid loss additive provided by the application is based on a molecular simulation mechanism, wherein the selection, ratio and reaction mechanism of raw materials are derived from molecular simulation of the action mechanism of functional groups and water molecules, the adsorption mechanism of functional groups and clay, and the interaction mechanism of functional groups / water / clay, and the type, ratio and distribution principle of the functional groups are strictly determined. The fluid loss amount of the fluid loss additive is only 6.4 mL after aging at 200 DEG C for 16 hours and is only 8.4 mL after aging at 230 DEG C for 16 hours, and the fluid loss additive has good temperature resistance, can effectively control the rheological property of a drilling fluid and improve the fluid loss reduction performance, and can ensure safe operation of deep wells and ultra-deep wells.

[0022] 3. The anti-high-temperature fluid loss additive preparation method provided by the application has a simple process, low requirements for an experimental environment, and is easy to realize the generation of the fluid loss additive. DETAILED DESCRIPTION

[0023] Figure 1 It is a conformation of an anti-high-temperature fluid loss additive simulation system.

[0024] Figure 2 It is a structure schematic diagram of three kinds of functional group monomers used in the anti-high-temperature fluid loss additive polymer simulated and constructed. In the figure, a is 1,7-bis-methylamino-octane, b is 1,7-bis-benzenesulfonyl-octane, and c is 1,2,6,7-tetracarboxy-heptane.

[0025] Figure 3 It is the number of hydrogen bonds between functional groups and water molecules in different water / additive binary systems changing with temperature and pressure conditions. In the figure, a is a 1,7-bis-methylamino-octane / water binary system, b is a 1,7-bis-benzenesulfonyl-octane / water binary system, and c is a 1,2,6,7-tetracarboxy-heptane / water binary system.

[0026] Figure 4 The variation of the solvent-accessible surface area of ​​functional groups in different water / agent binary systems with temperature and pressure conditions; In the figure, a is the 1,7-didimethylamino-octane / water binary system, b is the 1,7-dibenzenesulfonic acid-octane / water binary system, and c is the 1,2,6,7-tetracarboxylic acid-heptane / water binary system.

[0027] Figure 5 The variation of the number of hydrogen bonds between functional groups and water molecules in different water / clay / agent ternary systems with temperature and pressure conditions; In the figure, a is a ternary system of 1,7-didimethylamino-octane / water / clay, b is a ternary system of 1,7-dibenzenesulfonic acid-octane / water / clay, and c is a ternary system of 1,2,6,7-tetracarboxylic acid-heptane / water / clay.

[0028] Figure 6 The variation of the number of hydrogen bonds between water molecules in different water / clay / agent ternary systems with temperature and pressure conditions; In the figure, a is a ternary system of 1,7-didimethylamino-octane / water / clay, b is a ternary system of 1,7-dibenzenesulfonic acid-octane / water / clay, and c is a ternary system of 1,2,6,7-tetracarboxylic acid-heptane / water / clay.

[0029] Figure 7 Based on the results of optimizing the proportion and distribution of functional groups using molecular simulations, we analyzed the structure of three functional group monomers in the water / clay / agent ternary system, and the change of accessible surface area of ​​montmorillonite with temperature after the combination of the three functional group monomers. In the figure, a represents the 1,7-didimethylamino-octane structure, b represents the 1,7-dibenzenesulfonic acid-octane structure, c represents the 1,2,6,7-tetracarboxylic acid-heptane structure, and d represents the change in accessible surface area of ​​montmorillonite as a function of temperature after the combination of the three functional group monomers.

[0030] Figure 8 The image shows the mud cake after aging and filtration of the high-temperature filtration agent in Example 3 for 16 hours at different temperatures.

[0031] Figure 9 The image shows the sludge cake after aging and filtration of the filter loss reducer in Comparative Example 2 at different temperatures for 16 hours.

[0032] Figure 10 The infrared spectra of the high-temperature filtration reduction agent in Example 3 are shown at different temperatures.

[0033] Figure 11 The infrared spectra of the filtration loss reducer in Comparative Example 2 are shown at different temperatures.

[0034] Figure 12Thermogravimetric curves of the high-temperature filtration loss reducer in Example 3 are shown at different temperatures.

[0035] Figure 13 The thermogravimetric curves of the filter loss reducer in Comparative Example 2 at different temperatures. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments, but is not limited thereto. All raw materials used in the embodiments are conventional and commercially available; unless otherwise specified, the methods described are existing technologies.

[0037] Example 1 The inventors of this application screened various raw materials in the high-temperature filtration reduction agent based on the molecular simulation mechanism. The specific process is as follows.

[0038] 1. Simulation of the temperature resistance mechanism of different functional group combinations in high-temperature filtration loss reducing agents ① Constructing a simulation system First, using GROMACS, LAMMPS, or Materials Studio software, establish SPC / E, TIP3P, SPC, TIP4P, TIP4P / Ice, or TIP5P water molecule models. Then, select CLAYFF or OPLS-AA force fields (different water molecule models have different applicable temperatures and required force field parameters) to perform energy minimization calculations on the water molecule models. Similarly, establish models for high-temperature filtration reduction agents (monomers or polymers) and clay particles, and combine them with the water molecule models to form a water / agent binary simulation system or a water / agent / clay ternary simulation system. The XYZ three-dimensional dimensions of the simulation system are 60 Å × 60 Å × 60 Å, and the number of water molecules added is 5000. The specific conformation is as follows: Figure 1 As shown, the image is rendered using VMD software.

[0039] Secondly, within the temperature range of 1 bar and 283K-373K, the degree of fit between the simulated macroscopic parameters of the water phase and experimental values ​​was measured. A preliminary selection of water molecule types with a high degree of fit to the actual values ​​was made. Then, under high temperature and high pressure (100MPa, 373~583K), the degree of fit between the macroscopic parameters of the selected water molecule model and experimental values ​​was verified, determining a suitable water molecule model for simulation under high temperature and high pressure conditions. Subsequently, the changes in water molecule characteristic parameters were simulated under the same high temperature and high pressure conditions.

[0040] Simulation Procedure: The steepest descent algorithm was used to minimize energy, resulting in a reasonable distribution of water molecules in the system. After energy minimization, the system was equilibrated for 1 ns under the NVT ensemble (constant particle number, volume, and temperature). Then, the system was equilibrated under the NPT ensemble (constant particle number, pressure, and temperature) with Berendsen pressure control and nose-hoover temperature control for 1 ns to ensure that the system quickly reached the equilibrium pressure. The pressure control was then changed to Parrinello-Rahman, and a kinetic simulation was performed for 20 ns under the NPT ensemble to ensure the accuracy of the conformation of the high-temperature filtration loss agent simulation system. The trajectory data of the last 5 ns were selected for statistical analysis to determine its kinetic properties. The calculation methods for the Lennard-Jones (LJ)12-6 potential and coulomb potential of nonbonded interactions are shown in Equation (1).

[0041]

[0042] The mean square displacement (MSD) of water molecules in the system is calculated using the Einstein equation, as shown in equation (2). 1 / 6 of the slope of this function is the diffusion coefficient of water molecules.

[0043]

[0044] The changes in water phase structure are calculated using the radial distribution function (RDF), as shown in equation (3).

[0045]

[0046] Geometric mixing rules are used to calculate interactions between different atoms, with a cutoff radius set to a distance of 10 Å. Long-range electrostatics in the model are handled using a particle-particle-particle mesh (PPPM) method with a precision of 10⁻⁶. −4 The simulation process sets three-dimensional periodic boundary conditions.

[0047] ② The structures of the three functional group monomers used in the simulated high-temperature filtration loss reducing polymer. Using 1,7-didimethylamino-octane as the monomer with the dimethylamino functional group, 1,7-dibenzenesulfonyl-octane as the monomer with the benzenesulfonate functional group, and 1,2,6,7-tetracarboxy-heptane as the monomer with the carboxyl functional group, molecular structure models of these three functional group monomers were constructed using GROMACS, LAMMPS, or Materials Studio software, and energy minimization calculations were performed. Specifically, as follows... Figure 2 As shown.

[0048] ③ The interaction mechanism between the simulated high-temperature filtration loss reducing polymer and water Based on ① and ②, water / agent binary systems were constructed by reacting 1,7-didimethylamino-octane, 1,7-dibenzenesulfonic-octane, and 1,2,6,7-tetracarboxy-heptane with water, respectively. The variation of the number of hydrogen bonds between functional groups and water molecules in these different water / agent binary systems with temperature and pressure conditions was evaluated at 100–250 MPa and 373–583 K. The results are as follows: Figure 3 As shown.

[0049] Depend on Figure 3 It is evident that temperature significantly affects the number of hydrogen bonds. As temperature increases, the number of hydrogen bonds decreases. The order of hydrogen bond formation ability of the three functional groups with water molecules is: 1,2,6,7-tetracarboxy-heptane > 1,7-diphenylsulfonate-octane > 1,7-didimethylamino-octane. This means the carboxyl group has the strongest hydrogen bond formation ability with water molecules, followed by the benzenesulfonate group, and the dimethylamino group has the weakest. Furthermore, while 1,2,6,7-tetracarboxy-heptane has the strongest hydrogen bond formation ability with water molecules, its decrease is also the greatest with increasing temperature. In contrast, 1,7-diphenylsulfonate-octane and 1,7-dimethylamino-octane form fewer hydrogen bonds with water but exhibit greater stability.

[0050] The solvent accessible surface area (SASA) of functional groups in different water / agent binary systems was measured as a function of temperature and pressure conditions at pressures ranging from 100 to 250 MPa and from 373 to 583 K. The results are as follows: Figure 4 As shown.

[0051] Depend on Figure 4 It can be seen that the SASA value is lower in the water / agent binary system due to the smaller size of the individual functional groups. Specifically, in the 1,7-dibenzenesulfonic acid-octane / water binary system, the SASA value of the benzenesulfonic acid functional group decreases slightly with increasing temperature, indicating that the benzenesulfonic acid functional group in this system coils up at high temperatures. In contrast, the SASA values ​​of the functional groups in the other two water / agent binary systems are relatively stable.

[0052] ④ The interaction mechanism of the simulated high-temperature filtration loss reducing polymer with water in the presence of montmorillonite. This step uses montmorillonite as the clay component. Based on steps ① and ②, 1,7-didimethylamino-octane, 1,7-dibenzenesulfonyl-octane, and 1,2,6,7-tetracarboxy-heptane were used with montmorillonite and water to construct water / clay / agent ternary systems, respectively. The changes in the number of hydrogen bonds between functional groups and water molecules under different temperature and pressure conditions were evaluated in the water / clay / agent ternary systems at 100–250 MPa and 373–583 K. The results are as follows: Figure 5 As shown.

[0053] Depend on Figure 5It can be seen that in different water / clay / agent ternary systems, the number of hydrogen bonds formed between the three functional group monomers and water molecules decreases with increasing temperature. When the temperature rises from 373K to 583K, the 1,2,6,7-tetracarboxy-heptane / water / clay ternary system has the most hydrogen bonds with water molecules, and also the largest decrease, averaging 30.26%. 1,7-didimethylamino-octane is next, averaging 20.37%, while benzenesulfonic acid groups have the fewest, averaging 15.6%. The 1,7-dibenzenesulfonic acid-octane / water / clay ternary system forms the most stable hydrogen bonds. Furthermore, when the temperature reaches above 493K, the number of hydrogen bonds between carboxyl groups and water molecules tends to level off with temperature. Carboxyl and benzenesulfonic acid groups can give the polymer better solubility at high temperatures. This indicates that the presence of benzenesulfonic acid and carboxyl groups enhances the solubility stability of the treatment agent under high temperature and high pressure conditions.

[0054] The changes in the number of hydrogen bonds between water molecules in different water / clay / agent ternary systems under temperature and pressure conditions (100–250 MPa, 373–583 K) were evaluated. The results are as follows: Figure 6 As shown.

[0055] Depend on Figure 6 It can be seen that when the temperature rises from 373K to 583K, the decrease rates of the number of hydrogen bonds between water molecules in the water / clay / agent ternary system containing dimethylamino, benzenesulfonic acid, and carboxyl groups are 19.31%, 21.14%, and 27.05%, respectively. This indicates that the carboxyl polymer has a greater ability to disrupt the hydrogen bond network structure in the aqueous phase than the dimethylamino and benzenesulfonic acid polymers.

[0056] Based on the results of molecular simulations, the proportion and distribution of functional groups were optimized. The structures of the three functional group monomers in the water / clay / agent ternary system were analyzed. Simultaneously, the accessible surface area of ​​montmorillonite in the water / clay / agent ternary system composed of the three functional group monomers was measured as a function of temperature at 100–250 MPa and 373–583 K. The results are as follows: Figure 7 As shown.

[0057] Depend on Figure 7 It can be seen that 1,7-didimethylamino-octane exhibits the best adsorption effect on the montmorillonite surface, while 1,7-diphenylsulfonic acid-octane and 1,2,6,7-tetracarboxylic acid-heptane, due to their negative charge, have strong electrostatic repulsion with the montmorillonite surface, making them difficult to adsorb. At 373 K, 1,7-didimethylamino-octane is stably adsorbed on the montmorillonite surface in a spreading manner. As the temperature increases, the molecular kinetic energy increases, and the adsorption conformation of the functional group changes to a certain angle between the main chain carbon skeleton and the montmorillonite surface. Simultaneously, a certain degree of desorption inevitably occurs (583 K, 20 ns). The simulation of the adsorption conformation provides a theoretical basis for the selection of adsorption functional groups.

[0058] Based on the above simulation results, this invention clarifies the influence of functional group types and their arrangement on temperature resistance performance and the possibility of resistance to even higher temperatures, based on the interaction mechanism between different functional groups such as sulfonic acid group (benzenesulfonic acid group), carboxylic acid group, and methylamino group with water and clay at high temperatures, as well as the interaction mechanism between water molecules under the presence of these treatment agents. It identifies one or more combinations of sodium styrenesulfonate, maleimide, dimethyldiallylammonium chloride, and 1,7-dibenzenesulfonate-octane as temperature-resistant monomers; and one or more combinations of acrylic acid, acrylamide, vinyl alcohol, 1,7-didimethylamino-octane, and 1,2,6,7-tetracarboxylic acid-heptane as hydrophilic monomers. Then, using one or two combinations of N-vinylcaprolactam and N-vinylpyrrolidone as hybrid monomers, and combining them with the screened temperature-resistant monomers and hydrophilic monomers, a high-temperature filtration reduction agent is prepared.

[0059] Through molecular simulations, this invention reveals the number of hydrogen bonds between different functional groups and water molecules at high temperatures, the solvent-accessible surface area, and the interaction mechanisms between added water molecules and between the treatment agent and clay. It clarifies the types, proportions, and arrangement requirements of the functional groups. Therefore, based on the above mechanisms, the requirements for raw materials and the reaction principle are defined, and a reasonable combination of raw materials and preparation method are formulated.

[0060] Example 2 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 10 parts acrylamide, 10 parts N-vinylcaprolactam, 10 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0061] The preparation method of the above-mentioned high-temperature filtration loss reducing agent based on molecular simulation mechanism includes the following steps: Add NaOH to 100 parts of deionized water according to the specified ratio to obtain a NaOH solution; According to the formula, sodium p-styrene sulfonate and acrylamide were added to deionized water at room temperature and stirred until fully dissolved. Then, NaOH solution was added to adjust the pH to 7. Nitrogen gas was introduced while stirring for 10 minutes, and then the temperature was raised to 50°C and reacted under nitrogen for 2 hours. Dimethyl diallyl ammonium chloride, N-vinylcaprolactam and ammonium persulfate were added according to the formula, and the temperature was raised to 65°C and reacted under nitrogen for 2 hours. The temperature was raised to 80°C and the reaction was continued under nitrogen for 2 hours to obtain a gel solution. The gel solution was sealed and dried at 105°C to obtain a high-temperature filtration loss reducing agent based on a molecular simulation mechanism.

[0062] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:2:2:2.

[0063] Example 3 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 15 parts acrylamide, 10 parts N-vinylcaprolactam, 10 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0064] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:3:2:2.

[0065] The specific preparation method is the same as in Example 2.

[0066] Example 4 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 20 parts acrylamide, 10 parts N-vinylcaprolactam, 10 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0067] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:4:2:2.

[0068] The specific preparation method is the same as in Example 2.

[0069] Example 5 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 25 parts acrylamide, 10 parts N-vinylcaprolactam, 10 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0070] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:5:2:2.

[0071] The specific preparation method is the same as in Example 2.

[0072] Example 6 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 15 parts acrylamide, 5 parts N-vinylcaprolactam, 10 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0073] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:3:1:2.

[0074] The specific preparation method is the same as in Example 2.

[0075] Example 7 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 15 parts acrylamide, 15 parts N-vinylcaprolactam, 10 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0076] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:3:3:2.

[0077] The specific preparation method is the same as in Example 2.

[0078] Example 8 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 15 parts acrylamide, 10 parts N-vinylcaprolactam, 5 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0079] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:3:2:1.

[0080] The specific preparation method is the same as in Example 2.

[0081] Comparative Example 1 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts sodium p-styrene sulfonate, 15 parts acrylamide, 10 parts N-vinylcaprolactam, 15 parts dimethyl diallyl ammonium chloride, 0.03 parts ammonium persulfate, 30 parts NaOH, and 300 parts deionized water.

[0082] In this embodiment, the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride is 10:3:2:3.

[0083] The preparation method of the above-mentioned filtration loss reducing agent includes the following steps: Add NaOH to 100 parts of deionized water according to the specified ratio to obtain a NaOH solution; According to the formula, 2 sodium styrene sulfonate and acrylamide were added to 200 parts of deionized water and stirred until fully dissolved. Then, NaOH solution was added to adjust the pH to 7, and nitrogen gas was introduced while stirring for 10 minutes. Dimethyl diallyl ammonium chloride, N-vinylcaprolactam and ammonium persulfate were added according to the formula. Nitrogen gas was introduced while stirring at 60°C for 4 hours to obtain a gel solution. The gel solution was sealed and dried at 105°C, ground and passed through a 100-mesh sieve to obtain a high-temperature filtration loss reducing agent based on molecular simulation mechanism.

[0084] Comparative Example 2 A filtration loss reducing agent comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts of acrylamide, 10 parts of N-vinylcaprolactam, 10 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0085] The preparation method of the above-mentioned filtration loss reducing agent includes the following steps: Add NaOH to 100 parts of deionized water according to the specified ratio to obtain a NaOH solution; According to the formula, 2-acrylamido-2-methylpropanesulfonic acid and acrylamide were added to 200 parts of deionized water and stirred until fully dissolved. Then, NaOH solution was added to adjust the pH to 7, and nitrogen gas was introduced while stirring for 10 minutes. Dimethyl diallyl ammonium chloride, N-vinylcaprolactam and ammonium persulfate were added according to the formula. Nitrogen gas was introduced while stirring at 60°C for 4 hours to obtain a gel solution. The gel solution was sealed and dried at 105°C, ground and passed through a 100-mesh sieve to obtain a high-temperature filtration loss reducing agent based on molecular simulation mechanism.

[0086] Compared to Example 1, this comparative example replaces sodium styrene sulfonate with 2-acrylamido-2-methylpropanesulfonic acid, where 2-acrylamido-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride = 10:2:2:2.

[0087] Comparative Example 3 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts of acrylamide, 10 parts of N-vinylcaprolactam, 10 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0088] In this embodiment, the ratio of 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:3:2:2.

[0089] The specific preparation method is the same as that of Comparative Example 2.

[0090] Comparative Example 4 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 20 parts of acrylamide, 10 parts of N-vinylcaprolactam, 10 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0091] In this embodiment, the ratio of 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:4:2:2.

[0092] The specific preparation method is the same as that of Comparative Example 2.

[0093] Comparative Example 5 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 25 parts of acrylamide, 10 parts of N-vinylcaprolactam, 10 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0094] In this embodiment, 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride =10:5:2:2.

[0095] The specific preparation method is the same as that of Comparative Example 2.

[0096] Comparative Example 6 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts of acrylamide, 5 parts of N-vinylcaprolactam, 10 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0097] In this embodiment, the ratio of 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:3:1:2.

[0098] The specific preparation method is the same as that of Comparative Example 2.

[0099] Comparative Example 7 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts of acrylamide, 15 parts of N-vinylcaprolactam, 10 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0100] In this embodiment, the ratio of 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:3:3:2.

[0101] The specific preparation method is the same as that of Comparative Example 2.

[0102] Comparative Example 8 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts of acrylamide, 10 parts of N-vinylcaprolactam, 5 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0103] In this embodiment, the ratio of 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:3:2:1.

[0104] The specific preparation method is the same as that of Comparative Example 2.

[0105] Comparative Example 9 A high-temperature filtration loss reducing agent based on molecular simulation mechanism comprises the following raw materials in parts by weight: 50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts of acrylamide, 10 parts of N-vinylcaprolactam, 15 parts of dimethyldiallylammonium chloride, 0.03 parts of ammonium persulfate, 30 parts of NaOH, and 300 parts of deionized water.

[0106] In this embodiment, the ratio of 2-acrylamide-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:3:2:3.

[0107] The specific preparation method is the same as that of Comparative Example 2.

[0108] Test case 1. Temperature resistance and anti-aging performance test Freshwater-based slurry: 400mL water + 2.0g Na2CO3 + 16g bentonite, stir at high speed for 30min, and seal for curing for 24h.

[0109] According to GB / T16783.1-2014 standard, the dosage of filtration loss reducer was determined to be 1%. The filtration loss reducers prepared in Examples 2-8 and Comparative Examples 1-9 were added to the fresh water-based slurry, respectively, and stirred at high speed for 30 min. After aging at 200℃ and 230℃ for 16 h, respectively, the API filtration loss was tested using a quadruple filtration loss meter, and the apparent viscosity (AV), plastic viscosity (PV), and dynamic shear force (YP) of the aged slurry were tested using a six-speed rotational viscometer.

[0110] The API filtration loss and rheological results of Examples 2-8 and Comparative Examples 1-9 are shown in Tables 1-4.

[0111] Table 1. API filtration loss and rheological results of Examples 2-8 at 200°C

[0112] Table 2. API filtration loss and rheological results of Examples 2-8 at 230°C

[0113] Table 3. API filtration loss and rheological results of Comparative Examples 1-9 at 200℃

[0114] Table 4. API filtration loss and rheological results of Comparative Examples 1-9 at 230℃

[0115] As shown in Tables 1-4, in Comparative Examples 2-9, as the amount of acrylamide increased from 10 parts to 20 parts, the filtration loss first decreased and then stabilized, while the viscosity and shear stress gradually increased. This indicates that acrylamide affects the effect of the filtration loss reducer. By increasing the viscosity of the base slurry, it better hinders the penetration of water molecules into the formation, thereby reducing the filtration loss. However, the adsorption of amide groups on the surface is limited, so the filtration loss does not change much with the increase of acrylamide dosage. When the ratio of 2-acrylamido-2-methylpropanesulfonic acid:acrylamide:N-vinylcaprolactam:dimethyldiallylammonium chloride is 10:3:2:2, Comparative Example 2 exhibits the best temperature resistance, but it is only at 200℃. After the temperature increases to 230℃, the filtration loss increases significantly, while the viscosity and shear stress decrease sharply. After aging at 230℃ for 16 hours, the filtration loss reaches more than 18.00 mL, indicating that the hydrophilicity of the filtration loss reducers prepared in Comparative Examples 2-9 has significantly decreased, and they do not have a high-temperature resistance effect.

[0116] In Examples 2-8, as the amount of N-vinylcaprolactam increased from 10 parts to 25 parts, the filtration loss first decreased and then increased, while the viscosity and shear stress first increased and then decreased. This indicates that appropriate N-vinylcaprolactam is beneficial to enhancing the temperature resistance of the filtration loss reducer prepared in this invention. Furthermore, when the ratio of sodium styrene sulfonate: acrylamide: N-vinylcaprolactam: dimethyl diallyl ammonium chloride = 10:3:2:2, the comprehensive temperature resistance of Example 3 is the best. After aging at 200℃ for 16 hours, the filtration loss is only 6.4 mL, and after aging at 230℃ for 16 hours, the filtration loss is only 8.4 mL. It has good temperature resistance and can effectively regulate the rheology of drilling fluid and improve the filtration loss reduction performance to ensure safe operation in deep and ultra-deep wells.

[0117] In Comparative Example 1, the monomers from Examples 2-8 were used, and the preparation method was the same as in Comparative Examples 2-9. However, its temperature resistance was only 200°C, and it decreased significantly after the temperature reached 230°C. This demonstrates that only by using the synthetic route obtained from the mechanism study of this invention can this product be obtained.

[0118] 2. Observation of filtration loss during aging The mud cakes obtained after aging at 25, 180, 200, 220, and 230°C for 16 hours in Example 3 and Comparative Example 2 were observed, and the results were... Figures 8-9 As shown.

[0119] Depend on Figures 8-9 It can be seen that the mud cake properties of the fluid loss reducing agent prepared in Comparative Example 2 underwent significant changes, with the mud cake drying out and exhibiting varying degrees of cracks. In contrast, the mud cake properties of the fluid loss reducing agent prepared in Example 3 of this invention showed less change, with a more uniform particle distribution and a denser mud cake. This indicates that the fluid loss reducing agent has stronger temperature resistance, resulting in a more stable drilling fluid system and a better fluid loss reduction effect.

[0120] 3. Infrared analysis The molecular structures of the filtration loss reducing agents prepared in Example 3 and Comparative Example 2 were determined using an infrared spectrometer at 25, 180, 200, 220, and 230 °C. Figures 10-11 As shown.

[0121] Depend on Figures 10-11 It can be known that 1041.5cm -1 630.7cm -1 515cm -1 This is the characteristic absorption peak of sulfonic acid groups in SSS; 3468 cm⁻¹ -1 The absorption peak is for the NH stretching vibration, at 2931.8 cm⁻¹. -1 These are the vibrational absorption peaks of CH for methyl and methylene groups, characteristic peaks belonging to AM; 1680 cm⁻¹ -1 The characteristic absorption peak for the amide bond of N-vinylcaprolactam is 1463.9 cm⁻¹. -1 The absorption peak represents the stretching vibration of a five-membered nitrogen heterocycle and is a characteristic peak of diallyl dimethylammonium chloride. Infrared spectroscopy analysis indicates that the product prepared in this invention is the target high-temperature filtration reduction agent.

[0122] Then, the infrared spectrum of the filtration loss reducer prepared in Comparative Example 2 showed a gradual decrease in the number and type of functional groups after 200°C, and the spectrum became almost flat at 230°C, with almost no functional groups visible. In contrast, the functional groups in the infrared spectrum of the filtration loss reducer prepared in Example 3 were still present after 200°C / 230°C, and were even more prominent. This indicates that the filtration loss reducer obtained by selecting the monomer combination, functional group type and arrangement based on molecular simulation results, as well as the synthetic reaction strategy, is more stable at high temperatures, and the functional groups did not degrade or detach from the main chain.

[0123] 4. Thermogravimetric analysis The temperature resistance of the filtration loss reducing agents prepared in Example 3 and Comparative Example 2 was determined using a thermogravimetric analyzer, and the results are as follows: Figures 12-13 As shown. In thermogravimetric analysis, the first stage of mass loss is mainly due to interlayer dehydration or the detachment of bound water in the product, and the mass loss is not significant. The second stage is mainly due to the decomposition of functional groups or the separation of functional groups from the main chain.

[0124] Depend on Figures 12-13 It can be seen that the filtration loss reducer prepared in Comparative Example 2 had a mass loss of 7.02% in the first stage and a starting temperature of 281°C in the second stage. The filtration loss reducer prepared in Example 3 had a mass loss of 16.63% in the first stage and a starting temperature of 301°C in the second stage. Compared with Comparative Example 2, the filtration loss reducer prepared in Example 3 had a larger mass loss, indicating that the filtration loss reducer prepared in Example 3 had stronger hydrophilicity and a more stable molecular structure than Comparative Example 2, and therefore could better meet the current temperature resistance requirements for deep and ultra-deep aquifers.

[0125] 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 therein. Such 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 fluid loss additive based on molecular simulation mechanism, characterized in that, The raw materials include the following mass fractions: temperature-resistant monomer 50-100 parts, hydrophilic monomer 10-30 parts, heterocyclic monomer 2-10 parts, initiator 0.01-0.05 parts, pH regulator 25-35 parts, and deionized water 100-500 parts.

2. The anti-high temperature fluid loss additive based on molecular simulation mechanism according to claim 1, characterized in that, The temperature-resistant monomer is one or more combinations of sodium p-styrenesulfonate, maleimide, dimethyldiallylammonium chloride, and 1,7-bisphenylsulfonic acid octane; Further preferably, the temperature-resistant monomer is one or a combination of sodium p-styrenesulfonate and dimethyldiallylammonium chloride.

3. The anti-high temperature fluid loss additive based on molecular simulation mechanism according to claim 1, characterized in that, The hydrophilic monomer is one or more combinations of acrylic acid, acrylamide, vinyl alcohol, 1,2,6,7-tetracarboxyheptane, and 1,7-bisdimethylamino octane. Further preferably, the hydrophilic monomer is acrylamide.

4. The anti-high temperature fluid loss additive based on molecular simulation mechanism of claim 1, wherein, The heterocyclic monomer is one or a combination of N-vinylcaprolactam and N-vinylpyrrolidone. Further preferably, the heterocyclic monomer is N-vinylcaprolactam.

5. The anti-high temperature fluid loss additive based on molecular simulation mechanism of claim 1, wherein, The initiator is one or more combinations of azobisisobutyronitrile, ammonium persulfate, and potassium persulfate. Further preferably, the initiator is one or more combinations of azobisisobutyronitrile, ammonium persulfate, and potassium persulfate.

6. The anti-high temperature fluid loss additive based on molecular simulation mechanism of claim 1, wherein, The pH regulator is NaOH.

7. The anti-high temperature fluid loss additive based on molecular simulation mechanism of claim 1, wherein, The high-temperature-resistant filtrate reducer based on the molecular simulation mechanism includes the following mass fractions of raw materials: sodium p-styrenesulfonate 50 parts, acrylamide 15 parts, N-vinylcaprolactam 10 parts, dimethyldiallylammonium chloride 10 parts, ammonium persulfate 0.03 parts, NaOH 30 parts, and deionized water 300 parts.

8. The method for preparing the anti-high temperature fluid loss additive based on the mechanism of molecular simulation according to any one of claims 1-7, characterized in that, The steps include the following: A pH regulator solution with a mass fraction of 25-35% is prepared using a pH regulator; According to the ratio, part of the temperature-resistant monomer and the hydrophilic monomer are added to the deionized water at room temperature, and the pH regulator solution is added after stirring to fully dissolve, the pH value is adjusted to 6-7, nitrogen is introduced while stirring for 8-12 min, then the temperature is raised to 45-55°C, and the reaction is carried out under a nitrogen environment for 1.5-2.5 h; according to the ratio, the remaining temperature-resistant monomer, heterocyclic monomer, and initiator are continuously added, the temperature is raised to 60-70°C, and the reaction is carried out under a nitrogen environment for 1.5-2.5 h; the temperature is continuously raised to 75-85°C, and the reaction is continuously carried out under a nitrogen environment for 1.5-2.5 h, to obtain a gel solution; the gel solution is sealed and dried at 100-110°C to obtain the high-temperature-resistant filtrate reducer based on the molecular simulation mechanism.

9. Use of the high-temperature-resistant filtrate reducer based on the molecular simulation mechanism in claims 1-7 in the preparation of a drilling fluid.

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