A method for constructing quantitative structure-activity relationship of dendrimer molecular structure and salt tolerance, and application

Abstract

The application relates to a method for constructing a quantitative structure-activity relationship of a dendrimer molecular structure and salt tolerance and application. According to the quantitative structure-activity relationship, the salt tolerance of an oil field chemical polymer can be obtained according to the molecular structure of the dendrimer, without needing to pass through traditional experiments or complicated molecular simulation dynamics calculation. Meanwhile, the quantitative structure-activity relationship can be used to quickly screen the dendrimer with good salt tolerance, and has a good reference significance for the rapid design and research and development of the salt-resistant polymer for drilling fluid and even oil field chemicals.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical drilling fluid treatment agent technology, specifically relating to a method and application for constructing a quantitative structure-activity relationship of dendritic polymer molecular structure and salt resistance. Background Technology

[0002] Dendritic polymers (DPPs) are a new type of polymer with a dendritic structure. Their surfaces are rich in functional groups, and the molecules themselves are nanoscale with internal cavities. Due to their highly branched topology, dendritic molecules possess a compact, spherical structure in three-dimensional space. Currently, research on DPPs in petroleum engineering is still in its early stages, mainly focusing on utilizing their unique rheological properties and the active reactivity of their end groups. Much research has been conducted on shear-resistant polymers for improving oil recovery and amine inhibitors for drilling fluids. Polymer filtration reducers are key additives for ensuring drilling fluid performance and are used extensively in the field. Introducing DPPs into petroleum engineering can provide new means to solve some complex technical problems; however, research on DPP drilling fluid filtration reducers is currently limited, especially salt-resistant polymer filtration reducers, which remain a key research focus and challenge. Salt resistance is one of the important properties of oilfield chemical polymers. The damage of inorganic salts to polymers mainly manifests as viscosity reduction. Lower viscosity leads to poorer rheological properties of the drilling fluid, thus affecting the overall performance of the polymer solution. Therefore, when evaluating the salt resistance of polymers, the viscosity parameter of the polymer solution is crucial. Traditional experimental methods evaluate the salt resistance of polymer solutions by measuring the apparent viscosity of the polymer solution with a six-speed viscometer. This is a macroscopic evaluation method, which is subject to many limitations such as sample purity, source, and temperature conditions. Furthermore, it is believed that these factors have a significant impact and poor repeatability.

[0003] Molecular simulation technology is hailed as the third research method besides theoretical research and laboratory experiments. It uses computers as an aid to build molecular models at the atomic level and simulate the structure and behavior of molecules, thereby simulating various physical and chemical properties of molecular systems. Quantitative Structure-Activity Relationship (QSAR) refers to the use of theoretical calculations and statistical analysis tools to analyze the quantitative functional relationship between molecular structure descriptors and various physicochemical properties or activities. This allows for the study of the quantitative relationship between the structure of a series of compounds and their properties (such as surface tension), and the prediction of the properties of new compounds using these quantitative relationship models. Furthermore, QSAR models can help understand the structural factors that determine the properties of compounds, guiding subsequent molecular modifications.

[0004] Molecular simulations are widely used in the pharmaceutical, automotive, food, and aerospace industries, but their application in the petroleum industry, especially in upstream drilling engineering, is limited. While they have shown some application in drilling fluid polymer research, related patents are scarce. Existing patents CN104007463 A, CN103713320 A, and CN104007485 A respectively provide methods for creating and applying artificial shale physical models, establishing methods for building physical models of organic-rich shale mudstone, and establishing methods for building physical models of shale mudstone with complex pores. Although all fall under the geophysical research field of oil and gas exploration and development, the models constructed are all macroscopic physical models and cannot reflect the microscopic structure of shale mudstone. Patent CN111007233 A provides a method for analyzing the movement behavior of methane and carbon dioxide in the micropores of shale, but this patent uses numerical simulation methods, and the constructed model has poor applicability in the study of the exfoliation and expansion mechanism of shale mudstone.

[0005] Dendritic polymers are polymers composed of many long chains arranged in a tree-like structure. The single bonds within the molecules can rotate internally, resulting in many different conformations. Different conformations correspond to different molecular sizes, and in polymer physics, the radius of gyration R(g) is used to characterize the molecular size. When polymers are exposed to inorganic salts, the interaction between salt ions and polymer molecules causes changes in the polymer molecular size. R(g) can be obtained through molecular simulation calculations, thus characterizing the polymer's salt resistance. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a method for constructing a quantitative structure-property relationship between the molecular structure of dendritic polymers and their salt resistance from a molecular structure perspective. This method facilitates better simulation studies of the salt resistance of dendritic polymers from a molecular structure perspective, enabling rapid and effective evaluation of the salt resistance of drilling fluid dendritic polymers and providing technical support for drilling fluid performance in deep, ultra-high temperature formation environments.

[0007] Therefore, the first aspect of this invention provides a method for constructing a quantitative structure-property relationship between the molecular structure and salt resistance of dendritic polymers. This method, through QSAR analysis of commonly used water-soluble dendritic polymers, provides a quantitative structure-property relationship based on molecular simulation of the molecular structure and salt resistance of dendritic polymers, enabling rapid and effective evaluation of the salt resistance of drilling fluid dendritic polymers.

[0008] In some specific embodiments of the present invention, the method for constructing the quantitative structure-property relationship between dendritic polymer molecular structure and salt tolerance includes the following steps:

[0009] S1. Draw molecular structure models of water molecules, inorganic salt molecules, compounds that serve as the core in dendritic polymers, and compounds with bifunctional groups that react with the core in dendritic polymers, and optimize the structures.

[0010] S2, using the molecular structure models of the compounds that serve as the core in the dendritic polymer and the difunctional compounds that react with the core in the dendritic polymer drawn in the optimized step S1, construct the molecular structure model of the dendritic polymer and perform structural optimization.

[0011] S3, establish a box model of a polymer salt solution system containing a certain number of water molecules, inorganic salt molecules and dendritic polymer molecules in a minimum energy conformation, and set the density and temperature of the box.

[0012] S4, perform molecular dynamics calculations on the box of the polymer salt solution system model, and compare the box density value in the calculation result with the box density value set in step S3; when the deviation is less than the deviation range, perform molecular dynamics calculations of 100 to 1000 ps under the canonical ensemble;

[0013] S5. Analyze a series of data on the molecular dynamics equilibrium state obtained in step S4 to obtain the Rg probability distribution map, and calculate the Rg value by statistical averaging of the Rg probability distribution map.

[0014] S6. Based on the calculated Rg values ​​of a series of dendritic polymers, a statistical algorithm is used to obtain the quantitative structure-activity relationship between the molecular structure and salt tolerance of the dendritic polymers.

[0015] In this invention, by repeating steps S1-S5, a series of Rg values ​​for dendritic polymers are calculated.

[0016] In some embodiments of the present invention, in step S1, molecular structure models of water molecules, inorganic salt molecules, compounds that serve as the core in dendritic polymers, and compounds with bifunctional groups that react with the core in dendritic polymers are drawn using the drawing tools of Materials Studio software.

[0017] In this invention, the relevant molecular structure model is drawn using the Visualizer interface in the drawing tools of Materials Studio software.

[0018] In some embodiments of the present invention, the compound serving as the core in the dendritic polymer is selected from any one of bis(trimethylolpropane), pentaerythritol, and trimethylolpropane.

[0019] In other embodiments of the invention, the bifunctional compound that reacts with the core in the dendritic polymer is selected from any one of 2,2-dimethylolpropionic acid, trimethylolpropane-N,N-dihydroxyethyl-3-amino-2-propionate, oligomers of maleic anhydride and glycerol, and oligomers of maleic anhydride and diethanolamine.

[0020] In some embodiments of the present invention, in steps S1 and S2, structural optimization is performed using the Forcite module. Through structural optimization, the minimum energy conformation structure of the relevant model can be obtained.

[0021] In some other embodiments of the present invention, in step S2, a molecular model of the dendritic polymer is constructed using the Build tool.

[0022] In some embodiments of the present invention, in step S3, the polymer salt solution model box is built using the Amorphous Cell module.

[0023] In some other embodiments of the present invention, in step S3, the density of the box is set to 0.7–1.1 g / cm³. 3 The temperature is set to 298–493 K.

[0024] In some embodiments of the present invention, in step S4, the molecular dynamics calculation is performed using the dynamics calculation function of the Forcite module.

[0025] In some embodiments of the present invention, in step S5, the data obtained in step S4 is analyzed by the analysis function of the Forcite module.

[0026] In some embodiments of the present invention, the specific operation of performing molecular dynamics calculations on the box of the polymer salt water system model in step S4 is as follows: the box of the polymer salt water system model is first annealed under a canonical ensemble (NVT), and then subjected to molecular dynamics calculations of 100 to 1000 ps under an isothermal and isobaric ensemble (NPT).

[0027] In some embodiments of the present invention, in step S4, the deviation range is a deviation of less than 7%.

[0028] In some other embodiments of the present invention, in step S4, when the deviation is not less than the deviation range, the number of water molecules, inorganic salt molecules and dendritic polymer molecules contained in the box of the polymer salt aqueous solution system model is reset until the deviation is less than the deviation range.

[0029] In some embodiments of the present invention, in step S6, the statistical algorithm is a genetic function approximation algorithm.

[0030] In some specific embodiments of the present invention, the method specifically includes the following steps:

[0031] (1) Establish a single-component molecular structure model

[0032] In the Visualizer interface of Materials Studio software, molecular structures of water, inorganic salts, compounds acting as the core in dendritic polymers, and difunctional compounds reacting with the core in dendritic polymers were drawn. These molecular structures were then optimized using the Forcite module to obtain the minimum energy conformation. Next, the Build tool was used to construct a dendritic polymer molecular structure model from the molecular structures of the compounds acting as the core and the difunctional compounds reacting with the core, drawn in step S1, and then optimized. This process yields the minimum energy conformations of water, inorganic salts, and dendritic polymers.

[0033] (2) Establishing a model box for the polymer salt solution system

[0034] A box model of a polymer salt-water solution system containing a certain number of water molecules, inorganic salt molecules, and dendritic polymer molecules in a minimum energy conformation was constructed using the Amorphous Cell module, and the density of the box was set to 0.7–1.1 g / cm³. 3 The temperature is 298–493 K.

[0035] (3) Molecular dynamics calculations of equilibrium state

[0036] Molecular dynamics calculations were performed on the box of the polymer salt solution system model using the kinetic calculation function of the Forcite module. First, the box was annealed under a canonical ensemble (NVT), and then molecular dynamics calculations were performed for 100-1000 ps under an isothermal-isobaric ensemble (NPT). The box density value in the calculation results was compared with the box density value set in step (2). If the deviation was less than 7%, the box was subjected to kinetic calculations for 100-1000 ps under a canonical ensemble (NVT). If the deviation was not less than 7%, the number of water molecules, inorganic salt molecules and dendritic polymer molecules contained in the box of the polymer salt solution system model was reset until the deviation was less than 7%.

[0037] (4) Calculate Rg

[0038] The analysis function of the Forcite module is used to analyze a series of data on the molecular dynamics equilibrium state after NVT calculation, and to obtain the Rg probability distribution map. The Rg value is obtained by statistical averaging of the Rg probability distribution map.

[0039] (5) Constructing quantitative structure-activity relationship

[0040] Repeat steps (1)-(4) to calculate the radius of gyration Rg of a series of dendritic polymer salt solutions; then, based on the calculated radius of gyration Rg of a series of dendritic polymer salt solutions, use statistical algorithms to obtain the quantitative structure-activity relationship between the molecular structure and salt tolerance of the dendritic polymer.

[0041] The method described in this invention uses a combination of molecular mechanics and kinetic calculations to obtain the microscopic morphology and size of dendritic polymer molecules. Then, QSAR analysis is used to summarize the quantitative structure-activity relationship between the molecular structure and salt resistance of dendritic polymers, thereby obtaining their salt resistance through the molecular structure of dendritic polymers.

[0042] The second aspect of this invention provides the application of the method for constructing the molecular structure and quantitative structure-property relationship of dendritic polymers and their salt resistance as described in the first aspect of this invention in evaluating the salt resistance of dendritic polymers in drilling fluids.

[0043] The beneficial effects of this invention are as follows: The method described in this invention utilizes molecular simulation software to perform QSAR analysis on commonly used water-soluble dendritic polymers, constructing a quantitative structure-activity relationship (QSAR) between the molecular structure and salt tolerance of dendritic polymers. By utilizing the constructed QSAR, the salt tolerance of new dendritic polymers can be obtained based on their analyzed structures without the need for time-consuming molecular dynamics simulations, thus providing technical support for drilling fluid performance in deep, ultra-high temperature formation environments. Attached Figure Description

[0044] The invention will now be further described with reference to the accompanying drawings.

[0045] Figure 1 The optimized molecular structure model for the dendritic polymer HBP (DTMP-DMPA).

[0046] Figure 2 This is a structural model of the dendritic polymer HBP (DTMP-DMPA) in a salt solution system after molecular dynamics equilibrium.

[0047] Figure 3 This is a probability distribution diagram of the radius of gyration Rg of the dendritic polymer HBP (DTMP-DMPA).

[0048] Figure 4 This is the convergence curve for the QSAR descriptor. Detailed Implementation

[0049] To make the present invention easier to understand, the present invention will be further described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of the present invention. Unless otherwise specified, the raw materials or components used in the present invention can be obtained commercially or by conventional methods.

[0050] Example 1

[0051] The salt resistance of dendritic poly(bis(trimethylolpropane-2,2-dimethylolpropionic acid)) (HBP(DTMP-DMPA)) at a 10% NaCl ion concentration was evaluated.

[0052] (1) Establish a single-component molecular structure model

[0053] Using the Materials Studio software's drawing tools, molecular structure models of water molecules, NaCl molecules, the core compound bis(trimethylolpropane) (DTMP), and the bifunctional compound 2,2-dimethylolpropionic acid (DMPA) reacting with the core were drawn. Structure optimization was performed using the Forcite module with a COMPASSII force field. First-generation dendritic polymer molecular structure models of DTMP and DMPA were constructed using the Biuld tool, and further optimized using Forcite. The optimized molecular structure model of the dendritic polymer HBP (DTMP-DMPA) is shown below. Figure 1 As shown.

[0054] (2) Establish a model of the polymer salt solution system

[0055] The polymer solution system model was created using the Amorphous Cell module as follows: HBP (DTMP-DMPA) was selected, and the number of molecules was set to 1; NaCl molecules were selected, and the number of molecules was set to 27; water molecules were selected, and the number of molecules was set to 800; the force field was COMPASSII. The resulting model had a side length of... The box model of the polymer salt solution system. The density of the box is set to 1.0 g / cm³. 3 The temperature is 453K.

[0056] (3) Molecular dynamics calculations of equilibrium state

[0057] Molecular dynamics calculations were performed on the box model of the polymer salt solution system using the kinetics calculation function of the Forcite module. Specifically, the annealing function was selected in the Forcite module, and five cycles were performed from 300K to 500K to obtain a series of structures. The structure with the lowest energy was selected, and molecular dynamics calculations were performed using the kinetics function of the module. First, the NPT ensemble and 453K conditions were selected, and molecular dynamics calculations were performed at 100 ps and 100,000 steps. The temperature control method was Nose, and the pressure control method was Berendsen. The actual box density in the calculation results was 1.021 g / cm3, which was less than the deviation range. The next step, NVT ensemble molecular dynamics calculation, was performed with the same parameters as above, to obtain the structural model of the dendritic polymer in the salt solution system after molecular dynamic equilibrium, as shown below. Figure 2 As shown.

[0058] (4) Calculate Rg

[0059] Using the analysis function of the Forcite module, a series of data on the molecular dynamics equilibrium state after NVT calculation were analyzed to obtain the Rg probability distribution map, such as... Figure 3 As shown, the Rg value is obtained by statistical averaging of the Rg probability distribution map.

[0060] Example 2

[0061] The salt resistance of dendritic poly(trimethylolpropane-2,2-dimethylolpropionic acid) (HBP(TMP-DMPA)) at a 10% NaCl ion concentration was evaluated.

[0062] (1) Establish a single-component molecular structure model

[0063] Using the Materials Studio software's drawing tools, molecular structure models of water molecules, NaCl molecules, trimethylolpropane (TMP) as the core compound, and 2,2-dimethylolpropionic acid (DMPA), a bifunctional compound reacting with the core, were drawn. Structure optimization was performed using the Forcite module with a COMPASSII force field. First-generation dendritic polymer molecular structure models of TMP and DMPA were constructed using the Biuld tool, and further optimized using Forcite. The optimized molecular structure model of the dendritic polymer HBP (TMP-DMPA) was then obtained.

[0064] (2) Establish a model of the polymer salt solution system

[0065] The polymer solution system model was created using the Amorphous Cell module as follows: HBP (TMP-DMPA) was selected, and the number of molecules was set to 1; NaCl molecules were selected, and the number of molecules was set to 27; water molecules were selected, and the number of molecules was set to 800; the force field was selected as COMPASSII. The resulting model had a side length of... The box model of the polymer salt solution system. The density of the box is set to 1.0 g / cm³. 3 The temperature is 453K.

[0066] (3) Molecular dynamics calculations of equilibrium state

[0067] Molecular dynamics calculations were performed on the box model of the polymer salt solution system using the kinetics calculation function of the Forcite module. Specifically, the annealing function was selected in the Forcite module, and five cycles were performed from 300K to 500K to obtain a series of structures. The structure with the lowest energy was selected, and molecular dynamics calculations were performed using the kinetics function of the module. First, the NPT ensemble and 453K conditions were selected, and molecular dynamics calculations were performed at 100 ps and 100,000 steps. The temperature control method was Nose, and the pressure control method was Berendsen. The actual box density value in the calculation results was 1.014 g / cm³. 3 If the deviation is less than the specified range, proceed to the next step of NVT ensemble molecular dynamics calculation, with the same parameter selection as above, to obtain the structural model of the dendritic polymer in the salt solution system after molecular dynamic equilibrium.

[0068] (4) Calculate Rg

[0069] The analysis function of the Forcite module is used to analyze a series of data on the molecular dynamics equilibrium state after NVT calculation, and to obtain the Rg probability distribution map. The Rg value is obtained by statistical averaging of the Rg probability distribution map.

[0070] Example 3

[0071] The salt resistance of dendritic poly(trimethylolpropane-maleic anhydride / diethanolamine oligomer) (HBP(TMP-MAN / DEA)) at a 10% NaCl ion concentration was evaluated.

[0072] (1) Establish a single-component molecular structure model

[0073] Using the Materials Studio software's drawing tools, molecular structure models of water molecules, NaCl molecules, trimethylolpropane (TMP) as the core compound, and oligomers (MAN / DEA) containing bifunctional compounds maleic anhydride and diethanolamine reacting with the core were drawn. Structure optimization was performed using the Forcite module with a COMPASSII force field. First-generation dendritic polymer molecular structure models of TMP and MAN / DEA were constructed using the Biuld tool, and further optimized using Forcite, resulting in the optimized molecular structure model of the dendritic polymer HBP (TMP-MAN / DEA).

[0074] (2) Establish a model of the polymer salt solution system

[0075] The polymer solution system model was created using the Amorphous Cell module. Specifically: HBP (TMP-MAN / DEA) was selected, and the number of molecules was set to 1; NaCl molecules were selected, and the number of molecules was set to 27; water molecules were selected, and the number of molecules was set to 800; the force field was selected as COMPASSII. The resulting model had a side length of... The box model of the polymer salt solution system. The density of the box is set to 1.0 g / cm³. 3 The temperature is 453K.

[0076] (3) Molecular dynamics calculations of equilibrium state

[0077] Molecular dynamics calculations were performed on the box model of the polymer salt solution system using the kinetics calculation function of the Forcite module. Specifically, the annealing function was selected in the Forcite module, and five cycles were performed from 300K to 500K to obtain a series of structures. The structure with the lowest energy was selected, and molecular dynamics calculations were performed using the kinetics function of the module. First, the NPT ensemble and 453K conditions were selected, and molecular dynamics calculations were performed at 100 ps and 100,000 steps. The temperature control method was Nose, and the pressure control method was Berendsen. The actual box density value in the calculation results was 1.024 g / cm³. 3 If the deviation is less than the specified range, proceed to the next step of NVT ensemble molecular dynamics calculation, with the same parameter selection as above, to obtain the structural model of the dendritic polymer in the salt solution system after molecular dynamic equilibrium.

[0078] (4) Calculate Rg

[0079] The analysis function of the Forcite module is used to analyze a series of data on the molecular dynamics equilibrium state after NVT calculation, and to obtain the Rg probability distribution map. The Rg value is obtained by statistical averaging of the Rg probability distribution map.

[0080] Example 4

[0081] Evaluation of the salt resistance of dendritic poly(pentaerythritol-maleic anhydride / glycerol oligomer) (HBP(PETP-MAN / VG)) at 10% NaCl ion concentration.

[0082] (1) Establish a single-component molecular structure model

[0083] Using the Materials Studio software's drawing tools, molecular structure models were drawn for water molecules, NaCl molecules, pentaerythritol (PETP) as the core compound, and oligomers (MAN / VG) containing maleic anhydride and glycerol, both bifunctional compounds reacting with the core. Structure optimization was performed using the Forcite module with a COMPASSII force field. First-generation dendritic polymer molecular structure models of PETP and MAN / VG were constructed using the Biuld tool, and further optimized using Forcite. The optimized molecular structure model of the dendritic polymer HBP (PETP-MAN / VG) was then obtained.

[0084] (2) Establish a model of the polymer salt solution system

[0085] The polymer solution system model was created using the Amorphous Cell module. Specifically, HBP (PETP-MAN / VG) was selected, with a molecular count of 1; NaCl molecules were selected, with a molecular count of 27; water molecules were selected, with a molecular count of 800; and COMPASSII was selected as the force field. The resulting model had a side length of... The box model of the polymer salt solution system. The density of the box is set to 1.0 g / cm³. 3 The temperature is 453K.

[0086] (3) Molecular dynamics calculations of equilibrium state

[0087] Molecular dynamics calculations were performed on the box of the polymer salt solution system model using the kinetics calculation function of the Forcite module. Specifically, the annealing function was selected in the Forcite module, and five cycles were performed from 300K to 500K to obtain a series of structures. The structure with the lowest energy was selected, and molecular dynamics calculations were performed using the kinetics function of the module. First, the NPT ensemble and 453K conditions were selected, and molecular dynamics calculations were performed at 100 ps and 100,000 steps. The temperature control method was Nose, and the pressure control method was Berendsen. The actual box density value in the calculation results was 1.031 g / cm³. 3 If the deviation is less than the specified range, proceed to the next step of NVT ensemble molecular dynamics calculation, with the same parameter selection as above, to obtain the structural model of the dendritic polymer in the salt solution system after molecular dynamic equilibrium.

[0088] (4) Calculate Rg

[0089] The analysis function of the Forcite module is used to analyze a series of data on the molecular dynamics equilibrium state after NVT calculation, and to obtain the Rg probability distribution map. The Rg value is obtained by statistical averaging of the Rg probability distribution map.

[0090] Example 5

[0091] The salt resistance of dendritic poly(trimethylolpropane-trimethylolpropane-N,N-dihydroxyethyl-3-amino-2-propionate) (HBP(TMP-MMADEA)) at a 10% NaCl ion concentration was evaluated.

[0092] (1) Establish a single-component molecular structure model

[0093] Using the Materials Studio software's drawing tools, molecular structure models of water molecules, NaCl molecules, trimethylolpropane (TMP) as the core compound, and trimethylolpropane-N,N-dihydroxyethyl-3-amino-2-propionate (MMADEA), a bifunctional compound reacting with the core, were drawn. Structural optimization was performed using the Forcite module with a COMPASSII force field. First-generation dendritic polymer molecular structure models of TMP and MMADEA were constructed using the Biuld tool, and further optimized using Forcite. The optimized molecular structure model of the dendritic polymer HBP (TMP–MMADEA) was then obtained.

[0094] (2) Establish a model of the polymer salt solution system

[0095] The polymer solution system model was created using the Amorphous Cell module. Specifically: HBP (TMP-MMADEA) was selected, and the number of molecules was set to 1; NaCl molecules were selected, and the number of molecules was set to 27; water molecules were selected, and the number of molecules was set to 800; the force field was selected as COMPASSII. The resulting model had a side length of... The box model of the polymer salt solution system. The density of the box is set to 1.0 g / cm³. 3 The temperature is 453K.

[0096] (3) Molecular dynamics calculations of equilibrium state

[0097] Molecular dynamics calculations were performed on the box model of the polymer salt solution system using the kinetics calculation function of the Forcite module. Specifically, the annealing function was selected in the Forcite module, and five cycles were performed from 300K to 500K to obtain a series of structures. The structure with the lowest energy was selected, and molecular dynamics calculations were performed using the kinetics function of the module. First, the NPT ensemble and 453K conditions were selected, and molecular dynamics calculations were performed at 100 ps and 100,000 steps. The temperature control method was Nose, and the pressure control method was Berendsen. The actual box density value in the calculation results was 1.020 g / cm³. 3 If the deviation is less than the specified range, proceed to the next step of NVT ensemble molecular dynamics calculation, with the same parameter selection as above, to obtain the structural model of the dendritic polymer in the salt solution system after molecular dynamic equilibrium.

[0098] (4) Calculate Rg

[0099] The analysis function of the Forcite module is used to analyze a series of data on the molecular dynamics equilibrium state after NVT calculation, and to obtain the Rg probability distribution map. The Rg value is obtained by statistical averaging of the Rg probability distribution map.

[0100] Example 6

[0101] QSAR analysis was performed on the radius of gyration Rg of the dendritic polymer plugging and filtration loss reducing agent obtained in Examples 1-5 above. Before performing QSAR calculation, molecular descriptors must first be selected. 191 molecular descriptors were used in this calculation. After QSAR calculation using the input molecular descriptors, statistical analysis was performed on the data. The method used was the genetic function approximation algorithm. The approximate equation of the genetic function of the dendritic polymer is as follows:

[0102] Y = -0.020471446*X15 - 0.265038762*X31 + 0.232064928*X34 + 0.339317966*X62 + 0.866203243*X65 + 20.059413103*X173 + 3.457911776; where X15: polarity (VAMP descriptor) yzQuadrupole yz(VAMP Electrostatics)

[0103] X31: Mean polarizability (VAMP Electrostatics)

[0104] X34: Hydrogen bond acceptor (Fast Descriptor)

[0105] X62:Chi(0)(Fast Descriptors)Chi(0)(valence modified)(Fast Descriptors)

[0106] X65:Chi(3) (Fast Descriptors)Chi(3):path(valence modified) (Fast Descriptors)

[0107] X173: Fractional atomic charge-weighted negative surface area (Jurs descriptor) FNSA3 (Jurs Descriptors)

[0108] Comparing the descriptor data of the independent variables in the genetic function equation with the fitting equation given by the software, it can be seen that the sum of the electronic states of the descriptors: positive charge plays a major role in the molecular structure. As can be seen from the analysis of the index parameters, positive charge can improve the adsorption performance index parameters of dendritic polymers.

[0109] Molecular simulation software was used to simulate the relationship between the molecular structure of dendritic polymers and their adsorption performance parameters. Based on the same structure, a genetic function approximation algorithm was applied to obtain the genetic function approximation equation, establish the quantitative structure-activity relationship, and obtain the genetic function approximation equation curve, such as... Figure 4 As shown, the calculation curve converges, and the verification parameters R2 and R2-CV are both above 0.999, indicating that the simulation accuracy reaches 99%. The QSAR validity verification parameters demonstrate that the obtained equation is accurate and effective.

[0110] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for constructing a quantitative structure-activity relationship between the molecular structure and salt tolerance of dendritic polymers, comprising the following steps: S1. Draw molecular structure models of water molecules, inorganic salt molecules, compounds that serve as the core in dendritic polymers, and compounds with bifunctional groups that react with the core in dendritic polymers, and optimize the structures. S2, using the molecular structure models of the compounds that serve as the core in the dendritic polymer and the difunctional compounds that react with the core in the dendritic polymer drawn in the optimized step S1, construct the molecular structure model of the dendritic polymer and perform structural optimization. S3, establish a box model of a polymer salt solution system containing a certain number of water molecules, inorganic salt molecules and dendritic polymer molecules in a minimum energy conformation, and set the density and temperature of the box. S4, perform molecular dynamics calculations on the box of the polymer salt solution system model, and compare the box density value in the calculation result with the box density value set in step S3; when the deviation is less than the deviation range, perform molecular dynamics calculations of 100~1000ps under the canonical ensemble; S5. Analyze a series of data on the molecular dynamics equilibrium state obtained in step S4 to obtain the Rg probability distribution map, and calculate the Rg value by statistical averaging of the Rg probability distribution map. S6. Based on the calculated Rg values ​​of a series of dendritic polymers, a statistical algorithm is used to obtain the quantitative structure-activity relationship between the molecular structure and salt tolerance of the dendritic polymers. In step S1, the molecular structure models of water molecules, inorganic salt molecules, compounds that serve as the core in dendritic polymers, and difunctional compounds that react with the core in dendritic polymers are drawn using the Visualizer interface in the drawing tools of Materials Studio software. The compounds that serve as the core in dendritic polymers are selected from any one of bis(trimethylolpropane), pentaerythritol, and trimethylolpropane. The difunctional compounds that react with the core in dendritic polymers are selected from any one of 2,2-dimethylolpropionic acid, trimethylolpropane-N,N-dihydroxyethyl-3-amino-2-propionate, oligomers of maleic anhydride and glycerol, and oligomers of maleic anhydride and diethanolamine.

2. The method according to claim 1, characterized in that, In steps S1 and S2, structural optimization is performed using the Forcite module; and / or In step S2, a molecular model of the dendritic polymer is constructed using the Build tool.

3. The method according to claim 1 or 2, characterized in that, In step S3, the model box of the polymer salt solution system is built using the Amorphous Cell module; and / or The density of the box is set to 0.7~1.1 g / cm³. 3 The temperature is set to 298~493K.

4. The method according to claim 1 or 2, characterized in that, In step S4, the molecular dynamics calculations are performed using the dynamics calculation function of the Forcite module; and / or In step S5, the data obtained in step S4 is analyzed using the analysis function of the Forcite module.

5. The method according to claim 1 or 2, characterized in that, In step S4, the specific operation for performing molecular dynamics calculations on the box of the polymer salt solution system model is as follows: the box of the polymer salt solution system model is first annealed under a canonical ensemble, and then subjected to molecular dynamics calculations of 100~1000 ps under an isothermal and isobaric ensemble.

6. The method according to claim 1 or 2, characterized in that, In step S4, the deviation range is a deviation of less than 7%.

7. The method according to claim 1 or 2, characterized in that, In step S4, when the deviation is not less than the deviation range, the number of water molecules, inorganic salt molecules and dendritic polymer molecules contained in the box of the polymer salt aqueous solution system model is reset until the deviation is less than the deviation range.

8. The method according to claim 1 or 2, characterized in that, In step S6, the statistical algorithm is a genetic function approximation algorithm.

9. The application of the method for constructing the molecular structure and quantitative structure-property relationship of dendritic polymers and their salt resistance as described in any one of claims 1-8 in evaluating the salt resistance of dendritic polymers in drilling fluids.

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