A molecular simulation method and system for drilling fluid treatment agent / solvent mechanism

Abstract

The application provides a molecular simulation method for the mechanism of drilling fluid treating agent / solvent, comprising the following steps: constructing a drilling fluid treating agent / solvent binary system model; determining force field parameters and simulation parameters of the drilling fluid treating agent and the solvent molecules; sequentially performing dynamic equilibrium of the drilling fluid treating agent / solvent binary system under NVT ensemble and NPT ensemble according to the force field parameters and the simulation parameters; after the drilling fluid treating agent / solvent binary system reaches the specified temperature and pressure parameters, performing molecular dynamics simulation on the drilling fluid treating agent / solvent binary system under NPT ensemble, taking the last trajectory file to calculate dynamic parameters, and completing the micro evaluation of the drilling fluid treating agent binary system. The application can characterize the law of the interaction between the water-based drilling fluid treating agent and water molecules under high temperature and high pressure conditions from the atomic scale, and can in-situ characterize the micro dynamics of the treating agent molecules under high temperature environment, thereby reducing the experimental cost.

Description

Technical Field

[0001] This invention relates to the field of drilling fluid molecular simulation technology, and more specifically, to a molecular simulation method and system for the action mechanism of drilling fluid treatment agents / solvents. Background Technology

[0002] Drilling fluid is considered the lifeblood of petroleum engineering, directly impacting drilling safety. Numerous treatment agents are required in drilling fluid systems, such as filtration reducers, inhibitors, clay coating agents, and flow modifiers. During ultra-deep well drilling, the extremely high temperature and pressure environment can cause drilling fluid systems to fail, disrupting their colloidal stability and causing them to lose their original functions, thus threatening drilling safety. For example, the failure of filtration reducers can lead to a sharp increase in filtration loss, affecting the drilling fluid's wall-building performance; the failure of inhibitors can cause wellbore narrowing and stuck pipe when encountering shale; and the failure of flow modifiers can accelerate drill string wear and affect system viscosity. Evaluating the temperature resistance and mechanisms of treatment agents is challenging. Firstly, experimental methods have limited testable temperature and pressure ranges, particularly the inability to characterize the failure process and kinetic behavior of treatment agents under extremely high temperature and pressure in situ. Secondly, the required experimental instruments and equipment are expensive, making it difficult to comprehensively evaluate all aspects of the treatment agent. Molecular simulation technology can establish molecular structure models of drilling fluid treatment agents, revealing the performance of the treatment agents under high temperature and high pressure conditions at the microscopic level, thus providing a theoretical basis for explaining the failure mechanism of drilling fluid systems and developing new temperature-resistant treatment agents.

[0003] However, existing molecular simulation methods do not take into account the influence of solvent molecules on organic substances. Furthermore, solvent molecules significantly affect the solubility of organic substances. Compared to room temperature, the characteristic parameters of solvent molecules in drilling fluid systems at ultra-high temperatures, such as polarity, dielectric constant, hydrogen bonding, and density, all change considerably. Therefore, using existing technologies, it is difficult to simulate and analyze the failure mechanisms of drilling fluid treatment agents at ultra-high temperatures. Summary of the Invention

[0004] In view of this, the present invention proposes a molecular simulation method and system for the action mechanism of drilling fluid treatment agents / solvents, aiming to solve the problem that it is difficult to perform in-situ characterization of the microscopic kinetic properties of drilling fluid treatment agents under high temperature and high pressure conditions, and the experimental cycle and cost are both high in the existing technology.

[0005] This invention proposes a molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents, comprising the following steps:

[0006] Step 1: Construct a binary system model of drilling fluid treatment agent / solvent;

[0007] Step 2: Determine the force field parameters and simulation parameters of the drilling fluid treatment agent and solvent molecules. The simulation parameters include: temperature and pressure control method, step size, cutoff radius, trajectory output control, temperature, pressure, and periodic boundary conditions.

[0008] Step 3: Based on the force field parameters and the simulation parameters, the drilling fluid treatment agent / solvent binary system is subjected to kinetic equilibrium for 1-10 ns under the NVT ensemble and NPT ensemble in sequence to complete the system optimization;

[0009] Step 4: After the drilling fluid treatment agent / solvent binary system reaches the specified temperature and pressure parameters, perform a 10-20 ns molecular dynamics simulation of the drilling fluid treatment agent / solvent molecular binary system under the NPT ensemble, and use the trajectory file of the last 2-6 ns to calculate the dynamic parameters to complete the microscopic evaluation of the drilling fluid treatment agent / solvent molecular binary system.

[0010] Furthermore, in the molecular simulation method for the action mechanism of the drilling fluid treatment agent / solvent described above, step 1, constructing a binary molecular system model of the drilling fluid treatment agent / solvent, includes:

[0011] The molecular structure of the drilling fluid treatment agent was created using the modeling module in the molecular simulation software Material Studio.

[0012] A simulation box is created, and the drilling fluid treatment agent molecules are added to the simulation box. Then, multiple solvent molecules of preset molecular models are added to the simulation box to ensure that the solvent molecules cover the entire simulation box and have good contact with the drilling fluid treatment agent molecules, thus obtaining the structure file of the final drilling fluid treatment agent / solvent molecule binary system model.

[0013] Furthermore, in the above molecular simulation method for the action mechanism of drilling fluid treatment agent / solvent, the drilling fluid treatment agent molecule is 1,8-dicarboxamidoheptane or 1,7-dibenzenesulfonic acid-octane; and / or the solvent is water or ethanol, and the preset molecular model is SPC / E type.

[0014] Furthermore, in the molecular simulation method for the action mechanism of the drilling fluid treatment agent / solvent mentioned above, the force field parameters include: atom type, bond length, bond angle, dihedral angle, charge distribution, and non-bonded interaction parameters.

[0015] Furthermore, in the molecular simulation method for the action mechanism of the drilling fluid treatment agent / solvent described above, in step 2, the OPLS-AA force field parameters of the drilling fluid treatment agent are obtained through the Ligpargen website, and the force field parameters of the drilling fluid treatment agent molecules and solvent molecules are written together into the same .itp file.

[0016] Furthermore, in the molecular simulation method for the action mechanism of the drilling fluid treatment agent / solvent described above, the kinetic equilibrium process includes:

[0017] The energy of the aforementioned agent / solvent binary system is minimized to obtain the energy-minimized structure file;

[0018] Create an MDP file under the NVT ensemble, set MD to the time integration algorithm in the MDP file, set the time step and total number of steps, specify to continue the current simulation from the previous simulation state, use the v-rescale method to control the temperature of the system, and set the initial temperature to 373K-583K. Input the topology file, structure file and MDP file under the NVT ensemble in the energy minimization step as the initial file, repeatedly run gmx grompp to prepare simulation commands and gmx mdrun to execute simulation commands in the simulation energy minimization process, and output the structure file after equilibrium under the NVT ensemble and the state information file during the simulation process.

[0019] Create an MDP file under the NPT ensemble. In the MDP file, set MD to the time integration algorithm, set the time step and total number of steps, and specify that the simulation should continue from the previous simulation state. Use the v-rescale method to control the system temperature, setting the initial temperature to 373K-583K. Use the Berendsen method to control the system pressure, setting the initial pressure to 1000 bar. Input the structure file obtained from the NVT ensemble, the state information file during the simulation, the topology file, and the MDP file under the NPT ensemble. Repeatedly run the gmx grompp command to prepare the simulation command and the gmx mdrun command to execute the simulation command during the simulation energy minimization process. Output the structure file after equilibrium under the NPT ensemble and the state information file during the simulation.

[0020] Furthermore, in the above-mentioned molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents, step 4 includes the following steps:

[0021] Using the structure file obtained in step 3, create an mdp file under the NPT ensemble, set the total number of simulation steps, change the pressure control mode to Parrinello-Rahman, set the temperature to 373K, 403K, 433K, 463K, 493K, 523K, 553K and 583K respectively, and set the pressure control to 1000, 1500, 2000 and 2500 respectively. Repeat the dynamic simulation steps under the NPT ensemble in step S3 to obtain the structure file, energy file and trajectory file for the dynamic simulation temperature range of 373K-583K and the pressure range of 100MPa-250MPa.

[0022] Use the gmx make_ndx command to obtain the index file of the simulation system. Use the gmx hbond command to input the trajectory file, storage system architecture information file and index file from the previous step. Select the drilling fluid treatment agent molecules and solvent molecules to obtain the number of hydrogen bonds of the drilling fluid treatment agent molecules and solvent molecules.

[0023] Using the gmx msd command, input the trajectory file, storage architecture information file, and index file from the gmx make_ndx command steps, select the solvent molecule, and obtain the diffusion coefficient of the solvent molecule;

[0024] Using the gmx sasa command, input the trajectory file, storage architecture information file, and index file from the gmx msd command steps, select the drilling fluid treatment agent, and obtain the solvent-accessible surface area of ​​the drilling fluid treatment agent.

[0025] Furthermore, in the molecular simulation method for the action mechanism of the drilling fluid treatment agent / solvent described above, the energy minimization process includes the following steps:

[0026] Create a control file with the extension .mdp that describes the simulation parameters and a topology file with the extension .top;

[0027] The gmx grompp command is used to process topology files, structure files, and mdp files to obtain files with the .tpr extension that store simulation running parameters and architecture information.

[0028] The file containing simulation parameters and architecture information, with the extension .tpr, is run using the gmx mdrun command to obtain the energy-minimized architecture file.

[0029] The molecular simulation method for the action mechanism of drilling fluid treatment agent / solvent in this invention can characterize the interaction between water-based drilling fluid treatment agent and water molecules under high temperature and high pressure conditions at the atomic scale. This solves the problem of difficulty in in-situ characterization of the microscopic dynamic characteristics of treatment agent molecules under high temperature and high pressure conditions in drilling engineering. Based on the advantages of computational simulation, it can reduce experimental costs and shorten the research and development cycle.

[0030] This invention also provides a molecular simulation system for the action mechanism of drilling fluid treatment agents / solvents, comprising:

[0031] A model building module is used to build a binary system model of drilling fluid treatment agents and solvents;

[0032] A kinetic equilibrium module is used to optimize the drilling fluid treatment agent / solvent binary system so that the atoms in the drilling fluid treatment agent and solvent binary system model are in reasonable positions.

[0033] The kinetic simulation module is used to perform kinetic simulations on the drilling fluid treatment agent / solvent binary system to provide data for subsequent analysis.

[0034] The analysis module is used to analyze the kinetic parameters of the components in the drilling fluid treatment agent / solvent binary system during kinetic simulation, and to complete the mechanism of action analysis.

[0035] The molecular simulation system for the action mechanism of drilling fluid treatment agents / solvents in this invention solves the problem of difficulty in in-situ characterization of the microscopic dynamics of treatment agent molecules under high temperature and high pressure environments in drilling engineering. Based on the advantages of computational simulation, it can reduce experimental costs and shorten the research and development cycle. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0037] Figure 1 A schematic flowchart illustrating the molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents provided in this embodiment of the invention;

[0038] Figure 2 This is a model diagram of the 1,8-dicarboxamidoheptane / water binary system constructed in Example 1 of this invention;

[0039] Figure 3 This is a graph showing the change in the number of hydrogen bonds between water molecules as a function of temperature and pressure conditions in Example 1 of the present invention.

[0040] Figure 4 This is a graph showing the variation of solvent molecule diffusion coefficient with temperature and pressure conditions in Example 1 of the present invention;

[0041] Figure 5 This is a graph showing the change of SASA of 1,8-dicarboxamidoheptane in Example 1 of the present invention with temperature and pressure conditions;

[0042] Figure 6 This is a graph showing the change in the number of hydrogen bonds between water molecules as a function of temperature and pressure conditions in Example 2 of the present invention.

[0043] Figure 7 This is a graph showing the change of solvent molecule diffusion coefficient with temperature and pressure conditions in Example 2 of the present invention;

[0044] Figure 8 This is a graph showing the change in SASA of 1,7-dibenzenesulfonic acid-octane with temperature and pressure conditions in Example 2 of the present invention. Detailed Implementation

[0045] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] Method Implementation Examples:

[0047] See Figure 1 The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents in this invention includes the following steps:

[0048] Step S1: Construct a binary system model of drilling fluid treatment agent / solvent.

[0049] Specifically, the molecular structure of the drilling fluid treatment agent is created using the modeling module in the molecular simulation software Material Studio, thereby creating a drilling fluid treatment agent model;

[0050] Create a simulation box, add the drilling fluid treatment agent molecules into the simulation box, and then add multiple (e.g., 5000) solvent molecules from a preset molecular model into the simulation box, ensuring that the solvent molecules cover the entire simulation box and have good contact with the drilling fluid treatment agent molecules, to obtain the final structure file. The number of solvent molecules in the preset molecular model needs to take into account factors such as periodic boundaries, cutoff radii, and actual computational load. When modeling molecular simulations, a near-reasonable system needs to be established. For example, if the volume of the simulation box is fixed, and the temperature is set to 373K and the pressure to 1 bar, then the number of water molecules filled must make the density of the box close to the actual value of the aqueous phase under those temperature and pressure conditions. In other words, it needs to be selected according to the actual physical properties of the solvent. For example, when ethanol is chosen as the solvent, its density at room temperature is less than that of water, so the same box will require fewer molecules than when water is used as the solvent.

[0051] In practice, the molecular structure can be manually drawn using the "Draw" tool in the "Build" menu of the molecular simulation software Material Studio. In the molecular modeling interface, use the atom addition tool in the toolbar to add carbon, hydrogen, oxygen, and nitrogen atoms one by one to construct the molecular structure of the drilling fluid treatment agent. Use the bond addition tool in the toolbar to add bonds between atoms according to the type of chemical bond, constructing the chemical bonds in the molecule. As needed, the conformation of the molecule can be adjusted by dragging atoms or bonds to conform to the desired structure. Export the .gro file. Using the gmxsolvate command in Gromacs software, add one drilling fluid treatment agent molecule and 5000 solvent molecules, ensuring that the solvent molecules cover the entire box and have good contact with the drilling fluid treatment agent molecule. The model size is determined by the number of solvent molecules, resulting in the final structure file with the .gro extension, and its configuration is as follows. Figure 2 As shown.

[0052] Step S2: Determine the force field parameters and simulation parameters of the drilling fluid treatment agent and solvent molecules.

[0053] Specifically, the force field parameters include the names, types, charge distributions, bond lengths, bond angles, dihedral angles, and non-bonded interaction parameters of the atoms. The OPLS-AA force field parameters of the drilling fluid treatment agent are obtained from the Ligpargen website in ITP file format, and the force field parameters of the drilling fluid treatment agent molecules and solvent molecules are written into the same ITP file. The simulation parameters include: temperature and pressure control methods, step size, cutoff radius, trajectory output control, temperature, pressure, and periodic boundary conditions, etc.

[0054] In this embodiment, the drilling fluid treatment agent molecule is 1,8-dicarboxamidoheptane or 1,7-dibenzenesulfonic acid-octane; the solvent is water or ethanol; and the preset molecular model is SPC / E type.

[0055] Taking water as the solvent as an example, SPC / E type water molecules can be selected as the solvent. Gromacs comes with a variety of water molecule force field parameters, including SPC / E. The force field parameters of 1,8-dicarboxamidoheptane and water molecules are written together into the same .itp file.

[0056] The temperature and pressure parameters in this step refer to the temperature and pressure ranges for molecular dynamics simulations. These ranges can be set according to actual needs. For example, a temperature range of 373K-583K and a pressure range of 100MPa-250MPa can be selected.

[0057] Step S3: Based on the force field parameters and the simulation parameters, the agent / solvent binary system is kinetically balanced for 1-10 ns under the NVT and NPT ensembles, respectively, to complete system optimization. The equilibration time can also be 1-3 ns or 1-5 ns, depending on the complexity of the system.

[0058] Specifically, the dynamic equilibrium process includes:

[0059] Sub-step S31 involves minimizing the energy of the agent / solvent binary system to obtain a structure file with minimized energy. This structure file is the molecular structure file of the agent-solvent binary system, such as a data file including the molecular structure, atomic coordinates, and element types of the binary system.

[0060] Furthermore, when performing energy minimization in gromacs, the energy minimization process includes the following steps:

[0061] (1) Create a control file with the extension .mdp describing the simulation parameters and a topology file with the extension .top; these parameter files contain detailed simulation settings, including the energy minimization algorithm, convergence conditions, step size, etc. In this embodiment, the steepest descent method is selected as the energy minimization algorithm, which can effectively reduce the energy of the system. Set the maximum number of steps for energy minimization to 500,000. Usually, energy minimization will end early after reaching a certain convergence condition. Set the convergence condition for energy minimization (when the energy of the simulated system is less than the designed energy threshold, generally 100 kJ / mol), set the time step for energy minimization to 0.01 ns, set the frequency of outputting log files during energy minimization (e.g., 100-500 steps) and the frequency of outputting structure files during energy minimization (e.g., 100-500 steps), set the three-dimensional periodic boundary to xyz, and set the cutoff radius to 1 nm to improve computational efficiency, and the value of this cutoff radius does not exceed half of the shortest side of the three dimensions of the model in the XYZ directions.

[0062] (2) Use the gmx grompp command to process the topology file, structure file and mdp file to obtain a file with the .tpr extension that stores the simulation running parameters and architecture information.

[0063] Specifically, in Gromacs, a topology file describes the topological structure and parameters of a molecular system. First, a text file with the .top extension is created. In this topology file, the molecular structural information is written according to a specified format, including the names, types, and charges of atoms. Based on the molecular structure, the connection information between atoms is also written, including bonds, angles, and dihedral angles. Using the `gmx grompp` command, the topology file, structure file, and MDP file are input to obtain a file storing simulation parameters and system architecture information, with the .tpr extension.

[0064] (3) Use the gmx mdrun command to run the file with the .tpr extension that stores the simulation running parameters and architecture information to obtain the structure file after energy minimization.

[0065] Sub-step S32: Create an mdp file under the NVT ensemble. In the mdp file, set md to the time integration algorithm, set the time step and total number of steps, specify to continue the current simulation from the previous simulation state, use the v-rescale method to control the temperature of the system, and set the initial temperature to 373K-583K. Input the topology file, structure file and mdp file under the NVT ensemble from the energy minimization step as the initial file. Repeatedly run gmxgrompp to prepare the simulation command and gmx mdrun to execute the simulation command in the simulation energy minimization process. Output the structure file after equilibrium under the NVT ensemble and the state information file during the simulation process.

[0066] Specifically, create an mdp file under the NVT ensemble to define the simulation parameters under the NVT ensemble. The simulation time step can be 0.5-2 femtoseconds, preferably 1 femtosecond; step size * total number of steps = simulation time. If the step size is 1 femtosecond and the total number of steps is 1,000,000, then the simulation time is 1 ns.

[0067] Sub-step S33: Create an MDP file under the NPT ensemble. In the MDP file, set MD to the time integration algorithm, set the time step and total number of steps, specify to continue the current simulation from the previous simulation state, use the v-rescale method to control the system temperature, set the initial temperature to 373K-583K, use the Berendsen method to control the system pressure, set the initial pressure to 1000 bar, input the structure file obtained under the NVT ensemble, the state information file during the simulation process, the topology file, and the MDP file under the NPT ensemble, repeatedly run the gmx grompp to prepare the simulation command and gmx mdrun to execute the simulation command during the simulation energy minimization process, and output the structure file after equilibrium under the NPT ensemble and the state information file during the simulation process.

[0068] It should be noted that in this embodiment, "md" refers to "Molecular Dynamics". The time step and total number of steps are consistent with those in the NVT ensemble described above. The topology file remains the same throughout; it is the topology file for the energy minimization process.

[0069] Step S4: After the treatment agent / solvent binary system reaches the specified temperature and pressure parameters, perform a 10-20 ns molecular dynamics simulation on the drilling fluid treatment agent / solvent molecular binary system under the NPT ensemble. Take the trajectory file of the last 2-6 ns to calculate the dynamic parameters and complete the microscopic evaluation of the drilling fluid treatment agent / solvent molecular binary system.

[0070] Specifically, the kinetic parameters of the binary system include: the solvent accessible surface area (SASA) of the treatment agent, the number of hydrogen bonds between the treatment agent and water molecules, the diffusion coefficients of the treatment agent and water molecules, and the mean square displacement.

[0071] Here, the calculation method for the dynamic parameters of the binary system is a built-in method of the software. The software performs the calculations according to predetermined formulas and rules, and only requires inputting instructions.

[0072] Microscopic evaluation methods: Analyzing the changes in kinetic parameters under varying temperature and pressure conditions;

[0073] (1) The number of hydrogen bonds between the treatment agent and water molecules decreases with increasing temperature. The number of hydrogen bonds affects the solubility of the treatment agent. Therefore, this parameter can be used to characterize the effect of high temperature on the solubility of the treatment agent from a microscopic perspective.

[0074] In other words, at the microscopic level, the number of hydrogen bonds formed between the treatment agent and water molecules is highly correlated with the macroscopic solubility of the treatment agent. If the number of hydrogen bonds decreases at high temperatures, it indicates a decrease in the high-temperature solubility of the molecules, which may lead to the precipitation of dissolved molecules and the failure of the treatment agent.

[0075] (2) SASA is used to describe the surface area of ​​the treatment agent that can theoretically come into contact with the solvent. A high SASA value means that the treatment agent can theoretically come into contact with more water molecules, which is also beneficial to its dissolution and function.

[0076] Water molecules have a high diffusion coefficient, making it difficult for hydrogen bond donors and acceptors to meet the rules for hydrogen bond formation, which in turn leads to a reduction in the number of hydrogen bonds.

[0077] In other words, the solvent accessible surface area (SASA) characterizes the surface area that a molecule can theoretically contact with water molecules. At high temperatures, the SASA value of the treatment agent decreases, indicating that the number of water molecules that the treatment agent can contact is reduced, naturally increasing the risk of precipitation and leading to treatment agent failure.

[0078] Therefore, it can be seen that the present invention can simulate and analyze the failure mechanism of drilling fluid treatment agents under ultra-high temperature conditions.

[0079] This step further includes:

[0080] Using the structure file obtained in step S3, create an mdp file under the NPT ensemble, set the time step and total number of steps (e.g., 10,000 steps), change the temperature control method to Parrinello-Rahman, and set the temperatures to 373K, 403K, 433K, 463K, 493K, 523K, 553K and 583K respectively, and the pressure control to 1000bar, 1500bar, 2000bar and 2500bar respectively. Repeat the dynamic simulation steps under the NPT ensemble in step S3 to obtain the structure file, energy file and trajectory file for the dynamic simulation temperature range of 373K-583K and the pressure range of 100MPa-250MPa.

[0081] Use the gmx make_ndx command to obtain the index file of the simulation system. Use the gmx hbond command to input the trajectory file, storage system architecture information file and index file from the above steps. Select the drilling fluid treatment agent molecules and solvent molecules to obtain the number of hydrogen bonds of the drilling fluid treatment agent molecules and solvent molecules.

[0082] Using the gmx msd command, input the trajectory file, storage architecture information file, and index file from the gmx make_ndx command steps, select the solvent molecule, and obtain the diffusion coefficient of the solvent molecule;

[0083] Using the gmx sasa command, input the trajectory file, storage architecture information file, and index file from the gmx msd command steps, select the drilling fluid treatment agent, and obtain the solvent-accessible surface area of ​​the drilling fluid treatment agent.

[0084] In this embodiment, the storage architecture information file is a state information file with the .tpr extension. `gmx grompp` only generates the .tpr file, which is equivalent to packaging all the input files in the command into a single .tpr file. `gmx mdrun` runs the .tpr, and after execution, it generates structure files (GRO), trajectory files (XTC), energy files (EDR), etc.

[0085] The molecular simulation method for the action mechanism of drilling fluid treatment agent / solvent in this invention can characterize the interaction between water-based drilling fluid treatment agent and water molecules under high temperature and high pressure conditions at the atomic scale. This solves the problem of difficulty in in-situ characterization of the microscopic dynamic characteristics of treatment agent molecules under high temperature and high pressure conditions in drilling engineering. Based on the advantages of computational simulation, it can reduce experimental costs and shorten the research and development cycle.

[0086] System Implementation Example:

[0087] This invention also provides a molecular simulation system for the action mechanism of drilling fluid treatment agents / solvents, comprising: a model construction module, a kinetic equilibrium module, a kinetic simulation module, and an analysis module; wherein, the model construction module is used to construct a binary system model of the drilling fluid treatment agent and solvent; the kinetic equilibrium module is used to optimize the binary system of the drilling fluid treatment agent / solvent, so that the atoms in the model are in reasonable positions; the kinetic simulation module is used to perform kinetic simulation on the binary system of the drilling fluid treatment agent / solvent, providing data for subsequent analysis; the analysis module is used to analyze the kinetic parameters of the components of the binary system of the drilling fluid treatment agent / solvent during the kinetic simulation, and to complete the microscopic evaluation of the molecular binary system of the drilling fluid treatment agent / solvent.

[0088] The relevant parts of the system implementation and the above method implementation can be referred to each other, and will not be repeated here.

[0089] The present invention will be described in detail below with two embodiments:

[0090] Example 1

[0091] like Figure 1 The diagram shown is a schematic of the method flow in this embodiment. Amines are widely used in high-temperature drilling fluid inhibitors. Taking 1,8-dicarbamate-heptane as an example, a molecular model is constructed. The specific steps include:

[0092] S1. Construct drilling fluid treatment agent models and treatment agent / solvent binary system models.

[0093] Specifically, a 1,8-dicarboxamidoheptane model was created using the molecular simulation software Material Studio. The molecular structure of 1,8-dicarboxamidoheptane was created in the modeling module. The molecular structure was manually drawn using the "Draw" tool in the "Build" menu. In the molecular modeling interface, carbon, hydrogen, oxygen, and nitrogen atoms were added one by one using the atom addition tool in the toolbar to construct the molecular structure of 1,8-dicarboxamidoheptane. Bond addition tools were used in the toolbar to add bonds between atoms according to the type of chemical bond, constructing the chemical bonds in the molecule. The conformation of the molecule could be adjusted by dragging atoms or bonds as needed to conform to the desired structure. The .gro file was then exported. Using the gmx solvate command in Gromacs software, a 1,8-dicarboxamidoheptane polymer and 5000 SPC / E type water molecules were added, ensuring that the water molecules covered the entire box and had good contact with the 1,8-dicarboxamidoheptane molecule. The model size was determined by the number of water molecules, resulting in the final structure file with the .gro extension. Its configuration is as follows: Figure 2 As shown.

[0094] S2, determine the force field parameters of the treatment agent, the force field parameters of the solvent molecules, and the simulated temperature and pressure range.

[0095] The SMILES-compliant ASCII string derived from the 1,8-dicarboxamidoheptane structure was used to obtain OPLS-AA force field parameters via the Ligpargen website, in .itp file format. SPC / E type water molecules were selected as the solvent. Gromacs provides force field parameters for various types of water molecules, including SPC / E. The force field parameters of 1,8-dicarboxamidoheptane and water molecules were written together into the same .itp file.

[0096] S3, perform dynamic equilibrium steps (energy minimization, NVT ensemble equilibrium, and NPT ensemble equilibrium) on the initial binary system model to complete system optimization.

[0097] The system is minimized in energy, and then equilibrium is obtained under the NVT and NPT ensembles to obtain the equilibrium configuration. The specific steps include:

[0098] When performing energy minimization in Gromacs, a control file describing the simulation parameters needs to be created, with the extension .mdp (Molecular Dynamics Parameters). These parameter files contain detailed simulation settings, including the energy minimization algorithm, convergence criteria, step size, etc. The steepest descent method is chosen as the energy minimization algorithm. The steepest descent method is a commonly used energy minimization algorithm that effectively reduces the system's energy. The maximum number of steps for energy minimization is set to 500,000. Typically, energy minimization will terminate prematurely after reaching a certain convergence condition. The convergence criteria for energy minimization are set. Energy minimization will stop when the energy change of the system is less than this value. The step size for energy minimization is set to 0.01 ns. The frequency of outputting log files and structure files during energy minimization is also set. The three-dimensional periodic boundary is set to xyz, and the cutoff radius is set to 1 nm, which does not exceed half the shortest distance in the XYZ dimensions of the model.

[0099] In Gromacs, a topology file is a file that describes the topological structure and parameters of a molecular system. First, create a text file with the .top extension. In the topology file, write the structural information of the molecule according to the specified format, including the name, type, and charge of the atoms. Based on the structure of the molecule, write the connection information between the atoms, including bonds, angles, dihedral angles, etc.

[0100] Using the `gmx grompp` command, input the topology file, structure file, and `mdp` file to obtain a file storing simulation running parameters and architecture information, with the `.tpr` extension. Use the `gmx mdrun` command to run the `.tpr` file to obtain the structure file after energy minimization.

[0101] Create an MDP file under the NVT ensemble, set the time integration algorithm used in the simulation to MD, the time step to 1 ps, the total number of simulation steps to 1,000,000, specify to continue the simulation from the previous simulation, control the temperature coupling mode to V-rescale, set the initial temperature of the simulation to 373K-583K, use the topology file from the energy minimization step, the structure file after energy minimization, and the MDP file under the NVT ensemble, repeat the gmxgrompp and gmx mdrun commands in the energy minimization process to obtain the structure file after equilibrium under the NVT ensemble and the state information file during the simulation process, with the extension .cpt.

[0102] Create an MDP file for the NPT ensemble, using the same time integration algorithm, time step, control-temperature coupling method, initial temperature of 373K-583K, initial pressure of 1000 bar, and pressure control method of Berendsen as in the NVT ensemble. Using the structure file, .cpt file, topology file obtained from the NVT ensemble and the MDP file from the NPT ensemble, repeatedly use the gmx grompp and gmx mdrun commands to obtain the structure file and state information file for the NPT ensemble during the simulation process.

[0103] S4. Perform dynamic simulations under the NPT ensemble, calculate dynamic parameters, and complete the microscopic evaluation.

[0104] Using the final structure file from step S3, create an MDP file under the NPT ensemble. Set the total number of simulation steps to 10,000,000, change the pressure control mode to Parrinello-Rahman, and change the temperature settings to 373K, 403K, 433K, 463K, 493K, 523K, 553K, and 583K respectively. Set the pressure control to 1000bar, 1500bar, 2000bar, and 2500bar respectively. Repeat the dynamic simulation steps under the NPT ensemble in step S3 to obtain the structure file, energy file (with the .edr extension), and trajectory file (with the .xtc extension) for the temperature range of 373K-583K and the pressure range of 100MPa-250MPa during the dynamic simulation process.

[0105] Using the `gmx make_ndx` command, the index file of the simulation system is obtained. The trajectory file, system architecture information file, and index file are input using `gmx hbond`. Water molecules and 1,8-dicarboxamidoheptane are selected to obtain the number of hydrogen bonds between the water molecules and 1,8-dicarboxamidoheptane. Figure 3 As shown.

[0106] Use the `gmx msd` command to input the trajectory file, storage architecture information file, and index file. Select water molecules to obtain the diffusion coefficient of water molecules, such as... Figure 4 As shown.

[0107] Using the `gmx sasa` command, input the trajectory file, storage architecture information file, and index file, select 1,8-dicarboxamidoheptane, and obtain the solvent-accessible surface area of ​​1,8-dicarboxamidoheptane. For example... Figure 5 As shown.

[0108] Example 2

[0109] Specifically, a 1,7-diphenylsulfonate-octane model was created using the molecular simulation software Material Studio. The molecular structure of 1,7-diphenylsulfonate-octane was created in the modeling module. The molecular structure was manually drawn using the "Draw" tool in the "Build" menu. In the molecular modeling interface, carbon, hydrogen, oxygen, and nitrogen atoms were added one by one using the atom addition tool in the toolbar to construct the molecular structure of 1,7-diphenylsulfonate-octane. Bond addition tools were used in the toolbar to add bonds between atoms according to the type of chemical bond, constructing the chemical bonds in the molecule. The conformation of the molecule could be adjusted by dragging atoms or bonds as needed to conform to the desired structure. The .gro file was then exported. Using the gmx solvate command in Gromacs software, a 1,7-diphenylsulfonate-octane polymer and 5000 SPC / E type water molecules were added, ensuring that the water molecules covered the entire box and had good contact with the 1,7-diphenylsulfonate-octane molecule. The model size was determined by the number of water molecules, resulting in the final structure file with the .gro extension.

[0110] The ASCII string conforming to SMILES, derived from the 1,7-diphenylsulfonic acid-octane structure, was used to obtain OPLS-AA force field parameters via the Ligpargen website, in .itp file format. SPC / E type water molecules were selected as the solvent. Gromacs provides force field parameters for various types of water molecules, including SPC / E. The force field parameters of 1,7-diphenylsulfonic acid-octane and water molecules were written together into the same .itp file.

[0111] The system is minimized in energy, and then equilibrium is obtained under the NVT and NPT ensembles to obtain the equilibrium configuration. The specific steps include:

[0112] When performing energy minimization in Gromacs, a control file describing the simulation parameters needs to be created, with the extension .mdp (Molecular Dynamics Parameters). These parameter files contain detailed simulation settings, including the energy minimization algorithm, convergence criteria, step size, etc. The steepest descent method is chosen as the energy minimization algorithm. The steepest descent method is a commonly used energy minimization algorithm that effectively reduces the system's energy. The maximum number of steps for energy minimization is set to 500,000. Typically, energy minimization will terminate early after reaching a certain convergence condition. The convergence criteria for energy minimization are set. Energy minimization will stop when the energy change of the system is less than this value. The step size for energy minimization is set to 0.01 ns. The frequency of outputting log files and structure files during energy minimization is also set. A three-dimensional periodic boundary is set to xyz, and the cutoff radius is set to 1 nm, which does not exceed half the shortest distance in the XYZ dimensions of the model.

[0113] In Gromacs, a topology file is a file that describes the topological structure and parameters of a molecular system. First, you need to create a text file with the .top extension. In the topology file, write the structural information of the molecule according to the specified format, including the name, type, and charge of the atoms. Based on the structure of the molecule, write the connection information between the atoms, including bonds, angles, dihedral angles, etc.

[0114] Using the `gmx grompp` command, input the topology file, structure file, and `mdp` file to obtain a file storing simulation running parameters and architecture information, with the `.tpr` extension. Use the `gmx mdrun` command to run the `.tpr` file to obtain the structure file after energy minimization.

[0115] Create an MDP file under the NVT ensemble, set the time integration algorithm used in the simulation to MD, the time step to 1 ps, the total number of simulation steps to 1,000,000, specify to continue the simulation from the previous simulation, control the temperature coupling mode to V-rescale, set the initial temperature of the simulation to 373 K, use the topology file from the energy minimization step, the structure file after energy minimization, and the MDP file under the NVT ensemble, repeat the gmx grompp and gmx mdrun commands in the energy minimization process to obtain the structure file after equilibrium under the NVT ensemble and the state information file during the simulation process, with the extension .cpt.

[0116] Create an MDP file for the NPT ensemble, using the same time integration algorithm, time step, control-temperature coupling method, initial temperature of 373K, initial pressure of 1000, and pressure control method of Berendsen as in the NVT ensemble. Utilize the structure file, .cpt file, topology file obtained from the NVT ensemble and the MDP file from the NPT ensemble, and repeatedly use the gmxgrompp and gmx mdrun commands to obtain the structure file and state information file for the NPT ensemble during the simulation.

[0117] Using the structure file obtained in the previous NPT step, create an mdp file under the NPT ensemble. Set the total number of simulation steps to 10,000,000, change the pressure control mode to Parrinello-Rahman, and change the temperature settings to 373K, 403K, 433K, 463K, 493K, 523K, 553K, and 583K respectively. Set the pressure control to 1000, 1500, 2000, and 2500 respectively. Repeat the dynamic simulation steps under the NPT ensemble in the previous step to obtain the structure file, energy file (with the .edr extension), and trajectory file (with the .xtc extension) for the temperature range of 373K-583K and the pressure range of 100MPa-250MPa in the dynamic simulation process.

[0118] Using the `gmx make_ndx` command, the index file of the simulation system is obtained. The `gmx hbond` command is used to input the trajectory file, store the system architecture information file, and the index file. Water molecules and polymers are selected to obtain the number of hydrogen bonds between water molecules and 1,7-diphenylsulfonic acid-octane, such as... Figure 6 As shown, 1,7-dibenzenesulfonic acid-octane forms more hydrogen bonds with water molecules than 1,8-dicarbamate-heptane, and 1,7-dibenzenesulfonic acid-octane has better high-temperature solubility.

[0119] Use the `gmx msd` command to input the trajectory file, storage architecture information file, and index file. Select water molecules to obtain the diffusion coefficient of water molecules, such as... Figure 7 As shown, it can be seen that temperature has a much greater effect on the diffusion coefficient of water molecules than pressure.

[0120] Using the `gmx sasa` command, input the trajectory file, storage architecture information file, and index file, select 1,7-diphenylsulfonate-octane to obtain the solvent-accessible surface area of ​​1,7-diphenylsulfonate-octane. For example... Figure 8 As shown, the SASA of 1,7-dibenzenesulfonic acid-octane increases with increasing temperature, indicating that as temperature increases, the polymer chain segments expand, which is beneficial for the treatment agent to perform its function.

[0121] In summary, the present invention has the following beneficial effects:

[0122] 1. This method uses molecular simulation technology, which can simulate temperature and pressure without limitation. Under the condition that the model is correct and the conditions are permissible, it can simulate extremely high temperature and pressure, and achieve high temperature and high pressure that are difficult to achieve by experimental means. For example, the temperature can range from 0℃ to above 300℃, and the pressure can range from one atmosphere to hundreds of MPa.

[0123] 2. It can establish the molecular structure of materials, simulate the molecular-scale properties of materials, and achieve microscales that are difficult to achieve by experimental means, such as the nm level on the spatial scale and the ns or even ps level on the temporal scale.

[0124] 3. This method is characterized by its strong theoretical basis and numerous calculation parameters, and can comprehensively reflect the microscopic properties of the treatment agent.

[0125] 4. It has strong guiding significance and can be widely applied in the study of the interaction mechanism between drilling fluid treatment agents and water, with low experimental costs.

[0126] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents, characterized in that, Includes the following steps: Step 1: Construct a binary system model of drilling fluid treatment agent / solvent; Step 2: Determine the force field parameters and simulation parameters of the drilling fluid treatment agent and solvent molecules. The simulation parameters include: temperature and pressure control method, step size, cutoff radius, trajectory output control, temperature, pressure, and periodic boundary conditions. Step 3: Based on the force field parameters and the simulation parameters, the drilling fluid treatment agent / solvent binary system is subjected to kinetic equilibrium for 1-10 ns under the NVT ensemble and NPT ensemble in sequence to complete the system optimization; Step 4, after the drilling fluid treatment agent / solvent binary system reaches the specified temperature, pressure parameters, the drilling fluid treatment agent / solvent molecular binary system is subjected to molecular dynamics simulation under NPT ensemble for 10-20 ns, and the trajectory file of the last 2-6 ns is used to calculate the kinetic parameters, - The microscopic evaluation of the drilling fluid treatment agent / solvent molecular binary system is completed.

2. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 1, characterized in that, Step 1, constructing the binary system model of drilling fluid treatment agent / solvent includes: The molecular structure of the drilling fluid treatment agent was created using the modeling module in the molecular simulation software Material Studio. A simulation box is created, and the drilling fluid treatment agent molecules are added to the simulation box. Then, multiple solvent molecules of preset molecular models are added to the simulation box to ensure that the solvent molecules cover the entire simulation box and have good contact with the drilling fluid treatment agent molecules, thus obtaining the structure file of the final drilling fluid treatment agent / solvent molecule binary system model.

3. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 2, characterized in that, The drilling fluid treatment agent molecule is 1,8-dicarboxamidoheptane or 1,7-dibenzenesulfonic acid-octane; and / or the solvent is water or ethanol, and the preset molecular model is SPC / E type.

4. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 1, characterized in that, The force field parameters include: atom type, bond length, bond angle, dihedral angle, charge distribution, and nonbonded interaction parameters.

5. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 1, characterized in that, In step 2, the OPLS-AA force field parameters of the drilling fluid treatment agent are obtained through the Ligpargen website, and the force field parameters of the drilling fluid treatment agent molecules and solvent molecules are written together into the same .itp file.

6. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 1, characterized in that, The dynamic equilibrium process includes: The energy of the aforementioned agent / solvent binary system is minimized to obtain the energy-minimized structure file; Create an MDP file under the NVT ensemble, set MD to the time integration algorithm in the MDP file, set the time step and total number of steps, specify to continue the current simulation from the previous simulation state, use the v-rescale method to control the temperature of the system, and set the initial temperature to 373K-583K. Input the topology file, structure file and MDP file under the NVT ensemble in the energy minimization step as the initial file, repeatedly run gmx grompp to prepare simulation commands and gmx mdrun to execute simulation commands in the simulation energy minimization process, and output the structure file after equilibrium under the NVT ensemble and the state information file during the simulation process. Create an MDP file under the NPT ensemble. In the MDP file, set MD to the time integration algorithm, set the time step and total number of steps, and specify that the simulation should continue from the previous simulation state. Use the v-rescale method to control the system temperature, setting the initial temperature to 373K-583K. Use the Berendsen method to control the system pressure, setting the initial pressure to 1000 bar. Input the structure file obtained from the NVT ensemble, the state information file during the simulation, the topology file, and the MDP file under the NPT ensemble. Repeatedly run the gmx grompp command to prepare the simulation command and the gmx mdrun command to execute the simulation command during the simulation energy minimization process. Output the structure file after equilibrium under the NPT ensemble and the state information file during the simulation.

7. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 6, characterized in that, Step 4 includes the following steps: Using the structure file obtained in step 3, create an mdp file under the NPT ensemble, set the total number of simulation steps, change the pressure control mode to Parrinello-Rahman, set the temperature to 373K, 403K, 433K, 463K, 493K, 523K, 553K and 583K respectively, and set the pressure control to 1000, 1500, 2000 and 2500 respectively. Repeat the dynamic simulation steps under the NPT ensemble in step S3 to obtain the structure file, energy file and trajectory file for the dynamic simulation temperature range of 373K-583K and the pressure range of 100MPa-250MPa. Use the gmx make_ndx command to obtain the index file of the simulation system. Use the gmx hbond command to input the trajectory file, storage system architecture information file and index file from the previous step. Select the drilling fluid treatment agent molecules and solvent molecules to obtain the number of hydrogen bonds of the drilling fluid treatment agent molecules and solvent molecules. Using the gmx msd command, input the trajectory file, storage architecture information file, and index file from the gmx make_ndx command steps, select the solvent molecule, and obtain the diffusion coefficient of the solvent molecule; Using the gmx sasa command, input the trajectory file, storage architecture information file, and index file from the gmx msd command steps, select the drilling fluid treatment agent, and obtain the solvent-accessible surface area of ​​the drilling fluid treatment agent.

8. The molecular simulation method for the action mechanism of drilling fluid treatment agents / solvents according to claim 1, characterized in that, The energy minimization process includes the following steps: Create a control file with the extension .mdp that describes the simulation parameters and a topology file with the extension .top; The gmx grompp command is used to process topology files, structure files, and mdp files to obtain files with the .tpr extension that store simulation running parameters and architecture information. The file containing simulation parameters and architecture information, with the extension .tpr, is run using the gmx mdrun command to obtain the energy-minimized architecture file.

9. A molecular simulation system for the action mechanism of drilling fluid treatment agents / solvents, characterized in that, include: A model building module is used to build a binary system model of drilling fluid treatment agents and solvents; A kinetic equilibrium module is used to optimize the drilling fluid treatment agent / solvent binary system so that the atoms in the drilling fluid treatment agent and solvent binary system model are in reasonable positions. The kinetic simulation module is used to perform kinetic simulations on the drilling fluid treatment agent / solvent binary system to provide data for subsequent analysis. The analysis module is used to analyze the kinetic parameters of the components of the drilling fluid treatment agent / solvent binary system during the kinetic simulation process, and to complete the microscopic evaluation of the drilling fluid treatment agent / solvent molecular binary system.

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