Preparation method of oil displacement and plugging integrated gel

Abstract

The application discloses a preparation method of oil displacement and plugging integrated gel, and particularly relates to the technical field of oilfield chemicals, S1, reaction kinetics parameter solving; S2, dynamic topology network evolution simulation; S3, gel network crosslinking density calculation; S4, gel macroscopic mechanics parameter derivation; S5, pore throat scale plugging state determination. The application solves the reaction probability rate constant of initiation, chain growth, chain transfer and chemical crosslinking, and based on the dynamic simulation of the probability set starting time step promotion, realizes the recurrence of the growth of polymer chain and the network topology evolution process from the molecular reaction kinetics level. The microcosmic simulation mode starting from the chemical reaction mechanism replaces the traditional macroscopic mixing experiment, makes the formation process of the gel network transparent and traceable, and lays a foundation for deeply understanding the influence of the formula parameters on the network structure.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemicals technology, and in particular to a method for preparing an integrated oil displacement and plugging gel. Background Technology

[0002] The field of oilfield chemicals technology encompasses a wide range of chemical additives used in oil and gas exploration and development. Its core focus is the research and application of these chemicals to improve drilling efficiency, ensure well integrity, enhance reservoir permeability, improve oil recovery, and treat produced fluids. This field systematically involves drilling fluid treatment agents, cementing additives, fracturing and acidizing fluid additives, oil recovery aids such as demulsifiers and wax removers / inhibitors, as well as polymers, surfactants, and gel-based modifiers for enhanced oil recovery.

[0003] One method for preparing an integrated oil displacement and plugging gel refers to a specific process for generating a chemical agent that simultaneously improves the water-oil mobility ratio and plugs high-permeability channels. The technical aspects addressed in this topic encompass the selection and proportioning of components in the gel system, specifically by mixing and reacting the main polymer with a crosslinking agent, initiator, and necessary auxiliary additives under specific conditions. The preparation process typically controls the reaction temperature, solution pH, component concentration, and crosslinking reaction time to form a gel product with specific viscoelasticity, gelation time, and strength. This product can both displace crude oil in low-to-medium permeability layers and effectively plug high-permeability water-channeling areas.

[0004] The shortcomings of existing technologies lie in their high reliance on empirical control of macroscopic process parameters, such as reaction temperature, component concentration, and gelation time during physical mixing. This "black box" preparation process cannot reveal or control the topological structure of the gel network at the microscopic level. Researchers lack quantitative understanding of the degree of physical entanglement between polymer chains, the uniformity of chemical crosslinking point distribution, and the effective network density formed by the combined effects of the two crosslinking methods. Therefore, formulation optimization relies entirely on numerous, repetitive laboratory physical experiments and macroscopic performance characterization, resulting in a lengthy and costly development cycle. More importantly, the macroscopic viscoelasticity or strength measured in the laboratory cannot be directly correlated with the complex plugging and displacement behavior of the gel at the microscopic scale of reservoir pore throats, leading to significant uncertainty in the on-site applicability and success rate of the gel formulation. Summary of the Invention

[0005] The main objective of this invention is to provide a method for preparing an integrated oil displacement and sealing gel, which can effectively solve the problems mentioned above in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing an integrated oil displacement and plugging gel includes the following steps: S1. Calculation of reaction kinetic parameters: Obtain the concentrations of monomers, initiators, crosslinking agents and reaction temperature data for gel synthesis. Based on the Arrhenius equation and concentration parameters, calculate the probability rate constants of four reactions: initiation, chain growth, chain transfer and chemical crosslinking, and finally generate the probability set of reaction events. S2. Dynamic Topology Network Evolution Simulation: Based on reaction probability sets, the simulation is advanced through time steps. Each time step randomly executes reaction events, driving the dynamic growth of polymer chains. The system periodically analyzes the chain backbone topology, marking instantaneous physical entanglement points when chain A encircles chain B for a duration exceeding the local chain segment relaxation time. If a chemical crosslinking reaction occurs near this point, it is converted to a "permanently locked" state. The simulation ultimately generates a four-dimensional network topology database recording this evolution process. S3. Calculation of gel network crosslinking density: Using a four-dimensional network database, all physically entangled and chemically crosslinked points in a "permanently locked" state are traversed and accumulated to obtain the total number of effective crosslinking points. Dividing this number by the volume of the simulation system yields the effective crosslinking density of the gel. S4. Derivation of Macroscopic Mechanical Parameters of the Gel: Based on the effective crosslinking density, combined with the Boltzmann constant and reaction temperature, the elastic modulus of the gel is calculated. Simultaneously, by traversing the database to identify all chain segments, the shortest chain segment length is selected and its theoretical fracture stress is calculated, which is used as the yield strength of the gel. Finally, the elastic modulus and yield strength are packaged and output as a set of gel mechanical parameters. S5. Determination of Pore Throat Blockage Status: The yield limit in the gel mechanical parameter set is called, and the fluid pressure difference of each throat in the digital core pore network model is obtained. All throats blocked by gel are traversed, and their fluid pressure differences are compared with the gel yield limit. The number of throats with fluid pressure differences greater than the yield limit is counted, and the creep activation ratio of the pore throats is calculated.

[0007] Furthermore, the reaction event probability set includes the probability of triggering events, the probability of chain growth events, the probability of chain transfer events, and the probability of chemical cross-linking events. The four-dimensional network topology database specifically refers to the three-dimensional coordinates of nodes, the associated chain ID, the node formation time, and the node status identifier. The effective cross-linking density of the gel includes the locked physical entanglement density and the chemical cross-linking node density. The gel mechanical parameter set specifically includes the gel elastic modulus and the gel yield limit. The pore throat creep activation ratio includes the number of creep-activated throats and the total number of blocked throats.

[0008] Furthermore, the steps for calculating the reaction kinetic parameters specifically include: S101. Obtain the monomer concentration, initiator concentration, crosslinking agent concentration and reaction temperature data for gel synthesis. At the same time, retrieve the activation energy and pre-exponential factor of each of the four reactions: initiation, chain growth, chain transfer and chemical crosslinking. Perform exponential calculation on the reaction temperature, activation energy and pre-exponential factor according to the Arrhenius equation to calculate the initiation rate constant, chain growth rate constant, chain transfer rate constant and chemical crosslinking rate constant, and obtain the four types of reaction rate constant values. S102. For the four types of reaction rate constants, including the initiation rate constant, chain growth rate constant, chain transfer rate constant, and chemical crosslinking rate constant, these four constants are used as the basis for selecting reaction events, and they are uniformly encapsulated into a data set to generate a reaction event probability set.

[0009] Furthermore, the steps of the dynamic topology network evolution simulation specifically include: S201. Call the reaction event probability set and set the total simulation time step. In each time step, the system randomly selects a reaction event based on the probability values ​​of initiation, chain growth, chain transfer, and chemical crosslinking in the reaction event probability set and executes it. This execution updates the connection relationship and three-dimensional coordinates of the polymer chain, gradually building a polymer network. After the simulation reaches the total time step, the preliminary polymer network conformation is obtained. S202. For the preliminary polymer network conformation, the system periodically runs the original path analysis to calculate the skeleton topology path of all polymer chains. The system traverses all chain pairs. When it is determined that the skeleton path of a chain A surrounds another chain B, the system records the duration of the surround state and retrieves the local chain segment relaxation time of the chain segment. When the surround duration is greater than the chain segment relaxation time, the position is marked as an instantaneous physical entanglement point, and a list of instantaneous entanglement point coordinates is established. S203. The system calls the list of instantaneous entanglement point coordinates and retrieves the chemical crosslinking point location data recorded in the preliminary polymer network conformation. The system traverses all instantaneous entanglement point coordinates and determines whether the spatial distance between its three-dimensional coordinates and any chemical crosslinking point location is less than the preset locking radius threshold. If it is less, the node status is updated to "permanently locked". Finally, the system integrates the three-dimensional coordinates, associated chain IDs, formation time and status identifiers of all instantaneous and permanently locked nodes to establish a four-dimensional network topology database.

[0010] Furthermore, the step of calculating the crosslinking density of the gel network specifically includes: S301. Call the four-dimensional network topology database, which contains the three-dimensional coordinates of nodes, the ID of the associated chain, the formation time and the status identifier. The system initializes a counter to zero, and then traverses all node entries in the database. For each entry, extract its "status identifier" data item, and determine whether the text value of the "status identifier" data item is equal to the preset string "permanently locked". If the determination result is yes, the counter is incremented by one. If the determination result is no, the entry is skipped. After all entries have been traversed, the final value of the counter is obtained, and the count of locked physical entanglement points is generated. S302. Retrieve the total number of chemical crosslinking points recorded in the dynamic topology network evolution simulation step. This total number is the cumulative number of all chemical crosslinking reactions that occur during the simulation process. The system performs an arithmetic summation operation on the total number of chemical crosslinking points and the count of locked physical entanglement points obtained in the previous step. This operation adds the two independent count values, and the result represents the sum of all permanent constraint nodes in the network, thus establishing the total number of effective crosslinking points. S303. Obtain the three-dimensional volume value of the simulation system set in the dynamic topology network evolution simulation step. This value represents the spatial scale used for calculation. The system calls the total number of effective crosslinking points generated in the previous step and performs a division operation. In this operation, the total number of effective crosslinking points is used as the dividend, and the three-dimensional volume value of the simulation system is used as the divisor. The quotient obtained represents the number of permanent constraint nodes per unit volume, and the effective crosslinking density of the gel is generated.

[0011] Furthermore, the steps for deriving the macroscopic mechanical parameters of the gel specifically include: S401. Based on the effective crosslinking density of the gel, the system simultaneously retrieves the reaction temperature data obtained in the reaction kinetic parameter calculation step and the Boltzmann constant value in the known field. The system performs a multiplication operation on the effective crosslinking density of the gel, the Boltzmann constant and the reaction temperature. According to the rubber elasticity theory, the calculation result is defined as the shear modulus of the gel in thermodynamic equilibrium state and converted into the bulk modulus to obtain the gel elastic modulus value. S402. Call the four-dimensional network topology database established in the dynamic topology network evolution simulation step. This database contains node coordinates and involved chain IDs. The system traverses all permanently locked or transiently entangled nodes, extracts the chain segment length data of all polymer chains connecting these nodes, and performs a minimum value screening operation on all extracted chain segment length values. The minimum chain segment length selected is taken as the potential breakage point. Based on the bond energy of the polymer C-C bond and the minimum chain segment length, the theoretical macroscopic stress required to break the bond is calculated through a mechanical relationship to obtain the gel yield stress value. S403. For the gel yield stress value obtained in the previous step and the gel elastic modulus value obtained in sub-step 1, the system encapsulates these two core mechanical parameters in the form of a structured data package. This data package is used in the subsequent macroscopic mechanical calculation module to ensure that subsequent steps can be called as a whole to generate a gel mechanical parameter set.

[0012] Furthermore, the steps for determining the pore throat occlusion status specifically include: S501. Call the gel mechanical parameter group and obtain the digital core pore network model. The system traverses all throats in the model, filters out all throats blocked by gel according to their blocking status indicators, and extracts the fluid pressure difference value of each throat. At the same time, count all the selected throats and establish a set of blocking throat pressure difference and total number. S502. Call the pressure difference of the blocked throat and the fluid pressure difference of each throat in the total set, and use the yield limit in the gel mechanical parameter group as the judgment criterion. The system traverses the fluid pressure difference value of all blocked throats and compares the pressure difference value with the yield limit one by one. When the fluid pressure difference value is greater than the yield limit, the internal counter performs an increment operation to obtain the creep activated throat count value. S503. Based on the creep activation throat count value, and by calling the pressure difference of the blocked throat and the total number of blocked throats contained in the total set, the system performs a division operation with the creep activation throat count value as the dividend and the total number of blocked throats as the divisor. The quotient value obtained represents the proportion of throats that have undergone plastic flow, and generates the pore throat creep activation ratio.

[0013] Furthermore, the activation energies and pre-exponential factors of the four reactions in S101—initiation, chain growth, chain transfer, and chemical crosslinking—are obtained by querying and matching from a preset chemical reaction parameter library based on the initial ratio of monomer concentration, initiator concentration, and crosslinking agent concentration.

[0014] Furthermore, the local segment relaxation time in S202 is calculated using a dynamic relaxation function based on the number of monomer units contained in the segment in the preliminary polymer network conformation and the reaction temperature data obtained in S101.

[0015] Furthermore, the mechanical relationship in S402 is specifically: the bond energy of the polymer CC bond is divided by the square of the minimum chain segment length, and the result is multiplied by a preset material shear constant to estimate the gel yield stress value.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of this integrated oil displacement and plugging gel achieves the reproduction of polymer chain growth and network topology evolution from the perspective of molecular reaction dynamics by solving the reaction probability rate constants of initiation, chain growth, chain transfer and chemical crosslinking, and starting dynamic simulation based on this probability set to advance the time step. This microscopic simulation method based on chemical reaction mechanism replaces the traditional macroscopic mixing experiment, making the formation process of gel network transparent and traceable, laying the foundation for a deeper understanding of the influence of formulation parameters on network structure; (2) The preparation method of this integrated oil displacement and plugging gel, the simulation logic not only tracks the formation of chemical crosslinking points, but also innovatively identifies and marks instantaneous physical entanglement points and their transformation to a "permanently locked" state through periodic topological analysis and comparison of chain segment relaxation time. This fine characterization of physical entanglement and chemical crosslinking establishes a direct mapping from reactant concentration, temperature to the three-dimensional network morphology of the gel, so that the effective crosslinking density calculated subsequently is no longer a macroscopic inference value, but a direct statistical result derived from the microscopic topological structure, which significantly improves the accuracy of gel structure characterization; (3) The preparation method of this integrated oil displacement and plugging gel uses the precise effective crosslinking density to derive the elastic modulus and yield strength of the gel, and further substitutes these core mechanical parameters into the digital core pore network model to determine the creep activation ratio of the gel under a specific fluid pressure difference. This approach constructs a complete prediction link from the microscopic formulation of the gel to its macroscopic mechanical properties, and then to the plugging performance at the pore throat scale. This frees the screening and performance evaluation of the gel formulation from the dependence on a large number of physical trial-and-error experiments, and achieves efficient optimization at the simulation level. Attached Figure Description

[0017] Figure 1 This is a flowchart of the reaction kinetics parameter calculation process of the present invention; Figure 2 This is a flowchart illustrating the dynamic topology network evolution simulation of the present invention. Figure 3 This is a flowchart illustrating the calculation of the crosslinking density of the gel network according to the present invention; Figure 4 This is a flowchart illustrating the derivation of the macroscopic mechanical parameters of the gel in this invention. Figure 5 This is a flowchart for determining the pore throat dimensional occlusion status in this invention. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] Example 1, see Figure 1-5A method for preparing an integrated oil displacement and plugging gel includes the following steps: S1. Reaction Kinetic Parameter Calculation: Data on monomer, initiator, and crosslinking agent concentrations and reaction temperature for gel synthesis are obtained. Based on the Arrhenius equation and concentration parameters, the probability rate constants for four reactions—initiation, chain growth, chain transfer, and chemical crosslinking—are calculated, ultimately generating a probability set of reaction events. This probability set is the core input for subsequent dynamic topology network evolution simulation, transforming the macroscopic chemical formulation (concentration) and physical conditions (temperature) into the relative probability of microscopic reaction events (initiation, growth, transfer, and crosslinking) occurring within each time step in S2. In step S2, the system performs Monte Carlo random sampling based on this probability distribution to determine which reaction to execute next, thus ensuring that the polymer network growth process strictly follows the chemical reaction kinetics calculated in S1 in a statistical sense. S2. Dynamic Topology Network Evolution Simulation: Based on the reaction probability set, the simulation is advanced through time steps. Each time step randomly executes reaction events, driving the dynamic growth of polymer chains. The system periodically analyzes the chain backbone topology, marking instantaneous physical entanglement points when chain A encircles chain B for a duration exceeding the local chain segment relaxation time. If a chemical crosslinking reaction occurs near this point, it is converted to a "permanently locked" state. The simulation ultimately generates a four-dimensional network topology database recording this evolution process. This database serves as a bridge between microscopic simulation and macroscopic performance prediction. It not only contains the state markers ("permanently locked") required for calculating crosslinking density in S3, but also records the chain segment topology information (used to identify the shortest chain segment) required for deriving the yield limit in S4. The combination of the time dimension (node ​​formation time) and the spatial dimension (three-dimensional coordinates) in the database allows for a complete reproduction of the evolution history of the gel network, providing a necessary data foundation for in-depth analysis of the formation mechanism of the topology and the intrinsic relationship between mechanical properties. S3. Calculation of Gel Network Crosslink Density: A four-dimensional network database is invoked, and all physically entangled and chemically crosslinked points in a "permanently locked" state are traversed and accumulated to obtain the total number of effective crosslinked points. Dividing this number by the volume of the simulation system yields the effective crosslink density of the gel. This "effective" crosslink density is a key innovative parameter in this scheme; numerically, it equals the sum of the locked physical entanglement density and the chemical crosslink density. It surpasses the traditional method of only counting chemical bonds, considering even physically entangled points fixed by topological constraints as "crosslinked points" contributing to the network's elasticity. This definition is closer to the physical reality of gel materials because these locked entanglements also restrict the movement of polymer chains. Therefore, this density value is the most direct and crucial physical input parameter for calculating the gel's elastic modulus in S4. S4. Derivation of Macroscopic Mechanical Parameters of the Gel: Based on the effective crosslinking density, combined with the Boltzmann constant and reaction temperature, the elastic modulus of the gel is calculated. Simultaneously, by traversing the database to identify all chain segments, the shortest chain segment length is selected and its theoretical fracture stress is calculated, which is used as the yield strength of the gel. Finally, the elastic modulus and yield strength are packaged and output as a set of gel mechanical parameters. This set of parameters (elastic modulus and yield strength) together constitutes a complete quantitative description of the macroscopic mechanical behavior of the gel material. The elastic modulus characterizes the gel's ability to resist elastic deformation (stiffness), while the yield strength defines the critical stress threshold (strength) at which the gel transitions from elastic deformation to plastic flow or structural failure. These two parameters are decisive factors in evaluating whether the gel can effectively seal pores and throats; they will serve as the mechanical benchmark for determining the pore and throat sealing state in step S5. S5. Pore throat-scale plugging status determination: The yield limit in the gel mechanical parameter set is called, and the fluid pressure difference of each throat in the digital core pore network model is obtained. All throats plugged by the gel are traversed, and their fluid pressure differences are compared with the gel yield limit. The number of throats with fluid pressure differences greater than the yield limit is counted, and the creep activation ratio of the pore throat is calculated. This ratio (the ratio of creep-activated throats to the total number of plugged throats) is the final application output of this scheme, which intuitively quantifies the plugging failure rate of the gel in the simulated reservoir pore environment. This indicator directly correlates the chemical formulation parameters input in S1 with the final engineering application effect of S5 (i.e., the plugging ability in high-pressure differential water channeling). By analyzing this ratio, the optimization and adjustment of the formulation parameters in S1 can be guided in reverse to achieve the best oil displacement and plugging effect under specific reservoir conditions (specific pressure difference distribution).

[0020] The preparation method of the integrated oil displacement and plugging gel includes a reaction event probability set comprising the probabilities of initiation events, chain growth events, chain transfer events, and chemical cross-linking events. The four-dimensional network topology database specifically refers to the three-dimensional coordinates of nodes, associated chain IDs, node formation time, and node state identifiers. The effective cross-linking density of the gel includes the locked physical entanglement density and the chemical cross-linking node density. The gel mechanical parameter set specifically comprises the gel elastic modulus and gel yield strength. The pore throat creep activation ratio includes the number of creep-activated throats and the total number of blocked throats.

[0021] The specific steps for calculating the reaction kinetic parameters in the preparation method of the integrated oil displacement and plugging gel include: S101: Obtain the monomer concentration, initiator concentration, crosslinking agent concentration, and reaction temperature data for gel synthesis. Simultaneously, retrieve the activation energies and pre-exponential factors for the four reactions: initiation, chain growth, chain transfer, and chemical crosslinking. Using the Arrhenius equation, perform exponential calculations on the reaction temperature, activation energy, and pre-exponential factors to calculate the initiation rate constant, chain growth rate constant, chain transfer rate constant, and chemical crosslinking rate constant. These four rate constants represent the first quantitative calculation of the transformation from macroscopic input parameters (concentration and temperature) in S1 to microscopic reaction kinetics. Their magnitudes directly reflect the competitive relationship among the four reaction pathways under the current conditions. For example, if the chemical crosslinking rate constant is much larger than the chain growth rate constant, it tends to form a densely crosslinked but shorter chain network. These values ​​form the basis for constructing the standardized probability distribution in the subsequent S102 step. S102. For the four types of reaction rate constants—initiation rate constant, chain growth rate constant, chain transfer rate constant, and chemical crosslinking rate constant—these four constants are used as the basis for selecting reaction events and are uniformly encapsulated into a dataset to generate a reaction event probability set. The "encapsulation" operation in this step specifically refers to normalizing the four independent rate constants obtained in S101. In each simulation time step of S201, the system allocates the probability of random events based on the relative magnitudes of these four constants. For example, the probability of an initiation event is equal to the initiation rate constant divided by the sum of the four rate constants. Therefore, this generated reaction event probability set is a standardized probability distribution table, which serves as the direct input source for the Monte Carlo selection mechanism in S201, dominating each stochastic decision in the simulated network growth.

[0022] The specific steps of the dynamic topological network evolution simulation method for preparing the integrated oil displacement and plugging gel include: S201: The system calls the reaction event probability set and sets the total simulation time step. Within each time step, the system randomly selects a reaction event based on the initiation, chain growth, chain transfer, and chemical crosslinking probability values ​​in the reaction event probability set and executes it. This execution updates the connectivity and three-dimensional coordinates of the polymer chains, gradually building a polymer network. After the simulation reaches the total time step, a preliminary polymer network conformation is obtained. This preliminary conformation is a snapshot of data containing the atomic coordinates of all polymer chains, chemical bond connections, and the positions of formed chemical crosslinking points. At this point, this conformation only reflects the direct result of the chemical reaction driven by the reaction event probability set in S102. However, it has not yet undergone topological analysis; therefore, the "physical entanglement" state between chains is unknown and unlabeled at this stage. This conformation is the raw input data for S202 to perform topological path analysis and entanglement point identification. S202. For the preliminary polymer network conformation, the system periodically runs the original path analysis to calculate the skeletal topological path of all polymer chains. The system traverses all chain pairs. When it is determined that the skeletal path of chain A encircles another chain B, the system records the duration of this encirclement and retrieves the local chain segment relaxation time. When the encirclement duration is greater than the chain segment relaxation time, the position is marked as an instantaneous physical entanglement point, and a list of instantaneous entanglement point coordinates is established. Instantaneous indicates that these entanglement points are formed through topological encirclement, but their existence time is limited by the relaxation motion of the chain segment. By comparing with the local chain segment relaxation time, the system filters out those short-lived encirclements that form and unwind quickly and whose contribution to mechanical properties is negligible. Therefore, this coordinate list represents all topologically "effective" and "persistent" physical constraint candidate points, which are the only objects of consideration in S203 to determine whether they are "permanently locked." S203. The system retrieves the list of instantaneous entanglement point coordinates and the chemical crosslinking point location data recorded in the preliminary polymer network conformation. It iterates through all instantaneous entanglement point coordinates, determining whether the spatial distance between the instantaneous entanglement point's three-dimensional coordinates and any chemical crosslinking point location is less than a preset locking radius threshold. If less, the node's state is updated to "permanently locked." Finally, the system integrates the three-dimensional coordinates, associated chain IDs, formation time, and state identifiers of all instantaneous and permanently locked nodes to establish a four-dimensional network topology database. The determination of the "permanently locked" state is one of the core innovations of this scheme, simulating the synergistic effect between physical entanglement and chemical crosslinking. When a chemical crosslinking reaction (occurring randomly in S201) happens to fall near an existing instantaneous physical entanglement point (identified in S202) (less than the locking radius threshold), the formation of this chemical bond binds the physical entanglement that could have been loosened, transforming it into a permanent topological constraint. The final database integrates pure chemical crosslinking points and these locked physical entanglements, forming a complete description of the overall network constraints.

[0023] The preparation method of the integrated oil displacement and plugging gel and the calculation of the gel network crosslinking density specifically include the following steps: S301: The system invokes a four-dimensional network topology database, which contains the three-dimensional coordinates of nodes, association chain IDs, formation time, and status identifiers. A counter is initialized to zero. Then, all node entries in the database are traversed. For each entry, its "status identifier" data item is extracted. The system checks if the text value of this "status identifier" data item equals the preset string "permanently locked." If the result is yes, the counter is incremented; if the result is no, the entry is skipped. After traversing all entries, the final value of the counter is obtained, generating a count of locked physical entanglement points. This count is the first component of the gel's effective crosslinking density. Through the determination mechanism in S203, these "permanently locked" nodes are mechanically equivalent to a chemical crosslinking point, and they also contribute to the network's elastic modulus. The operation in S301, by traversing the database generated in S203 and filtering and accumulating based on the "permanently locked" status identifier, achieves accurate quantification of this specific type of topological constraint. This value will be combined with the number of purely chemical crosslinking points counted in S302 to constitute the total effective constraints of the network. S302: Retrieve the total number of chemical crosslinking points recorded in the dynamic topology network evolution simulation step. This total number represents the cumulative number of all chemical crosslinking reactions that occurred during the simulation. The system performs an arithmetic summation operation on this total number of chemical crosslinking points and the count of locked physical entanglements obtained in the previous step. This operation adds the two independent count values, and the result represents the sum of all permanently constrained nodes in the network, establishing the total number of effective crosslinking points. This total number is the core molecule for calculating the effective crosslinking density of the gel. It combines the topological constraints (count of locked physical entanglements) counted in S301 with the chemical constraints (total number of chemical crosslinking points) recorded during the simulation S201 into a single value through arithmetic summation. This merging operation physically unifies two different sources of constraint points that have the same mechanical effect (i.e., restricting chain segment movement). This total number represents the set of all stress-bearing nodes in the network and is the basis for density normalization in S303. S303. Obtain the three-dimensional volume value of the simulation system set in the dynamic topology network evolution simulation step. This value represents the spatial scale used for calculation. The system calls the total number of effective crosslinking points generated in the previous step and performs a division operation. In this operation, the total number of effective crosslinking points is used as the dividend, and the three-dimensional volume value of the simulation system is used as the divisor. The quotient value obtained represents the number of permanent constraint nodes per unit volume, generating the gel effective crosslinking density. By dividing by the three-dimensional volume of the simulation system, the total number of effective crosslinking points (an extensional quantity) obtained in S302 is converted into the gel effective crosslinking density (an intrinsic quantity). This density value is a parameter characterizing the intrinsic properties of the material, eliminating the influence of the size of the simulation system on the results. As the number of constraint points per unit volume, this density value can be directly substituted into the equation derived from the rubber elasticity statistical theory in S401 to calculate macroscopic mechanical parameters such as the elastic modulus, thereby quantitatively linking the microscopic network topology with the macroscopic material properties.

[0024] The preparation method of the integrated oil displacement and plugging gel and the derivation of its macroscopic mechanical parameters specifically include the following steps: S401: Based on the effective crosslinking density of the gel, and simultaneously retrieving the reaction temperature data obtained in the reaction kinetics parameter calculation step, as well as the Boltzmann constant value from the known domain, the system multiplies the effective crosslinking density, Boltzmann constant, and reaction temperature. According to rubber elasticity theory, the calculation result is defined as the shear modulus of the gel in thermodynamic equilibrium, and then converted into the bulk modulus to obtain the gel elastic modulus value. This step is based on the statistical theory of rubber elasticity in polymer physics. This theory states that the macroscopic elastic modulus of an ideal elastic network is proportional to its effective crosslinking density. The product of the effective crosslinking density of the gel (representing the number of constraints per unit volume) generated in S303, the Boltzmann constant, and the reaction temperature, is, in dimensional terms, energy density or pressure (modulus). This calculation transforms the purely topological statistical result in S3 into the first core macroscopic mechanical parameter, namely, the material stiffness. S402. The system invokes the four-dimensional network topology database established in the dynamic topology network evolution simulation step. This database contains node coordinates and related chain IDs. The system traverses all permanently locked or transiently entangled nodes, extracts the chain segment length data of all polymer chains connecting these nodes, and performs a minimum value screening operation on all extracted chain segment length values. The screened minimum chain segment length is taken as the potential breakage point. Based on the bond energy of the polymer CC bond and the minimum chain segment length, the theoretical macroscopic stress required for the bond to break is calculated through a mechanical relationship, yielding the gel yield stress value. The derivation of this yield stress value is based on the "weakest link" theory. The macroscopic breakage of the gel network is assumed to be caused by the breakage of the shortest and most restrictive chain segment in the network. S402 identifies and screens this shortest chain segment length by traversing the database (containing all nodes). This length determines the maximum elongation that the chain segment can withstand before the CC bond reaches its breakage limit (determined by the bond energy). Through mechanical formulas (such as converting bond energy into force and then dividing by the effective cross-sectional area or square length of the chain segment), this microscopic bond fracture force is converted into the macroscopic yield stress, that is, the material's ultimate strength. S403. Based on the gel yield stress value obtained in the previous step and the gel elastic modulus value obtained in sub-step 1, the system encapsulates these two core mechanical parameters in the form of a structured data package. This data package is used in subsequent macroscopic mechanical calculation modules, ensuring that subsequent steps can be called as a whole to generate a gel mechanical parameter set. This step encapsulates the elastic modulus (stiffness) calculated in S401 and the yield stress (strength) calculated in S402 into a single data structure. This parameter set constitutes a complete description of the mechanical behavior of the gel material, defining the key characteristics of the material's stress-strain response curve. In the pore throat scale determination in S5, the elastic modulus is used to calculate the degree of deformation of the gel under a given pressure difference, while the yield strength (as a criterion) is used to determine whether the deformation exceeds the material's bearing capacity and creep occurs. Therefore, this parameter set serves as a bridge connecting material simulation and application simulation.

[0025] The preparation method of the integrated oil displacement and plugging gel and the steps for determining the pore throat-scale plugging status specifically include: S501: The system calls the gel mechanical parameter set and obtains the digital core pore network model. It then traverses all throats in the model, filtering out all gel-filled throats based on their blocking status indicators. It extracts the fluid pressure differential values ​​for each throat and counts all selected throats, establishing a set of blocking throat pressure differentials and total numbers. This dataset forms the basis for the status determination in step S5. First, it filters out all gel-filled throats from the vast digital core pore network model using "blocking status indicators," achieving precise location of the analysis object. Then, it extracts all fluid pressure differential values ​​that the driving fluid attempts to pass through these blocking points; these pressure differentials constitute the "load" borne by the gel. Simultaneously, the count (total number) of these throats provides the denominator for calculating the creep activation ratio in S503. This dataset combines all the "load" data required for comparison and determination in S502 and the denominator required for calculating the ratio in S503. S502: The system retrieves the pressure differential of the plugged throats and the fluid pressure differentials of each throat in the total count set. Using the yield limit in the gel mechanical parameter set as the criterion, the system iterates through all the fluid pressure differential values ​​of the plugged throats, comparing each value with the yield limit. When the fluid pressure differential is greater than the yield limit, the internal counter increments by one, obtaining the creep-activated throat count. This step is the core determination of gel plugging effectiveness. It uses the inherent material property (gel yield limit) derived in S403 as the criterion, comparing it one by one with the external load (fluid pressure differential) borne by each throat collected in S501. When the external load (pressure differential) exceeds the material's internal resistance limit (yield limit), the gel in that throat is determined to have undergone plastic flow or "creep activation" and is counted. This count value (creep-activated throat count value) represents the total number of pores and throats where gel plugging has failed under the current reservoir conditions, and is the numerator of the proportion calculated in S503. S503. Based on the creep-activated throat count, and referring to the pressure differential of the plugged throats and the total number of plugged throats included in the total set, the system performs a division operation, using the creep-activated throat count as the dividend and the total number of plugged throats as the divisor. The resulting quotient represents the proportion of throats experiencing plastic flow, generating the pore-throat creep activation ratio. This ratio is the final output of the entire simulation scheme (S1 to S5), linking the microscopic gel preparation parameters (S1) with the macroscopic reservoir application effect (S5). By dividing the number of failed throats counted in S502 (numerator) by the total number of plugged throats counted in S501 (denominator), this ratio (e.g., 0.1 or 10%) intuitively quantifies the plugging efficiency of the gel in a specific digital core model. This value can be used to guide the optimization of the gel formulation: if the ratio is too high, the parameters in S1 need to be adjusted to increase the yield limit in S4; if the ratio is too low (which may lead to over-plugging of medium- and low-permeability oil layers), the opposite adjustment is required.

[0026] In the preparation method S101 of the integrated oil displacement and plugging gel, the activation energies and pre-exponential factors of the four reactions—initiation, chain growth, chain transfer, and chemical crosslinking—are obtained by querying and matching them from a pre-set chemical reaction parameter library based on the initial ratio of monomer concentration, initiator concentration, and crosslinking agent concentration. This matching and query mechanism is a prerequisite for ensuring the physical authenticity of the calculation results of S101. This chemical reaction parameter library stores a large amount of known, experimentally calibrated kinetic data (activation energies and pre-exponential factors) of monomer-initiator-crosslinking agent systems. When S101 obtains a specific gel synthesis ratio (such as acrylamide monomer concentration or a specific initiator concentration), the system automatically retrieves and calls the activation energy and pre-exponential factor corresponding to that chemical system. This input based on empirical data ensures that the subsequent rate constant values ​​of the four types of reactions calculated by S101 are a true reflection of the reactivity of the specific gel formulation, rather than arbitrary assumptions.

[0027] In the preparation method S202 of the integrated oil displacement and plugging gel, the local segment relaxation time is calculated using a dynamic relaxation function based on the number of monomer units contained in the segment in the preliminary polymer network conformation of the gel and the reaction temperature data obtained in S101. This calculation step makes the criterion for determining "instantaneous physical entanglement points" (local segment relaxation time) in S202 dynamically adaptable. The input to this dynamic relaxation function (e.g., the Rouse model or Reptation model) is the microstructure of the segment (number of monomer units, i.e., chain length) and the macroscopic environment of S101 (reaction temperature). This means that for shorter segments or at higher temperatures, the calculated relaxation time is shorter, and the system has more stringent requirements for the duration of entanglement; conversely, longer segments have longer relaxation times. This adaptive criterion makes the instantaneous entanglement points selected by S202 more consistent with the real physical processes of polymer dynamics.

[0028] The mechanical relationship in the preparation method S402 of the integrated oil displacement and sealing gel is as follows: the bond energy of the C-C bond in the polymer of the integrated oil displacement and sealing gel is divided by the square of the minimum chain segment length of the integrated oil displacement and sealing gel, and the result is multiplied by a preset material shear constant to estimate the gel yield stress value. This mechanical relationship provides a clear mathematical path for the cross-scale calculation from microscopic chain segment length to macroscopic yield stress in S402. Its physical meaning is: the energy (bond energy) required to break a C-C bond is distributed to the "failure volume" defined by the shortest chain segment (proportional to the square or cube of the minimum chain segment length), thereby obtaining an energy density or stress value. This preset material shear constant is used to correct for the scale difference and stress transfer effect between single bond breakage and macroscopic material yield. Through this formula, the geometric parameters (minimum chain segment length) of the "weakest ring" selected in S402 are directly converted into the macroscopic mechanical strength parameters required in S403.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an integrated oil displacement and plugging gel, characterized in that, Includes the following steps: S1. Calculation of reaction kinetic parameters: Obtain the concentrations of monomers, initiators, crosslinking agents and reaction temperature data for gel synthesis. Based on the Arrhenius equation and concentration parameters, calculate the probability rate constants of four reactions: initiation, chain growth, chain transfer and chemical crosslinking, and finally generate the probability set of reaction events. S2. Dynamic Topology Network Evolution Simulation: Based on reaction probability sets, the simulation is advanced through time steps. Each time step randomly executes reaction events, driving the dynamic growth of polymer chains. The system periodically analyzes the chain backbone topology, marking instantaneous physical entanglement points when chain A encircles chain B for a duration exceeding the local chain segment relaxation time. If a chemical crosslinking reaction occurs near this point, it is converted to a "permanently locked" state. The simulation ultimately generates a four-dimensional network topology database recording this evolution process. S3. Calculation of gel network crosslinking density: Using a four-dimensional network database, all physically entangled and chemically crosslinked points in a "permanently locked" state are traversed and accumulated to obtain the total number of effective crosslinking points. Dividing this number by the volume of the simulation system yields the effective crosslinking density of the gel. S4. Derivation of Macroscopic Mechanical Parameters of the Gel: Based on the effective crosslinking density, combined with the Boltzmann constant and reaction temperature, the elastic modulus of the gel is calculated. Simultaneously, by traversing the database to identify all chain segments, the shortest chain segment length is selected and its theoretical fracture stress is calculated, which is used as the yield strength of the gel. Finally, the elastic modulus and yield strength are packaged and output as a set of gel mechanical parameters. S5. Determination of Pore Throat Blockage Status: The yield limit in the gel mechanical parameter set is called, and the fluid pressure difference of each throat in the digital core pore network model is obtained. All throats blocked by gel are traversed, and their fluid pressure differences are compared with the gel yield limit. The number of throats with fluid pressure differences greater than the yield limit is counted, and the creep activation ratio of the pore throats is calculated.

2. The method for preparing an integrated oil displacement and plugging gel according to claim 1, characterized in that: The reaction event probability set includes the probability of triggering events, chain growth events, chain transfer events, and chemical cross-linking events. The four-dimensional network topology database specifically refers to the three-dimensional coordinates of nodes, associated chain IDs, node formation time, and node status identifiers. The effective cross-linking density of the gel includes the locked physical entanglement density and the chemical cross-linking node density. The gel mechanical parameter set specifically includes the gel elastic modulus and the gel yield limit. The pore throat creep activation ratio includes the number of creep-activated throats and the total number of blocked throats.

3. The method for preparing an integrated oil displacement and plugging gel according to claim 1, characterized in that: The steps for calculating the reaction kinetic parameters specifically include: S101. Obtain the monomer concentration, initiator concentration, crosslinking agent concentration and reaction temperature data for gel synthesis. At the same time, retrieve the activation energy and pre-exponential factor of each of the four reactions: initiation, chain growth, chain transfer and chemical crosslinking. Perform exponential calculation on the reaction temperature, activation energy and pre-exponential factor according to the Arrhenius equation to calculate the initiation rate constant, chain growth rate constant, chain transfer rate constant and chemical crosslinking rate constant, and obtain the four types of reaction rate constant values. S102. For the four types of reaction rate constants, including the initiation rate constant, chain growth rate constant, chain transfer rate constant, and chemical crosslinking rate constant, these four constants are used as the basis for selecting reaction events, and they are uniformly encapsulated into a data set to generate a reaction event probability set.

4. The method for preparing an integrated oil displacement and plugging gel according to claim 1, characterized in that: The specific steps of the dynamic topology network evolution simulation include: S201. Call the reaction event probability set and set the total simulation time step. In each time step, the system randomly selects a reaction event based on the probability values ​​of initiation, chain growth, chain transfer, and chemical crosslinking in the reaction event probability set and executes it. This execution updates the connection relationship and three-dimensional coordinates of the polymer chain, gradually building a polymer network. After the simulation reaches the total time step, the preliminary polymer network conformation is obtained. S202. For the preliminary polymer network conformation, the system periodically runs the original path analysis to calculate the skeleton topology path of all polymer chains. The system traverses all chain pairs. When it is determined that the skeleton path of a chain A surrounds another chain B, the system records the duration of the surround state and retrieves the local chain segment relaxation time of the chain segment. When the surround duration is greater than the chain segment relaxation time, the position is marked as an instantaneous physical entanglement point, and a list of instantaneous entanglement point coordinates is established. S203. The system calls the list of instantaneous entanglement point coordinates and retrieves the chemical crosslinking point location data recorded in the preliminary polymer network conformation. The system iterates through all instantaneous entanglement point coordinates and determines whether the spatial distance between its three-dimensional coordinates and any chemical crosslinking point location is less than the preset locking radius threshold. If it is less, the node status is updated to "permanently locked". Finally, the system integrates the three-dimensional coordinates, associated chain IDs, formation time and status identifiers of all instantaneous and permanently locked nodes to establish a four-dimensional network topology database.

5. The method for preparing an integrated oil displacement and plugging gel according to claim 1, characterized in that: The specific steps for calculating the crosslinking density of the gel network include: S301. Call the four-dimensional network topology database, which contains the three-dimensional coordinates of nodes, the ID of the associated chain, the formation time and the status identifier. The system initializes a counter to zero, and then traverses all node entries in the database. For each entry, extract its "status identifier" data item, and determine whether the text value of the "status identifier" data item is equal to the preset string "permanently locked". If the determination result is yes, the counter is incremented by one. If the determination result is no, the entry is skipped. After all entries have been traversed, the final value of the counter is obtained, and the count of locked physical entanglement points is generated. S302. Retrieve the total number of chemical crosslinking points recorded in the dynamic topology network evolution simulation step. This total number is the cumulative number of all chemical crosslinking reactions that occur during the simulation process. The system performs an arithmetic summation operation on the total number of chemical crosslinking points and the count of locked physical entanglement points obtained in the previous step. This operation adds the two independent count values, and the result represents the sum of all permanent constraint nodes in the network, thus establishing the total number of effective crosslinking points. S303. Obtain the three-dimensional volume value of the simulation system set in the dynamic topology network evolution simulation step. This value represents the spatial scale used for calculation. The system calls the total number of effective crosslinking points generated in the previous step and performs a division operation. In this operation, the total number of effective crosslinking points is used as the dividend, and the three-dimensional volume value of the simulation system is used as the divisor. The quotient obtained represents the number of permanent constraint nodes per unit volume, and the effective crosslinking density of the gel is generated.

6. The method for preparing an integrated oil displacement and plugging gel according to claim 1, characterized in that: The specific steps for deriving the macroscopic mechanical parameters of the gel include: S401. Based on the effective crosslinking density of the gel, the system simultaneously retrieves the reaction temperature data obtained in the reaction kinetic parameter calculation step and the Boltzmann constant value in the known field. The system performs a multiplication operation on the effective crosslinking density of the gel, the Boltzmann constant and the reaction temperature. According to the rubber elasticity theory, the calculation result is defined as the shear modulus of the gel in thermodynamic equilibrium state and converted into the bulk modulus to obtain the gel elastic modulus value. S402. Call the four-dimensional network topology database established in the dynamic topology network evolution simulation step. This database contains node coordinates and involved chain IDs. The system traverses all permanently locked or transiently entangled nodes, extracts the chain segment length data of all polymer chains connecting these nodes, and performs a minimum value screening operation on all extracted chain segment length values. The minimum chain segment length selected is taken as the potential breakage point. Based on the bond energy of the polymer C-C bond and the minimum chain segment length, the theoretical macroscopic stress required to break the bond is calculated through a mechanical relationship to obtain the gel yield stress value. S403. For the gel yield stress value obtained in the previous step and the gel elastic modulus value obtained in sub-step 1, the system encapsulates these two core mechanical parameters in the form of a structured data package. This data package is used in the subsequent macroscopic mechanical calculation module to ensure that subsequent steps can be called as a whole to generate a gel mechanical parameter set.

7. The method for preparing an integrated oil displacement and plugging gel according to claim 1, characterized in that: The steps for determining the pore throat occlusion status specifically include: S501. Call the gel mechanical parameter group and obtain the digital core pore network model. The system traverses all throats in the model, filters out all throats blocked by gel according to their blocking status indicators, and extracts the fluid pressure difference value of each throat. At the same time, count all the selected throats and establish a set of blocking throat pressure difference and total number. S502. Call the pressure difference of the blocked throat and the fluid pressure difference of each throat in the total set, and use the yield limit in the gel mechanical parameter group as the judgment criterion. The system traverses the fluid pressure difference value of all blocked throats and compares the pressure difference value with the yield limit one by one. When the fluid pressure difference value is greater than the yield limit, the internal counter performs an increment operation to obtain the creep activated throat count value. S503. Based on the creep activation throat count value, and by calling the pressure difference of the blocked throat and the total number of blocked throats contained in the total set, the system performs a division operation with the creep activation throat count value as the dividend and the total number of blocked throats as the divisor. The quotient value obtained represents the proportion of throats that have undergone plastic flow, and generates the pore throat creep activation ratio.

8. The method for preparing an integrated oil displacement and plugging gel according to claim 3, characterized in that: The activation energies and pre-exponential factors of the four reactions in S101—initiation, chain growth, chain transfer, and chemical crosslinking—are obtained by querying and matching from a preset chemical reaction parameter library based on the initial ratio of monomer concentration, initiator concentration, and crosslinking agent concentration.

9. The method for preparing an integrated oil displacement and plugging gel according to claim 4, characterized in that: The localized chain segment relaxation time in S202 is calculated using a dynamic relaxation function based on the number of monomer units contained in the chain segment in the preliminary polymer network conformation and the reaction temperature data obtained in S101.

10. The method for preparing an integrated oil displacement and plugging gel according to claim 6, characterized in that: The mechanical relationship in S402 is specifically: the bond energy of the polymer CC bond is divided by the square of the minimum chain segment length, and the result is multiplied by a preset material shear constant to estimate the gel yield stress value.

Images