An acid-rock reaction rate prediction method based on film coating with a coating liquid

Abstract

The application provides a kind of acid rock reaction rate prediction method based on coating liquid coating, belong to petroleum geology test technical field, this method includes: based on coating and acid rock reaction experiment, fitting reaction rate equation based on acid liquid concentration, reaction rate equation based on temperature and fractal dimension calculation formula;And coating concentration and coating temperature are experimentally fitted respectively, obtain the reaction rate influenced by coating concentration and the reaction rate influenced by coating temperature;Establish the numerical simulation model of acid rock reaction, and use the reaction rate equation based on temperature, carry out numerical simulation, obtain the reaction kinetics equation of coating flow influence under reservoir temperature and the reaction kinetics equation of coating time influence under reservoir temperature, and the optimal comprehensive coating factor is fitted to obtain, the acid rock reaction rate of comprehensive coating factor is predicted. The application solves the problem that acid rock reaction rate after coating cannot be predicted, and provides theoretical basis and data support for optimization of acid fracturing process parameters.

Description

Technical Field

[0001] This invention belongs to the field of petroleum geological testing technology, and in particular relates to a method for predicting acid rock reaction rates based on coating liquid. Background Technology

[0002] Acid fracturing technology plays an irreplaceable role in oil and gas field development as a key engineering technology for improving the permeability of carbonate reservoirs and increasing the productivity of single wells. The core principle of acid fracturing technology is to inject acid to open the reservoir into fractures, while simultaneously dissolving the fractured rock matrix in a non-uniform manner, thereby constructing acid-etched fracture channels with high conductivity or expanding pore space to enhance the fluid permeability. However, in the stimulation of deep and ultra-deep carbonate reservoirs, the high reservoir temperature leads to a fast acid-rock reaction rate and a short effective acid action distance, making it difficult to stimulate deep reservoirs.

[0003] To address the above issues, scholars have conducted extensive research. Currently, the main methods for slowing down the flow rate include: increasing the acid viscosity or reducing the liquid phase ratio; controlling the flow rate by adjusting the viscosity; altering the physical properties of the acid; reducing the acid activity; and achieving cooling and viscous fingering through pre-fluid acid pressure and alternating injection acid pressure.

[0004] When reservoir temperatures exceed 150℃, existing acid fracturing systems and processes are poorly understood. Using only acid fracturing results in rapid acid consumption and a short effective range. Therefore, new acid fracturing processes need to be explored to overcome the technical bottlenecks in deep reservoir acid fracturing.

[0005] To address this, existing technologies have proposed a film-coated slow acid fracturing technique, which involves injecting fracturing fluid containing a film-coating solution before acid injection. The film-coating solution is an aqueous solution of coupling agent prepared at the required concentration, which can coat the fracture wall, delay the contact between the acid and the wall, reduce acid consumption, and increase the effective action distance of the acid. However, the acid-rock reaction kinetic equations used in existing studies do not take the film-coating factor into account, and therefore cannot calculate the acid-rock reaction rate under different film-coating conditions.

[0006] This invention focuses on the acid-rock reaction after coating with a coating liquid on a rock surface. It conducts indoor experiments and numerical simulations of the acid-rock reaction with a flow coating liquid, fits the reaction kinetic equation considering the rock coating, and obtains the acid-rock reaction rate relationship under different rock coating conditions, thus solving the defects and shortcomings of the existing technology. Summary of the Invention

[0007] To address the aforementioned shortcomings in the existing technology, this invention provides a method for predicting acid-rock reaction rates based on a coating liquid, which solves the problem that existing acid-rock reaction rate prediction methods cannot predict the acid-rock reaction rate after coating.

[0008] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for predicting acid-rock reaction rates based on a coating liquid, comprising the following steps: S1. Based on the film coating and acid-rock reaction experiments, by fitting the reaction kinetic equations of film coating concentration and film coating temperature, the reaction rate equation based on acid concentration, the reaction rate equation based on temperature, and the fractal dimension calculation formula are obtained. S2. Using the reaction rate equation based on acid concentration, the reaction rate equation based on temperature, and the fractal dimension calculation formula, the coating concentration and coating temperature were experimentally fitted to obtain the reaction rate affected by coating concentration and the reaction rate affected by coating temperature. S3. Establish a numerical simulation model of acid-rock reaction, and based on the preset reservoir temperature, preset coating flow rate and preset coating time, use the temperature-based reaction rate equation to conduct numerical simulation and obtain the reaction kinetic equations of the effect of coating flow rate on reservoir temperature and the effect of coating time on reservoir temperature. S4. Based on the reaction rate affected by coating concentration, reaction rate affected by coating temperature, reaction kinetic equations affected by coating flow rate under reservoir temperature, and reaction kinetic equations affected by coating time under reservoir temperature, the optimal comprehensive coating factor is fitted and the acid rock reaction rate of the comprehensive coating factor is predicted.

[0009] The beneficial effects of this invention are as follows: By conducting indoor experiments on fluidized bed-coated acid rock reaction, this invention fits the reaction kinetic equations under different coating concentrations and coating temperatures, obtaining the reaction rates affected by coating concentration and coating temperature. For the first time, the coating factor is introduced into the acid rock reaction rate prediction model, solving the problem that existing acid rock reaction kinetic equations fail to consider coating factors and cannot calculate acid rock reaction rates under different coating conditions, thus providing a theoretical basis and data support for the optimization of acid fracturing process parameters.

[0010] Further, S1 includes the following steps: S101. Based on the film coating and acid-rock reaction experiments, the decrease in acid concentration per unit time is expressed as a function fitting constant. S102. By introducing the area of ​​the reaction interface, the function fitting constant is corrected to obtain the concentration-based reaction rate equation. S103. Take the logarithm of the concentration-based reaction rate equation, obtain the reaction rate constant and reaction order by obtaining the logarithm of the acid-rock reaction rate and the logarithm of the acid concentration and performing linear regression. S104. Based on the Arrhenius ionization theory, the dependence of the reaction rate constant on temperature is obtained according to the reaction rate constant. S105. Substitute the temperature dependence of the reaction rate constant into the concentration-based reaction rate equation and combine it with the reaction order to obtain the temperature-based reaction rate equation. S106. Based on the sum of the acid erosion volumes at various points on the rock surface and the reaction area of ​​the rock, the average drop height is obtained, and based on the box dimension method, the fractal dimension calculation formula is obtained through transformation.

[0011] Furthermore, the temperature-based reaction rate equation is as follows: ; in, This indicates the reaction rate based on temperature. and All represent the fitting results. Denotes Avogadro's constant. Indicates the reaction temperature. Indicates the initial reaction temperature. Indicates the acid concentration. Indicates the reaction order.

[0012] The beneficial effects of the above-mentioned further scheme are as follows: This invention establishes reaction rate equations based on acid concentration, reaction rate equations based on temperature, and fractal dimension calculation formulas by combining coating and acid-rock reaction experiments with kinetic equation fitting. By taking logarithmic linear regression to calibrate the reaction rate constant and reaction order, the solution process of nonlinear kinetic parameters is simplified and the fitting accuracy is improved. Furthermore, by introducing Arrhenius theory to establish the dependence of the reaction rate constant on temperature, accurate extrapolation and prediction of reaction rates under different temperature conditions are achieved. By introducing the box-dimensional method to calculate the fractal dimension, quantitative characterization of the heterogeneity of rock dissolution surfaces is achieved, providing a complete kinetic parameter basis and surface morphology description method for subsequent reaction rate prediction under the influence of multiple factors such as coating concentration, coating temperature, coating flow rate, and coating time.

[0013] Furthermore, S2 includes the following steps: S201. Based on the preset experimental temperature and preset coating concentration, the reaction rate and fractal dimension of each preset coating concentration are calculated using the reaction rate equation based on acid concentration and the fractal dimension calculation formula. S202. Based on the reaction rate of each preset coating concentration and the fractal dimension of the preset coating concentration, select the optimal coating concentration and obtain the fitting curve between the coating concentration and the acid rock reaction rate. S203. Based on the fitting curve of coating concentration and acid rock reaction rate, obtain the relative reaction rate of each preset coating concentration and fit it to obtain the empirical formula of the relative reaction rate of each preset coating concentration. S204. Based on the empirical formula for the relative reaction rate of each preset coating concentration, and combined with the reaction rate equation based on acid concentration, the reaction rate affected by coating concentration is fitted to obtain the reaction rate. S205. Based on the optimal coating concentration and preset coating temperature, the reaction rate and fractal dimension of each preset coating temperature are calculated using the temperature-based reaction rate equation and fractal dimension calculation formula. S206. Based on the reaction rate at each preset coating temperature and the fractal dimension of the preset coating temperature, obtain the fitting curve between the coating temperature and the acid rock reaction rate. S207. Based on the fitting curve of coating temperature and acid rock reaction rate, obtain the relative reaction rate of each preset coating concentration and fit it to obtain the empirical formula of the relative reaction rate of each preset coating concentration. S208. Based on the empirical formula for the relative reaction rate of each preset coating concentration, and combined with the temperature-based reaction rate equation, the reaction rate affected by the coating concentration is fitted to obtain the reaction rate.

[0014] Furthermore, the expression for the effect of the coating concentration on the reaction rate is as follows: ; in, This indicates the effect of coating concentration on the reaction rate. Indicates the coating concentration. Indicates the acid concentration; The expression for the effect of coating temperature on the reaction rate is as follows: ; ; in, This indicates the effect of coating temperature on the reaction rate. This indicates the relative reaction rate at different coating temperatures. This indicates the reaction rate at different coating temperatures. Indicates the reaction rate without a membrane. Indicates the coating temperature.

[0015] The beneficial effects of the above-mentioned further scheme are as follows: This invention establishes a quantitative characterization method for the reaction rate under the influence of coating concentration and coating temperature. In terms of coating concentration, the reaction rate and fractal dimension under different coating concentrations are experimentally determined, the optimal coating concentration is selected, and the concentration-rate relationship curve is fitted. An empirical formula for the relative reaction rate is derived, and combined with the reaction rate equation based on acid concentration, the reaction rate expression of the influence of coating concentration is obtained. In terms of coating temperature, based on the optimal coating concentration condition, the reaction rate expression of the influence of coating temperature is obtained using the same method. This realizes the independent quantification of the influence of the two key process parameters, coating concentration and coating temperature, on the acid rock reaction rate, providing two independent correction factors for subsequent multi-factor comprehensive prediction. It also provides a quantitative basis for the preparation of coating solution concentration and the selection of injection temperature in on-site construction.

[0016] Furthermore, step S3 includes the following steps: S301. Based on the fluid seepage in porous media, the deposition of suspended particles in the coating liquid, the acid-rock reaction, the delaying effect of the coating on dissolution, and the micropore structure of the reservoir, a numerical simulation model of the acid-rock reaction is established. S302. A numerical simulation model based on acid-rock reaction is used to perform numerical simulation based on the preset reservoir temperature and preset coating flow rate, and the simulation calculation results of preset reservoir temperature and preset coating flow rate are obtained. S303. Based on the simulation calculation results of the preset reservoir temperature and preset coating flow rate, obtain the relative response rate between the coating flow rate and the coating effect; S304. Using an exponential model, regression analysis is performed on the relative response rate of the coating flow rate and the effect of coating to obtain the coating flow rate fitting curve and the reservoir temperature fitting curve. An empirical formula for the relative response rate of the effect of the preset coating flow rate at the preset reservoir temperature is obtained through fitting. S305. Based on the empirical formula for the relative reaction rate affected by the preset coating flow rate at the preset reservoir temperature, and combined with the temperature-based reaction rate equation, the reaction kinetic equation for the effect of coating flow rate at the reservoir temperature is obtained. S306. A numerical simulation model based on acid-rock reaction is used to perform numerical simulation based on the preset reservoir temperature and preset coating time, and the simulation calculation results of preset reservoir temperature and preset coating time are obtained. S307. Based on the simulation calculation results of the preset reservoir temperature and preset coating time, obtain the relative response rate between coating time and coating effect; S308. Using an exponential model, regression analysis is performed on the relative response rate of the coating time and the effect of coating to obtain the coating time fitting curve and the reservoir temperature fitting curve. An empirical formula for the relative response rate of the effect of the preset coating time at the preset reservoir temperature is obtained through fitting. S309. Based on the empirical formula for the relative reaction rate affected by the preset coating time at the preset reservoir temperature, and combined with the temperature-based reaction rate equation, the reaction kinetic equation for the effect of coating time on the reservoir temperature is obtained.

[0017] Furthermore, the reaction kinetic equation for the effect of membrane flow rate on reservoir temperature is as follows: ; ; in, This indicates the effect of coating flow rate on the reaction rate at reservoir temperature. This represents the relative reaction rate affected by different coating flow rates at different reservoir temperatures. This indicates the effect of membrane flow rate on the reaction rate at different reservoir temperatures. Indicates the coating flow rate. Indicates the coating temperature; The reaction kinetic equations for the effect of coating time on reservoir temperature are shown below: ; ; in, This indicates the effect of coating time on the reaction rate at reservoir temperature. This indicates the relative reaction rate affected by different coating times at different reservoir temperatures. This indicates the effect of different coating times on the reaction rate at different reservoir temperatures. Indicates the film covering time.

[0018] The beneficial effects of the above-mentioned further scheme are as follows: This invention establishes a numerical simulation model of acid-rock reaction through multi-physics coupling mechanisms such as porous media fluid seepage, deposition of suspended particles of coating fluid, acid-rock reaction, the delaying effect of coating on dissolution, and reservoir micropore structure; and by using temperature-based reaction rate equations for two process parameters, coating flow rate and coating time, respectively, and using an exponential model to perform regression analysis on the simulation results, the reaction kinetic equations for the influence of coating flow rate and coating time on reservoir temperature are obtained, realizing the quantitative characterization of the influence of coating flow rate and coating time on acid-rock reaction rate, and successfully extrapolating the reaction kinetic parameters obtained under indoor experimental conditions to actual reservoir temperature and injection conditions, effectively making up for the difficulty of obtaining parameters under high temperature and high pressure conditions by purely experimental methods; at the same time, it provides direct quantitative basis for optimizing the injection flow rate and injection time of coating fluid in field construction.

[0019] Furthermore, the 301 includes the following steps: S3011. Based on the flow basis of acid rock reaction, according to the fluid seepage in porous media, the dynamic transmission of fluid is described by the differential equation of the Brinkman equation, and the main governing equation of fluid seepage in porous media is constructed. S3012. Based on the physical process of coating, according to the deposition of suspended particles in coating liquid, using the classical particle migration and deposition model, by converting the coating liquid particles lost in the fluid into solid deposits, a coating liquid suspended particle deposition and coating dynamics model is constructed. S3013. Based on the physical process of acid etching, according to the acid-rock reaction, using the chemical reaction rate and the speed at which acid is transported from the liquid phase to the liquid-solid interface in the pores, the mass transfer coefficient is obtained. Combined with the change of rock porosity with chemical reaction, an acid-rock reaction and mass transfer kinetic model is constructed. S3014. Based on the delaying effect of coating on dissolution, by introducing time step functions characterizing the coating stage and time step functions characterizing the acid etching stage, the delaying principle of coating on acid rock reaction is obtained through synchronous simulation. S3015. Based on the reservoir's micropore structure and the influence of porosity changes on permeability, pore radius, and specific surface area, a dynamic model of the reservoir's micropore structure and macroscopic properties is constructed by defining the permeability change equation, the pore radius dynamic equation, and the initial specific surface area change equation. S3016 integrates the master equation of fluid seepage in porous media, the deposition and kinetic model of suspended particles in the coating fluid, the acid-rock reaction and mass transfer kinetic model, the delay principle of coating on acid-rock reaction, and the dynamic change model of reservoir micropore structure and macroscopic physical properties to obtain a numerical simulation model of acid-rock reaction.

[0020] The beneficial effects of the above-mentioned further solutions are as follows: This invention describes the flow behavior of fluids in fractured and porous media by constructing a multi-physics coupled numerical simulation model of acid-rock reaction; it simulates the attachment and deposition process of coated fluid suspended particles on the rock surface through a classical particle migration and deposition model; it establishes an acid-rock reaction and mass transfer kinetic model by coupling chemical reaction rate and mass transfer coefficient; it realizes the mathematical description of the coating delay effect on dissolution by introducing a time step function to characterize the coating stage and acid etching stage respectively; and it establishes the connection between microscopic pore structure evolution and macroscopic property changes through the dynamic correlation equation between porosity-permeability-pore radius-specific surface area; the model integrates five major modules: flow, coating, reaction, delay effect, and dynamic property changes, providing a complete theoretical basis and calculation platform for subsequent numerical simulation of coating flow rate and coating time, enabling reliable prediction data to be obtained through numerical means even under extreme high temperature and high pressure conditions that cannot be directly obtained through experiments.

[0021] Furthermore, step S4 includes the following steps: S401. Based on the reaction kinetic equations of the influence of coating concentration, coating temperature, coating flow rate, and coating time on the reservoir temperature, the coating factors including coating concentration, coating temperature, coating flow rate, and coating time are obtained. S402. Fit the effect of coating factors on the reaction rate to obtain the comprehensive coating factors; S403. Based on the reaction rate calculated by numerical simulation based on the active reaction sites of the ideal interface, and the reaction rate fitted by experiment based on the experimental performance of the coating liquid and acid liquid and the actual active sites of the experimental rock slab interface, the experimental results and simulation calculation results are obtained by setting the same conditions and performing numerical simulation and experimental fitting respectively. S404. Divide the experimental results and the simulation calculation results to obtain the active area correction factor. Then, use the active area correction factor to transform and fit the comprehensive coating factor to obtain the optimal comprehensive coating factor. S405. Based on the optimal comprehensive coating factors and combined with the temperature-based reaction rate equation, the final reaction rate equation is obtained and predicted to obtain the acid rock reaction rate based on the comprehensive coating factors.

[0022] Furthermore, the final reaction rate equation is as follows: ; ; in, This represents the acid-rock reaction rate considering all factors related to the coating. This represents the optimal overall coating factors. Indicates the coating concentration. Indicates the coating temperature. Indicates the coating flow rate. Indicates the film covering time.

[0023] The beneficial effects of the above-mentioned further solutions are as follows: This invention obtains a comprehensive coating factor by comprehensively fitting four independently influencing coating factors: coating concentration, coating temperature, coating flow rate, and coating time. This achieves a holistic quantitative characterization of the coating effect under multi-factor coupling conditions. Furthermore, by introducing an active area correction factor, the numerical simulation results based on an ideal interface are compared and corrected with the experimental fitting results based on a real rock slab interface. This eliminates the deviation between the idealized model and the heterogeneity of the real rock surface, improving the engineering applicability of the prediction model. The obtained optimal comprehensive coating factor and final reaction rate equation enable accurate prediction of the acid rock reaction rate under coating conditions. This provides a direct calculation basis and theoretical support for the synergistic optimization of multiple process parameters such as coating fluid concentration, injection flow rate, injection time, and injection temperature in acid fracturing operations. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method of the present invention.

[0025] Figure 2 The image shows the scanning results of the acid rock reaction with the preset coating concentration in this embodiment.

[0026] Figure 3 This is a logarithmic coordinate fitting curve of acid-rock reaction rate and acid concentration in this embodiment.

[0027] Figure 4 This is a scan result of the coated acid rock reaction at the preset coating temperature in this embodiment.

[0028] Figure 5 This is a curve showing the fitting relationship between the acid-rock reaction rate and the coating temperature in this embodiment.

[0029] Figure 6 This is a fitting curve of the relative reaction rate of the coating flow rate and reservoir temperature with respect to the coating effect in this embodiment.

[0030] Figure 7 This is a fitting curve of the relative reaction rate of the coating time and reservoir temperature with respect to the coating effect in this embodiment.

[0031] Figure 8 This is a bar chart showing the relationship between the fractal dimension difference and the coating temperature in this embodiment.

[0032] Figure 9 This is a comparison chart of the calculated reaction rate values ​​with the experimental and simulated values ​​in this embodiment. Detailed Implementation

[0033] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0034] Before describing this embodiment, the following terms will be explained: Arrielius theory: Arrielius's theory of ionization; Brinkman equation: the differential equation of the Brinkman equation; Comsol: An advanced numerical simulation software; Matlab: Matrix Lab, a statistical and econometric mathematical software.

[0035] Example like Figure 1 As shown, this invention provides a method for predicting acid-rock reaction rates based on a coating liquid, the implementation of which is as follows: S1. Based on the film coating and acid-rock reaction experiments, by fitting the reaction kinetic equations for film coating concentration and film coating temperature, the reaction rate equations based on acid concentration, the reaction rate equations based on temperature, and the fractal dimension calculation formula are obtained. The specific steps are as follows: S101. Based on the film coating and acid-rock reaction experiments, the decrease in acid concentration per unit time is expressed as a function fitting constant. S102. By introducing the area of ​​the reaction interface, the function fitting constant is corrected to obtain the concentration-based reaction rate equation.

[0036] In this embodiment, reaction kinetics were fitted through coating and acid-rock reaction experiments. By simultaneously fitting the reaction kinetic equations for different coating concentrations and coating temperatures, a temperature-based reaction rate equation and a fractal dimension calculation formula were obtained. Specifically: The specific experiments on coating and acid-rock reaction are as follows: The processed rock slabs were dried, weighed, photographed, and scanned using a 3D scanner to obtain the crack morphology and weight of the rock slabs before the experiment. The required coating solution and acid solution were prepared according to the experimental design. Apply red glue around the rock slab and place it into the rock slab holder. Do not apply red glue to the crack surface of the experimental reaction. Seal the rock slab holder and let it stand for more than 6 hours to ensure that the red glue solidifies. Connect the heating system, intermediate container and horizontal flow pump. Add the coating liquid heated to the appropriate temperature to the first intermediate container and add the acid solution heated to the appropriate temperature to the second intermediate container. Heat the rock slab to the required coating temperature for the experiment, turn on the horizontal flow pump, and allow the coating liquid in the first intermediate container to flow through the crack surface of the rock slab within the designed time according to the designed flow rate. If coating is not required, this experimental step only involves heating the rock slab and turning on the horizontal flow pump. The pipeline was switched so that the acid in the second intermediate container could flow through the rock slab crack surface within the designed time according to the designed flow rate. Stop heating, turn off the flow pump, disassemble the pipelines and heating system, remove the rock slab holder, clean the instruments, and organize the equipment. The rock slab was cleaned, dried, weighed, photographed, and scanned using a 3D scanner to obtain the crack morphology and weight of the rock slab after the experiment. The experiment was then completed.

[0037] In this embodiment, the method for calculating the acid-rock reaction rate is as follows: The acid-rock reaction rate can be expressed as the decrease in acid concentration per unit time, or as the amount of rock dissolved per unit area per unit time. Based on mass action quantification, at constant temperature and pressure, the reaction rate is related to the concentrations of each reacting substance.m The product of powers is directly proportional; For acid-rock reactions (liquid-solid phase reactions), the concentration of the solid reactants can be considered constant. Under isothermal and isobaric conditions, the acid-rock reaction rate is as follows: ; in, Indicates reaction time t The acid concentration at any given time. express t time, Represents the function fitting constant. Indicates the reaction order; Since acid-rock reactions are typical multiphase reactions, the area (area-volume ratio) at the reaction interface has a significant impact on the reaction rate. Therefore, when processing experimental data, the area-volume ratio is introduced to correct the reaction rate, and a reaction rate constant is obtained. After correction, the concentration-based reaction rate equation is obtained, as shown below: ; in, express t The acid-rock reaction rate at time t, The surface-to-volume ratio, specifically the area at the reaction interface, Indicates the volume of acid solution. Indicates the surface area of ​​the reacting rock. This represents the reaction rate constant.

[0038] S103. Take the logarithm of the concentration-based reaction rate equation, obtain the reaction rate constant and reaction order by obtaining the logarithm of the acid-rock reaction rate and the logarithm of the acid concentration and performing linear regression. S104. Based on the Arrhenius ionization theory, the dependence of the reaction rate constant on temperature is obtained according to the reaction rate constant. S105. Substitute the temperature dependence of the reaction rate constant into the concentration-based reaction rate equation and combine it with the reaction order to obtain the temperature-based reaction rate equation.

[0039] Taking the logarithm of the expression for the reaction rate, as shown below: ; According to the reaction rate constant K and reaction rate order m Under certain conditions, it is a constant; therefore, the logarithm of the acid-rock reaction rate is used. Logarithm of acid concentration Plot a scatter plot and use the least squares method to logarithmize the acid-rock reaction rate. Logarithm of acid concentration Perform linear regression to obtain the reaction rate constant. and reaction order Values ​​were used to determine the acid-rock reaction kinetic equations; Since temperature is a key kinetic parameter determining the acid-rock reaction rate, increasing temperature not only enhances interfacial chemical reactions by increasing the percentage of activated molecules but also accelerates ion diffusion and mass transfer by improving fluid transport properties. Simultaneously, the change in the solubility of reaction products with temperature also has a synergistic effect on the reaction pathway. Based on Arrielius theory, the reaction rate constant is obtained. Temperature Dependencies typically follow these patterns: ; in, Represents the reaction rate constant. and All represent the fitting results. Denotes Avogadro's constant. Indicates the reaction temperature; Substituting the temperature dependence of the reaction rate constant into the concentration-based reaction rate equation, we obtain the temperature-based reaction rate equation, as shown below: ; in, This indicates the initial reaction temperature.

[0040] S106. Based on the sum of the acid erosion volumes at various points on the rock surface and the reaction area of ​​the rock, the average drop height is obtained, and based on the box dimension method, the fractal dimension calculation formula is obtained through transformation.

[0041] In this embodiment, the average drop height is obtained based on the sum of the acid etching volumes at various points on the rock surface and the reaction area of ​​the rock, and is defined as follows: ; in, Indicates the average descent altitude. Indicates the initial height. Indicates the height after the reaction. Indicates the total number of reaction points; Since there are various methods for calculating fractal dimension, including the box method, spectral dimension method, structure function method, size method, and carpet covering method, the box method is chosen because it does not require estimating the surface area of ​​the rough surface and is easily implemented through programming. The formula for calculating the fractal dimension of a rock fracture surface is as follows: ; Based on the box method's calculation formula, the expression for the fractal dimension, obtained through transformation, is shown below: ; in, Denotes the fractal dimension. Indicates the first i +1 box quantity, Indicates the first i Number of boxes Indicates the first i +1 box size, Indicates the first i The box size.

[0042] S2. Using reaction rate equations based on acid concentration, reaction rate equations based on temperature, and fractal dimension calculation formulas, experimental fitting was performed on coating concentration and coating temperature to obtain the reaction rates affected by coating concentration and coating temperature, respectively. The specific steps are as follows: S201. Based on the preset experimental temperature and preset coating concentration, the reaction rate and fractal dimension of each preset coating concentration are calculated using the reaction rate equation based on acid concentration and the fractal dimension calculation formula. S202. Based on the reaction rate of each preset coating concentration and the fractal dimension of the preset coating concentration, select the optimal coating concentration and obtain the fitting curve between the coating concentration and the acid rock reaction rate. S203. Based on the fitting curve of coating concentration and acid rock reaction rate, obtain the relative reaction rate of each preset coating concentration and fit it to obtain the empirical formula of the relative reaction rate of each preset coating concentration. S204. Based on the empirical formula for the relative reaction rate of each preset coating concentration, and combined with the reaction rate equation based on acid concentration, the reaction rate affected by coating concentration is fitted to obtain the reaction rate.

[0043] In this embodiment, the preset experimental temperature is 180°C. The preset coating concentrations included 0%, 2%, 4%, 6%, 8%, and 10%. Experimental fitting was performed using a reaction rate equation based on acid concentration to calculate the reaction rate and fractal dimension of each preset coating concentration. The effect of coating concentration on the reaction rate was then determined through fitting. Specifically: By studying the changes in the reaction rate, average descent height, and fractal dimension difference of acid-rock reaction after different coating concentrations, the fractal dimension difference, which represents the change in roughness before and after the acid-rock reaction, was used to analyze the change in the retardation effect of the coating. At the same time, the reaction rate equation based on the acid concentration was fitted to calculate the reaction rate of each preset coating concentration, and the numerical experimental results are shown in Table 1. Table 1 is the experimental results of acid-rock reaction with different coating concentrations.

[0044] Table 1

[0045] It can be seen that when there is no coating solution, the acid solution produces strong overall dissolution on the rock surface. Since it is pure dolomite, the dissolution is relatively uniform. The difference in fractal dimension is the smallest when there is no coating solution, and the dissolution non-uniformity is low. As the coating concentration increases, the degree of dissolution begins to decrease. like Figure 2 As shown in the scan image, the deep groove phenomenon has been alleviated, but there are large areas of dissolution pits on the surface, the fractal dimension difference has begun to increase, and the dissolution non-uniformity has begun to increase, indicating that the molecular film coverage formed by the coating liquid is currently insufficient. At 6%, the etched surface exhibited a smoothing characteristic with several small-area dissolution pits, the largest fractal dimension difference, and the greatest dissolution non-uniformity. The three-dimensional scanning results showed the gentlest height distribution gradient, with no obvious local deep pits. At 8% and 10%, the etched surface did not show large-area dissolution pits, and the fractal dimension difference decreased slightly. The three-dimensional scanning results showed a relatively gentle height distribution gradient, indicating that the film formed by the coating solution had a good effect on delaying hydrogen ion diffusion. In summary, a coating concentration of 6% is optimal, as it results in the largest difference in fractal dimension, high roughness, and strongest dissolution non-uniformity. This also indicates that the coating layer exhibits the strongest non-uniformity at this concentration, which aligns with the atomic force analysis results for different coating concentrations. Higher roughness of the coating solution is more conducive to slowing down the acid-rock reaction rate; therefore, a coating concentration of 6% yields the best slowing effect.

[0046] In this embodiment, the preset experimental temperature is 180°C. The reaction rate was fitted linearly with the logarithm of the acid-rock reaction rate at different acid concentrations. The results showed a reaction rate constant K = 1.3 × 10⁻⁶ and a reaction order m = 1.0678. The correlation was good, and the reaction order was close to 1, indicating that the acid-rock reaction process closely resembled first-order reaction kinetics. The preset experimental temperature of 180°C was also obtained. The reaction rate at this point is expressed as follows: ; like Figure 3 As shown, the relationship between coating concentration and acid-rock reaction rate is not a simple linear one; with increasing coating concentration, the acid-rock reaction rate initially decreases rapidly and then levels off; the reaction rate reaches its minimum at a concentration of 6%, approximately 1.1 × 10⁻⁶. -6 mol / (cm 2 The reaction rate (s) was higher than that of the uncoated group (1.45 × 10⁻⁶ s). -6 mol / (cm 2 s)) decreased by approximately 23%; In the low concentration range, increasing the coating concentration helps to form a denser and more comprehensive protective film on the rock surface, thereby enhancing the retardation effect on hydrogen ion diffusion; however, when the concentration exceeds 6%, the reaction rate curve tends to flatten, indicating that further increasing the coating concentration has little effect on slowing down the reaction rate. Therefore, the relative reaction rates at different coating concentrations were adopted. ,in, This indicates the reaction rate at different coating temperatures. This represents the reaction rate without a membrane. By fitting the data in the graph, we can obtain the result based on 180. Relative reaction rates at different coating concentrations at experimental temperatures The empirical formula is expressed as follows: ; in, This indicates the coating concentration, specifically 100 times the preset coating concentration, without a percentage sign; Combined with the preset experimental temperature of 180 The reaction rate was determined at the preset experimental temperature of 180°C. The effect of the coating concentration on the reaction rate is expressed as follows: ; in, This indicates the effect of coating concentration on the reaction rate.

[0047] S205. Based on the optimal coating concentration and preset coating temperature, the reaction rate and fractal dimension of each preset coating temperature are calculated using the temperature-based reaction rate equation and fractal dimension calculation formula. S206. Based on the reaction rate at each preset coating temperature and the fractal dimension of the preset coating temperature, obtain the fitting curve between the coating temperature and the acid rock reaction rate. S207. Based on the fitting curve of coating temperature and acid rock reaction rate, obtain the relative reaction rate of each preset coating concentration and fit it to obtain the empirical formula of the relative reaction rate of each preset coating concentration. S208. Based on the empirical formula for the relative reaction rate of each preset coating concentration, and combined with the temperature-based reaction rate equation, the reaction rate affected by the coating concentration is fitted to obtain the reaction rate.

[0048] In this embodiment, to study the changes in acid-rock reaction rate, average descent height, and fractal dimension difference under different coating temperatures and whether the coating is applied, based on the optimal coating concentration, the preset coating temperatures include: 90... 105 120 135 150 165 and 180 Experimental fitting was performed using a temperature-based reaction rate equation to calculate the reaction rate and fractal dimension of each preset coating temperature, and the reaction rate affected by the coating temperature was obtained by fitting. The reaction rate equation based on the coating temperature was fitted, and the reaction rate at each preset coating temperature was calculated. The experimental results are shown in Table 2. Table 2 shows the experimental results of the acid rock reaction with and without flow at different coating temperatures.

[0049] Table 2

[0050] It can be seen that in the rock slab without coating liquid, the acid produced strong overall dissolution on the surface of the rock slab, forming an obvious acid etching groove or protrusion zone on the surface of the rock slab. The dissolution was relatively uniform, and the fractal dimension difference of the uncoated rock slab was small. In the rock slab with coating liquid, all rock slab surfaces had dissolution pits of different areas, the degree of dissolution was lower, and the dissolution non-uniformity was stronger. like Figure 4 scan images and Figure 8 The histogram of fractal dimension differences shows that the fractal dimension differences after the acid rock reaction following the coating are relatively large, all greater than 0.7; at 90 Up to 135 In the middle section, there were many dissolution pits after acid etching, and the difference in fractal dimension was relatively large, indicating that the film coverage formed by the coating solution was insufficient; at 150 Up to 180 In the meantime, the solution pits after acid etching decreased slightly, and the difference in fractal dimension also decreased slightly. This indicates that under the same coating time, high temperature is conducive to promoting the chemical bonding between the coating solution and the hydroxyl groups on the rock surface, thereby establishing a film layer that hinders the diffusion of hydrogen ions. like Figure 5 As shown, regardless of whether flow coating treatment is performed, the acid-rock reaction rate exhibits a non-linear increasing trend with increasing experimental temperature, especially at 150°C. After that, the slope of the curve increased significantly; According to the Arrhenius equation, increasing temperature significantly increases the diffusion coefficient and effective collision frequency of hydrogen ions, leading to a dramatic increase in the reactivity of acid-rock reactions with higher activation energies. This is particularly relevant at the pre-set experimental temperature of 180°C. The reaction rate at a given temperature is obtained by modifying the Arrhenius equation, as shown in the following expression: ; like Figure 5 As shown, at 90 Up to 180 Within the specified range, the acid-rock reaction rate after coating was consistently lower than that without coating, indicating that the coating solution has good temperature resistance and a slowing effect; at 90°C... Up to 150 Within the range, the difference in acid-rock reaction rates between the coated and uncoated areas remained relatively stable; at 150... Up to 180 In the range, although the reaction rate increased significantly, the rate growth gradient of the coated group was slower than that of the uncoated group, indicating that under high temperature conditions, the coating liquid can still chemically bond with the hydroxyl groups on the rock surface to form a tight film layer that is resistant to high temperature acid corrosion. Obtain the relative reaction rate at different coating temperatures (Laminated / Unlaminated), among which, The reaction rate is represented by the effect of coating temperature. Relative reaction rate data at different coating temperatures are fitted to obtain the relative reaction rates at different coating temperatures. The empirical formula is expressed as follows: ; in, Indicates the coating temperature; Based on the empirical formula for relative reaction rates at different coating temperatures, and combined with temperature-based reaction rates, the reaction rate affected by coating temperature is obtained, as shown in the following expression: ; in, This indicates the effect of coating temperature on the reaction rate; Does the average drop height after acid rock reaction completely match the change in reaction rate at different coating temperatures? At 90°C... Up to 150 Within the range, the average drop height difference between covered and uncovered membranes remained relatively stable; at 150... Up to 180 Within the interval, the average descent height growth gradient of the coated group was slower than that of the uncoated group.

[0051] S3. Establish a numerical simulation model for acid-rock reaction, and based on the preset reservoir temperature, preset coating flow rate, and preset coating time, use the temperature-based reaction rate equation to perform numerical simulation, obtaining the reaction kinetic equations for the influence of coating flow rate and coating time at reservoir temperature. The specific steps are as follows: S301. Based on the fluid seepage in porous media, deposition of suspended particles in the coating fluid, acid-rock reaction, the delaying effect of the coating on dissolution, and the microstructure of the reservoir, a numerical simulation model of the acid-rock reaction is established. The specific steps are as follows: S3011. Based on the flow basis of acid rock reaction, according to the fluid seepage in porous media, the dynamic transmission of fluid is described by the differential equation of the Brinkman equation, and the main governing equation of fluid seepage in porous media is constructed. S3012. Based on the physical process of coating, according to the deposition of suspended particles in the coating liquid, using the classical particle migration and deposition model, by converting the coating liquid particles lost in the fluid into solid deposits, a coating liquid suspended particle deposition and coating dynamics model is constructed.

[0052] In this embodiment, a numerical simulation model of acid-rock reaction is established, including: The governing equations for fluid seepage in porous media are established. Specifically, when a fluid containing a coating solution and a gelling acid flows in a dolomite porous medium, it is simultaneously affected by fluid viscous shear and the resistance of the porous framework. The Brinkman equation is used to describe the momentum transfer of the fluid, and the expression of the governing equation is shown below: ; in, Indicates the porosity of porous media. Indicates fluid density, This represents the Darcy velocity vector. express t time, For differential operators, Indicates fluid pressure. This represents the unit tensor, specifically the identity matrix. Represents the viscous stress tensor. Indicates fluid dynamic viscosity, Indicates the permeability of porous media. Indicates the non-Darcy coefficient. Indicates the source or sink quality flow rate. Represents a volume force vector; Meanwhile, the fluid flow satisfies the following continuity equation: ; Among them, the viscous stress tensor The following conditions must be met: ; in, Indicates matrix transpose; A model for the deposition and kinetics of suspended particles in the coating solution was established. Specifically, during the injection of the coating solution, the coated particles migrated with the fluid in the pores and continuously adhered to the surface of the dolomite pores to form a protective film. Therefore, the solute transport satisfies the classical particle migration-deposition model, as shown in the following expression: ; in, Indicates the density of suspended particles. Indicates the longitudinal dispersion coefficient. Indicates the seepage velocity. Indicates the deposition coefficient; The longitudinal dispersion coefficient With sedimentation coefficient The specific parameters were obtained from the fitting results in the literature, and the suspended particle size was set to 12.9. The expression is as follows: ; ; in, Indicates dynamic viscosity; The coating fluid particles lost in the fluid are converted into solid-phase deposits, and the main governing equation for deposition is expressed as follows: ; in, Indicates initial porosity. Indicates the density of the skeletal particles. This represents the mass deposition density of the coating fluid per unit volume of rock. As the film is applied, the pore space is occupied by sediments, causing the reservoir porosity to decrease over time. The evolution relationship is as follows: ; in, This indicates the reservoir porosity when coated.

[0053] S3013. Based on the physical process of acid etching, according to the acid-rock reaction, using the chemical reaction rate and the speed at which acid is transported from the liquid phase to the liquid-solid interface in the pores, the mass transfer coefficient is obtained. In addition, combined with the change of rock porosity with chemical reaction, an acid-rock reaction and mass transfer kinetic model is constructed.

[0054] In this embodiment, an acid-rock reaction and mass transfer kinetics model is established, specifically: During the acid-rock reaction stage, gelled acid enters the pores and reacts with the dolomite matrix. The reaction rate depends not only on surface reaction kinetics but also on the mass transfer and diffusion of hydrogen ions from the acid solution to the liquid-solid interface. The reaction leads to acid consumption and an increase in porosity. This increase in porosity results in corresponding changes in permeability, pore radius, and specific surface area. However, when the porosity reaches 0.99, the reaction ceases, and porosity, pore radius, and specific surface area no longer increase. The chemical reaction rate is determined by the following formula: ; in, This indicates the amount of hydrogen ions consumed in the acid solution. Represents the surface reaction rate constant. This indicates the concentration of the acid at the liquid-solid surface. This indicates the concentration of the acid at the liquid-solid surface; Concentration of acid at the liquid-solid surface The expression is as follows: ; in, Indicates the acid concentration. It represents the mass transfer coefficient, which is the rate at which acid is transported from the liquid phase to the liquid-solid interface within the pores; The mass transfer coefficient The expression for evaluating is shown below: ; ; ; in, Represents the Reynolds number. Represents the Schmitt number, Indicates the effective diffusion coefficient. Indicates the pore radius. Indicates the density of the liquid. This represents the velocity vector in the Brinkman equation. Indicates the viscosity of the liquid; As the reaction and dissolution proceed, the porosity of the rock will change. The equation for the change in porosity with the chemical reaction is as follows: ; in, The solubility of an acid is expressed as the mass of solid dissolved per mole of acid in a reaction. This indicates the density of the rock.

[0055] S3014. Based on the delaying effect of coating on dissolution, by introducing time step functions characterizing the coating stage and time step functions characterizing the acid etching stage, the delaying principle of coating on acid rock reaction is obtained through synchronous simulation.

[0056] In this embodiment, the principle of delaying acid-rock reaction by coating is established. By mathematically quantifying the delaying effect of coating on dissolution, the two independent physical processes of coating kinetics and acid-rock reaction are connected in series, and the deposition of coating liquid on the dolomite surface is analyzed. It altered the microscopic surface morphology of the matrix, significantly reducing the direct contact area between the acid and the rock; An effective specific surface area change function is introduced to construct a bridge between the two stages, and the effective specific surface area after being affected by the film coating is defined. The expression is as follows: ; in, Indicates the effective specific surface area after the coating effect. This represents the maximum theoretical amount of sediment that the pore surface can hold. Indicates an empirical multiple; the effective specific surface area affected by the coating. The concentration of acid at the liquid-solid surface in the rate of substitution chemical reactions That is, to obtain the comprehensive reaction rate that takes into account the delaying effect of the coating; In Comsol numerical solutions, a time step function is introduced. (Characterizing the coating stage) and (Characterizing the acid etching stage) The principle of microscopic pore deformation can be unified into a global porosity change control equation, allowing for both film coating calculation and acid-rock reaction calculation in a single simulation, eliminating the need to simulate the two calculations separately. The expression is as follows: ; ; ; in, Indicates the final porosity. Indicates the porosity after acid etching. This represents the time step function characterizing the coating stage. This represents the time step function characterizing the acid etching stage. Indicates the film covering time.

[0057] S3015. Based on the reservoir's micropore structure and the influence of porosity changes on permeability, pore radius, and specific surface area, a dynamic model of the reservoir's micropore structure and macroscopic properties is constructed by defining the permeability change equation, the pore radius dynamic equation, and the initial specific surface area change equation. S3016 integrates the master equation of fluid seepage in porous media, the deposition and kinetic model of suspended particles in the coating fluid, the acid-rock reaction and mass transfer kinetic model, the delay principle of coating on acid-rock reaction, and the dynamic change model of reservoir micropore structure and macroscopic physical properties to obtain a numerical simulation model of acid-rock reaction.

[0058] In this embodiment, a dynamic change model of reservoir micropore structure and macroscopic properties is established, specifically: Coating reduces porosity, while acid-rock reactions increase porosity. Changes in porosity simultaneously alter permeability, pore radius, and specific surface area. The equations defining these parameter changes are as follows: Permeability change equation: ; in, Indicates the permeability of porous media. Indicates the initial penetration rate. Denotes the non-Darcy coefficient, and ; Dynamic equation for pore radius: ; in, Indicates the pore radius. Indicates the initial pore radius; Equation for change in initial specific surface area: ; in, This represents the initial specific surface area.

[0059] In this embodiment, the master equation for fluid seepage in porous media, the deposition and kinetic model of suspended particles in the coating fluid, the acid-rock reaction and mass transfer kinetic model, the principle of delaying acid-rock reaction by the coating, and the dynamic change model of reservoir micropore structure and macroscopic physical properties are integrated to obtain a numerical simulation model of acid-rock reaction. The master equation governing fluid flow in the porous medium describes fluid flow; the coating fluid suspended particle deposition and coating kinetics model describes coating fluid particle deposition and coating kinetics; the acid-rock reaction and mass transfer kinetics model determines the chemical reaction rate, and through the principle of delaying acid-rock reaction by coating, the influence of coating on effective specific surface area is introduced, and the coating stage and acid etching stage are unified by a time step function, so that two-stage calculations can be completed in one simulation; the reservoir micropore structure and macroscopic property dynamic change model is used to update the dynamic changes in permeability, pore radius and specific surface area caused by porosity changes.

[0060] S302. A numerical simulation model based on acid-rock reaction is used to perform numerical simulation based on the preset reservoir temperature and preset coating flow rate, and the simulation calculation results of preset reservoir temperature and preset coating flow rate are obtained. S303. Based on the simulation calculation results of the preset reservoir temperature and preset coating flow rate, obtain the relative response rate between the coating flow rate and the coating effect; S304. Using an exponential model, regression analysis is performed on the relative response rate of the coating flow rate and the effect of coating to obtain the coating flow rate fitting curve and the reservoir temperature fitting curve. An empirical formula for the relative response rate of the effect of the preset coating flow rate at the preset reservoir temperature is obtained through fitting. S305. Based on the empirical formula for the relative reaction rate affected by the preset coating flow rate at the preset reservoir temperature, and combined with the temperature-based reaction rate equation, the reaction kinetic equation for the effect of coating flow rate at the reservoir temperature is obtained.

[0061] In this embodiment, based on the numerical simulation model of acid-rock reaction, the preset reservoir temperature includes 90°C. 120 150 and 180 The preset coating flow rates include 0, 1, 10, 20, 50, 75, and 100 ml / min; The numerical geometric model is based on centimeter-scale cracks. Therefore, the simulated coating flow rate is kept within the experimental scale range to ensure that the acid concentration change calculated by the numerical simulation has reliable experimental support. The simulation results are shown in Table 3. Table 3 shows the simulation results of different coating flow rates at different reservoir temperatures.

[0062] Table 3

[0063] The reaction rate after coating was calculated based on temperature-based reaction rate; an exponential model was used to calculate the reaction rate at 90°C. Under-membrane flow rate ( The relative reaction rate affected by coating A regression analysis was performed to examine the relationship between (reaction rate after coating / without coating), where, The effect of different coating flow rates at different temperatures on the reaction rate is shown in the fitted curves of coating flow rate versus relative reaction rate, and the results are as follows: Figure 6 As shown; Based on 90 The average reaction rate after coating was calculated for 120. 150 and 180 The average reaction rate after coating was calculated, combined with the reaction rate without coating, to determine the relative reaction rates at different temperatures. The effect of different coating flow rates at different temperatures on the reaction rate The relative reaction rate curve was fitted, and then a linear equation for the relative reaction rate was fitted. An exponential model was then used for regression analysis. The fitting curves and results of reservoir temperature versus relative reaction rate are shown below. Figure 6 As shown; Based on the simulation results and fitting curves of different coating flow rates at different reservoir temperatures, in the low flow rate range (1~50 ml / min), the reaction rate after coating showed a significant decreasing trend as the coating flow rate increased. This indicates that in this range, the increase in flow rate enhanced the mass transfer efficiency of titanate coupling agent molecules in the coating solution to the rock surface boundary layer, promoted the rapid construction of a dense protective film, and thus gradually enhanced the retardation effect. In the high flow rate range (>50 ml / min), when the flow rate exceeds the critical value (approximately 50~60 ml / min), the reaction rate after coating increases slightly, exhibiting a significant diminishing marginal effect. This indicates that at the current process scale, simply increasing the flow rate has limited effect on inhibiting the reaction rate. Combining 90 Based on the fitting results at different reservoir temperatures and the fitting results at different temperatures, an empirical formula for the relative reaction rate affected by different coating flow rates at different temperatures is obtained, as shown in the following expression: ; in, The coating flow rate is used to represent the reaction kinetics equation for the effect of coating flow rate on reservoir temperature, and combined with the temperature-based reaction rate, the equation is shown below: ; in, This represents the reaction rate affected by the coating flow rate at reservoir temperature, specifically the reaction kinetic equations after different coating flow rates at different temperatures.

[0064] S306. A numerical simulation model based on acid-rock reaction is used to perform numerical simulation based on the preset reservoir temperature and preset coating time, and the simulation calculation results of preset reservoir temperature and preset coating time are obtained. S307. Based on the simulation calculation results of the preset reservoir temperature and preset coating time, obtain the relative response rate between coating time and coating effect; S308. Using an exponential model, regression analysis is performed on the relative response rate of the coating time and the effect of coating to obtain the coating time fitting curve and the reservoir temperature fitting curve. An empirical formula for the relative response rate of the effect of the preset coating time at the preset reservoir temperature is obtained through fitting. S309. Based on the empirical formula for the relative reaction rate affected by the preset coating time at the preset reservoir temperature, and combined with the temperature-based reaction rate equation, the reaction kinetic equation for the effect of coating time on the reservoir temperature is obtained.

[0065] In this embodiment, the variation law of coating quality with time under different temperatures was investigated. Based on the previous study on coating flow rate, the coating time was further extended from 30 min to 150 min to obtain the preset coating time, so as to explore whether there is a saturation inflection point in the coating process and its stability at high temperature. To ensure the continuity and comparability of data analysis, the results of the completed 30 min numerical simulation calculation were included in the analysis. A numerical simulation design scheme was established to conduct numerical simulation, and the simulation calculation results are shown in Table 4. Table 4 is a table of simulation calculation results of different coating times under different reservoir temperatures.

[0066] Table 4

[0067] The reaction rate after coating was calculated based on temperature-based reaction rate; an exponential model was used to calculate the reaction rate at 90°C. Lower coating time ( The relative reaction rate affected by coating A regression analysis was performed to examine the relationship between (reaction rate after coating / without coating), where, The effect of different coating times at different temperatures on the reaction rate is shown in the fitted curves and results. Figure 7 As shown; Based on 90 The average reaction rate after coating was calculated for 120. 150 and 180 The average reaction rate after coating was calculated, combined with the reaction rate without coating, to determine the relative reaction rates at different temperatures. And use an exponential model to perform regression analysis on it.

[0068] Combining simulation results and fitted curves from different reservoir temperatures and coating times, under the simulated temperature gradient, the reaction rate after coating exhibits a pattern of first rapidly decreasing and then slightly increasing with increasing coating time. Within the range of 30-90 min, the reaction rate after coating decreases rapidly with increasing time, indicating that within this range, increasing coating time promotes the coverage of the coating liquid film. When the coating time exceeds 120 min, the reaction rate decreases further. With 120 The reaction rate increases slightly after coating, and when the coating time exceeds 100 min, the reaction rate increases to 150. With 180 The reaction rate increased slightly after the coating was applied, and the effect of simply extending the coating time on the slowing effect became negligible.

[0069] Combining 90 Based on the fitting results at different reservoir temperatures and the fitting results at different temperatures, an empirical formula for the relative reaction rate affected by different coating times at different temperatures can be obtained, as shown in the following expression: ; in, The coating time is represented by the value; combined with the temperature-based reaction rate, the reaction kinetic equation for the effect of coating time on reservoir temperature is obtained, as shown in the following expression: ; in, This represents the reaction rate affected by coating time at reservoir temperature, specifically the reaction kinetic equations for the effects of different coating times at different temperatures.

[0070] S4. Based on the reaction kinetic equations affecting the coating concentration, coating temperature, coating flow rate, and coating time at reservoir temperature, the optimal comprehensive coating factor is fitted to obtain the optimal comprehensive coating factor, and the acid-rock reaction rate of the comprehensive coating factor is predicted. The specific steps are as follows: S401. Based on the reaction kinetic equations of the influence of coating concentration, coating temperature, coating flow rate, and coating time on the reservoir temperature, the coating factors including coating concentration, coating temperature, coating flow rate, and coating time are obtained. S402. Fit the effect of coating factors on the reaction rate to obtain the comprehensive coating factors.

[0071] In this embodiment, the reaction rate is affected by the coating concentration. The effect of coating temperature on reaction rate Reaction kinetic equations under the influence of membrane flow rate at reservoir temperature And the reaction kinetic equations of the effect of coating time on reservoir temperature. Four coating factors were obtained, including coating concentration. Coating temperature , membrane flow rate and lamination time ; The effects of the four coating factors on the reaction rate were fitted to obtain the comprehensive coating factor, as shown in the following expression: ; in, This indicates a comprehensive consideration of coating factors. Represents the global compensation coefficient. This represents the coefficient that incorporates the coating concentration into the overall coating factors. This represents the coefficient that incorporates the coating temperature into the overall coating factors. This represents the coefficient that incorporates the coating flow rate into the overall coating factors. The coefficients represent the factors that fit the coating time into the overall coating factors. The coefficients mentioned above are the symbols representing the constants in the formulas for the relative reaction rates corresponding to the coating concentration, temperature, flow rate, and time.

[0072] S403. Based on the reaction rate calculated by numerical simulation based on the active reaction sites of the ideal interface, and the reaction rate fitted by experiment based on the experimental performance of the coating liquid and acid liquid and the actual active sites of the experimental rock slab interface, the experimental results and simulation calculation results are obtained by setting the same conditions and performing numerical simulation and experimental fitting respectively. S404. Divide the experimental results and the simulation calculation results to obtain the active area correction factor. Then, use the active area correction factor to transform and fit the comprehensive coating factor to obtain the optimal comprehensive coating factor.

[0073] In this embodiment, since the simulated reaction rates in the simulation calculations of different coating flow rates and coating times at different reservoir temperatures are based on the active reaction sites of the ideal interface, and the reaction rates affected by different coating concentrations and different coating temperatures are based on the experimental performance of the coating solution and acid solution and the actual active sites of the experimental rock panel interface, which come from different scales, a correction factor for the active area related to the coating temperature is used for conversion; the active factor is obtained by dividing the experimental results under the same conditions by the simulation calculation results. Experimental results on the effect of different coating temperatures on the acid-rock reaction rate show that the coating solution has a general slowing effect at low temperatures, insufficient film density, and a large active area, resulting in a large correction factor. As the coating temperature increases, the slowing effect is enhanced, the film density is enhanced, the active area decreases, and the correction factor gradually decreases. Specifically, 90 The correction factor is 2.1, 120. It is 1.6, 150 1.1, 180 The value was 1.09. Then, the coating concentration, coating temperature, coating flow rate, coating time, and reaction rate under the corresponding conditions were imported into Matlab for fitting. The final fitting results show the optimal comprehensive coating factors as follows: ; in, This represents the optimal comprehensive coating factors; the reaction rates calculated from indoor experiments and numerical simulations are verified against the results calculated using the final fitted reaction rate formula, resulting in the following... Figure 9 The comparison results shown show that the root mean square error between the calculated and experimental results under different coating concentrations, coating temperatures, coating flow rates, and coating times is 1%-14%, indicating that the fitted final reaction rate calculation formula has high reliability and accuracy and can effectively calculate the acid-rock reaction rate under different coating conditions.

[0074] S405. Based on the optimal comprehensive coating factors and combined with the temperature-based reaction rate equation, the final reaction rate equation is obtained and predicted to obtain the acid rock reaction rate based on the comprehensive coating factors.

[0075] Based on the optimal comprehensive coating factors and combined with the temperature-based reaction rate equation, the final reaction rate equation is obtained as follows: ; in, This represents the acid-rock reaction rate considering factors such as coating concentration. Coating temperature , membrane flow rate and lamination time The overall reaction rate; The acid-rock reaction rate is predicted based on the final reaction rate, thus obtaining the comprehensive coating factor.

Claims

1. A method for predicting acid-rock reaction rates based on a coating liquid, characterized in that, Includes the following steps: S1. Based on the film coating and acid-rock reaction experiments, by fitting the reaction kinetic equations of film coating concentration and film coating temperature, the reaction rate equation based on acid concentration, the reaction rate equation based on temperature, and the fractal dimension calculation formula are obtained. S2. Using the reaction rate equation based on acid concentration, the reaction rate equation based on temperature, and the fractal dimension calculation formula, the coating concentration and coating temperature were experimentally fitted to obtain the reaction rate affected by coating concentration and the reaction rate affected by coating temperature. S3. Establish a numerical simulation model of acid-rock reaction, and based on the preset reservoir temperature, preset coating flow rate and preset coating time, use the temperature-based reaction rate equation to conduct numerical simulation and obtain the reaction kinetic equations of the effect of coating flow rate on reservoir temperature and the effect of coating time on reservoir temperature. S4. Based on the reaction rate affected by coating concentration, reaction rate affected by coating temperature, reaction kinetic equations affected by coating flow rate under reservoir temperature, and reaction kinetic equations affected by coating time under reservoir temperature, the optimal comprehensive coating factor is fitted and the acid rock reaction rate of the comprehensive coating factor is predicted.

2. The method for predicting acid-rock reaction rates based on coating liquid according to claim 1, characterized in that, S1 includes the following steps: S101. Based on the film coating and acid-rock reaction experiments, the decrease in acid concentration per unit time is expressed as a function fitting constant. S102. By introducing the area of ​​the reaction interface, the function fitting constant is corrected to obtain the concentration-based reaction rate equation. S103. Take the logarithm of the concentration-based reaction rate equation, obtain the reaction rate constant and reaction order by obtaining the logarithm of the acid-rock reaction rate and the logarithm of the acid concentration and performing linear regression. S104. Based on the Arrhenius ionization theory, the dependence of the reaction rate constant on temperature is obtained according to the reaction rate constant. S105. Substitute the temperature dependence of the reaction rate constant into the concentration-based reaction rate equation and combine it with the reaction order to obtain the temperature-based reaction rate equation. S106. Based on the sum of the acid erosion volumes at various points on the rock surface and the reaction area of ​​the rock, the average drop height is obtained, and based on the box dimension method, the fractal dimension calculation formula is obtained through transformation.

3. The method for predicting acid-rock reaction rates based on coating liquid according to claim 2, characterized in that, The temperature-based reaction rate equation is shown below: in, This indicates the reaction rate based on temperature. and All represent the fitting results. Represents Avogadro's constant. Indicates the reaction temperature. Indicates the initial reaction temperature. Indicates the acid concentration. Indicates the reaction order.

4. The method for predicting acid-rock reaction rates based on coating liquid according to claim 1, characterized in that, S2 includes the following steps: S201. Based on the preset experimental temperature and preset coating concentration, the reaction rate and fractal dimension of each preset coating concentration are calculated using the reaction rate equation based on acid concentration and the fractal dimension calculation formula. S202. Based on the reaction rate of each preset coating concentration and the fractal dimension of the preset coating concentration, select the optimal coating concentration and obtain the fitting curve between the coating concentration and the acid rock reaction rate. S203. Based on the fitting curve of coating concentration and acid rock reaction rate, obtain the relative reaction rate of each preset coating concentration and fit it to obtain the empirical formula of the relative reaction rate of each preset coating concentration. S204. Based on the empirical formula for the relative reaction rate of each preset coating concentration, and combined with the reaction rate equation based on acid concentration, the reaction rate affected by coating concentration is fitted to obtain the reaction rate. S205. Based on the optimal coating concentration and preset coating temperature, the reaction rate and fractal dimension of each preset coating temperature are calculated using the temperature-based reaction rate equation and fractal dimension calculation formula. S206. Based on the reaction rate at each preset coating temperature and the fractal dimension of the preset coating temperature, obtain the fitting curve between the coating temperature and the acid rock reaction rate. S207. Based on the fitting curve of coating temperature and acid rock reaction rate, obtain the relative reaction rate of each preset coating concentration and fit it to obtain the empirical formula of the relative reaction rate of each preset coating concentration. S208. Based on the empirical formula for the relative reaction rate of each preset coating concentration, and combined with the temperature-based reaction rate equation, the reaction rate affected by the coating concentration is fitted to obtain the reaction rate.

5. The method for predicting acid-rock reaction rates based on coating liquid according to claim 4, characterized in that, The expression for the effect of coating concentration on the reaction rate is shown below: in, This indicates the effect of coating concentration on the reaction rate. Indicates the coating concentration. Indicates the acid concentration; The expression for the effect of coating temperature on the reaction rate is shown below: in, This indicates the effect of coating temperature on the reaction rate. This indicates the relative reaction rate at different coating temperatures. This indicates the reaction rate at different coating temperatures. Indicates the reaction rate without a membrane. Indicates the coating temperature.

6. The method for predicting acid-rock reaction rates based on coating liquid according to claim 1, characterized in that, S3 includes the following steps: S301. Based on the fluid seepage in porous media, the deposition of suspended particles in the coating liquid, the acid-rock reaction, the delaying effect of the coating on dissolution, and the micropore structure of the reservoir, a numerical simulation model of the acid-rock reaction is established. S302. A numerical simulation model based on acid-rock reaction is used to perform numerical simulation based on the preset reservoir temperature and preset coating flow rate, and the simulation calculation results of preset reservoir temperature and preset coating flow rate are obtained. S303. Based on the simulation calculation results of the preset reservoir temperature and preset coating flow rate, obtain the relative response rate between the coating flow rate and the coating effect; S304. Using an exponential model, regression analysis is performed on the relative response rate of the coating flow rate and the effect of coating to obtain the coating flow rate fitting curve and the reservoir temperature fitting curve. An empirical formula for the relative response rate of the effect of the preset coating flow rate at the preset reservoir temperature is obtained through fitting. S305. Based on the empirical formula for the relative reaction rate affected by the preset coating flow rate at the preset reservoir temperature, and combined with the temperature-based reaction rate equation, the reaction kinetic equation for the effect of coating flow rate at the reservoir temperature is obtained. S306. A numerical simulation model based on acid-rock reaction is used to perform numerical simulation based on the preset reservoir temperature and preset coating time, and the simulation calculation results of preset reservoir temperature and preset coating time are obtained. S307. Based on the simulation calculation results of the preset reservoir temperature and preset coating time, obtain the relative response rate between coating time and coating effect; S308. Using an exponential model, regression analysis is performed on the relative response rate of the coating time and the effect of coating to obtain the coating time fitting curve and the reservoir temperature fitting curve. An empirical formula for the relative response rate of the effect of the preset coating time at the preset reservoir temperature is obtained through fitting. S309. Based on the empirical formula for the relative reaction rate affected by the preset coating time at the preset reservoir temperature, and combined with the temperature-based reaction rate equation, the reaction kinetic equation for the effect of coating time on the reservoir temperature is obtained.

7. The method for predicting acid-rock reaction rates based on coating liquid according to claim 6, characterized in that, The reaction kinetic equation for the effect of membrane flow rate on reservoir temperature is shown below: in, This indicates the effect of coating flow rate on the reaction rate at reservoir temperature. This represents the relative reaction rate affected by different coating flow rates at different reservoir temperatures. This indicates the effect of membrane flow rate on the reaction rate at different reservoir temperatures. Indicates the coating flow rate. Indicates the coating temperature; The reaction kinetic equations for the effect of coating time on reservoir temperature are shown below: in, This indicates the effect of coating time on the reaction rate at reservoir temperature. This indicates the relative reaction rate affected by different coating times at different reservoir temperatures. This indicates the effect of different coating times on the reaction rate at different reservoir temperatures. Indicates the film covering time.

8. The method for predicting acid-rock reaction rates based on coating liquid according to claim 6, characterized in that, S301 includes the following steps: S3011. Based on the flow basis of acid rock reaction, according to the fluid seepage in porous media, the dynamic transmission of fluid is described by the differential equation of the Brinkman equation, and the main governing equation of fluid seepage in porous media is constructed. S3012. Based on the physical process of coating, according to the deposition of suspended particles in coating liquid, using the classical particle migration and deposition model, by converting the coating liquid particles lost in the fluid into solid deposits, a coating liquid suspended particle deposition and coating dynamics model is constructed. S3013. Based on the physical process of acid etching, according to the acid-rock reaction, using the chemical reaction rate and the speed at which acid is transported from the liquid phase to the liquid-solid interface in the pores, the mass transfer coefficient is obtained. Combined with the change of rock porosity with chemical reaction, an acid-rock reaction and mass transfer kinetic model is constructed. S3014. Based on the delaying effect of coating on dissolution, by introducing time step functions characterizing the coating stage and time step functions characterizing the acid etching stage, the delaying principle of coating on acid rock reaction is obtained through synchronous simulation. S3015. Based on the reservoir's micropore structure and the influence of porosity changes on permeability, pore radius, and specific surface area, a dynamic model of the reservoir's micropore structure and macroscopic properties is constructed by defining the permeability change equation, the pore radius dynamic equation, and the initial specific surface area change equation. S3016 integrates the master equation of fluid seepage in porous media, the deposition and kinetic model of suspended particles in the coating fluid, the acid-rock reaction and mass transfer kinetic model, the delay principle of coating on acid-rock reaction, and the dynamic change model of reservoir micropore structure and macroscopic physical properties to obtain a numerical simulation model of acid-rock reaction.

9. The method for predicting acid-rock reaction rates based on coating liquid according to claim 1, characterized in that, S4 includes the following steps: S401. Based on the reaction kinetic equations of the influence of coating concentration, coating temperature, coating flow rate, and coating time on the reservoir temperature, the coating factors including coating concentration, coating temperature, coating flow rate, and coating time are obtained. S402. Fit the effect of coating factors on the reaction rate to obtain the comprehensive coating factors; S403. Based on the reaction rate calculated by numerical simulation based on the active reaction sites of the ideal interface, and the reaction rate fitted by experiment based on the experimental performance of the coating liquid and acid liquid and the actual active sites of the experimental rock slab interface, the experimental results and simulation calculation results are obtained by setting the same conditions and performing numerical simulation and experimental fitting respectively. S404. Divide the experimental results and the simulation calculation results to obtain the active area correction factor. Then, use the active area correction factor to transform and fit the comprehensive coating factor to obtain the optimal comprehensive coating factor. S405. Based on the optimal comprehensive coating factors and combined with the temperature-based reaction rate equation, the final reaction rate equation is obtained and predicted to obtain the acid rock reaction rate based on the comprehensive coating factors.

10. The method for predicting acid-rock reaction rates based on coating liquid according to claim 9, characterized in that, The final reaction rate equation is as follows: in, This represents the acid-rock reaction rate considering all factors related to the coating. This represents the optimal overall coating factors. Indicates the coating concentration. Indicates the coating temperature. Indicates the coating flow rate. Indicates the film covering time.

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