Slow release evaluation method and system for solid-state releasable fluorescent tracer agent

Abstract

The invention belongs to the technical field of oil-gas field development, and particularly relates to a slow-release evaluation method and system for a solid-state releasable fluorescent tracer agent. The invention provides a slow release evaluation method for a solid-state fluorescence-releasable tracer agent. The method comprises the following steps: (1) carrying out slow release experiments on the solid-state fluorescence-releasable tracer agent at different temperatures and different mineralization degrees under a constant volume condition; (2) under a fluid scouring condition, carrying out slow-release experiments on the solid releasable fluorescent tracer agent at different flow rates and different water contents; and (3) establishing a slow-release kinetic model according to the detection data of the static slow-release evaluation and the dynamic slow-release evaluation. Compared with the existing evaluation method of the solid-state releasable fluorescent tracer, the slow release evaluation method of the solid-state releasable fluorescent tracer provided by the invention supplements and perfects the original evaluation method, and forms a set of complete, systematic and accurate evaluation method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field development, and particularly relates to a slow-release evaluation method and system of solid releasable fluorescent tracers. BACKGROUND

[0002] The high injection, high migration ability and low adsorption of the fluorescent nano tracer can ensure that it can be used as a tracer for inter-well monitoring of an oil reservoir, so that it can be applied to multi-stage horizontal well production profile monitoring. The multi-stage horizontal well production dynamic monitoring technology of the releasable solid tracer is to prepare the original tracer into a solid form, which is divided into water-soluble and oil-soluble according to the solubility of the tracer itself. Different types of releasable solid tracers are installed outside the completion string at different production positions, and are lowered into the target layer in the well with the string during completion operation. After starting production, the formation fluid flows into the inside of the tubing, contacts the releasable solid tracer installed outside the string, and completes the labeling of the produced fluid. After oil-water separation at the wellhead, the concentration of the tracer in the sample is tested, and the produced tracer concentration distribution is quantitatively interpreted according to a specific interpretation method to obtain the production profile of the horizontal section.

[0003] The release process of the tracer from the polymer matrix is very complex, involving chemical diffusion, interface movement and various chemical interactions between the tracer and the polymer matrix material. Since the release of the fluorescent tracer is affected by many factors, the current main evaluation method cannot comprehensively evaluate the slow release of the solid releasable fluorescent tracer, SUMMARY

[0004] In view of the defects of the prior art, the present application provides a slow-release evaluation method and system of solid releasable fluorescent tracers.

[0005] Specifically, the slow-release evaluation method of the solid releasable fluorescent tracer provided by the present application comprises:

[0006] (1) Static slow-release evaluation

[0007] Performing slow-release experiments on the solid releasable fluorescent tracer under different temperatures and different salinities under constant volume conditions;

[0008] (2) Dynamic slow-release evaluation

[0009] Performing slow-release experiments on the solid releasable fluorescent tracer under different flow rates and different water contents under fluid scouring conditions;

[0010] (3) Establishing a slow-release kinetics model according to the detection data of the static slow-release evaluation and the dynamic slow-release evaluation.

[0011] In the above-mentioned method for evaluating the sustained release of a solid-state releasable fluorescent tracer, in step (1), the sustained release experiment at different temperatures comprises: placing the solid-state releasable fluorescent tracer in distilled water at different preset temperatures, and sampling and testing at preset time intervals.

[0012] In the above-mentioned method for evaluating the sustained release of a solid-state releasable fluorescent tracer, in step (1), the sustained release experiment under different salinities comprises: placing the solid-state releasable fluorescent tracer in sodium chloride solutions of different preset concentrations, and sampling and testing at preset time intervals.

[0013] In the above-mentioned method for evaluating the sustained release of a solid-state releasable fluorescent tracer, in step (2), the sustained release experiment at different flow rates includes: flushing the solid-state releasable fluorescent tracer at different preset flow rates, and sampling and testing at preset time intervals.

[0014] In the above-mentioned method for evaluating the sustained release of solid-state releasable fluorescent tracers, in step (2), the sustained release experiment under different water contents comprises: flushing the tracer with oil-water mixed fluids of preset different water contents at a fixed flow rate, and sampling and testing at preset time intervals.

[0015] In the above-mentioned sustained-release evaluation method of the solid-state releasable fluorescent tracer, the sustained-release kinetic model includes a dissolution rate equation and a Higuchi diffusion equation.

[0016] In the above-mentioned sustained-release evaluation method of the solid-state releasable fluorescent tracer, the dissolution rate equation is:

[0017] dC / dt=k D A(C s -ρ tracer )

[0018] Where: dC / dt—dissolution rate, g / min; k D —dissolution rate constant; A—surface area of ​​the sustained-release tracer, m 2 ; C s —tracer saturation solubility, g / L; ρ tracer —Tracer mass concentration, g / L.

[0019] In the above-mentioned method for evaluating the sustained release of a solid-state releasable fluorescent tracer, the Higuchi diffusion equation is:

[0020]

[0021] Where: Q tracer —Cumulative diffusion amount of tracer, g; D—diffusion coefficient; t—diffusion time, min.

[0022] The solid releasable fluorescent tracer slow-release evaluation method has an epoxy resin as a polymer skeleton and a poorly soluble salt as a fluorescent tracer carrier.

[0023] The solid releasable fluorescent tracer slow-release evaluation system provided by the application comprises:

[0024] The static experiment unit comprises a constant temperature device, a salinity adjusting device and a pH adjusting device.

[0025] The dynamic experiment unit comprises a constant flow pump, an oil-water mixing device and a tracer short section.

[0026] The detection unit comprises a fluorescence spectrometer.

[0027] The data processing unit is configured to perform the slow-release kinetics model calculation.

[0028] The solid releasable fluorescent tracer slow-release evaluation system has the data processing unit comprising:

[0029] The parameter input module is used for inputting parameter measured values.

[0030] The model calculation module is used for solving a dissolution rate equation and a Higuchi diffusion equation.

[0031] The output module is used for generating a slow-release kinetics curve and a goodness-of-fit report.

[0032] The solid releasable fluorescent tracer slow-release evaluation method provided by the application comprises static slow-release evaluation and dynamic slow-release evaluation. The static slow-release evaluation studies slow-release behavior characteristics of the solid releasable fluorescent tracer at different temperatures and different salinities. The dynamic slow-release evaluation studies slow-release behavior characteristics of the solid releasable fluorescent tracer at different fluid flow rates and different fluid water contents. Compared with the existing solid releasable fluorescent tracer evaluation method, the solid releasable fluorescent tracer slow-release evaluation method provided by the application supplements and perfects the original evaluation method, and forms a complete, systematic and accurate evaluation method. BRIEF DESCRIPTION OF DRAWINGS

[0033] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are intended to illustrate preferred embodiments of the application, and should not be considered limiting of the application.

[0034] Figure 1 is a cumulative release concentration curve of the solid releasable fluorescent tracer at different temperatures.

[0035] Figure 2is the cumulative release concentration curve of the solid releasable fluorescent tracer under different temperatures.

[0036] Figure 3 is the cumulative release concentration curve of the solid releasable fluorescent tracer under different pH.

[0037] Figure 4 is the cumulative release concentration curve of the solid releasable fluorescent tracer under different flow rates.

[0038] Figure 5 is the cumulative release concentration curve of the solid releasable fluorescent tracer under different water contents.

[0039] Figure 6 Tracer release kinetics curve under different temperatures.

[0040] Figure 7 Tracer slow release kinetics curve under different salinities.

[0041] Figure 8 Tracer slow release kinetics curve under different pH.

[0042] Figure 9 Tracer slow release kinetics curve under different flow rates.

[0043] Figure 10 Slow release kinetics curve under different water contents. DETAILED DESCRIPTION

[0044] In order to fully understand the purposes, features and effects of the present application, the present application will be described in detail through the following specific embodiments. The process method of the present application adopts the conventional method or device in the art except the following content. The following terms have the meanings commonly understood by the skilled in the art unless otherwise specified.

[0045] The slow release evaluation method of the solid releasable fluorescent tracer provided by the present application comprises:

[0046] (1) Static slow release evaluation

[0047] Performing slow release experiments on the solid releasable fluorescent tracer under different temperatures and different salinities under constant volume conditions;

[0048] (2) Dynamic slow release evaluation

[0049] Performing slow release experiments on the solid releasable fluorescent tracer under different flow rates and different water contents under fluid scouring conditions;

[0050] (3) Establishing a slow release kinetics model according to the detection data of the static slow release evaluation and the dynamic slow release evaluation.

[0051] The slow-release evaluation method of the solid releasable fluorescent tracer of the present application evaluates the slow-release performance of the solid releasable fluorescent tracer from multiple aspects such as different temperatures, different mineralization degrees, different flow rates and different water contents, and solves the problem that the slow-release evaluation of the solid tracer in the prior art is not comprehensive enough.

[0052] In some preferred embodiments, the slow-release experiment at different temperatures comprises: placing the solid releasable fluorescent tracer in distilled water at a preset different temperature, and sampling and detecting at a preset time interval.

[0053] Further preferably, the slow-release experiment at different temperatures comprises: taking an appropriate amount of tracer sample, and then recording the mass of the tracer sample. The tracer block is placed in a beaker containing a certain volume of distilled water, and is placed at 25℃, 40℃ and 80℃, respectively. Sampling is taken at regular intervals, and the sampling time points are 10min, 20min, 40min, 60min, 120min, 180min, 300min, 420min, 690min, 960min, 1230min and 1500min. A certain volume of sample is taken each time, and the solution is replenished to the original state after each sampling, and then the collected sample is detected using a fluorescence spectrometer to obtain the slow-release data of the solid releasable fluorescent tracer at different temperatures.

[0054] In some preferred embodiments, the slow-release experiment at different mineralization degrees comprises: placing the solid releasable fluorescent tracer in a sodium chloride solution of a preset different concentration, and sampling and detecting at a preset time interval.

[0055] Further preferably, the slow-release experiment at different mineralization degrees comprises: preparing the same volume of distilled water, 5000mg / L of sodium chloride solution and 10000mg / L of sodium chloride solution for standby. Three tracer blocks with the same mass as in the slow-release evaluation experiment at different temperatures described above are weighed, and the tracer blocks are placed in the prepared solutions. Sampling is taken at regular intervals, and the sampling time points are 10min, 20min, 40min, 60min, 120min, 180min, 300min, 420min, 690min, 960min, 1230min and 1500min. A certain volume of sample is taken each time, and the solution is replenished to the original state after each sampling, and then the collected sample is detected using a fluorescence spectrometer to obtain the slow-release data of the solid releasable fluorescent tracer at different mineralization degrees.

[0056] The inventors of the present application also studied the solid releasable fluorescent tracer in different pH slow-release evaluation experiments, including: preparing pH 5.0, pH 7.0, and pH 9.0 solutions for standby. Three pieces of tracers with the same mass as in the slow-release evaluation experiments at different temperatures were weighed, and the tracer pieces were placed in the different pH solutions prepared in advance. Regular sampling was performed, and the sampling time points were 10 min, 20 min, 40 min, 60 min, 120 min, 180 min, 300 min, 420 min, 690 min, 960 min, 1230 min, and 1500 min. A certain volume of sample was taken each time, and the solution was replenished to the original state after each sampling, and then the collected samples were detected by a fluorescence spectrometer to obtain the slow-release data of the solid releasable fluorescent tracer at different pH values. It was found through practice that under different pH conditions, the cumulative release rate curves of the tracers were basically coincided, and the slow-release rates were consistent, indicating that pH had little effect on the slow-release rate of the tracer. Therefore, the slow-release experiments of the solid releasable fluorescent tracer at different pH values are not included in the slow-release evaluation method of the solid releasable fluorescent tracer.

[0057] In some preferred embodiments, the slow-release experiment at different flow rates includes: flushing the solid releasable fluorescent tracer at preset different flow rates, and sampling and detecting at preset time intervals.

[0058] Further preferably, the slow-release experiment at different flow rates includes: weighing pieces of tracers with the same mass as in the slow-release evaluation experiments at different temperatures, and performing different flow rate flushing experiments thereon. The experiment uses a constant flow pump injection method, and 5 different flow rates (100 mL / min, 200 mL / min, 300 mL / min, 400 mL / min, and 500 mL / min) are used to flush the solid releasable fluorescent tracer pieces. Regular sampling was performed, and the sampling time points were 1 min, 5 min, 10 min, 30 min, and 60 min. A certain volume of sample was taken each time, and then the collected samples were detected by a fluorescence spectrometer to obtain the slow-release data of the solid releasable fluorescent tracer at different flow rates.

[0059] In some preferred embodiments, the slow-release experiment at different water contents includes: under a fixed flow rate, flushing the tracer with oil-water mixed fluids with preset different water contents, and sampling and detecting at preset time intervals.

[0060] Further preferably, the slow-release experiment at different water contents comprises: taking the tracer blocks with the same mass as in the slow-release evaluation experiment at different temperatures, and then performing the slow-release experiment of the tracer at different water contents. The experiment first selects a fixed flow rate (for example, 300 mL / min), and then uses 10 different water content (for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%) oil-water mixed fluid, and uses the constant flow pump injection method to flush the solid releasable fluorescent tracer blocks. After one group of experiments is completed, the experimental flow rate is changed to repeat the above steps for the next group of experiments. Sample periodically, take 2 mL of sample each time, and then use a fluorescence spectrometer to detect the collected sample to obtain the slow-release data of the solid releasable fluorescent tracer at different water contents.

[0061] The slow-release mechanism of the solid releasable fluorescent tracer is obtained by summarizing the evaluation experiment results: depending on the interaction between the fluid and the tracer and the time of contact and soaking in the fluid, the experimental results show that there are two processes of the target fluid invading the tracer, which correspond to two release principles of the releasable tracer. First, the release rate of the tracer is related to the saturated solubility of the tracer, and the relationship is as follows:

[0062] dC / dt=k D A(C s -ρtracer) (1)

[0063] In the formula, dC / dt is the dissolution rate, g / min; k is the dissolution rate constant; A is the slow-release tracer surface area, m D ; C is the tracer saturated solubility, g / L; and p is the tracer mass concentration, g / L. 2 s tracer

[0064] In the formula, the dissolution rate constant k D is a parameter related to mass transfer, which describes the rate of diffusion of the tracer from the solid surface to the solution. It is not an inherent physical and chemical constant of the tracer, but is closely related to the mass transfer process. Generally, it is measured by a laboratory dynamic dissolution experiment: the slow-release tracer with a known surface area A is placed in a container filled with simulated formation water or injection water, and is stirred (to simulate formation fluid flow) at a constant temperature and pressure. Sample at different time points, and measure the concentration of the tracer in the solution. Through multiple experimental data, the dissolution rate constant k

[0065] In the formula, the tracer saturated solubility C s ​​​The maximum concentration of tracer that can be achieved in solution under specific temperature, pressure, and solvent (usually formation or injection water) conditions. The tracer solubility is determined by laboratory saturation solubility test: excess tracer solid is added to simulated formation or injection water, and stirred well at constant temperature and pressure (simulated formation conditions) until solubility equilibrium is reached. The unsolved tracer is then removed by filtration or centrifugation, and the supernatant is analyzed quantitatively (e.g., by chromatography, spectroscopy, etc.) to determine the concentration of the tracer. The range is typically between mg / L and g / L.

[0066] Second, when the solid releasable fluorescent tracer is completely covered by the target fluid, i.e., the target fluid fills the matrix pores, the mass concentration of the tracer in the fluid increases continuously, and the dissolution rate decreases continuously. When the mass concentration of the tracer in the fluid approaches the saturation solubility of the tracer, the dissolution process stops. After the dissolution process of the tracer ends, a diffusion release process begins, which is a continuous and slow process. Over time, the release rate of the tracer tends to a constant. At this time, the cumulative release amount of the tracer is directly proportional to the contact area of the releasable tracer. The diffusion process is described by the Higuchi diffusion equation, as shown in equation (2).

[0067]

[0068] In the formula: Q tracer — cumulative diffusion amount of the tracer, g; A— surface area of the slow-release tracer, m 2 ; D— diffusion coefficient; t— diffusion time, min.

[0069] wherein the diffusion coefficient D is a physical quantity representing the degree of diffusion of the tracer in the porous medium. It is difficult to directly measure the overall diffusion coefficient of the tracer, and laboratory experiments are usually used to sample and analyze in core flow experiments, and the overall diffusion coefficient is calculated by calculating the cumulative amount of the tracer. The mathematical expression is:

[0070]

[0071] In the formula: V p — total pore volume of the core sample, m3;

[0072] T— time used for injecting Vp volume, s;

[0073] L— length of the core sample, m;

[0074] V— cumulative tracer discharge measured, m3;

[0075] U ξ — U value corresponding to the measured relative concentration ξ.

[0076] In another aspect, the present application also provides a solid releasable fluorescent tracer sustained release evaluation system, comprising:

[0077] a static experiment unit comprising a constant temperature device, a salinity adjusting device, and a pH adjusting device;

[0078] a dynamic experiment unit comprising a constant flow pump, an oil-water mixing device, and a tracer short section;

[0079] a detection unit comprising a fluorescence spectrometer; and

[0080] a data processing unit configured to perform the sustained release kinetics model calculation.

[0081] In some preferred embodiments, the data processing unit comprises:

[0082] a parameter input module for inputting parameter measured values;

[0083] a model calculation module for solving a dissolution rate equation and a Higuchi diffusion equation;

[0084] an output module for generating a sustained release kinetics curve and a goodness-of-fit report.

[0085] Embodiments

[0086] The present application is further illustrated by the following examples, but the present application is not limited to the scope of the examples. The experimental methods in the following examples are not specified, and are performed according to conventional methods and conditions.

[0087] The solid releasable fluorescent tracer used in this test is a long strip after high-temperature curing, with epoxy resin as the polymer skeleton and a poorly soluble salt as the fluorescent tracer carrier. The preparation method is as follows:

[0088] First, 5 g of epoxy resin polymer material (Araldite GY 282 purchased from Huntsman Advanced Materials) is heated and stirred uniformly in a constant temperature oven at 120°C; then 0.12 g of FITC fluorescent nanotracer is added and stirred until fully mixed; 1.3 g of poorly soluble salt (CaC2O4) is then added to the beaker containing the above mixture of epoxy resin and fluorescent nanotracer, and the mixture is stirred until uniform; the mixture is poured into a polytetrafluoroethylene mold and cured in a constant temperature oven at 90°C. After curing, the prepared releasable solid tracer is removed from the mold for use.

[0089] The sustained release evaluation method of the solid releasable fluorescent tracer provided by the present application comprises the following steps:

[0090] (1) Sustained release evaluation experiment at different temperatures

[0091] The experiment begins with preparing a clean beaker and adding 200 mL of water. Next, a pre-prepared tracer block is added to the beaker. The experiment is conducted at three different temperatures: 25°C, 40°C, and 80°C. To ensure sufficient release of the marker from the beaker, samples are taken regularly throughout the experiment. The sampling intervals are shown in Table 1. Each sample is 2 mL. Immediately after sampling, the same volume of water is added to the beaker to maintain a constant water volume of 200 mL. The collected samples are analyzed using a fluorescence spectrometer to obtain sustained-release data for the solid-state releasable fluorescent tracer at different temperatures.

[0092] Table 1 Static sampling design

[0093] Sample No. 1 2 3 4 5 6 7 8 9 10 11 12 Time (min) 10 20 40 60 120 180 300 420 690 960 1230 1500

[0094] Figure 1 is the cumulative release concentration curve of solid-state releasable fluorescent tracer at different temperatures, such as Figure 1 As shown in the figure, the release rate of the releasable solid tracer increases with increasing temperature. The release rate after stabilization at room temperature is 0.0045 μg / L / min, rising to 0.018 μg / L / min at 80°C, showing a significant upward trend. This is because the diffusion coefficient of a substance is primarily dependent on temperature. Higher temperatures increase the diffusion coefficient of the tracer substance and the cumulative amount of tracer substance released, resulting in a trend of faster release rates as the temperature rises.

[0095] (2) Slow-release evaluation experiment under different mineralization

[0096] First, prepare three clean beakers, then add 200mL of pure water, 200mL of 5000mg / L sodium chloride solution, and 200mL of 10000mg / L sodium chloride solution to the three beakers respectively to establish three different experimental conditions. Next, add an equal amount of the prepared tracer block to each beaker to study its release behavior under different salinity environments. Regular sampling is required during the experiment. The sampling interval is shown in Table 1, and the sampling volume is fixed at 2mL each time. After sampling, the amount of liquid removed should be immediately and accurately replenished into the beaker to keep the total liquid volume of each beaker constant at 200mL. The collected samples were tested using a fluorescence spectrometer to obtain the sustained release data of the solid-state releasable fluorescent tracer under different salinities.

[0097] Figure 2 is the cumulative release concentration curve of solid-state releasable fluorescent tracer under different mineralization degrees, Figure 2It can be seen that the increase of salinity inhibits the release of the releasable solid tracer, and the release rate after stabilization decreases from 0.0045 μg / L / min to 0.0029 μg / L / min as the salinity increases from 0 mg / L to 10000 mg / L. The reason for this phenomenon is that the salinity affects the dispersion degree of the tracer in the medium, and generally the higher the salinity, the worse the dispersion degree of the tracer in the medium, and the shorter the dissolution stage time, thereby resulting in the decrease of the cumulative release amount.

[0098] (3) Slow-release evaluation experiment under different pH values

[0099] Three clean beakers were prepared, and then solutions with pH 5.0, pH 7.0 and pH 9.0 were added to the three beakers respectively to establish three different experimental conditions. Then, the prepared equal amount of tracer blocks were added to each beaker to study the release behavior of the tracer blocks under different pH environments. During the experiment, sampling was required at regular intervals, and the sampling interval is shown in Table 1. The sampling volume was fixed at 2 mL each time. After sampling, the removed liquid was immediately accurately supplemented back to the beaker to keep the total liquid volume of each beaker constant at 200 mL. The collected samples were detected by a fluorescence spectrometer to obtain the slow-release data of the releasable solid fluorescent tracer under different pH values.

[0100] Figure 3 is the cumulative release concentration curve of the releasable solid fluorescent tracer under different pH values. As shown in Figure 3 , under the conditions of pH 5.0, pH 7.0 and pH 9.0, the tracer cumulative release rate curves are basically coincident, and the slow-release rates of the three are consistent, indicating that the pH has little effect on the slow-release rate of the tracer. Therefore, the slow-release experiment of the releasable solid fluorescent tracer under different pH values is not included in the slow-release evaluation method of the releasable solid fluorescent tracer.

[0101] (4) Slow-release evaluation experiment under different flow rates

[0102] The tracer blocks with the same mass as in the above experiment were prepared and placed in the tracer segment. After the device was ready, the constant flow pump was started and different flow rates were set according to the experimental design. Here, 100 mL / min, 200 mL / min, 300 mL / min, 400 mL / min and 500 mL / min were set as five flow rate levels to simulate the effect of different flow conditions on the release of the tracer. After the flow-through system started to work and the flow rate was stable and the fluid filled the entire pipeline system, the outlet valve was opened to start the entire sampling process. The sampling interval is shown in Table 2, and the sampling volume was fixed at 2 mL each time. The collected samples were detected by a fluorescence spectrometer to obtain the slow-release data of the releasable solid fluorescent tracer under different flow rates.

[0103] Table 2 Dynamic sampling design

[0104] Sample No. 1 2 3 4 5 Time (min) 1 5 10 30 60

[0105] Figure 4 is the cumulative release concentration curve of the solid releasable fluorescent tracer under different flow rates. As shown in Figure 4 : different fluorescent intensities are detected in the sample under different flow rates, and the change of the fluorescent intensity is first decreased and then increased with the increase of the flow rate. When the experimental fluid flow rate is less than 300 mL / min, the fluorescent intensity decreases with the increase of the flow rate, and when the experimental fluid flow rate is greater than 300 mL / min, the fluorescent intensity increases with the increase of the flow rate. The reason for this trend can be attributed to: when the flow rate is less than 300 mL / min, with the increase of the flow rate, the flow rate increases, the contact time of unit volume of fluid with the solid marker decreases, the dissolution of the fluorescent nanoparticles decreases, and therefore the detected fluorescent intensity decreases. When the flow rate is greater than 300 mL / min, with the increase of the flow rate, the scouring force of the fluid on the marker increases, the concentration difference increases, resulting in an increase in the dissolution rate of the carrier, and more fluorescent nanoparticles are washed into the fluid, and therefore the detected fluorescent intensity increases.

[0106] (5) Slow release evaluation experiment under different water contents

[0107] Prepare the tracer block with the same mass as in the above experiment, and place it inside the tracer short section. Determine a fixed flow rate (300 mL / min), and then use 10 different water content oil-water mixed fluids (10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%) to flush the solid releasable fluorescent tracer block by using a constant flow pump injection method. Start the flow system, and after the flow rate is stable and the fluid fills the entire pipeline system, open the outlet valve to start the entire sampling process. The sampling interval is shown in Table 2, and the sampling volume is fixed at 2 mL each time. After one set of experiments, replace the experimental flow rate and repeat the above steps to continue the next set of experiments. The collected samples are detected by using a fluorescence spectrometer to obtain the slow release data of the solid releasable fluorescent tracer under different water contents.

[0108] Figure 5 is the cumulative release concentration curve of the solid releasable fluorescent tracer under different water contents. As shown in Figure 5 , through multiple experiments, it is found that the experimental results under different flow rates have similar trends, so take the flow rate of 300 mL / min as an example. With the decrease of the water content, the fluorescent intensity decreases, which is because the water-soluble marker is selected for the experiment, the contact opportunity between water and the surface of the solid releasable long-acting marker decreases with the decrease of the water content, resulting in a decrease in the dissolution of the carrier, and therefore the amount of fluorescent nanoparticles diffusing into the fluid decreases.

[0109] (6) Data processing unit configuration and function verification. Based on the experimental data provided by the embodiments of the application, the following verification results can prove the realizability of the system.

[0110] 1. Parameter input module

[0111] Function: Input static and dynamic experimental parameters (temperature, salinity, pH, flow rate, water content). The measured data is imported through Excel table or CSV file, and the system automatically checks the parameter range.

[0112] 2. Model calculation module

[0113] Based on the dissolution rate equation (dC / dt = k D ·A·(C s -C)) and Higuchi diffusion equation (Q tracer =A·D 1 / 2 ·t 1 / 2 ) for calculation.

[0114] Verification: Dissolution rate equation: The dissolution rate constant k D is inverted through static experimental data, k D = 0.0032 L / (g·min) at 25℃, k D = 0.0135 L / (g·min) at 80℃. Higuchi diffusion equation: D = 1.2×10 -6 m 2 / min is inverted through dynamic experimental data, which is consistent with the static diffusion experimental result D = 1.1×10 -6 m 2 / min. Multi-factor coupling calculation: Combined with flow rate and water content parameters, the release amount under dynamic conditions is calculated.

[0115] 3. Output module

[0116] Generate slow-release kinetic curve and goodness-of-fit report.

[0117] 4. Goodness-of-fit report

[0118] 4.1 Goodness-of-fit analysis of static experiment

[0119] 4.1.1 Temperature experiment

[0120] (1) Slow-release kinetic curve

[0121] Experimental conditions: 25℃, 40℃, 80℃, pH = 7.0, salinity = 0 mg / L (distilled water).

[0122] Data fitting model: dissolution rate equation

[0123] From Figure 6 The release kinetics curves at different temperatures show that the experimental data points are highly consistent with the fitting curve of the Higuchi diffusion equation. At 25°C, the release rate is slow (slope 0.0032 pg / L / min), and at 80°C, the release rate is significantly accelerated (slope 0.0135 pg / L / min). The model predicts that the deviation from the experimental data is ≤3%.

[0124] (2) Goodness-of-fit report

[0125] Table 3 Goodness-of-fit report at different temperatures

[0126]

[0127] 4.1.2 Salinity experiment

[0128] (1) Release kinetics curve

[0129] Experimental conditions: salinity = 0, 5000, 10000 mg / L (NaCl solution), temperature = 25°C, pH = 7.0.

[0130] Data fitting model: Higuchi diffusion equation

[0131] From Figure 7 The release kinetics curves at different salinities show that the release rate under 10000 mg / L NaCl conditions is reduced to 0.0029 pg / L / min, with a deviation of ≤7% from the predicted value of the Higuchi equation (0.0027 pg / L / min). The salinity adjustment error is ≤1%.

[0132] (2) Goodness-of-fit report

[0133] Table 4 Goodness-of-fit report at different salinities

[0134]

[0135] 4.1.3 pH experiment

[0136] (1) Release kinetics curve

[0137] Experimental conditions: pH = 5.0, 7.0, 9.0, salinity = 0 mg / L, temperature = 25°C.

[0138] Data fitting model: Higuchi diffusion equation

[0139] From Figure 8 The release kinetics curves at different pHs show that the release rates at pH 5.0, 7.0, and 9.0 are relatively small, indicating that pH has no significant effect on the release rate, and the system optimizes the redundant variables.

[0140] (2) Goodness of fit report

[0141] Table 5. Goodness of fit report at different pH

[0142]

[0143] 4.2. Goodness of fit analysis of dynamic experiments

[0144] 4.2.1 Flow rate experiment

[0145] (1) Release kinetics curve

[0146] Experimental conditions: Temperature = 25 °C, salinity = 0 mg / L, flow rate = 100, 300, 500 mL / min.

[0147] Data fitting model: Higuchi diffusion equation

[0148] Release kinetics curves of tracer at different flow rates are shown in Figure 9 . When the flow rate is < 300 mL / min, the release rate decreases with increasing flow rate; when the flow rate is > 300 mL / min, the release rate increases with increasing flow rate (enhanced scouring effect). The goodness of fit of the dynamic experimental data to the Higuchi equation is R 2 ≥ 0.95, and the calculated diffusion coefficient D is 1.2 x 10 -6 m 2 / min.

[0149] (2) Goodness of fit report

[0150] Table 6. Goodness of fit report at different flow rates

[0151]

[0152] 4.2.2 Water cut experiment

[0153] (1) Release kinetics curve

[0154] Experimental conditions: Water cut = 10%, 50%, 100%, temperature = 25 °C, salinity = 0 mg / L, flow rate = 300 mL / min.

[0155] Data fitting model: Higuchi diffusion equation.

[0156] Release kinetics curves at different water cuts are shown in Figure 10 . When the water cut decreases from 100% to 10%, the fluorescence intensity decreases by 62.5%, with a deviation of ≤ 5% from the predicted value, matching the water cut control accuracy (± 1%) of the oil-water mixing device.

[0157] (2) Goodness of fit report

[0158] Table 7 goodness of fit report at different moisture contents

[0159]

[0160]

[0161] 5. Results:

[0162] The data processing unit of the present application is proved to be realizable by the following verification results:

[0163] Release kinetics curve chart: the model calculation module accurately solves the dissolution rate equation and Higuchi diffusion equation, the goodness of fit (R 2≥0.95), and verifies the correctness of the release mechanism.

[0164] Goodness of fit report: R 2 and statistical test results (p>0.05) show that there is no significant difference between the model and the experimental data.

[0165] System operation verification: the accuracy of the hardware equipment meets the experimental requirements (error ≤2%), the software stability is high (repeatability error ≤5%), and it is suitable for industrial application. The release kinetics curve and report generated by the output module are consistent with the experimental data.

[0166] The present application has been disclosed in the foregoing by preferred embodiments, but those skilled in the art should understand that these embodiments are only used to depict the present application, and should not be understood as limiting the scope of the present application. It should be noted that any changes and substitutions equivalent to these embodiments should be considered as covered by the scope of the claims of the present application. Therefore, the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A method for evaluating the sustained release of a solid-state releasable fluorescent tracer, characterized in that: include: (1) Static sustained-release evaluation Under constant volume conditions, sustained release experiments were conducted on solid-state releasable fluorescent tracers at different temperatures and salinities. (2) Dynamic sustained-release evaluation Under the condition of fluid flushing, the sustained release experiment of solid releasable fluorescent tracer was carried out at different flow rates and different water contents. (3) Establishing a sustained-release kinetic model based on the detection data of the static sustained-release evaluation and the dynamic sustained-release evaluation.

2. The evaluation method according to claim 1, wherein: In step (1), the sustained-release experiment at different temperatures includes: placing the solid-state releasable fluorescent tracer in distilled water at different preset temperatures, and sampling and testing at preset time intervals.

3. The evaluation method according to claim 1, wherein: In step (1), the sustained-release experiment under different salinities includes: placing the solid-state releasable fluorescent tracer in sodium chloride solutions of different preset concentrations, and taking samples for detection at preset time intervals.

4. The evaluation method according to claim 1, wherein: In step (2), the sustained-release experiment at different flow rates includes: flushing the solid-state releasable fluorescent tracer at different preset flow rates, and sampling and testing at preset time intervals.

5. The evaluation method according to claim 1, wherein: In step (2), the sustained-release experiment under different water contents includes: flushing the tracer with oil-water mixed fluids of different preset water contents at a fixed flow rate, and sampling and testing at preset time intervals.

6. The evaluation method according to claim 1, wherein: The sustained-release kinetic model includes a dissolution rate equation and a Higuchi diffusion equation.

7. The evaluation method according to claim 6, wherein: The dissolution rate equation is: dC / dt=k D A(C s -ρ tracer ) Where: dC / dt—dissolution rate, g / min; k D —dissolution rate constant; A—surface area of ​​the sustained-release tracer, m 2 ; C s —tracer saturation solubility, g / L; ρ tracer —Tracer mass concentration, g / L.

8. The evaluation method according to claim 6, wherein: The Higuchi diffusion equation is: Where: Q tracer —Cumulative diffusion of tracer, g; D—diffusion coefficient; t—diffusion time, min.

9. The evaluation method according to claim 1, wherein: The solid-state releasable fluorescent tracer uses epoxy resin as a polymer skeleton and insoluble salt as a fluorescent tracer carrier.

10. A sustained-release evaluation system for a solid-state releasable fluorescent tracer, characterized in that: include: Static experimental unit, including constant temperature device, mineralization adjustment device, pH adjustment device; Dynamic experimental unit, including constant flow pump, oil-water mixing device, and tracer nipple; a detection unit comprising a fluorescence spectrometer; and The data processing unit is configured to execute the sustained-release kinetic model calculation.

11. The sustained-release evaluation system of solid-state releasable fluorescent tracer according to claim 10, characterized in that: The data processing unit includes: Parameter input module, used to input parameter measured values; Model calculation module, used to solve the dissolution rate equation and Higuchi diffusion equation; Output module, used to generate sustained-release kinetic curves and goodness-of-fit reports.

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