Rapid polymer injection performance evaluation method based on molecular linearity degree

Abstract

The invention discloses a rapid polymer injection performance evaluation method based on molecular linearity, which comprises the following steps: determining a molecular gyration radius Rg0 and a hydrodynamic radius Rh0 of a polymer molecular chain at an angle of 0, and quantitatively characterizing the linear degree of the polymer molecular chain by a ratio of Rg0 / Rh0; according to the method, the injection performance of polymers with similar molecular weights and the same concentration is quickly evaluated by utilizing a rule that the higher the Rg0 / Rh0 ratio is, the higher the linear degree of molecular chains is and the better the injection performance of the polymers in polymer solutions with similar molecular weights and the same concentration under a certain mineralization degree condition; by adopting the technical scheme provided by the invention to evaluate the injection performance of the polymer, the evaluation result is accurate and reliable, the experiment time consumption is greatly reduced, and the working efficiency is greatly improved.

Description

Technical Field

[0001] This disclosure relates to the field of tertiary oil recovery technology in oilfield development, and in particular to a rapid evaluation method for polymer injection performance based on molecular linearity. Background Technology

[0002] Polymer flooding is one of the leading technologies for the sustained and stable production of Daqing Oilfield. This technology effectively improves the oil recovery rate of reservoirs after waterflooding, playing a crucial role in supporting Daqing Oilfield's annual crude oil production of 30 million tons. Currently, Daqing Oilfield's polymer flooding employs a classified reservoir development strategy, with a certain correlation between reservoir permeability and polymer molecular weight. Reservoirs are roughly divided into Class I, Class II, and Class III reservoirs based on permeability differences. Among them, Class I reservoirs have an effective permeability higher than 500 × 10⁻⁶. -3 μm 2 The effective permeability of Class II oil reservoirs is 150×10⁻⁶. -3 μm 2 ~500×10 -3 μm 2 Between; Class III oil reservoirs have an effective permeability of less than 150×10⁻⁶. -3 μm 2 The polymers used for oil displacement are mostly partially hydrolyzed polyacrylamide, with a small amount being functional salt-resistant polymers, and their molecular weight ranges from 3 × 10⁻⁶. 6 g / mol ~ 30 × 10 6 g / mol. In polymer flooding development of classified oil reservoirs, Class I reservoirs typically use polymers with a molecular weight of 19 × 10⁻⁶ g / mol. 6 g / mol ~ 25 × 10 6 g / mol polymer; Class II oil layers typically use polymers with a molecular weight of 12×10 6 g / mol ~ 16 × 10 6 g / mol polymer; Class III oil layers typically use polymers with a molecular weight of 5×10 6 g / mol~8×10 6 Polymer in g / mol.

[0003] The mechanism by which polymer flooding enhances oil recovery lies in two aspects: First, after the polymer solution is injected into the formation, it increases the viscosity of the displacing phase due to its viscosity-enhancing properties, improving the mobility ratio between the displacing and submerged phases and increasing the sweep efficiency of the water-flooded zone. Second, the adsorption and retention of polymers in the formation reduces the total fluid mobility in the high-permeability water-flooded zone, narrows the difference in waterline advance velocity between high and low permeability zones, adjusts the water absorption profile, and expands the swept volume. Furthermore, the polymer solution can also improve the micro-displacement efficiency due to its elasticity. Therefore, the mechanism of polymer flooding in enhancing oil recovery lies in improving the sweep efficiency and oil displacement efficiency of the displacement process. Sweep efficiency is a prerequisite for oil displacement efficiency; only when the oil layer is effectively swept can the viscoelasticity of the polymer further enhance the micro-displacement efficiency. Therefore, the primary factor in improving the efficiency of polymer flooding is to improve the sweep efficiency of the polymer solution.

[0004] The sweep efficiency of a polymer solution is closely related to its injection performance. Under the same concentration and similar molecular weight, a polymer solution with stronger injection capability can penetrate into reservoir pore throats of larger volume and smaller size, achieving a wider sweep range. In the process of developing polymer flooding schemes for classified oil reservoirs, injection performance is an important polymer screening indicator. Under the condition that other properties meet the development requirements, polymers with better injection performance are usually selected as oil displacement agents.

[0005] To evaluate the injection performance of polymers, core flow tests are typically conducted. There are two main approaches: one approach compares the injection performance of polymers with similar molecular weights by examining whether polymer solutions of the same concentration can be injected into cores with a specific permeability. Taking the core flow test of a Class III oil reservoir as an example, the molecular weight is approximately 8 × 10⁻⁶. 6 Different polymers at g / mol were prepared into 1000 mg / L solutions under the same conditions and injected at a rate of 0.2 ml / min into an atmosphere with an permeability of approximately 100 × 10⁻⁶ g / mol. -3 μm 2 Water flooding, polymer flooding, and subsequent water flooding were performed on the core samples. The compatibility of the polymer solution with the core was determined by the pressure change curves at the injection end. If the pressure value during the polymer flooding stage continuously increases instead of fluctuating steadily, or if the pressure value during the subsequent water flooding stage cannot be reduced to below 2 / 3 of the stable polymer flooding pressure, or even if the subsequent water flooding pressure continues to increase, it is determined that the polymer solution of that concentration is not suitable for the core with that permeability, resulting in core blockage.

[0006] Another approach is to evaluate the injection performance of polymers with similar molecular weights by determining the lower limit of injectable permeability of polymer solutions of the same concentration. Taking core flow experiments in Class III oil reservoirs as an example, the molecular weight is approximately 8 × 10⁻⁶. 6 Different polymers at g / mol were prepared into 1000 mg / L solutions under the same conditions. A group of core samples with gradually decreasing permeability (e.g., 150 × 10⁻⁶ g / mol) were selected. -3μm 2 100×10 -3 μm 2 75×10 -3 μm 2 50×10 -3 μm 2 Flow experiments were conducted on each sample according to its permeability, from highest to lowest. Polymer solution was injected into the core at a rate of 0.2 ml / min for water flooding, polymer flooding, and subsequent water flooding. The compatibility between the polymer and the core was determined by examining the pressure change curves at the injection end. When the core permeability dropped to a certain value, if the pressure during the polymer flooding stage of the flow experiment continuously increased instead of fluctuating smoothly, or if the pressure during the subsequent water flooding stage could not be reduced to below 2 / 3 of the stable polymer flooding pressure, or even if the subsequent water flooding pressure continued to increase, then the core permeability at this point was considered to be the lower limit of the core permeability for which that polymer concentration could be injected.

[0007] Both of the aforementioned flow experiment methods for evaluating polymer injection performance have certain limitations. The first method can only determine whether a polymer meets the permeability requirements for classified oil reservoirs, but it cannot further evaluate the injection performance of multiple polymers that meet the permeability requirements. The second method can determine the lower limit of injectable permeability of the polymer solution; the lower the lower limit of injectable permeability, the better the injection performance. However, measuring the lower limit of injectable permeability of a single polymer involves multiple core flow experiments, and the workload of flow experiments increases exponentially with the number of polymers. Assuming a single core flow experiment takes one working day, this method is extremely time-consuming and inefficient in determining the lower limit of injectable permeability for different polymers. Based on the current state of technology, it is necessary to provide a rapid method for evaluating polymer injection performance, which can quickly assess the injection performance of polymer solutions with similar molecular weights and concentrations by comparing specific technical indicators under the same conditions. Summary of the Invention

[0008] In view of this, this disclosure provides a rapid evaluation method for polymer injection performance based on molecular linearity, which solves the problems of long time consumption and low efficiency in the current method of evaluating polymer injection performance using core flow experiments.

[0009] To achieve the above-mentioned objectives, the rapid evaluation method for polymer injection performance based on molecular linearity provided in this disclosure includes:

[0010] Under the same mineralization conditions, the molecular gyration radius R of polymer solutions with similar molecular weights and concentrations at 0° was measured. g0 and hydrodynamic radius R h0 , with R g0 / R h0 The ratio quantitatively characterizes the linearity of polymer molecular chains; based on R... g0 / Rh0 The higher the ratio, the higher the linearity of the polymer molecular chain, and the better the polymer injection performance. This rule is used to evaluate the injection performance of various polymers.

[0011] In this disclosure and possible embodiments, the similar molecular weights refer to polymers with a molecular weight difference of 0 to 1.0 × 10⁻⁶. 6 g / mol.

[0012] In this disclosure and possible embodiments, the molecular gyration radius R of the polymer molecular chain at angle 0 is obtained by static light scattering experiments. g0 .

[0013] In this disclosure and possible embodiments, the hydrodynamic radius R of the polymer molecular chain at angle 0 is obtained by dynamic light scattering experiments. h0 .

[0014] In this disclosure and possible embodiments, the hydrodynamic radius R of the polymer molecular chain at angle 0 is... h0 The hydrodynamic radius R of polymer molecules under different measurement angles θ h sin 2 (θ / 2) is plotted as a scatter plot and then subjected to linear trend regression.

[0015] In this disclosure and possible embodiments, when performing dynamic and static light scattering experiments, the experimental samples are filtered using a needle filter with a pore size ranging from 0.2 to 5.0 μm.

[0016] In this disclosure and possible embodiments, the polymer solution concentration is 50–200 mg / L.

[0017] In this disclosure and possible embodiments, the mineralization ranges from 15,000 to 40,000 mg / L.

[0018] In this disclosure and possible embodiments, the molecular gyration radius R of the polymer molecular chain at angle 0 is obtained by static light scattering experiment. g0 The methods include:

[0019] (1) A wide-angle laser light scattering instrument was used. The static light scattering Zimm Plot Software was selected. The measurement angle θ range was set to 20 to 80 degrees, increasing by 5 degrees. The light intensity was set to 50%, the light flux to 400, and the dark current was measured multiple times and the average value was taken.

[0020] (2) Filter about 8 ml of solvent into a clean scintillation bottle using a syringe filter with a pore size of 0.8 μm, and record the mass of the scintillation bottle and the solvent.

[0021] (3) Set the filter wheel to a wavelength of 532nm, run the measurement process, and measure the intensity of the scattered light from the background solvent;

[0022] (4) Close the filter wheel, remove the scintillation bottle containing the solvent, wipe the decahydronaphthalene off the bottle wall with filter paper, and weigh the scintillation bottle as the reference mass for the next sample addition.

[0023] (5) A certain amount of polymer solution is filtered into the scintillation bottle using a needle filter with a pore size of 2 to 5 μm and dispersed evenly. The concentration of polymer in the scintillation bottle is calculated based on the initial concentration of the polymer solution and the mass added.

[0024] (6) Set the filter wheel to a wavelength of 532nm, run the measurement process, and measure the intensity of scattered light from the polymer solution at this concentration point; after the measurement is completed, turn off the filter wheel;

[0025] (7) Repeat steps (4) to (6) to measure at least 5 concentration points, and control the polymer concentration to increase by a certain value when adding polymer solution;

[0026] (8) After the measurement is completed, run the Calculate procedure to obtain the static light scattering Zimm plot. The calculation program will then use K... c / ΔR g sin 2 Plot (θ / 2)+qc and extrapolate to θ→0 and c→0 to obtain the molecular weight of the measured polymer solution, the second virial coefficient, and R at zero angle. g0 Among them, K c λ is a constant that depends on the polymer-solvent system, temperature, and wavelength λ of the incident light; q is an arbitrary constant with a value of 100,000, which is used to make the graph unfold into a clear grid; θ is the measurement angle; and c is the measurement concentration.

[0027] In this disclosure and possible embodiments, the hydrodynamic radius R of the polymer molecular chain at angle 0 is obtained through dynamic light scattering experiments. h0 The methods include:

[0028] (1) Use a wide-angle laser light scattering instrument, turn the filter wheel off, adjust the light intensity to 100%, and the light flux to 200;

[0029] (2) Select Dynamic Light Scattering, input sample and instrument parameters, select Measured Baseline for the baseline, and check use dust filter; create new Count Rate History, Correlation Function, Non-Negatively Constrained Least squares: Regularized (Contin) interfaces in sequence;

[0030] (3) The measurement angle is set to 5 angles: 20°, 35°, 50°, 65°, and 80°.

[0031] (4) Filter 1 / 3 to 2 / 3 of the volume of the polymer solution into a clean scintillation bottle using a needle filter with a pore size of 2 to 5 μm, and place the scintillation bottle in the measuring tank;

[0032] (5) Set the filter wheel to 532nm wavelength and begin measurement until the end of the process. Take the average value of multiple measurements and determine the hydrodynamic radius R of the polymer solution at different angles. h；

[0033] (6) R h sin 2 Plot a scatter plot of (θ / 2) and perform a linear trend regression on the scatter plot. The intersection of this trend line with the vertical axis is the hydrodynamic radius R of the polymer solution at zero angle. h0 .

[0034] The beneficial effects of this invention are as follows:

[0035] The present invention provides a rapid evaluation method for polymer injection performance based on molecular linearity, which measures the molecular gyration radius R of the polymer molecular chain at a 0-degree angle. g0 and hydrodynamic radius R h0 , with R g0 / R h0 The ratio of R to α is used to quantitatively characterize the linearity of polymer molecular chains; under certain mineralization conditions, polymer solutions with similar molecular weights and concentrations are used to determine the linearity of R. g0 / R h0 The higher the ratio, the higher the linearity of the molecular chain, and the better the polymer injection performance. This allows for rapid comparison of the injection performance of polymers with similar molecular weights and concentrations. The technical solution provided by this invention provides accurate and reliable evaluation results for evaluating polymer injection performance, significantly reduces experimental time, and greatly improves work efficiency. Attached Figure Description

[0036] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0037] Figure 1 Example Zimm plot of static light scattering;

[0038] Figure 2 For dynamic light scattering R h sin 2 (θ / 2) Scatter linear regression example plot;

[0039] Figure 3 For the medium linear polymer R g0 R h0 And a schematic diagram of the molecular morphology;

[0040] Figure 4 For highly linear polymer R g0 R h0 And a schematic diagram of the molecular morphology;

[0041] Figure 5 This is a Zimm plot of the static light scattering of the PT2500 polymer in Example 1.

[0042] Figure 6 The dynamic light scattering R of the PT2500 polymer in Example 1 h sin 2 (θ / 2) Scatter linear regression plot;

[0043] Figure 7 The static light scattering Zimm plot of the DS2500 polymer in Example 2;

[0044] Figure 8 Dynamic light scattering R of DS2500 polymer in Example 2 h sin 2 (θ / 2) Scatter linear regression plot. Detailed Implementation

[0045] The present disclosure is described below based on specific embodiments; however, it is worth noting that the present disclosure is not limited to these specific embodiments. In the following detailed description of the present disclosure, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.

[0046] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0047] To rapidly evaluate the injection performance of polymer solutions with similar molecular weights and concentrations, the principle of this disclosed rapid polymer injection performance evaluation method based on molecular linearity is as follows:

[0048] Polymers used for oil displacement are typically polyacrylamide and its modified forms. These are dry powder polymers produced by free radical polymerization of acrylamide monomers (AM) or AM plus specific functional monomers, followed by hydrolysis, granulation, drying, pulverization, and sieving. Because AM monomers and other functional monomers have only one reactive head group participating in free radical polymerization, the molecular backbone of these oil displacement polymers is linear, without branching or cross-linking. Furthermore, AM monomers are widely available and reasonably priced, making them a common component in polymer oil displacement agents, accounting for approximately 85%–100% of the total monomer composition. Since the repeating units of these polymers are mostly acrylamide, they are polymers with similar molecular weights and chain lengths. Polymer solutions with similar molecular weights and concentrations exhibit certain microscopic morphologies in solution. These morphologies are influenced by steric hindrance, charge interactions, van der Waals forces, and other factors, resulting in varying degrees of linearity in the polymer molecular chains. The higher the linearity of the molecular chain, the more extended the molecular chain is, and the lower the probability of it coiling or tangling into a cluster. This is conducive to the polymer molecular chain passing through smaller rock pores and channels with smaller molecular shapes, thereby improving the sweep efficiency of the polymer solution.

[0049] Figure 3 For the medium linear polymer R g0 R h0 And a schematic diagram of the molecular morphology. Figure 4 For highly linear polymer R g0 R h0 And a schematic diagram of the molecular morphology, from the appendix Figure 3 Combined with appendix Figure 4 As shown, R g0 / R h0 Molecular chains with larger ratios tend to have more linear polymer chain morphology and a higher degree of linearity. Therefore, the linearity of polymer molecular chains used for oil displacement can be expressed by their molecular gyration radius R at zero angle. g0 and hydrodynamic radius R h0 The ratio is used to quantitatively characterize it.

[0050] Based on the above-mentioned method principle, the technical solution adopted in this disclosure is: by dynamic and static light scattering, the molecular gyration radius R of polymer solutions with similar molecular weights and the same concentration at 0 degrees is determined under certain mineralization conditions. g0 and hydrodynamic radius R h0 The value, in R g0 / R h0 R is used to quantitatively characterize the linearity of polymer molecular chains. g0 / R h0The larger the ratio, the higher the linearity of the polymer molecular chain and the better the polymer injection performance.

[0051] In specific embodiments, since light scattering experiments require high sample cleanliness, bubbles, dust, and impurities can cause significant errors and influences on the experiment. To ensure accurate and reliable measurement results, both dynamic and static light scattering experiments require sample filtration. Filtration is typically performed using a needle filter with a pore size ranging from 0.2 to 5.0 μm. High-concentration polymers or hydrophobic polymers exhibiting hydrophobic association have excessively strong intermolecular forces, which can lead to difficulties in solution filtration and large fluctuations and poor repeatability in measurement results. To improve the accuracy of measurement results and address the aforementioned problems of difficult filtration and poor repeatability of high-concentration or associated polymer solutions, it is preferable to dilute the polymer solution to a concentration of 50–200 mg / L, while adding a certain amount of NaCl to achieve a mineralization of 15,000–40,000 mg / L in the diluted solution. This approach results in experimental results with high accuracy and repeatability.

[0052] In a specific embodiment, the "certain degree of mineralization" refers to a polymer solution mineralization of 15,000–40,000 mg / L; the "similar molecular weight" refers to a polymer molecular weight difference of 0–1.0 × 10⁻⁶ mg / L. 6 g / mol; the same concentration refers to a polymer solution concentration between 50 and 200 mg / L.

[0053] In a specific embodiment, the molecular chain gyration radius R of the polymer at 0-degree angle g0 The values ​​were obtained using the static light scattering Zimmplot method. The experimental instrument was a BI-200SM wide-angle laser light scattering instrument (Brookhaven Instrument Corporation, USA). The specific experimental steps included:

[0054] (1) Select the static light scattering Zimm Plot Software and set the relevant experimental and sample parameters. Set the measurement angle θ range to 20–80 degrees, increasing in increments of 5 degrees. Set the light intensity to 50% and the luminous flux to 400. Take the average value after multiple measurements of the dark current (dark count rate).

[0055] (2) Use a syringe filter with a pore size of 0.8 μm to filter about 8 ml of solvent into a clean scintillation bottle. The mass of the scintillation bottle and the solvent must be accurately recorded during the experiment.

[0056] (3) Set the filter wheel to a wavelength of 532nm, run the measurement process, and measure the intensity of the scattered light from the background solvent;

[0057] (4) Close the filter wheel, remove the scintillation bottle containing the solvent, wipe the decahydronaphthalene off the bottle wall with filter paper, and weigh the scintillation bottle as the reference mass for the next sample addition.

[0058] (5) Use a needle filter with a pore size of 2-5 μm to filter a certain amount of polymer solution into the above scintillation bottle and disperse it evenly. Calculate the concentration of polymer in the scintillation bottle based on the initial concentration of the polymer solution and the mass added.

[0059] (6) Set the filter wheel to a wavelength of 532 nm, run the measurement process, and determine the intensity of scattered light from the polymer solution at that concentration point. After the measurement is complete, turn off the filter wheel;

[0060] (7) Repeat steps (4) to (6) to measure at least 5 concentration points, and try to control the polymer concentration to increase by a certain value when adding polymer solution;

[0061] (8) After the measurement is completed, run the Calculate procedure to obtain the results as shown in the attached figure. Figure 1 The Zimm Plot image shown. The computational program will use K... c / ΔR g (K c (The constant is related to the polymer-solvent system, temperature, and wavelength λ of the incident light) for sin 2 Plot (θ / 2)+qc (q is an arbitrary constant, taking the value 100000, used to make the graph spread out into a clear grid; θ is the measurement angle; c is the measurement concentration), and extrapolate towards θ→0 and c→0 to obtain the molecular weight of the measured polymer solution, the second virial coefficient, and R at zero angle. g0 .

[0062] In a specific embodiment, the R of the polymer molecular chain h0 The value was determined by measuring the molecular hydrodynamic radius of the polymer at different angles θ, and then expressed as R. h sin 2 A scatter plot of (θ / 2) is generated, and a linear trend regression is performed on the scatter plot to obtain the result, as shown in the attached figure. Figure 2 As shown. The hydrodynamic radius of polymer molecules at different angles θ was measured by dynamic light scattering. The experimental instrument was a BI-200SM wide-angle laser light scattering instrument (Brookhaven Instrument Corporation, USA). The experimental steps included:

[0063] (1) Set the filter wheel to the off position, adjust the light intensity to 100%, and the light flux to 200;

[0064] (2) Select Dynamic Light Scattering, input sample and instrument parameters, select Measured Baseline, and check "use dust filter". Create new Count Rate History, Correlation Function, and Non-Negatively Constrained Least squares: Regularized (Continued) interfaces in sequence.

[0065] (3) The measurement angle is set to 5 angles: 20°, 35°, 50°, 65°, and 80°.

[0066] (4) Filter 1 / 3 to 2 / 3 of the volume of the polymer solution into a clean scintillation bottle using a needle filter with a pore size of 2 to 5 μm, and place the scintillation bottle in the measuring tank;

[0067] (5) Set the filter wheel to 532nm wavelength and begin measurement until the end of the process. Take the average value of multiple measurements and determine the hydrodynamic radius R of the polymer solution at different angles. h ;

[0068] (6) R h sin 2 Plot a scatter plot of (θ / 2) and perform a linear trend regression on the scatter plot (see attached diagram). Figure 2 The intersection of this trend line and the vertical axis is the hydrodynamic radius R of the polymer solution at zero angle. h0 .

[0069] The following are various specific embodiments of this disclosure.

[0070] Example 1

[0071] This embodiment uses the method disclosed herein to measure the linearity of a polymer molecular chain. The polymer is partially hydrolyzed polyacrylamide PT2500, produced by Daqing Petrochemical, with a degree of hydrolysis of 22.3%, a solid content of 90.1%, and a molecular weight of approximately 2.5 × 10⁻⁶. 7 g / mol, its functional monomers mainly include acrylamide and sodium acrylate formed by the hydrolysis of acrylamide.

[0072] In this embodiment, the polymer solution was prepared by using simulated clean water (450 mg / L NaCl solution) to form a mother liquor with a mass concentration of 5000 mg / L, and then diluted with simulated sewage (50000 mg / L NaCl solution) to form a diluted solution with a concentration of 50 mg / L and a mineralization of 15000 mg / L.

[0073] The steps for measuring the linearity of polymer molecular chains in this embodiment are as follows:

[0074] 1. The gyrorotation radius R of the polymer molecular chain at 0-degree angle was determined using the static light scattering Zimm plot method. g0 The measurement, specifically the experimental steps, include:

[0075] (1) Select the static light scattering Zimm Plot Software and set the measurement angle θ to the range of 20 to 80 degrees, increasing in increments of 5 degrees. Set the light intensity to 50% and the luminous flux to 400. Take the average value after multiple measurements of the dark current (dark count rate).

[0076] (2) Filter about 8 ml of solvent into a clean scintillation bottle using a syringe filter with a pore size of 0.8 μm. The initial mass of the scintillation bottle and the solvent is 13.333 g and 8.273 g, respectively.

[0077] (3) Set the filter wheel to a wavelength of 532nm, run the measurement process, and measure the intensity of the scattered light from the background solvent.

[0078] (4) Close the filter wheel, remove the scintillation bottle containing the solvent, wipe the decahydronaphthalene off the bottle wall with filter paper, and weigh the scintillation bottle as the reference mass for the next sample addition.

[0079] (5) A certain amount of polymer solution was filtered into the above scintillation bottle using a needle filter with a pore size of 5.0 μm and dispersed evenly. The concentration of polymer in the scintillation bottle was calculated based on the initial concentration of the polymer solution and the mass added.

[0080] (6) Set the filter wheel to a wavelength of 532 nm, run the measurement process, and determine the intensity of scattered light from the polymer solution at that concentration point. After the measurement is completed, turn off the filter wheel.

[0081] (7) Repeat steps (4) to (6) to measure at least 5 concentration points, and try to control the polymer concentration to increase by a certain value when adding polymer solution; the 5 measured concentration points of polymer solution are 0.010155196mg / ml, 0.013667136mg / ml, 0.019386017mg / ml, 0.024102387mg / ml and 0.028457364mg / ml.

[0082] (8) After the measurement is completed, run the Calculate procedure to obtain the results as shown in the attached figure. Figure 5 The image shown is a Zimm plot. The computational program uses K... c / ΔR g (K c (The constant is related to the polymer-solvent system, temperature, and wavelength λ of the incident light) for sin 2Plot (θ / 2)+qc (q is an arbitrary constant, taking the value 100000, used to make the graph spread out into a clear grid; θ is the measurement angle; c is the measurement concentration), and extrapolate towards θ→0 and c→0 to obtain the molecular weight of the measured polymer solution, the second virial coefficient, and R at zero angle. g0 .

[0083] After the above measurement process, the molecular weight of PT2500 partially hydrolyzed polyacrylamide is 2.56 × 10⁻⁶. 7 g / mol; molecular chain gyration radius R at 0 angle g0 It is 242nm.

[0084] 2. Dynamic light scattering is used to determine the hydrodynamic radius R of the polymer at angle 0. h0 The specific experimental steps for measurement include:

[0085] (1) Set the filter wheel to the off state, adjust the light intensity to 100%, and the light flux to 200.

[0086] (2) Select Dynamic Light Scattering, input sample and instrument parameters, select Measured Baseline, and check "use dust filter". Create new Count Rate History, Correlation Function, and Non-Negatively Constrained Least squares: Regularized (Continuing) interfaces in sequence.

[0087] (3) The measurement angles are set to 5 angles: 20°, 35°, 50°, 65°, and 80°. The R value for each measurement angle is... h Repeat the measurement 2 to 4 times and take the average of the results. The measurement results are shown in Table 1 below:

[0088] Table 1. D for 5 measurement angles h and average value (D) h =2R h )

[0089]

[0090] (4) Filter 1 / 3 to 2 / 3 of the volume of the polymer solution into a clean scintillation bottle using a needle filter with a pore size of 5.0 μm, and place the scintillation bottle in the measuring tank.

[0091] (5) Set the filter wheel to 532nm wavelength and begin measurement until the end of the process. Take the average value of multiple measurements and determine the hydrodynamic radius R of the polymer solution at different angles. h ;

[0092] (6) R h sin 2 Plot a scatter plot of (θ / 2) and perform a linear trend regression on the scatter plot. The intersection of this trend line with the vertical axis is the hydrodynamic radius R of the polymer solution at angle 0. h0 The results are attached. Figure 6 .

[0093] After the above measurement and calculation process, the hydrodynamic radius R of PT2500 partially hydrolyzed polyacrylamide at angle 0 was determined. h0 It is 123.26nm.

[0094] 3. Calculation of the linearity of polymer molecular chains, the results are shown in Table 2:

[0095] Table 2. Linearity of Polymer Molecular Chains in Example 1

[0096]

[0097] Example 2

[0098] This embodiment uses the method disclosed herein to measure the linearity of the molecular chain of the second polymer. The second polymer has a similar molecular weight to the polymer in Example 1. The second polymer is the salt-resistant polymer DS2500. The monomers used in the synthesis of DS2500 salt-resistant polymer include acrylamide, salt-resistant monomers, and rigid monomers. It is produced by Daqing Petrochemical, has a degree of hydrolysis of 22.5%, a solid content of 89.7%, and a molecular weight of approximately 2.5 × 10⁻⁶. 7 g / mol.

[0099] In this embodiment, the polymer solution is prepared in the same way as in Example 1.

[0100] The steps for measuring the linearity of polymer molecular chains in this embodiment are as follows:

[0101] 1. Polymer chain gyrometry radius R at 0° g0 Measurement:

[0102] The measurement methods and procedures were the same as in Example 1, with the initial masses of the scintillation bottle and solvent being 13.332 g and 8.337 g, respectively. The five measured concentration points of the polymer solution were 0.011651022 mg / ml, 0.016372146 mg / ml, 0.020750808 mg / ml, 0.024143176 mg / ml, and 0.028017378 mg / ml. The static light scattering Zimm plot of the DS2500 salt-resistant polymer is attached. Figure 7 As shown.

[0103] After the above measurement process, the molecular weight of the DS2500 salt-resistant polymer is 2.54 × 10⁻⁶. 7 g / mol; molecular chain gyration radius R at 0 angle g0 It is 257nm.

[0104] 2. Hydrodynamic radius R of polymer molecular chain at 0° h0 Measurement:

[0105] The measurement method and steps are the same as in Example 1, and R for each measurement angle is... h Repeat the measurement 2 to 4 times and take the average of the results. The measurement results are shown in Table 3 below:

[0106] Table 3. D for 5 measurement angles h and average value (D) h =2R h )

[0107]

[0108]

[0109] With R h sin 2 Plot a scatter plot of (θ / 2) and perform linear trend regression on the scatter plot to obtain the attached... Figure 8 .

[0110] After the above measurement and calculation process, the hydrodynamic radius R of the DS2500 salt-resistant polymer at 0 angle is... h0 It is 107.47nm.

[0111] 3. Calculation of the linearity of polymer molecular chains, the results are shown in Table 4:

[0112] Table 4. Linearity of Polymer Molecular Chains in Example 2

[0113]

[0114] Comparative Example 1

[0115] I. Core flow experiments were conducted to determine the lower limit of injectable permeability for both PT2500 polymer and DS2500 salt-resistant polymer in Examples 1 and 2.

[0116] In this comparative example, the polymer solution was prepared into a stock solution with a mass concentration of 5000 mg / L using simulated clean water (450 mg / L NaCl solution), and then diluted with simulated sewage (5000 mg / L NaCl solution) to a release solution with a concentration of 1000 mg / L.

[0117] In this comparative example, the lower limit of injectable permeability of the polymer was determined by flow experiments using a QY-C12 multifunctional oil displacement device (Huaan Technology Co., Ltd., Jiangsu). The detailed steps are as follows:

[0118] (1) Select a set of core samples with decreasing permeability for flow experiments;

[0119] (2) Select the core with the highest permeability among the above cores, measure and record the parameters such as the length L and diameter D of the natural core, place the core into the holder, apply an annular pressure of ΔP of 4 MPa, and then evacuate for 2 hours.

[0120] (3) At a specific rate, saturate the evacuated natural rock core with simulated sewage (5000 mg / L NaCl solution, the same below), record the sewage volume V1 when the pressure gauge value returns to zero, and calculate the pore volume V and porosity Φ of the rock core.

[0121] (4) Inject simulated sewage at different rates, record the pressure difference ΔP when the pressure is stable, calculate the effective permeability K of the core according to Darcy's law, and take the average value after multiple measurements.

[0122] (5) With 0.2cm 3 At a rate of / min, wastewater, polymer solution, and wastewater were sequentially injected for water flooding, polymer flooding, and subsequent water flooding. The pressure differences ΔP1, ΔP2, and ΔP3 when the pressure was stable at each stage were recorded.

[0123] (6) Calculate the drag coefficient F based on the pressure difference changes in each process. r With residual drag coefficient F rr ;

[0124] (7) Repeat steps (2) to (6) above, and gradually reduce the core permeability to conduct flow experiments. When the core permeability drops to a certain value, the pressure value in the polymer flooding stage of the flow experiment continues to rise instead of fluctuating steadily, or the pressure value in the subsequent water flooding stage cannot drop to below 2 / 3 of the stable polymer flooding pressure, or even the subsequent water flooding pressure continues to rise, the core permeability at this time is considered to be the lower limit of the core permeability that can be injected with polymer of this concentration.

[0125] In this comparative example, the core permeability ranges from 500 to 200 mD, decreasing by approximately 50 mD.

[0126] Based on the above-mentioned method for measuring the lower limit of injectable permeability, the lower limit of injectable permeability of PT2500 polymer in this comparative example is 285.32 md, and the lower limit of injectable permeability of DS2500 salt-resistant polymer is 233.52 md.

[0127] II. Evaluation results of Examples 1-2 and Comparative Example 1:

[0128] Based on Examples 1-2 and Comparative Example 1, the molecular chain gyration radius R at 0-degree angle can be summarized for polymers PT2500 and DS2500. g0 Hydrodynamic radius R at 0 angle h0 The lower limit of injectable permeability is shown in Table 5.

[0129] Table 5 R in Examples 1-2 g0、 R h0 and lower limit of injectable permeability

[0130]

[0131] The data in Table 5 show that the "R" of the two polymers PT2500 and DS2500 g0 / R h0 The values ​​are 1.96 and 2.39 respectively, for the DS2500 polymer's "R" value. g0 / R h0 "A larger value indicates that, under similar molecular weight conditions, the same mineralization and concentration, the DS2500 polymer has a higher degree of molecular chain linearity, a lower probability of molecular chains coiling or tangling, and a greater ability to enter smaller rock pores with a smaller volume, resulting in better injection performance."

[0132] The above experimental results can be further verified by examining the functional monomers of the two polymers. The monomer of PT2500 polymer is acrylamide, while the monomers of DS2500 polymer, in addition to acrylamide, also contain salt-resistant monomers and rigid monomers. Salt-resistant monomers can alleviate the compression effect of mineralization on the polymer double layer to a certain extent, making it less likely for polymer molecular chains to curl up into clusters. Rigid monomers have greater steric hindrance, which also reduces the probability of polymers entangled into clusters to a certain extent.

[0133] The lower limits of injectable permeability for polymers DS2500 and PT2500 under the same conditions are 233.52 mD and 285.32 mD, respectively. According to the principle that polymers with lower lower limits of injectable permeability have better injection performance, polymer DS2500 has better injection performance, which is consistent with the results of the rapid evaluation method for polymer injection performance based on molecular linearity of the present invention.

[0134] The above experimental results show that, under conditions of similar molecular weight, same mineralization and concentration, the polymer's "R" g0 / R h0 "The larger numerical value, the higher degree of linearity of the molecular chain, the lower limit of permeability that can be injected into the rock core, and the better injection performance further verify the feasibility and accuracy of the technical solution of the present invention."

[0135] Example 3

[0136] This embodiment uses the method of the present invention and the core flow experiment method to determine the "R" of two polymers with similar molecular weights under the same conditions. g0 / R h0 "Values ​​and lower limits of injectable core permeability. One polymer is partially hydrolyzed polyacrylamide PT1600, produced by Daqing Petrochemical, with a degree of hydrolysis of 24.1%, a solid content of 90.2%, and a molecular weight of approximately 1.6 × 10⁻⁶." 7 The functional monomers mainly include acrylamide and sodium acrylate formed by the hydrolysis of acrylamide. Another polymer is KY1600, produced by Daqing Chemical Group, with a degree of hydrolysis of 23.8%, a solid content of 90.4%, and a molecular weight of approximately 1.6 × 10⁻⁶ g / mol. 7 g / mol, its functional monomers mainly include acrylamide, sodium acrylate formed by hydrolysis of acrylamide, salt-resistant monomers and rigid monomers.

[0137] In this embodiment, the polymer solution used for dynamic and static light scattering is prepared by using simulated clean water (450 mg / L NaCl solution) to prepare a stock solution with a mass concentration of 5000 mg / L, and then diluted with simulated sewage (50000 mg / L NaCl solution) to a diluted solution with a concentration of 100 mg / L and a mineralization of 25000 mg / L.

[0138] In this embodiment, the polymer solution used in the flow experiment was prepared as a stock solution with a mass concentration of 5000 mg / L using simulated clean water (450 mg / L NaCl solution), and then diluted with simulated wastewater (5000 mg / L NaCl solution) to a release solution with a concentration of 1000 mg / L.

[0139] In this embodiment, the polymer molecular chain gyrometry radius R at 0 degrees is... g0 The measurement method and measuring instruments are the same as in Example 1.

[0140] In the PT1600 static light scattering process, the initial masses of the scintillation bottle and solvent were 13.324 g and 8.246 g, respectively. The five measured concentrations of the polymer solution were 0.014944783 mg / ml, 0.022168697 mg / ml, 0.029824412 mg / ml, 0.039146828 mg / ml, and 0.051009229 mg / ml.

[0141] During the static light scattering process of KY1600, the initial masses of the scintillation bottle and solvent were 13.368 g and 8.191 g, respectively. The five measured concentrations of the polymer solution were 0.011125583 mg / ml, 0.018582223 mg / ml, 0.026147741 mg / ml, 0.034752112 mg / ml, and 0.044411245 mg / ml.

[0142] In this embodiment, the hydrodynamic radius R of the polymer molecular chain at 0 angle is... h0 The measurement method and measuring instruments are the same as in Example 2.

[0143] In this embodiment, a needle filter with a pore size of 3.0 μm is used to filter the polymer solution into the scintillation bottle.

[0144] In this embodiment, the method and instrument for measuring the lower limit of injectable permeability of the polymer solution are the same as those in Comparative Example 1.

[0145] The core permeability ranges from 300 to 100 mD, decreasing by about 50 mD.

[0146] After the above measurement process, the molecular chain gyration radius R of the two polymers PT1600 and KY1600 at 0 angle in this embodiment was determined. g0 Hydrodynamic radius R at 0 angle h0 The lower limit of injectable permeability is shown in Table 6:

[0147] Table 6. R values ​​for polymers PT1600 and KY1600 g0 R h0 and lower limit of injectable permeability

[0148]

[0149] The data in the table show that the "R" of polymers PT1600 and KY1600... g0 / R h0 The values ​​are 2.01 and 2.22 respectively, for the KY1600 polymer's "R" value. g0 / R h0 "A larger value indicates that, under similar molecular weight conditions, the same degree of mineralization and concentration, the molecular chain linearity of the KY1600 polymer is higher."

[0150] Under the same conditions, the lower limits of injectable permeability for polymers PT1600 and KY1600 were 133.68 mD and 114.24 mD, respectively, indicating that polymer KY160 had better injection performance.

[0151] The above experiments further verified that, under conditions of similar molecular weight, same mineralization, and concentration, the polymer's "R" g0 / R h0 "With larger values, higher linearity of molecular chains, a lower lower limit of permeability that can be injected into the core, and better injection performance."

[0152] Example 4

[0153] This embodiment uses the method of the present invention and the core flow experiment method to determine the "R" of two polymers with similar molecular weights under the same conditions. g0 / R h0 "Numerical values ​​and lower limit of injectable core permeability, among which one polymer is partially hydrolyzed polyacrylamide PT800, produced by Daqing Petrochemical, with a degree of hydrolysis of 21.9%, a solid content of 90.7%, and a molecular weight of approximately 8.0 × 10⁻⁶." 6 The functional monomers mainly include acrylamide and sodium acrylate formed by the hydrolysis of acrylamide. Another polymer is TS800, produced by Daqing Zaichuang Technology Co., Ltd., with a degree of hydrolysis of 22.7%, a solid content of 91.3%, and a molecular weight of approximately 8.0 × 10⁻⁶ g / mol. 6 g / mol, its functional monomers mainly include acrylamide, sodium acrylate formed by the hydrolysis of acrylamide, and hydrophobic monomers.

[0154] In this embodiment, the polymer solution used for dynamic and static light scattering is prepared by using simulated clean water (450 mg / L NaCl solution) to prepare a stock solution with a mass concentration of 5000 mg / L, and then diluted with simulated sewage (50000 mg / L NaCl solution) to a diluted solution with a concentration of 200 mg / L and a mineralization of 40000 mg / L.

[0155] In this embodiment, the polymer solution used in the flow experiment was prepared as a stock solution with a mass concentration of 5000 mg / L using simulated clean water (450 mg / L NaCl solution), and then diluted with simulated wastewater (5000 mg / L NaCl solution) to a release solution with a concentration of 1000 mg / L.

[0156] In this embodiment, the polymer molecular chain gyrometry radius R at 0 degrees is... g0 The measurement method and measuring instruments are the same as in Example 1.

[0157] During the PT800 static light scattering process, the initial masses of the scintillation bottle and solvent were 13.352 g and 8.207 g, respectively. The five measured concentrations of the polymer solution were 0.011517308 mg / ml, 0.018205384 mg / ml, 0.025395526 mg / ml, 0.03294108 mg / ml, and 0.04147403 mg / ml.

[0158] During the TS800 static light scattering process, the initial masses of the scintillation bottle and solvent were 13.302 g and 8.321 g, respectively. The five measured concentrations of the polymer solution were 0.011686657 mg / ml, 0.018055556 mg / ml, 0.02553458 mg / ml, 0.033402689 mg / ml, and 0.043003904 mg / ml.

[0159] In this embodiment, the hydrodynamic radius R of the polymer molecular chain at 0 angle is... h0 The measurement method and measuring instruments are the same as in Example 2.

[0160] In this embodiment, a needle filter with a pore size of 2.0 μm is used to filter the polymer solution into the scintillation bottle.

[0161] In this embodiment, the method and instrument for measuring the lower limit of injectable permeability of the polymer solution are the same as those in Comparative Example 1.

[0162] The core permeability ranges from 200 to 30 mD, decreasing by about 50 mD.

[0163] After the above measurement process, the molecular chain gyration radius R of the two polymers PT800 and TS800 at 0 angle in this embodiment was determined. g0 Hydrodynamic radius R at 0 angle h0 The lower limit of injectable permeability is shown in Table 7:

[0164] Table 7. R values ​​for polymers PT800 and TS800 g0 R h0 and lower limit of injectable permeability

[0165]

[0166] The data in the table shows that the "R" of polymers PT800 and TS800 g0 / R h0 The values ​​are 1.91 and 1.75 respectively, for the PT800 polymer's "R" value. g0 / R h0 "A larger value indicates that, under similar molecular weight conditions, and with the same degree of mineralization and concentration, the PT800 polymer exhibits a higher degree of linearity in its molecular chain."

[0167] The lower limits of injectable permeability for polymers PT800 and TS800 under the same conditions were 75.69 mD and 99.26 mD, respectively, indicating that polymer PT800 has better injection performance.

[0168] From a molecular structure perspective, the TS800 polymer contains hydrophobic monomers, which readily form hydrophobic network structures in solution, significantly increasing the probability of polymer bending, entanglement, and winding.

[0169] The above experiments further verified that, under conditions of similar molecular weight, same mineralization, and concentration, the polymer's "R" g0 / R h0 "With larger values, higher linearity of molecular chains, a lower lower limit of permeability that can be injected into the core, and better injection performance."

[0170] Comparative Example 2

[0171] This comparative example aims to evaluate R at different angles for an unfiltered polymer solution. h value.

[0172] In this comparative example, the polymer measured was the same as in Example 1, which was partially hydrolyzed polyacrylamide PT2500.

[0173] In this comparative example, the polymer solution was prepared in the same way as in Example 1.

[0174] In this comparative example, R of the polymer at different angles h The measurement employs dynamic light scattering, and the specific experimental steps include:

[0175] (1) Set the filter wheel to the off state, adjust the light intensity to 100%, and the light flux to 200.

[0176] (2) Select Dynamic Light Scattering, input sample and instrument parameters, select Measured Baseline, and check "use dust filter". Create new Count Rate History, Correlation Function, and Non-Negatively Constrained Least squares: Regularized (Continuing) interfaces in sequence.

[0177] (3) The measurement angle is set to 20, 35, 50, 65 and 80 degrees.

[0178] (4) Use a pipette to transfer 1 / 3 to 2 / 3 of the volume of the polymer solution into a clean scintillation bottle, and place the scintillation bottle in the measuring tank.

[0179] (5) Set the filter wheel to 532nm wavelength and begin measurement until the end of the process. Take the average value of multiple measurements and determine the hydrodynamic radius R of the polymer solution at different angles. h The measurement results are shown in Table 8:

[0180] Table 8. Hydrodynamic radius D of polymer solution at different angles in Comparative Example 2. h (D h =2R h )

[0181]

[0182] Compared to D at the same measurement angle in Table 1 h Values, Table 8 D at the same angle hThe presence of some abnormal values ​​is likely due to bubbles, dust, or impurities in the polymer, indicating that unfiltered polymer solutions can cause significant errors and impacts on the experiment. Therefore, to ensure accurate and reliable measurement results, both dynamic and static light scattering experiments require filtration of the experimental samples.

[0183] The embodiments described above are merely illustrative of implementation methods of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent disclosure. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent disclosure should be determined by the appended claims.

Claims

1. A rapid evaluation method for polymer injection performance based on molecular linearity, characterized in that, include: Under the same mineralization conditions, the molecular gyration radius R of polymer solutions with similar molecular weights and concentrations at 0° was measured. g0 and hydrodynamic radius R h0 , with R g0 / R h0 The ratio quantitatively characterizes the linearity of polymer molecular chains; based on R... g0 / R h0 The higher the ratio, the higher the linearity of the polymer molecular chain, and the better the polymer injection performance. This rule is used to evaluate the injection performance of various polymers.

2. The rapid evaluation method for polymer injection performance according to claim 1, characterized in that: The term "similar molecular weights" refers to polymers with a molecular weight difference between 0 and 1.0 × 10⁻⁶. 6 g / mol.

3. The rapid evaluation method for polymer injection performance according to claim 1 or 2, characterized in that: The molecular gyration radius R of the polymer molecular chain at 0° was obtained by static light scattering experiments. g0 .

4. The rapid evaluation method for polymer injection performance according to claim 3, characterized in that: The hydrodynamic radius R of the polymer molecular chain at 0 angle was obtained through dynamic light scattering experiments. h0 .

5. The rapid evaluation method for polymer injection performance according to claim 4, characterized in that: The hydrodynamic radius R of the polymer molecular chain at 0 angle h0 The hydrodynamic radius R of polymer molecules under different measurement angles θ h sin 2 (θ / 2) is plotted as a scatter plot and then subjected to linear trend regression.

6. The rapid evaluation method for polymer injection performance according to claim 4 or 5, characterized in that: During dynamic and static light scattering experiments, the experimental samples were filtered using a needle filter with a pore size ranging from 0.2 to 5.0 μm.

7. The rapid evaluation method for polymer injection performance according to claim 6, characterized in that: The polymer solution concentration is 50–200 mg / L.

8. The rapid evaluation method for polymer injection performance according to claim 7, characterized in that: The mineralization range is 15,000 to 40,000 mg / L.

9. The rapid evaluation method for polymer injection performance according to claim 3, characterized in that, The molecular gyration radius R of the polymer molecular chain at 0 angle is obtained by static light scattering experiment. g0 The methods include: (1) A wide-angle laser light scattering instrument was used. The static light scattering Zimm Plot Software was selected. The measurement angle θ range was set to 20 to 80 degrees, increasing by 5 degrees. The light intensity was set to 50%, the light flux to 400, and the dark current was measured multiple times and the average value was taken. (2) Filter about 8 ml of solvent into a clean scintillation bottle using a syringe filter with a pore size of 0.8 μm, and record the mass of the scintillation bottle and the solvent. (3) Set the filter wheel to a wavelength of 532nm, run the measurement process, and measure the intensity of the scattered light from the background solvent; (4) Close the filter wheel, remove the scintillation bottle containing the solvent, wipe the decahydronaphthalene off the bottle wall with filter paper, and weigh the scintillation bottle as the reference mass for the next sample addition. (5) A certain amount of polymer solution is filtered into the scintillation bottle using a needle filter with a pore size of 2 to 5 μm and dispersed evenly. The concentration of polymer in the scintillation bottle is calculated based on the initial concentration of the polymer solution and the mass added. (6) Set the filter wheel to a wavelength of 532nm, run the measurement process, and measure the intensity of scattered light from the polymer solution at this concentration point; after the measurement is completed, turn off the filter wheel; (7) Repeat steps (4) to (6) to measure at least 5 concentration points, and control the polymer concentration to increase by a certain value when adding polymer solution; (8) After the measurement is completed, run the Calculate procedure to obtain the static light scattering Zimm plot. The calculation program will then use K... c / ΔR g sin 2 Plot (θ / 2)+qc and extrapolate to θ→0 and c→0 to obtain the molecular weight of the measured polymer solution, the second virial coefficient, and R at zero angle. g0 Among them, K c λ is a constant that depends on the polymer-solvent system, temperature, and wavelength λ of the incident light; q is an arbitrary constant with a value of 100,000, which is used to make the graph unfold into a clear grid; θ is the measurement angle; and c is the measurement concentration.

10. The rapid evaluation method for polymer injection performance according to claim 4, characterized in that, The hydrodynamic radius R of the polymer molecular chain at 0 angle was obtained through dynamic light scattering experiments. h0 The methods include: (1) Use a wide-angle laser light scattering instrument, turn the filter wheel off, adjust the light intensity to 100%, and the light flux to 200; (2) Select Dynamic Light Scattering, input sample and instrument parameters, select Measured Baseline for the baseline, and check use dust filter; create new Count Rate History, Correlation Function, Non-Negatively Constrained Least squares: Regularized (Contin) interfaces in sequence; (3) The measurement angle is set to 5 angles: 20°, 35°, 50°, 65°, and 80°. (4) Filter 1 / 3 to 2 / 3 of the volume of the polymer solution into a clean scintillation bottle using a needle filter with a pore size of 2 to 5 μm, and place the scintillation bottle in the measuring tank; (5) Set the filter wheel to 532nm wavelength and begin measurement until the end of the process. Take the average value of multiple measurements and determine the hydrodynamic radius R of the polymer solution at different angles. h； (6) R h sin 2 Plot a scatter plot of (θ / 2) and perform a linear trend regression on the scatter plot. The intersection of this trend line with the vertical axis is the hydrodynamic radius R of the polymer solution at zero angle. h0 .

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