A method for determining polymer injection time considering polymer injection water cut of oil well

Abstract

The application relates to the technical field of oil well polymer injection, and discloses a polymer injection timing determination method considering water content of oil well polymer injection, which comprises the following steps: collecting the water content of the oil well, counting the cumulative production time of the oil well from the collection moment; marking a target collection moment, determining the instantaneous trend value and fluctuation stability of the target collection moment; collecting different rock samples of the oil well, and obtaining the formation heterogeneity of the oil well; calculating the polymer injection timing judgment index of the collection moment according to the instantaneous trend value and the fluctuation stability of the collection moment and the formation heterogeneity of the oil well; calculating the adaptive threshold value of the collection moment according to the formation heterogeneity of the oil well and the cumulative production time of the oil well from the collection moment, and determining the polymer injection timing according to the polymer injection timing judgment index and the adaptive threshold value of the collection moment. The application can determine an accurate polymer injection timing.

Description

Technical Field

[0001] This application relates to the field of polymer injection technology in oil wells, and specifically to a method for determining the timing of polymer injection considering the water cut of the oil well. Background Technology

[0002] Polymer injection in oil wells is an enhanced oil recovery (EOR) process primarily used in the secondary or tertiary stages of oilfield recovery. It improves the oil-water mobility ratio by injecting a polymer solution into the formation, expanding the water drive sweep volume, increasing oil displacement efficiency, and ultimately boosting oil recovery. Injecting polymer too early may result in ineffective water channel blocking, leading to wasted resources and the potential for inducing new high-conductivity channels. Injecting too late, however, causes a significant increase in water cut and severe oil-water interface imbalance, making it difficult for the polymer to distribute effectively in key locations and drastically reducing oil displacement. Therefore, precise timing of polymer injection allows it to function optimally when water channeling is evident but not yet out of control, maximizing production gains while minimizing resource waste.

[0003] Generally, the numerical relationship between the moisture content and a preset threshold is used as the basis for judging the timing of polymer injection. However, the moisture content is constantly changing and unstable. The actual heterogeneity of the formation will also affect the timing of polymer injection. Therefore, the timing of polymer injection determined solely by the moisture content is often out of touch with actual production and formation conditions, affecting the utilization efficiency and production increase of polymer. Summary of the Invention

[0004] This application provides a method for determining the timing of polymer injection considering the water cut of the oil well, in order to solve the problem of mismatch between the determination of the timing of polymer injection and actual production and formation conditions. The specific technical solution adopted is as follows:

[0005] One embodiment of this application provides a method for determining the timing of polymer injection considering the water cut of the oil well, the method comprising the following steps:

[0006] Collect the water cut of the oil well at different collection times and calculate the cumulative production time of the oil well from the start of operation to the collection time;

[0007] Any collection time is recorded as the target collection time. Based on the difference in moisture content between the target collection time and all collection times within a first preset time before the target collection time, and the instantaneous rate of change of moisture content at the target collection time, the instantaneous trend value of the target collection time is determined. Based on the degree to which the instantaneous trend value of the target collection time and all collection times within a first preset time before the target collection time deviates from the average instantaneous trend value, the fluctuation stability of the target collection time is determined.

[0008] Collect different rock samples from the oil well and obtain the formation heterogeneity of the oil well based on all rock samples;

[0009] Based on the instantaneous trend value and fluctuation stability at the time of collection, as well as the formation heterogeneity of the oil well, the polymer injection timing judgment index at the time of collection is calculated.

[0010] Based on the formation heterogeneity of the oil well and the cumulative production time from the start of operation to the collection time, an adaptive threshold for the collection time is calculated. The timing of polymer injection is then determined based on the polymer injection timing judgment index and the adaptive threshold at the collection time.

[0011] Furthermore, the cumulative production time from the start of well operation to the collection time is specifically defined as the time interval between the collection time and the start time of well operation.

[0012] Furthermore, the specific method for obtaining the instantaneous trend value at the target acquisition time is as follows:

[0013] The absolute value of the ratio of the difference in moisture content between the target sampling time and the previous sampling time to the difference in time between the target sampling time and the previous sampling time is taken as the instantaneous rate of change of moisture content.

[0014] The range of all moisture contents at the target sampling time and within the first preset time before the target sampling time is recorded as the local moisture content range at the target sampling time.

[0015] The ratio of the instantaneous rate of change of moisture content at the target sampling time to the local moisture content range is recorded as the instantaneous trend value at the target sampling time.

[0016] Furthermore, the specific method for determining the fluctuation stability at the target acquisition time is as follows:

[0017] Based on the target sampling time and all instantaneous moisture content change rates within the first preset time before the target sampling time, determine the local average moisture content change rate at the target sampling time;

[0018] The normalized value of the mean of the absolute values ​​of the differences between the instantaneous moisture content change rate at the target sampling time and the local average moisture content change rate at the target sampling time within the first preset time period prior to the target sampling time is denoted as the fluctuation stability at the target sampling time.

[0019] Furthermore, the method for determining the local average moisture content change rate is as follows:

[0020] The average of all instantaneous moisture content change rates at the target sampling time and within the first preset time before the target sampling time is recorded as the local average moisture content change rate at the target sampling time.

[0021] Furthermore, the method for obtaining the formation heterogeneity of the oil well is as follows:

[0022] The permeability of the rock samples was measured, and the coefficient of variation of the permeability of all rock samples was recorded as the permeability variation coefficient of the oil well.

[0023] The mineral dispersion factor of the rock sample is calculated based on the rock sample, and the mean of the mineral dispersion factor of all rock samples is recorded as the first mean of the oil well.

[0024] The mean of the normalized value of the permeability variation coefficient of the oil well and the normalized value of the first mean is denoted as the formation heterogeneity of the oil well.

[0025] Furthermore, the calculation method for the injection timing determination index at the acquisition time is as follows:

[0026] The negatives of the first and second weighting coefficients and the third weighting coefficient are used as the weights of the instantaneous trend value, the fluctuation stability, and the formation heterogeneity of the oil well at the acquisition time, respectively. The instantaneous trend value, fluctuation stability, and formation heterogeneity are weighted and summed, and the normalized value of the weighted sum is recorded as the polymer injection timing judgment index at the acquisition time.

[0027] Furthermore, the formula for calculating the adaptive threshold at the acquisition time is:

[0028] Calculate the slope coefficient based on the formation heterogeneity of the oil well;

[0029] The formula for calculating the adaptive threshold at the acquisition time is:

[0030]

[0031] in, Indicates the time of data collection Adaptive threshold; This indicates the first preset threshold. This indicates the second preset threshold. Represents an exponential function with the natural constant as its base; Indicates the time of data collection The time interval between the average water exposure time of the block; This represents the slope coefficient.

[0032] Furthermore, the formula for calculating the slope coefficient is:

[0033]

[0034] in, This represents the preset base slope coefficient; Indicates the magnification factor; This indicates the formation heterogeneity of the oil well.

[0035] Furthermore, the specific method for determining the injection timing based on the injection timing determination index and adaptive threshold at the acquisition time includes:

[0036] When the injection timing determination index at the time of data acquisition is greater than or equal to the adaptive threshold, injection is initiated at the time of data acquisition.

[0037] The beneficial effects of this application are:

[0038] This application first quantifies the rate of change in water cut to obtain instantaneous trend values. A larger instantaneous trend value indicates a rapid increase or decrease in the produced water cut due to water channeling, necessitating timely polymer injection. Considering that the instantaneous trend value of water cut may be affected by various factors, leading to instability in the quantification results of the rate of change, the stability of water cut change is quantified to improve the reliability of the quantification, obtaining the fluctuation stability at the time of data collection. Furthermore, considering that formation differences in oil wells directly affect the polymer migration path and plugging effect, different rock samples from the oil well are collected to evaluate the homogeneity of different formations and obtain the formation heterogeneity of the oil well. Further, based on the instantaneous trend value and fluctuation stability at the time of data collection, as well as the formation heterogeneity of the oil well, a polymer injection timing judgment index is calculated at the time of data collection. The polymer injection timing judgment index indicates the necessary level for polymer injection at the corresponding data collection time. The comprehensive evaluation results of the importance of polymer injection are as follows: Considering the different formation conditions and working states of the oil wells, an adaptive threshold for the collection time is calculated based on the formation heterogeneity and the cumulative production time from the start of operation to the collection time. The slope coefficient determined by the formation heterogeneity allows for a smaller adaptive threshold for oil wells with stronger heterogeneity, enabling the adaptive threshold to distinguish between different oil wells and improving the accuracy of polymer injection timing selection. Finally, the polymer injection timing is determined based on the polymer injection timing judgment index at the collection time and the adaptive threshold, avoiding premature polymer injection caused by dynamic changes in water cut and local fluctuations, thereby avoiding excessive polymer consumption. At the same time, the polymer injection timing is matched with the formation heterogeneity differences of the oil wells, improving the accuracy of polymer injection timing selection, solving the problem of mismatch between the determination of polymer injection timing and actual production and formation conditions, and improving the oil recovery rate achieved by the polymer injection process. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A schematic flowchart illustrating a method for determining the timing of polymer injection considering the water cut of polymer injection in an oil well, provided in one embodiment of this application;

[0041] Figure 2 This is a flowchart illustrating the instantaneous trend value acquisition process provided in one embodiment of this application. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] Please see Figure 1 The diagram illustrates a flowchart of a method for determining the timing of polymer injection considering the water cut of a well, according to an embodiment of this application. The method includes the following steps:

[0044] Step S001: Collect the water cut of the oil well at different collection times and calculate the cumulative production time of the oil well from the start of operation to the collection time.

[0045] A radio frequency resonance water content meter is installed on the outlet pipeline of the three-phase separator in the oil well, and the water content is collected in real time using the radio frequency resonance water content meter.

[0046] Preferably, in one embodiment of this application, the moisture content is collected every 10 seconds. In practical applications, as other implementation methods, the implementer can decide the sampling frequency according to the actual situation, and this application does not impose any special restrictions.

[0047] Preprocessing of the moisture content data is performed to suppress the influence of noise. Specifically, median filtering is used to suppress impulse noise, high-pass filtering is used to separate trend and dynamic signals to obtain high-frequency signals from the moisture content data, and cubic spline interpolation is used to resample the missing data. The preprocessing of moisture content is a well-known technique and will not be elaborated further.

[0048] Thus, the moisture content at different sampling times was obtained.

[0049] Step S002: Record any collection time as the target collection time. Based on the difference in moisture content between the target collection time and all collection times within a first preset time before the target collection time, and the trend of moisture content change at the target collection time, determine the instantaneous trend value of the target collection time. Based on the degree to which the instantaneous trend value of the target collection time and all collection times within a first preset time before the target collection time deviates from the average instantaneous trend value, determine the fluctuation stability of the target collection time.

[0050] Water cut is constantly changing due to its rising trend and short-term fluctuations. Therefore, it's necessary to determine the state and timing of polymer injection in oil wells based on the water cut trend. When water cut rises rapidly, water channeling may be forming, such as water channeling in high-permeability layers, which gradually becomes dominant. This is the critical period for polymer injection to shut off water, requiring timely intervention. When water cut rises slowly, it may be in a stable production phase with a relatively balanced oil-water distribution. In this case, injecting polymer too early would only waste polymer, and it's necessary to wait for the right time. Therefore, it's necessary to quantify the rate of water cut change to determine a more accurate timing for polymer injection.

[0051] Record any sampling time as the target sampling time. Based on the differences in moisture content at the target sampling time and within the first preset time before the target sampling time, as well as the trend of moisture content change at the target sampling time, determine the instantaneous trend value of the target sampling time.

[0052] The absolute value of the ratio of the difference in moisture content between the target sampling time and the previous sampling time to the time difference between the target sampling time and the previous sampling time is taken as the instantaneous moisture content change rate; the range of all moisture contents within the first preset time period before the target sampling time is recorded as the local moisture content range at the target sampling time; the ratio of the instantaneous moisture content change rate at the target sampling time to the local moisture content range is recorded as the instantaneous trend value at the target sampling time. In this embodiment, the first preset time period is set to 5 minutes.

[0053] The instantaneous trend value is used to quantify the rate of change in water cut. The faster the rate of change in water cut, the larger the instantaneous trend value. In this case, water channeling causes a rapid increase or decrease in the produced water cut, and polymer injection should be carried out more promptly. Furthermore, the instantaneous trend value is determined based on the range, which can eliminate the problem of large differences in water cut between different oil wells, resulting in large differences in the quantification results of the rate of change in water cut.

[0054] The same method can be used to obtain the instantaneous trend value at any given time point. The flowchart for obtaining the instantaneous trend value is as follows: Figure 2 As shown.

[0055] Various operations within the wellbore, such as starting and stopping the pump, adjusting its displacement, and switching between gas-liquid two-phase flow states, can cause fluctuations in water cut. Simultaneously, blockages caused by clay expansion and particle migration in the pores, or changes in the aggregation state of the previously injected fluid, can disrupt pressure balance and lead to abrupt changes in water cut. Therefore, the instantaneous trend value of water cut may be affected by numerous factors, resulting in unstable quantification of the rate of water cut change. Further efforts are needed to improve the reliability of quantifying water cut changes.

[0056] The mean of all instantaneous moisture content change rates at the target sampling time and within the first preset time before the target sampling time is denoted as the local average moisture content change rate at the target sampling time; the normalized value of the mean of the absolute values ​​of the differences between the instantaneous moisture content change rates at all sampling times at the target sampling time and within the first preset time before the target sampling time and the local average moisture content change rate at the target sampling time is denoted as the fluctuation stability at the target sampling time.

[0057] It should be noted that this embodiment uses the Z-Score standard normalization method to calculate the normalized value. In practical applications, implementers may use other methods of existing technology, such as the maximum-minimum normalization method or the sigmoid function, to calculate the normalized value, and no limitation is made here.

[0058] In the process of obtaining fluctuation stability, the local average moisture content change rate is used as the benchmark value. The absolute deviation is used to measure the degree to which all moisture contents deviate from the benchmark value within the first preset time before the target collection time. That is, fluctuation stability is used to quantify the stability of moisture content change. The greater the fluctuation stability, the more stable the moisture content change, and the more reliable the probability evaluation of the injection timing determined based on the instantaneous trend value.

[0059] The fluctuation stability at any given time point can be obtained using the same method.

[0060] At this point, the instantaneous trend value and fluctuation stability at each data collection moment are obtained.

[0061] Step S003: Collect different rock samples from the oil well and obtain the formation heterogeneity of the oil well based on all rock samples.

[0062] Formation heterogeneity refers to the uneven distribution of permeability across different spatial locations in various oil wells, which directly affects the migration path and plugging effect of polymers. Formations with strong heterogeneity are more prone to forming high-permeability channels, posing a higher risk of water channeling and requiring earlier polymer injection. Conversely, homogeneous formations require later polymer injection to avoid resource waste. Therefore, it is necessary to evaluate the degree of formation variation in oil wells to further improve the accuracy of determining the timing of polymer injection.

[0063] Rock samples were drilled from different formations in the oil well, and the permeability of the rock samples was measured using a gas permeability meter. The coefficient of variation of the permeability of all rock samples was calculated and recorded as the permeability coefficient of variation of the oil well. The mineral dispersion factor of the rock samples was obtained based on the rock samples, and the mean of the mineral dispersion factor of all rock samples was recorded as the first mean of the oil well. The mean of the normalized value of the permeability coefficient of variation of the oil well and the normalized value of the first mean was recorded as the formation heterogeneity of the oil well.

[0064] Among them, formation heterogeneity is used to evaluate the homogeneity of different formations in oil wells; the calculation of the coefficient of variation and the mineral dispersion factor are well-known techniques and will not be elaborated further.

[0065] It should be noted that this embodiment uses the Z-Score standard normalization method to calculate the normalized value. In practical applications, implementers may use other methods of existing technology, such as the maximum-minimum normalization method or the sigmoid function, to calculate the normalized value, and no limitation is made here.

[0066] At this point, the formation heterogeneity of the oil well is obtained.

[0067] Step S004: Calculate the polymer injection timing judgment index at the time of collection based on the instantaneous trend value and fluctuation stability at the time of collection, as well as the formation heterogeneity of the oil well.

[0068] Based on the instantaneous trend value and fluctuation stability at the time of data collection, as well as the formation heterogeneity of the oil well, the polymer injection timing judgment index at the time of data collection is calculated.

[0069] The inverses of the first and second weighting coefficients and the third weighting coefficient are used as the weights of the instantaneous trend value, the fluctuation stability, and the formation heterogeneity of the oil well at the acquisition time, respectively. The instantaneous trend value, fluctuation stability, and formation heterogeneity are weighted and summed, and the normalized value of the weighted sum is recorded as the polymer injection timing judgment index at the acquisition time.

[0070] The greater the instantaneous trend value and formation heterogeneity, and the smaller the fluctuation stability, the more necessary it is to perform polymer injection at the corresponding acquisition time, and the greater the polymer injection timing judgment index at the acquisition time.

[0071] In this embodiment, the sum of the first, second, and third weighting coefficients is 1. The values ​​of the first, second, and third weighting coefficients are 0.4, 0.2, and 0.4, respectively. Specifically, the values ​​of the first, second, and third weighting coefficients are determined using the response surface methodology. The response surface methodology is an experimental design method that optimizes parameter combinations to achieve the best response value. Using the response surface methodology to determine the values ​​of the first, second, and third weighting coefficients is a well-known technique and will not be elaborated further.

[0072] Thus, the injection timing determination index at the time of collection is obtained.

[0073] Step S005: Calculate the adaptive threshold for the collection time based on the formation heterogeneity of the oil well and the cumulative production time from the start of the oil well operation to the collection time. Determine the polymer injection timing based on the polymer injection timing judgment index and the adaptive threshold at the collection time.

[0074] Furthermore, considering the different formation conditions and working states of the oil wells, the adaptive judgment threshold corresponding to the polymer injection timing judgment index of the oil well at each collection time is determined.

[0075] Based on the formation heterogeneity of the oil well and the cumulative production time from well operation to the acquisition time, the adaptive threshold for the acquisition time is calculated. The formula for calculating the adaptive threshold for the acquisition time is:

[0076]

[0077]

[0078] in, Indicates the time of data collection Adaptive threshold; This represents the first preset threshold, which is the minimum value that can be taken within the range of the adaptive threshold. The value of the first preset threshold should be greater than or equal to 0.1 and less than or equal to 0.3. The first preset threshold is determined through a small-scale injection experiment. In this embodiment, the value of the first preset threshold is 0.3. This represents the second preset threshold, which is the maximum value that can be taken within the range of the adaptive threshold. The second preset threshold should be greater than the first preset threshold. The value of the second preset threshold should be greater than or equal to 0.7 and less than or equal to 0.9. The second preset threshold is determined through a small-scale injection experiment. In this embodiment, the value of the second preset threshold is 0.9. Represents an exponential function with the natural constant as its base; Indicates the time of data collection The time interval between the average water exposure time of the block; This represents the slope coefficient, which is used to control the degree of change in the adaptive threshold. This represents the preset basic slope coefficient. The value of the basic slope coefficient should be greater than or equal to 0.005 and less than or equal to 0.02. In this embodiment, the value of the basic slope coefficient is 0.01. This represents the amplification factor, which is determined by Bayesian optimization of the pilot well group. This indicates the formation heterogeneity of the oil well.

[0079] The selection of parameters for Bayesian optimization calibration of the pilot well group is a well-known technique and will not be elaborated further. Specifically, when using Bayesian optimization calibration of the pilot well group to determine the amplification factor, a Gaussian process surrogate model is established with the increase in oil production per ton of polymer as the objective function. The kernel function is set to Matern3 / 2, the prior mean is set to 0, and the acquisition function is EI. Three to five different polymer injection tests are conducted on-site for each oil well to obtain the optimal value of the amplification factor.

[0080] The average time to water breakthrough in a block refers to the average time from the start of production to the arrival of groundwater at the bottom of the well during the oilfield development process. Water breakthrough occurs when a well starts production and the groundwater reaches the bottom of the well.

[0081] In the early stages of oil well production, when the water cone has just formed, the water phase saturation is low, and the flow channels are not yet fully developed, polymers are more likely to form effective plugs at the water phase front. There is no need to counteract the dominant seepage of the water phase under high water cut. A smaller first preset threshold can trigger polymer injection, achieving efficient water shut-off with a lower dosage. However, in the later stages of oil well production, the water cut is extremely high, the water phase has occupied the main seepage channels, the oil-water interface is disordered, and the polymer is easily washed away and diluted by the high water cut, resulting in a significant decrease in oil displacement efficiency. A larger second preset threshold can avoid ineffective polymer injection. The essence of the first and second preset thresholds is to dynamically adjust the value of the adaptive threshold to match polymer injection at different stages.

[0082] The slope coefficient determined by the formation heterogeneity can make the adaptive threshold of oil wells with stronger heterogeneity smaller, so that the adaptive threshold can distinguish different oil wells and improve the accuracy of polymer injection timing selection.

[0083] When the injection timing determination index at the acquisition time is greater than or equal to the adaptive threshold, the acquisition time has reached the injection timing, and injection is started at the acquisition time; when the injection timing determination index at the acquisition time is less than the adaptive threshold, the injection timing has not reached, and injection is not started.

[0084] Determining the timing of polymer injection based on the injection timing index and adaptive threshold at the time of data collection can avoid premature polymer injection caused by dynamic changes in water cut and local fluctuations, thereby preventing excessive consumption of polymer. At the same time, matching the formation heterogeneity differences of the oil well when determining the injection timing improves the accuracy of polymer injection timing selection.

[0085] This allows for the precise determination of the timing for polymer injection in oil wells.

[0086] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the polymer injection timing considering the polymer injection water cut of an oil well, characterized in that, The method includes the following steps: Collect the water cut of the oil well at different collection times and calculate the cumulative production time of the oil well from the start of operation to the collection time; Any collection time is recorded as the target collection time. Based on the difference in moisture content between the target collection time and all collection times within a first preset time before the target collection time, and the instantaneous rate of change of moisture content at the target collection time, the instantaneous trend value of the target collection time is determined. Based on the degree to which the instantaneous trend value of the target collection time and all collection times within a first preset time before the target collection time deviates from the average instantaneous trend value, the fluctuation stability of the target collection time is determined. Collect different rock samples from the oil well and obtain the formation heterogeneity of the oil well based on all rock samples; Based on the instantaneous trend value and fluctuation stability at the time of collection, as well as the formation heterogeneity of the oil well, the polymer injection timing judgment index at the time of collection is calculated. Based on the formation heterogeneity of the oil well and the cumulative production time from the start of operation to the collection time, the adaptive threshold for the collection time is calculated, and the polymer injection timing is determined based on the polymer injection timing judgment index and the adaptive threshold at the collection time. The specific method for obtaining the instantaneous trend value at the target acquisition time is as follows: Based on the moisture content at the target sampling time and within the first preset time before the target sampling time, calculate the derivative of the moisture content at the target sampling time with respect to the sampling time, and record the absolute value of the derivative as the instantaneous rate of change of moisture content at the target sampling time. The range of all moisture contents at the target sampling time and within the first preset time before the target sampling time is recorded as the local moisture content range at the target sampling time. The ratio of the instantaneous rate of change of moisture content at the target sampling time to the local moisture content range is recorded as the instantaneous trend value at the target sampling time. The calculation method for the injection timing determination index at the acquisition time is as follows: The negatives of the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient are used as the weights of the instantaneous trend value, the fluctuation stability, and the formation heterogeneity of the oil well at the acquisition time, respectively. The instantaneous trend value, fluctuation stability, and formation heterogeneity are weighted and summed, and the normalized value of the weighted sum is recorded as the polymer injection timing judgment index at the acquisition time. The formula for calculating the adaptive threshold at the acquisition time is: Calculate the slope coefficient based on the formation heterogeneity of the oil well; The formula for calculating the adaptive threshold at the acquisition time is: in, Indicates the time of data collection Adaptive threshold; This indicates the first preset threshold. This indicates the second preset threshold. Represents an exponential function with the natural constant as its base; Indicates the time of data collection The time interval between the average water exposure time of the block; Indicates the slope coefficient; The formula for calculating the slope coefficient is: in, This represents the preset base slope coefficient; Indicates the magnification factor; Indicates the formation heterogeneity of the oil well; The specific method for determining the injection timing based on the injection timing determination index and adaptive threshold at the acquisition time includes: When the injection timing determination index at the time of data acquisition is greater than or equal to the adaptive threshold, injection is initiated at the time of data acquisition.

2. The method for determining the timing of polymer injection considering the water cut of oil wells according to claim 1, characterized in that, The cumulative production time from the start of well operation to the collection time is specifically defined as the time interval between the collection time and the start time of well operation.

3. The method for determining the timing of polymer injection considering the water cut of oil wells according to claim 1, characterized in that, The specific method for determining the fluctuation stability at the target acquisition time is as follows: Based on the target sampling time and all instantaneous moisture content change rates within the first preset time before the target sampling time, determine the local average moisture content change rate at the target sampling time. The normalized value of the mean of the absolute values ​​of the differences between the instantaneous moisture content change rate at the target sampling time and the local average moisture content change rate at the target sampling time within the first preset time period prior to the target sampling time is denoted as the fluctuation stability at the target sampling time.

4. The method for determining the timing of polymer injection considering the water cut of the oil well, as described in claim 3, is characterized in that... The method for determining the rate of change of the local average moisture content is as follows: The average of all instantaneous moisture content change rates at the target sampling time and within the first preset time before the target sampling time is recorded as the local average moisture content change rate at the target sampling time.

5. The method for determining the timing of polymer injection considering the water cut of oil wells according to claim 1, characterized in that, The method for obtaining the formation heterogeneity of the oil well is as follows: The permeability of the rock samples was measured, and the coefficient of variation of the permeability of all rock samples was recorded as the permeability variation coefficient of the oil well. The mineral dispersion factor of the rock sample is calculated based on the rock sample, and the mean of the mineral dispersion factor of all rock samples is recorded as the first mean of the oil well. The mean of the normalized value of the permeability variation coefficient of the oil well and the normalized value of the first mean is denoted as the formation heterogeneity of the oil well.

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