Fracturing crack identification and prediction system and method based on tracer agent

Abstract

The invention discloses a tracer-based fracturing crack identification and prediction system and method, and particularly relates to the technical field of environmental safety prediction. Comprising a tracer injection module, a tracer injection optimization module, a tracer crack flow path acquisition module, a fracturing crack propagation stability analysis module, a fracturing crack propagation anomaly evaluation module and a fracturing crack anomaly prediction response module. The method comprises the following steps: calculating a fracturing operation safety control index, scientifically adjusting a tracer injection strategy through calculation and combination of real-time data and an early-warning mechanism, realizing balance between safety and operation efficiency, monitoring data through a flow path, calculating a crack propagation stability early-warning index, early-warning the stability of a crack propagation behavior, and realizing early-warning of the stability of the crack propagation behavior on the basis of an entropy sudden increase theory. And calculating a crack propagation anomaly prediction coefficient, quantifying a risk value of crack propagation, and realizing accurate crack anomaly early warning and response of fracturing operation.

Description

Technical Field

[0001] The present invention relates to the technical field of fracture safety prediction, and more specifically, to a tracer-based fracturing fracture identification and prediction system and method. Background Art

[0002] Tracer technology is a key tool for identifying and monitoring fracturing fractures. According to its physical and chemical properties, tracers can be divided into radioactive tracers, chemical tracers, and nano tracers, etc. Selecting stable tracers under specific geological conditions can further improve the accuracy of fracture monitoring. By injecting specific tracers during the fracturing process, these tracers can provide dynamic information of the fractures as they flow in the rock fractures with the fracturing fluid, which can help engineers track the formation and propagation paths of the fractures. In the oil and gas extraction field, by integrating advanced tracer technology and fracture identification technology, the formation and propagation of fractures can be accurately identified and predicted, thereby guiding the fracturing operation and improving the safety of the operation.

[0003] Shale gas is an unconventional natural gas resource, usually stored in low-permeability shale formations. In order to extract shale gas economically and efficiently, hydraulic fracturing technology is usually required to create artificial fractures, thereby improving the fluidity and recovery rate of natural gas.

[0004] However, in its actual use, there are still some drawbacks. For example, in the existing fracturing fracture identification and prediction methods, the fusion processing of tracer data and fracture flow path data is insufficient, and there is a lack of a unified data model, making it difficult to comprehensively reflect the stability of fracture propagation.

[0005] In the existing fracturing fracture identification and prediction methods, fracture propagation parameters are mostly analyzed separately, lacking a coupled effect model, unable to accurately evaluate, and unable to warn of the out-of-control risk of fractures, resulting in insufficient control of the safety risk of fracture operations. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a tracer-based fracturing fracture identification and prediction system and method for solving the problems raised in the above background art.

[0007] To achieve the above object, the present invention provides the following technical solution: A tracer-based fracturing fracture identification and prediction system, comprising:

[0008] A tracer injection module: for injecting a tracer into the fracturing fluid, injecting the fracturing fluid from the wellbore through the target formation, and collecting fracturing operation data when the fracturing fluid is injected.

[0009] A tracer injection optimization module: for calculating a fracturing operation safety control index when the fracturing fluid is injected according to the fracturing operation data when the fracturing fluid is injected, and optimizing the tracer injection strategy.

[0010] Tracer fracture flow path acquisition module: It is used to obtain the flow path monitoring data of the fracturing fluid injected from the wellbore into the target formation every t time periods. The flow path monitoring data includes a fracture coordinate data acquisition unit and a fracture propagation data acquisition unit.

[0011] Fracture propagation stability analysis module: According to the fracture coordinate data collected by the fracture coordinate data acquisition unit, calculate the fracture propagation stability warning index when the fracturing fluid is injected from the wellbore into the target formation, and conduct a warning on the fracture propagation stability.

[0012] Fracture propagation anomaly evaluation module: According to the fracture propagation data collected by the fracture propagation data acquisition unit, based on the entropy sudden increase theory, calculate the fracture propagation anomaly prediction coefficient of the fracturing fluid injected from the wellbore into the target formation for each time period.

[0013] Fracture propagation anomaly prediction response module: It is used to obtain the fracture propagation anomaly prediction coefficient of the fracturing fluid injected from the wellbore into the target formation for each time period, compare it with the preset fracture propagation anomaly prediction coefficient, and process it.

[0014] Preferably, the tracer has environmental friendliness, high stability and detectability, and can be evenly distributed during the fracturing process and enter the fracture with the fracturing fluid;

[0015] The fracturing operation data includes the initial concentration of the tracer, the injection rate of the fracturing fluid, and the formation pressure.

[0016] Preferably, the tracer injection optimization module is specifically:

[0017] S31: The calculation formula of the fracturing operation safety control index is:

[0018]

[0019] Among them, ω represents the fracturing operation safety control index, qh represents the initial concentration of the tracer, QH 预 represents the preset initial concentration of the tracer, qv represents the injection rate of the fracturing fluid, QV 预 represents the preset injection rate of the fracturing fluid, qp represents the formation pressure, QP 预 represents the preset formation pressure;

[0020] S32: Obtain the fracturing operation safety control index during the injection of fracturing fluid, and compare it with the early warning range of the fracturing operation safety control index. If the fracturing operation safety control index is greater than or equal to the maximum value of the early warning range of the fracturing operation safety control index, it indicates that the operation safety assessment during the injection of this fracturing fluid is within the safe range, and continued construction is allowed. If the fracturing operation safety control index is less than the maximum value of the early warning range of the fracturing operation safety control index and greater than or equal to the minimum value of the early warning range of the fracturing operation safety control index, it indicates that the operation parameters during the injection of this fracturing fluid need to be adjusted, and the operation safety assessment is within the early warning range. If the fracturing operation safety control index is less than the minimum value of the early warning range of the fracturing operation safety control index, it indicates that the operation safety assessment during the injection of this fracturing fluid is within the dangerous range, and the operation should be stopped immediately;

[0021] S33: When the fracturing operation safety control index is less than the maximum value of the early warning range of the fracturing operation safety control index and greater than or equal to the minimum value of the early warning range of the fracturing operation safety control index, the fracturing operation data adjustment strategy is to optimize 50% QH during the injection of fracturing fluid 预 <qh≤70%QH 预 and optimize qv≤80%QV during the injection of fracturing fluid 预 and monitor qp<70%QP during the injection of fracturing fluid 预 and the fracturing operation data adjustment priority is formation pressure > fracturing fluid injection rate > initial tracer concentration.

[0022] Preferably, the tracer fracture flow path acquisition module is specifically:

[0023] Fracture coordinate data acquisition unit: Every t time periods, acquire the fracture positions (x i , y i ) where the fracturing fluid is injected from the wellbore into the target formation, where i = 1, 2,... n, and i represents the serial number of the i-th sub-time period;

[0024] Fracture propagation data acquisition unit: Every t time periods, acquire the fracture propagation direction, fracture propagation length, and fracture propagation width of the fracture where the fracturing fluid is injected from the wellbore into the target formation, and mark them as σ i 、kh i 、km i .

[0025] Preferably, the fracturing fracture propagation stability analysis module is specifically:

[0026] S51: Calculate the fracture propagation spatial displacement for each time period through the fracture positions:

[0027]

[0028] Where, D iThe crack propagation spatial displacement in the $i$-th sub-period, $x$ i The $x$-axis coordinate of the crack in the $i$-th sub-period, $y$ i The $y$-axis coordinate of the crack in the $i$-th sub-period, $x$ i+1 The $x$-axis coordinate of the crack in the $(i + 1)$-th sub-period, $y$ i+1 The $y$-axis coordinate of the crack in the $(i + 1)$-th sub-period;

[0029] S52: The calculation formula for the crack propagation stability warning index is:

[0030]

[0031] where $\alpha$ represents the crack propagation stability warning index, and $n$ represents the number of sub-periods;

[0032] S53: Set a preset crack propagation stability warning index, and the formula is:

[0033]

[0034] where $\alpha$ 预 represents the preset crack propagation stability warning index, $D$ max represents the maximum value of the crack propagation spatial displacement, $D$ min represents the minimum value of the crack propagation spatial displacement;

[0035] S54: Obtain the crack propagation stability warning index when injecting fracturing fluid from the wellbore into the target formation, and compare it with the preset crack propagation stability warning index. If the crack propagation stability warning index is greater than the preset crack propagation stability warning index, it indicates that there is an abnormality in the fracturing crack propagation behavior during the injection of fracturing fluid, and immediately issue an abnormal warning for the fracturing crack propagation stability. Otherwise, it indicates that the fracturing crack propagation behavior during the injection of fracturing fluid is safe.

[0036] Preferably, the calculation formula for the crack propagation abnormality prediction coefficient is:

[0037] $\beta$ i $= KS$ i $\times JS$ i $+ max(0, MC$ i $- MH$ warn )

[0038] where $\beta$ i represents the crack propagation abnormality prediction coefficient in the $i$-th sub-period, $KS$ i represents the crack entropy change rate in the $i$-th sub-period, $JS$ i represents the crack entropy change acceleration in the $i$-th sub-period, $MC$ iDenoted as the crack propagation abnormal risk intensity of the $i$-th sub-period, MH warn Denoted as the warning threshold of the crack propagation abnormal risk intensity.

[0039] Preferably, the crack propagation abnormal prediction coefficient is specifically:

[0040] S71: Normalize the crack propagation direction, crack propagation length, and crack propagation width to obtain:

[0041]

[0042] Wherein, Denoted as the normalized value of the crack propagation direction of the $i$-th sub-period, Denoted as the normalized value of the crack propagation length of the $i$-th sub-period, Denoted as the normalized value of the crack propagation width of the $i$-th sub-period, σ i Denoted as the crack propagation direction of the $i$-th sub-period, σ 预 Denoted as the preset crack propagation direction, σ max Denoted as the maximum value of the crack propagation direction, kh i Denoted as the crack propagation length of the $i$-th sub-period, kh max Denoted as the maximum value of the crack propagation length, km i Denoted as the crack propagation width of the $i$-th sub-period, km max Denoted as the maximum value of the crack propagation width;

[0043] S72: Calculate the crack entropy:

[0044] S i = -∑ σ ∑ kh ∑ km p i $(σ, kh, km) * log_2p$ i $(σ, kh, km)$

[0045] Wherein, S i Denoted as the crack entropy of the $i$-th sub-period, p i $(σ, kh, km)$ denotes the probability distribution of the crack of the $i$-th sub-period in the direction σ, length kh, and width km;

[0046] Calculate the crack entropy change rate:

[0047] Wherein, KS i Denoted as the crack entropy change rate of the $i$-th sub-period, S i-1 Denoted as the crack entropy of the $(i - 1)$-th sub-period, and t denotes the interval duration of each time period;

[0048] Calculate the crack entropy change acceleration:

[0049] Among them, JS i represents the crack entropy change acceleration in the i-th sub-time period, and KS i-1 represents the crack entropy change rate in the (i - 1)-th sub-time period;

[0050] S73: Calculate the crack propagation abnormal risk intensity:

[0051] MC i = JS i × exp(KS i )

[0052] Among them, MC i represents the crack propagation abnormal risk intensity in the i-th sub-time period;

[0053] S74: If MC i ≤ MH warn , then MC i - MH warn ≤ 0. At this time, max(0, negative value), output the result of β i as KS i × JS i + 0. If MC i > MH warn , then MC i - MH warn > 0. At this time, max(0, positive value), output the result of β i as KS i × JS i +(MC i - MH warn ).

[0054] Preferably, the fracturing crack abnormal prediction response module is specifically:

[0055] Obtain the crack propagation abnormal prediction coefficient of the fracturing fluid injected from the wellbore into the target formation in each time period, and compare it with the preset crack propagation abnormal prediction coefficient. If the crack propagation abnormal prediction coefficient of the fracturing fluid injected from the wellbore into the target formation in a certain time period is greater than the preset crack propagation abnormal prediction coefficient, it indicates that the abnormal degree of the fracturing crack in this time period is high. At this time, there are potential safety hazards in the fracturing operation, and an abnormal warning is immediately given and the operation is stopped. Otherwise, it indicates that the fracturing crack propagation in this time period is stable and no intervention is required.

[0056] Preferably, a tracer-based fracturing crack identification and prediction method includes the following steps:

[0057] Step S01: Tracer injection: Used to inject a tracer into the fracturing fluid, inject the fracturing fluid from the wellbore through the target formation, and collect fracturing operation data when the fracturing fluid is injected;

[0058] Step S02: Tracer injection optimization: Used to calculate the fracturing operation safety control index when the fracturing fluid is injected based on the fracturing operation data when the fracturing fluid is injected, and optimize the tracer injection strategy;

[0059] Step S03: Tracer fracture flow path acquisition: Used to obtain the flow path monitoring data of the fracturing fluid injected from the wellbore into the target formation every t time periods. The step S03: Tracer fracture flow path acquisition includes a fracture coordinate data acquisition sub-step and a fracture propagation data acquisition sub-step, and the flow path monitoring data includes fracture coordinate data and fracture propagation data;

[0060] Step S04: Fracture propagation stability analysis of fracturing: Used to receive the flow path monitoring data transmitted by the tracer fracture flow path acquisition step, and calculate the fracture propagation stability warning index when the fracturing fluid is injected from the wellbore into the target formation based on the fracture coordinate data collected by the fracture coordinate data acquisition sub-step, and conduct a warning on the fracture propagation stability of fracturing;

[0061] Step S05: Abnormal evaluation of fracturing fracture propagation: Used to receive the flow path monitoring data transmitted by the tracer fracture flow path acquisition step, and calculate the fracture propagation abnormal prediction coefficient of the fracturing fluid injected from the wellbore into the target formation in each time period based on the fracture propagation data collected by the fracture propagation data acquisition sub-step according to the entropy value sudden increase theory;

[0062] Step S06: Fracture propagation abnormal prediction response of fracturing: Used to obtain the fracture propagation abnormal prediction coefficient of the fracturing fluid injected from the wellbore into the target formation in each time period, compare it with the preset fracture propagation abnormal prediction coefficient, and process it.

[0063] Technical effects and advantages of the present invention:

[0064] 1. The present invention provides a fracturing fracture identification and prediction system and method based on a tracer. By collecting the fracturing operation data when the fracturing fluid is injected, the fracturing operation safety control index when the fracturing fluid is injected is calculated. When the fracturing operation safety control index is less than the maximum value of the fracturing operation safety control index warning interval and greater than or equal to the minimum value of the fracturing operation safety control index warning interval, the fracturing operation data adjustment strategy is to optimize 50% QH when the fracturing fluid is injected 预 <qh≤70%QH 预 and optimize qv≤80%QV when the fracturing fluid is injected 预 and monitor qp<70%QP when the fracturing fluid is injected 预In a fracturing operation, by dynamically calculating a safety control index and combining real-time data with an early warning mechanism, the tracer injection strategy can be scientifically adjusted to achieve a balance between safety and operation efficiency.

[0065] 2. The present invention provides a system and method for identifying and predicting fracturing fractures based on tracers. By obtaining monitoring data on the flow path of fracturing fluid injected from a wellbore into a target formation every t time periods, and calculating a fracture propagation stability early warning index when the fracturing fluid is injected from the wellbore into the target formation according to the fracture coordinate data collected by the fracture coordinate data acquisition unit, and comparing it with a preset fracture propagation stability early warning index. If the fracture propagation stability early warning index is greater than the preset fracture propagation stability early warning index, it indicates that there is an abnormality in the fracture propagation behavior when the fracturing fluid is injected, and an immediate early warning of the fracture propagation stability abnormality is carried out. Otherwise, it indicates that the fracture propagation behavior when the fracturing fluid is injected is safe. By real-time dynamically monitoring the fracture coordinate data, the stability of the fracture propagation behavior is warned, improving the operation safety. According to the fracture propagation data collected by the fracture propagation data acquisition unit, based on the theory of sudden increase in entropy value, a fracture propagation abnormality prediction coefficient for the fracturing fluid injected from the wellbore into the target formation in each time period is calculated, and compared with a preset fracture propagation abnormality prediction coefficient. If the fracture propagation abnormality prediction coefficient for the fracturing fluid injected from the wellbore into the target formation in a certain time period is greater than the preset fracture propagation abnormality prediction coefficient, it indicates that the degree of fracture abnormality in this time period is high, and there is a safety hazard in the fracturing operation at this time. An immediate early warning is carried out and the operation is stopped. Otherwise, it indicates that the fracture propagation in this time period is stable and no intervention is required. Through the coupled calculation of the fracture entropy change rate, fracture entropy change acceleration and fracture propagation abnormality risk intensity, the dynamic changes in the direction, length and width of the fracture propagation are converted into a single abnormality coefficient, combined with an adaptive early warning threshold, to quantify the risk value of the fracture propagation, avoiding one-sided judgment and realizing accurate fracture abnormality early warning and response for the fracturing operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a schematic structural diagram of a system for identifying and predicting fracturing fractures based on tracers according to the present invention.

[0067] Figure 2 It is a schematic structural diagram of a tracer fracture flow path acquisition module according to the present invention.

[0068] Figure 3 It is a schematic flow diagram of a method for identifying and predicting fracturing fractures based on tracers according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0069] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0070] Please refer to Figure 1 As shown, the present invention provides a tracer-based fracturing fracture identification and prediction system, including a tracer injection module, a tracer injection optimization module, a tracer fracture flow path acquisition module, a fracturing fracture propagation stability analysis module, a fracturing fracture propagation anomaly evaluation module, and a fracturing fracture anomaly prediction and response module.

[0071] The tracer injection module is connected to the tracer injection optimization module, the tracer injection optimization module is connected to the tracer fracture flow path acquisition module, the tracer fracture flow path acquisition module is connected to the fracturing fracture propagation stability analysis module and the fracturing fracture propagation anomaly evaluation module, and the fracturing fracture propagation anomaly evaluation module is connected to the fracturing fracture anomaly prediction and response module.

[0072] The tracer injection module: is used to inject the tracer into the fracturing fluid, inject the fracturing fluid from the wellbore through the target formation, and collect the fracturing operation data when the fracturing fluid is injected.

[0073] In a possible design, the tracer has environmental friendliness, high stability, and detectability, and can be evenly distributed during the fracturing process and enter the fracture with the fracturing fluid.

[0074] In a possible design, the fracturing operation data includes the initial concentration of the tracer, the injection rate of the fracturing fluid, and the formation pressure.

[0075] The tracer injection optimization module: is used to calculate the fracturing operation safety control index when the fracturing fluid is injected according to the fracturing operation data when the fracturing fluid is injected, and optimize the tracer injection strategy.

[0076] In a possible design, the tracer injection optimization module is specifically:

[0077] S01: The calculation formula of the fracturing operation safety control index is:

[0078]

[0079] Among them, ω represents the fracturing operation safety control index, qh represents the initial concentration of the tracer, QH 预 represents the preset initial concentration of the tracer, qv represents the injection rate of the fracturing fluid, QV 预is expressed as the preset fracturing fluid injection rate, qp is expressed as the formation pressure, QP 预 is expressed as the preset formation pressure;

[0080] S02: Obtain the fracturing operation safety control index during fracturing fluid injection, and compare it with the early warning range of the fracturing operation safety control index. If the fracturing operation safety control index is greater than or equal to the maximum value of the early warning range of the fracturing operation safety control index, it indicates that the operation safety assessment during this fracturing fluid injection is within the safe range, and continuous construction is allowed. If the fracturing operation safety control index is less than the maximum value of the early warning range of the fracturing operation safety control index and greater than or equal to the minimum value of the early warning range of the fracturing operation safety control index, it indicates that the operation parameters during this fracturing fluid injection need to be adjusted, and the operation safety assessment is within the early warning range. If the fracturing operation safety control index is less than the minimum value of the early warning range of the fracturing operation safety control index, it indicates that the operation safety assessment during this fracturing fluid injection is within the dangerous range, and the operation should be stopped immediately;

[0081] S03: When the fracturing operation safety control index is less than the maximum value of the early warning range of the fracturing operation safety control index and greater than or equal to the minimum value of the early warning range of the fracturing operation safety control index, the fracturing operation data adjustment strategy is to optimize 50% QH during fracturing fluid injection 预 <qh ≤ 70% QH 预 , optimize qv ≤ 80% QV during fracturing fluid injection 预 , monitor qp < 70% QP during fracturing fluid injection 预 , and the priority of fracturing operation data adjustment is formation pressure > fracturing fluid injection rate > initial tracer concentration.

[0082] The present invention provides another embodiment, which is as follows:

[0083] S01: If the initial tracer concentration during a certain fracturing fluid injection is 80 ppm, the preset initial tracer concentration is 100 ppm, and the fracturing fluid injection rate is 12 m 3 / min, and the preset fracturing fluid injection rate is 20 m 3 / min, and the formation pressure is 35 MPa, and the preset formation pressure is 50 MPa;

[0084] S02: Calculate the fracturing operation safety control index as:

[0085]

[0086] S03: Set the early warning range of the fracturing operation safety control index to 0.3 - 0.7. Since ω < 0.3, it indicates that the operation safety assessment during this fracturing fluid injection is within the dangerous range, and the operation should be stopped immediately.

[0087] Please refer to Figure 2As shown, the tracer fracture flow path acquisition module: is used to obtain the flow path monitoring data of the fracturing fluid injected from the wellbore into the target formation every t time periods. The flow path monitoring data includes a fracture coordinate data acquisition unit and a fracture propagation data acquisition unit, and the flow path monitoring data includes fracture coordinate data and fracture propagation data.

[0088] In a possible design, the tracer fracture flow path acquisition module is specifically:

[0089] The fracture coordinate data acquisition unit: acquires the fracture position (x i , y i ) of the fracturing fluid injected from the wellbore into the target formation every t time periods, where i = 1, 2,... n, and i represents the number of the i-th sub-time period;

[0090] The fracture propagation data acquisition unit: acquires the fracture propagation direction, fracture propagation length, and fracture propagation width of the fracturing fluid injected from the wellbore into the target formation every t time periods, and marks them as σ i , kh i , km i .

[0091] The fracturing fracture propagation stability analysis module: is used to receive the flow path monitoring data transmitted by the tracer fracture flow path acquisition module, and calculate the fracture propagation stability warning index when the fracturing fluid is injected from the wellbore into the target formation according to the fracture coordinate data acquired by the fracture coordinate data acquisition unit, and conduct a warning on the fracturing fracture propagation stability.

[0092] In a possible design, the fracturing fracture propagation stability analysis module is specifically:

[0093] S01: Calculate the fracture propagation spatial displacement of each time period through the fracture position:

[0094]

[0095] where D i represents the fracture propagation spatial displacement of the i-th sub-time period, x i represents the x-axis coordinate of the fracture in the i-th sub-time period, y i represents the y-axis coordinate of the fracture in the i-th sub-time period, x i+1 represents the x-axis coordinate of the fracture in the (i + 1)-th sub-time period, and y i+1 represents the y-axis coordinate of the fracture in the (i + 1)-th sub-time period;

[0096] S02: The calculation formula of the fracture propagation stability warning index is:

[0097]

[0098] Among them, α represents the crack propagation stability warning index, and n represents the number of sub-periods;

[0099] S03: Set the preset crack propagation stability warning index, and the formula is:

[0100]

[0101] Among them, α 预 represents the preset crack propagation stability warning index, D max represents the maximum value of the crack propagation spatial displacement, D min represents the minimum value of the crack propagation spatial displacement;

[0102] Obtain the crack propagation stability warning index when injecting fracturing fluid from the wellbore into the target formation, and compare it with the preset crack propagation stability warning index. If the crack propagation stability warning index is greater than the preset crack propagation stability warning index, it indicates that there is an abnormality in the fracturing crack propagation behavior when injecting the fracturing fluid, and immediately conduct an abnormal warning for the crack propagation stability of the fracturing crack. Otherwise, it indicates that the fracturing crack propagation behavior when injecting the fracturing fluid is safe.

[0103] The fracturing crack propagation abnormality evaluation module: used to receive the flow path monitoring data transmitted by the tracer crack flow path acquisition module, and calculate the crack propagation abnormality prediction coefficient of injecting fracturing fluid from the wellbore into the target formation in each time period based on the entropy sudden increase theory according to the crack propagation data collected by the crack propagation data acquisition unit.

[0104] In a possible design, the fracturing crack propagation abnormality evaluation module is specifically:

[0105] S01: Normalize the crack propagation direction, crack propagation length, and crack propagation width to obtain:

[0106]

[0107] Among them, represents the normalized value of the crack propagation direction in the i-th sub-period, represents the normalized value of the crack propagation length in the i-th sub-period, represents the normalized value of the crack propagation width in the i-th sub-period, σ i represents the crack propagation direction in the i-th sub-period, σ 预 represents the preset crack propagation direction, σ max represents the maximum value of the crack propagation direction, kh i represents the crack propagation length in the i-th sub-period, kh maxDenoted as the maximum value of the crack propagation length, km i Denoted as the crack propagation width in the i-th sub-period, km max Denoted as the maximum value of the crack propagation width;

[0108] S02: Calculate the crack entropy:

[0109] S i =-∑ σ ∑ kh ∑ km p i (σ, kh, km)*log2p i (σ, kh, km)

[0110] Where, S i Denoted as the crack entropy in the i-th sub-period, p i (σ, kh, km) Denoted as the probability distribution of the crack in the i-th sub-period in the direction σ, length kh, and width km;

[0111] Specifically, when the crack entropy value is higher, the crack propagation is more unpredictable (such as sudden direction change, sudden increase in length, width oscillation), and when the crack entropy value decreases, the crack propagation is stable;

[0112] Calculate the crack entropy change rate:

[0113] Where, KS i Denoted as the crack entropy change rate in the i-th sub-period, S i-1 Denoted as the crack entropy in the (i - 1)-th sub-period, and t denotes the time interval of each time period;

[0114] Calculate the crack entropy change acceleration:

[0115] Where, JS i Denoted as the crack entropy change acceleration in the i-th sub-period, KS i-1 Denoted as the crack entropy change rate in the (i - 1)-th sub-period;

[0116] Specifically, when the crack entropy change acceleration is higher, the crack propagation is more unpredictable, and when the crack entropy change acceleration decreases, the crack propagation is stable;

[0117] S03: Calculate the crack propagation abnormal risk intensity:

[0118] MC i =JS i ×exp(KS i )

[0119] Where, MC i Denoted as the crack propagation abnormal risk intensity in the i-th sub-period;

[0120] Specifically, the greater the risk intensity of abnormal crack propagation, the higher the risk of abnormal crack propagation;

[0121] S04: The calculation formula for the abnormal crack propagation prediction coefficient is:

[0122] β i = KS i × JS i + max(0, MC i - MH warn )

[0123] where β i represents the abnormal crack propagation prediction coefficient for the i-th sub-period, KS i represents the crack entropy change rate for the i-th sub-period, JS i represents the crack entropy change acceleration for the i-th sub-period, MC i represents the risk intensity of abnormal crack propagation for the i-th sub-period, MH warn represents the warning threshold of the risk intensity of abnormal crack propagation;

[0124] S05: If MC i ≤ MH warn , then MC i - MH warn ≤ 0, at this time max(0, negative value), and the output result of β i is KS i × JS i + 0. If MC i > MH warn , then MC i - MH warn > 0, at this time max(0, positive value), and the output result of β i is KS i × JS i +(MC i - MH warn ).

[0125] In this embodiment, it should be specifically noted that the warning threshold of the risk intensity of abnormal crack propagation is specifically:

[0126] S01: According to the historical risk intensity of abnormal crack propagation, obtain the mean and standard deviation of the risk intensity of abnormal crack propagation, △MC, μ;

[0127] S01: The calculation formula for the warning threshold of the risk intensity of abnormal crack propagation is: MH warn = △MH + 2μ

[0128] where MH warnThe early warning threshold is denoted as the risk intensity of abnormal fracture propagation, △MC is denoted as the mean value of the risk intensity of abnormal fracture propagation, and μ is denoted as the standard deviation of the risk intensity of abnormal fracture propagation.

[0129] The fracturing fracture abnormal prediction response module: is used to obtain the abnormal prediction coefficient of fracture propagation when fracturing fluid is injected from the wellbore into the target formation in each time period, compare it with the preset abnormal prediction coefficient of fracture propagation, and process it.

[0130] In a possible design, the fracturing fracture abnormal prediction response module is specifically:

[0131] Obtain the abnormal prediction coefficient of fracture propagation when fracturing fluid is injected from the wellbore into the target formation in each time period, compare it with the preset abnormal prediction coefficient of fracture propagation. If the abnormal prediction coefficient of fracture propagation when fracturing fluid is injected from the wellbore into the target formation in a certain time period is greater than the preset abnormal prediction coefficient of fracture propagation, it indicates that the degree of abnormal fracturing fracture in this time period is high. At this time, there is a safety hazard in the fracturing operation, and an abnormal warning is immediately given and the operation is stopped. Otherwise, it indicates that the fracture propagation in this time period is stable and no intervention is required.

[0132] Please refer to Figure 3 As shown, the present invention provides a method for identifying and predicting fracturing fractures based on tracers, including the following steps:

[0133] Step S01: Tracer injection: used to inject tracers into the fracturing fluid, inject the fracturing fluid from the wellbore through the target formation, and collect the fracturing operation data when the fracturing fluid is injected.

[0134] Step S02: Tracer injection optimization: used to calculate the fracturing operation safety control index when the fracturing fluid is injected according to the fracturing operation data when the fracturing fluid is injected, and optimize the tracer injection strategy.

[0135] Step S03: Tracer fracture flow path collection: used to obtain the flow path monitoring data of the fracturing fluid injected from the wellbore into the target formation every t time periods. The step S03: Tracer fracture flow path collection includes a fracture coordinate data collection sub-step and a fracture propagation data collection sub-step, and the flow path monitoring data includes fracture coordinate data and fracture propagation data.

[0136] Step S04: Fracturing fracture propagation stability analysis: used to receive the flow path monitoring data transmitted by the tracer fracture flow path collection step, calculate the fracture propagation stability early warning index when the fracturing fluid is injected from the wellbore into the target formation according to the fracture coordinate data collected by the fracture coordinate data collection sub-step, and conduct early warning of the fracturing fracture propagation stability.

[0137] Step S05: Abnormal evaluation of fracture propagation: It is used to receive the flow path monitoring data transmitted by the tracer fracture flow path acquisition step, calculate the fracture propagation anomaly prediction coefficient of the target formation injecting fracturing fluid from the wellbore in each time period based on the entropy value sudden increase theory according to the fracture propagation data collected by the fracture propagation data acquisition sub-step.

[0138] Step S06: Abnormal prediction response of fracture propagation: It is used to obtain the fracture propagation anomaly prediction coefficient of the target formation injecting fracturing fluid from the wellbore in each time period, compare it with the preset fracture propagation anomaly prediction coefficient, and process it.

[0139] In this embodiment, it should be specifically noted that the present invention calculates the fracturing operation safety control index when injecting fracturing fluid by collecting the fracturing operation data. When the fracturing operation safety control index is less than the maximum value of the fracturing operation safety control index warning interval and greater than or equal to the minimum value of the fracturing operation safety control index warning interval, the fracturing operation data adjustment strategy is to optimize 50%QH when injecting fracturing fluid 预 <qh≤70%QH 预 , optimize qv≤80%QV when injecting fracturing fluid 预 , monitor qp<70%QP when injecting fracturing fluid 预 In the fracturing operation, by dynamically calculating the safety control index and combining real-time data with the warning mechanism, the tracer injection strategy can be scientifically adjusted to achieve the balance between safety and operation efficiency.

[0140] In the present invention, by obtaining the monitoring data of the flow path of the fracturing fluid injected from the wellbore into the target formation every t time periods, and calculating the fracture propagation stability warning index when the fracturing fluid is injected from the wellbore into the target formation according to the fracture coordinate data collected by the fracture coordinate data acquisition unit, and comparing it with the preset fracture propagation stability warning index. If the fracture propagation stability warning index is greater than the preset fracture propagation stability warning index, it indicates that there is an abnormality in the fracture propagation behavior during the injection of the fracturing fluid, and an immediate warning of the abnormal fracture propagation stability is given. On the contrary, it indicates that the fracture propagation behavior during the injection of the fracturing fluid is safe. By real-time dynamically monitoring the fracture coordinate data, the stability of the fracture propagation behavior is warned, and the operation safety is improved. According to the fracture propagation data collected by the fracture propagation data acquisition unit, based on the theory of sudden increase in entropy value, the fracture propagation abnormality prediction coefficient of the target formation when the fracturing fluid is injected from the wellbore in each time period is calculated, and compared with the preset fracture propagation abnormality prediction coefficient. If the fracture propagation abnormality prediction coefficient of the target formation when the fracturing fluid is injected from the wellbore in a certain time period is greater than the preset fracture propagation abnormality prediction coefficient, it indicates that the degree of fracture abnormality in this time period is high, and there is a potential safety hazard in the fracturing operation at this time. An immediate warning of the abnormality and the operation are stopped. On the contrary, it indicates that the fracture propagation in this time period is stable and no intervention is required. Through the coupled calculation of the fracture entropy change rate, the fracture entropy change acceleration and the fracture propagation abnormality risk intensity, the dynamic changes of the direction, length and width of the fracture propagation are converted into a single abnormality coefficient, combined with the adaptive warning threshold, and the risk value of the fracture propagation is quantified, avoiding one-sided judgment and realizing accurate fracture abnormality warning and response for the fracturing operation.

[0141] Finally, the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tracer-based fracturing fracture identification and prediction system, characterized in that Including: Tracer injection module: used to inject a tracer into the fracturing fluid, inject the fracturing fluid from the wellbore through the target formation, and collect fracturing operation data when the fracturing fluid is injected; Tracer injection optimization module: used to calculate the fracturing operation safety control index when the fracturing fluid is injected based on the fracturing operation data when the fracturing fluid is injected, and optimize the tracer injection strategy; Tracer fracture flow path acquisition module: used to obtain the flow path monitoring data of the fracturing fluid injected from the wellbore into the target formation every t time periods, and the flow path monitoring data includes a fracture coordinate data acquisition unit and a fracture propagation data acquisition unit; Fracture propagation stability analysis module for fracturing: calculate the fracture propagation stability warning index when the fracturing fluid is injected from the wellbore into the target formation based on the fracture coordinate data collected by the fracture coordinate data acquisition unit, and conduct a warning on the fracture propagation stability for fracturing; Fracture propagation abnormality evaluation module for fracturing: calculate the fracture propagation abnormality prediction coefficient of the fracturing fluid injected from the wellbore into the target formation in each time period based on the fracture propagation data collected by the fracture propagation data acquisition unit and based on the entropy value sudden increase theory; Fracture propagation abnormality prediction response module for fracturing: used to obtain the fracture propagation abnormality prediction coefficient of the fracturing fluid injected from the wellbore into the target formation in each time period, compare it with the preset fracture propagation abnormality prediction coefficient, and process it.

2. The tracer-based fracturing fracture identification and prediction system according to claim 1, wherein: The tracer has environmental friendliness, high stability and detectability, and can be evenly distributed during the fracturing process and enter the fracture with the fracturing fluid; The fracturing operation data includes the initial concentration of the tracer, the injection rate of the fracturing fluid, and the formation pressure.

3. The tracer-based fracturing fracture identification and prediction system according to claim 1, wherein: The tracer injection optimization module is specifically: S31: The calculation formula of the fracturing operation safety control index is: Among them, ω represents the safety control index for the fracturing operation, qh represents the initial tracer concentration, and QH 预 represents the preset initial tracer concentration, qv represents the injection rate of the fracturing fluid, and QV 预 represents the preset injection rate of the fracturing fluid, qp represents the formation pressure, and QP 预 represents the preset formation pressure; S32: Obtain the fracturing operation safety control index when the fracturing fluid is injected, compare it with the warning interval of the fracturing operation safety control index. If the fracturing operation safety control index is greater than or equal to the maximum value of the warning interval of the fracturing operation safety control index, it indicates that the operation safety assessment when the fracturing fluid is injected is within the safe range, and continuous construction is allowed. If the fracturing operation safety control index is less than the maximum value of the warning interval of the fracturing operation safety control index and greater than or equal to the minimum value of the warning interval of the fracturing operation safety control index, it indicates that the operation parameters when the fracturing fluid is injected need to be adjusted, and the operation safety assessment is within the warning range. If the fracturing operation safety control index is less than the minimum value of the warning interval of the fracturing operation safety control index, it indicates that the operation safety assessment when the fracturing fluid is injected is within the dangerous range, and the operation should be stopped immediately; S33: When the fracturing operation safety control index is less than the maximum value of the fracturing operation safety control index warning range and greater than or equal to the minimum value of the fracturing operation safety control index warning range, the fracturing operation data adjustment strategy is to optimize 50% QH during fracturing fluid injection. 预 <qh ≤ 70% QH 预 , optimize qv ≤ 80% QV during fracturing fluid injection. 预 , monitor qp < 70% QP during fracturing fluid injection. 预 , the priority of fracturing operation data adjustment is formation pressure > fracturing fluid injection rate > initial tracer concentration.

4. A tracer-based fracturing fracture identification and prediction system according to claim 1, wherein: The tracer fracture flow path acquisition module is specifically: Fracture coordinate data acquisition unit: Every t time periods, collect the fracture positions (x i , y i ) where the fracturing fluid is injected into the target formation from the wellbore, where i = 1, 2,... n, and i represents the number of the i-th sub-time period; Fracture propagation data acquisition unit: Every t time periods, the fracture propagation direction, fracture propagation length, and fracture propagation width of the fracturing fluid injected into the target formation from the wellbore are collected and marked as σ i , kh i , km i .

5. The tracer-based fracturing fracture identification and prediction system according to claim 1, characterized in that: The fracture propagation stability analysis module for fracturing is specifically: S51: Calculate the spatial displacement of fracture propagation in each time period through the fracture position: Among them, D i represents the crack propagation spatial displacement in the i-th sub-time period, x i represents the x-axis coordinate of the crack in the i-th sub-time period, y i represents the y-axis coordinate of the crack in the i-th sub-time period, x i+1 represents the x-axis coordinate of the crack in the (i + 1)-th sub-time period, y i+1 represents the y-axis coordinate of the crack in the (i + 1)-th sub-time period; S52: The calculation formula of the fracture propagation stability warning index is: Among them, α represents the fracture propagation stability warning index, and n represents the number of sub-time periods; S53: Set a preset fracture propagation stability warning index, and the formula is: Among them, α 预 represents a preset crack propagation stability warning index, D max represents the maximum value of the spatial displacement of crack propagation, D min represents the minimum value of the spatial displacement of crack propagation; S54: Obtain the fracture propagation stability warning index when fracturing fluid is injected from the wellbore into the target formation, and compare it with the preset fracture propagation stability warning index. If the fracture propagation stability warning index is greater than the preset fracture propagation stability warning index, it indicates that the fracturing fracture propagation behavior during this injection of fracturing fluid is abnormal, and immediately issue an abnormal warning for the fracturing fracture propagation stability. Otherwise, it indicates that the fracturing fracture propagation behavior during this injection of fracturing fluid is safe.

6. The tracer-based fracturing fracture identification and prediction system according to claim 1, wherein: The calculation formula for the fracture propagation abnormality prediction coefficient is: β i = KS i × JS i + max(0, MC i - MH warn ) Among them, β i represents the crack propagation anomaly prediction coefficient for the i-th sub-period, KS i represents the crack entropy change rate for the i-th sub-period, JS i represents the crack entropy change acceleration for the i-th sub-period, MC i represents the crack propagation anomaly risk intensity for the i-th sub-period, MH warn represents the warning threshold for the crack propagation anomaly risk intensity.

7. The tracer-based fracturing fracture identification and prediction system according to claim 6, characterized in that: The fracture propagation abnormality prediction coefficient is specifically: S71: Normalize the fracture propagation direction, fracture propagation length, and fracture propagation width to obtain: Among them, represents the normalized value of the crack propagation direction in the $i$-th sub-time period, represents the normalized value of the crack propagation length in the $i$-th sub-time period, represents the normalized value of the crack propagation width in the $i$-th sub-time period, $\sigma$ i represents the crack propagation direction in the $i$-th sub-time period, $\sigma$ 预 represents the preset crack propagation direction, $\sigma$ max represents the maximum value of the crack propagation direction, $k_h$ i represents the crack propagation length in the $i$-th sub-time period, $k_h$ max represents the maximum value of the crack propagation length, $k_m$ i represents the crack propagation width in the $i$-th sub-time period, $k_m$ max represents the maximum value of the crack propagation width; S72: Calculate the fracture entropy: S i = -∑ σ ∑ kh ∑ km p i (σ, kh, km) * log2p i (σ, kh, km) Among them, S i represents the crack entropy of the i-th sub-period, and p i (σ, kh, km) represents the probability distribution of the crack in the i-th sub-period in the direction σ, length kh, and width km; Calculate the entropy change rate of the crack: Among them, KS i represents the crack entropy change rate of the i-th sub-period, and S i-1 represents the crack entropy of the (i - 1)-th sub-period, and t represents the interval duration of each time period; Calculate the entropy change acceleration of the crack: Among them, JS i represents the crack entropy change acceleration of the i-th sub-period, and KS i-1 represents the crack entropy change rate of the (i - 1)-th sub-period; S73: Calculate the fracture propagation abnormal risk intensity: MC i = JS i × exp(KS i ) Among them, MC i represents the abnormal risk intensity of crack propagation in the i-th sub-time period; S74: If MC i ≤MH warn , then MC i -MH warn ≤0, at this time max(0, negative value), the output of β i is KS i ×JS i +0, if MC i >MH warn , then MC i -MH warn >0, at this time max(0, positive value), the output of β i is KS i ×JS i +(MC i -MH warn ).

8. A tracer-based fracturing fracture identification and prediction system according to claim 1, characterized in that: The fracturing fracture abnormality prediction response module is specifically: Obtain the fracture propagation abnormality prediction coefficients of the target formation when injecting fracturing fluid from the wellbore at each time period, and compare them with the preset fracture propagation abnormality prediction coefficients. If the fracture propagation abnormality prediction coefficient of the target formation when injecting fracturing fluid from the wellbore at a certain time period is greater than the preset fracture propagation abnormality prediction coefficient, it indicates that the degree of fracturing fracture abnormality at this time period is high, and there are potential safety hazards in the fracturing operation at this time. Immediately issue an abnormal warning and stop the operation. Otherwise, it indicates that the fracturing fracture propagation at this time period is stable and no intervention is required.

9. A tracer-based fracture identification and prediction method, using a tracer-based fracture identification and prediction system according to any one of claims 1-8, characterized in that: It includes the following steps: Step S01: Tracer injection: Used to inject a tracer into the fracturing fluid, inject the fracturing fluid from the wellbore through the target formation, and collect the fracturing operation data when the fracturing fluid is injected. Step S02: Tracer injection optimization: Used to calculate the fracturing operation safety control index when the fracturing fluid is injected based on the fracturing operation data when the fracturing fluid is injected, and optimize the tracer injection strategy. Step S03: Tracer fracture flow path collection: Used to obtain the flow path monitoring data of the target formation when injecting fracturing fluid from the wellbore every t time periods. Step S03: Tracer fracture flow path collection includes a fracture coordinate data collection sub-step and a fracture propagation data collection sub-step. The flow path monitoring data includes fracture coordinate data and fracture propagation data. Step S04: Fracturing fracture propagation stability analysis: Used to receive the flow path monitoring data transmitted by the tracer fracture flow path collection step, and calculate the fracture propagation stability warning index when injecting fracturing fluid from the wellbore into the target formation based on the fracture coordinate data collected by the fracture coordinate data collection sub-step, and conduct a warning for the fracturing fracture propagation stability. Step S05: Fracturing fracture propagation abnormality evaluation: Used to receive the flow path monitoring data transmitted by the tracer fracture flow path collection step, and calculate the fracture propagation abnormality prediction coefficients of the target formation when injecting fracturing fluid from the wellbore at each time period based on the fracture propagation data collected by the fracture propagation data collection sub-step, based on the entropy sudden increase theory. Step S06: Fracturing fracture abnormality prediction response: Used to obtain the fracture propagation abnormality prediction coefficients of the target formation when injecting fracturing fluid from the wellbore at each time period, compare them with the preset fracture propagation abnormality prediction coefficients, and process them.

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