A composite temporary plugging and diverting repeated fracturing method and system

Abstract

The present application relates to the field of oil production technology, and specifically to a composite temporary plugging and re-fracturing method and system, the method comprising: obtaining casing pressure data at each acquisition moment of an oil well to form an oil well casing pressure sequence; constructing a casing pressure distribution trend sequence based on the distribution of the maximum value, the difference of the maximum value, and the differential distribution around each acquisition moment in the oil well casing pressure sequence; forming a fracturing identification sequence for the elements within a window of a preset size where each extreme value in the casing pressure distribution trend sequence is located; determining the fracturing identification degree of the fracturing identification sequence; and determining the time when cracks appear based on the fracturing identification degree and a preset judgment threshold. The present application aims to improve the accuracy of identifying the time when cracks appear in oil wells.

Description

Technical Field

[0001] The present application relates to the technical field of oil extraction, and in particular to a composite temporary plugging, diverting and repeated fracturing method and system. Background Art

[0002] With the decreasing oil resources and the increasing difficulty of discovering new oil fields, it is particularly critical and urgent to ensure and improve the production and extraction efficiency of existing old oil fields. Existing technologies generally increase the production of oil fields by temporary plugging and switching to fracturing technology.

[0003] Temporary plugging and diversion fracturing technology is an advanced oil and gas field production increase measure. It intentionally plugs existing fractures or perforation channels during repeated fracturing to guide the fracturing fluid to flow to previously underdeveloped reservoir areas. This method can effectively change the flow path of the fracturing fluid and the expansion direction of the fractures, prompting fractures to form in new or more favorable directions, increasing the contact area and permeability of the reservoir, and achieving more layers of utilization in the reservoir, thereby improving the recovery rate.

[0004] For temporary plugging and diverting fracturing technology, the casing pressure reaches a maximum value due to cracks in the oil well. Therefore, the casing pressure data or oil pressure analysis during the fracturing process is generally used to identify the time when the cracks in the oil well break. However, since the machine will vibrate strongly when the oil well is temporarily plugged and diverted for fracturing, it is easy to have inaccurate identification when identifying the cracks using existing technologies. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a composite temporary plugging and diverting repeated fracturing method and system, and the technical solutions adopted are as follows:

[0006] In a first aspect, an embodiment of the present application provides a composite temporary plugging diversion repeated fracturing method, the method comprising the following steps:

[0007] Acquire casing pressure data of the oil well at each acquisition moment to form an oil well casing pressure sequence;

[0008] Based on the distribution of the maximum value, the difference of the maximum value and the differential distribution around each acquisition moment in the casing pressure sequence of the oil well, the casing pressure distribution trend sequence is constructed;

[0009] Acquire extreme values ​​in the casing pressure distribution trend sequence; form a fracturing identification sequence for elements in a window of a preset size where each extreme value in the casing pressure distribution trend sequence is located; determine the fracturing identification degree of the fracturing identification sequence based on the numerical difference between the elements in the fracturing identification sequence and the central element, and the numerical difference on both sides of the central element;

[0010] The fracturing recognition degree is segmented by threshold value, and divided into a basic judgment class and a fracture recognition class; the recognition gap between the basic judgment class and the fracture recognition class is calculated; the recognition gap is compared with the preset judgment threshold to determine the time when the fracture appears when the oil well is temporarily plugged and turned to repeated fracturing.

[0011] Preferably, the process of constructing the casing pressure distribution trend sequence includes:

[0012] The elements in the window centered at each acquisition moment in the casing pressure sequence of the oil well are used to form a casing pressure subsequence at each acquisition moment;

[0013] Get the sign function value of the difference between the position numbers of the maximum value and the minimum value in the casing pressure subsequence;

[0014] Get the range of the casing pressure subsequence and the mean of the difference sequence;

[0015] The product of the sign function value, the range and the mean of the difference sequence is taken as the casing pressure distribution trend of the casing pressure subsequence;

[0016] The casing pressure distribution trend quantities of the casing pressure subsequences at all acquisition moments are combined into a casing pressure distribution trend sequence.

[0017] Preferably, the method for determining the fracturing recognition degree of the fracturing recognition sequence comprises:

[0018] determining a fracturing vibration amplitude value of the fracturing identification sequence based on a numerical difference between the elements in the fracturing identification sequence and the central element;

[0019] Based on the numerical difference between the two sides of the central element of the fracturing identification sequence, the left-right imbalance of the fracturing identification sequence is determined;

[0020] The fracturing recognition degree of the fracturing recognition sequence is determined based on the fracturing vibration amplitude value and the left-right imbalance degree of the fracturing.

[0021] Preferably, the method for determining the fracturing vibration amplitude value of the fracturing identification sequence comprises:

[0022] The numerical difference between each element in the fracturing identification sequence and the central element is calculated respectively, and the average value of all the differences calculated in the fracturing identification sequence is taken as the fracturing vibration amplitude value of the fracturing identification sequence.

[0023] Preferably, the left-right imbalance of the fracturing identification sequence is the difference between the mean values ​​of the elements on both sides of the central element of the fracturing identification sequence.

[0024] Preferably, the fracturing recognition degree of the fracturing recognition sequence is obtained by multiplying the fracturing vibration amplitude value by the left-right imbalance degree of the fracturing.

[0025] Preferably, the division method is:

[0026] Obtaining the segmentation threshold of the fracturing recognition degree of all fracturing recognition sequences;

[0027] The fracturing recognition degrees less than the segmentation threshold are grouped into the basic judgment class; the fracturing recognition degrees greater than or equal to the segmentation threshold are grouped into the fracture recognition class.

[0028] Preferably, the calculation process of identifying the gap is:

[0029] Get the maximum value in the judgment base class; get the minimum value in the crack identification class;

[0030] The difference between the minimum and maximum values ​​is used as the identification gap between the basic class and the crack identification class.

[0031] Preferably, the method for determining the crack occurrence time includes:

[0032] When the identification gap is smaller than the preset judgment threshold, it is determined that no cracks occur in the oil well;

[0033] Otherwise, the time corresponding to all elements in the fracture identification class is taken as the time when the fractures of the oil wells appear.

[0034] In the second aspect, an embodiment of the present application also provides a composite temporary plugging and diverting repeated fracturing system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above-mentioned composite temporary plugging and diverting repeated fracturing methods when executing the computer program.

[0035] This application has at least the following beneficial effects:

[0036] This application realizes the composite temporary plugging and diverting fracturing technology by identifying the moment when cracks appear in oil wells. Compared with the general analysis of the change state of pressure response data during monitoring fracturing to identify the moment when cracks appear in oil wells, due to the temporary plugging and diverting fracturing process of oil production, large-scale production equipment can easily affect the data collected by the pressure gauge during operation, making the identification of the fracturing moment inaccurate and affecting the fracturing effect. This application constructs a casing pressure distribution trend sequence by analyzing the maximum and differential distribution around each element in the casing pressure sequence of the oil well, which is used to characterize the changing state of casing pressure during data collection and distinguish the changes in casing pressure before and after the cracks appear; by analyzing the numerical differences of elements near the extreme values ​​in the casing pressure distribution trend sequence, the fracturing recognition degree is determined to eliminate the interference of casing vibration in identifying cracks in oil wells; by analyzing the numerical distribution of fracturing recognition degree, combined with the recognition gap between the occurrence of cracks and the absence of cracks, the moment when cracks appear in oil wells is determined, thereby effectively improving the accuracy of identifying the moment when cracks appear in oil wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a flowchart of a composite temporary plugging and diversion repeated fracturing method provided by an embodiment of the present application;

[0039] Figure 2 It is a flowchart of a method for determining the fracturing recognition degree of a fracturing recognition sequence provided by an embodiment of the present application. Detailed implementation manners

[0040] In order to further elaborate on the technical means and effects adopted by the present application to achieve the intended invention purpose, the following, in combination with the drawings and preferred embodiments, details the specific implementation manners, structures, features and effects of a composite temporary plugging and diversion repeated fracturing method and system proposed according to the present application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0042] The following specifically describes the specific solutions of a composite temporary plugging and diversion repeated fracturing method and system provided by the present application with reference to the drawings.

[0043] A composite temporary plugging and diversion repeated fracturing method and system provided by an embodiment of the present application.

[0044] Specifically, a composite temporary plugging and diversion repeated fracturing method is provided as follows. Please refer to Figure 1 , and the method includes the following steps:

[0045] The first step is to obtain the casing pressure data at each acquisition moment of the production well to form a well casing pressure sequence.

[0046] The operation process of the composite temporary plugging and diversion fracturing technology for the production well is specifically as follows:

[0047] S1: First, inject working fluid into the wellbore of the oil well until the liquid level reaches a position parallel to the wellbore outlet. At this time, add a special composite temporary plugging agent to the working fluid. The temporary plugging agent is mainly composed of PGA modified material and rigid material, which can effectively form a temporary plugging in the well.

[0048] S2: After the composite temporary plugging agent is injected, the critical waiting stage begins. At this stage, the temporary plugging agent will fully act in the well to effectively plug the original cracks and ensure that these cracks are completely closed. In this embodiment, the composite temporary plugging agent is selected from two or more of soluble acrylic resin, gelatin, sulfonated lignin, sulfonated asphalt, sulfonated lignite, polyvinyl alcohol and polyester amide. The working fluid has the function of transporting the temporary plugging agent. In this embodiment, hydroxypropyl guar gum is selected as the working fluid. The implementer can select working fluids with other components, such as oleic acid clean fracturing fluid, slippery water, linear gum, etc.

[0049] S3: After confirming that the cracks in the wellbore are completely blocked, the fracturing fluid is then injected into the wellbore. This fracturing fluid has appropriate viscosity and sand carrying capacity, and can effectively fractur the oil well under high pressure. By forming new cracks in the rock or expanding existing cracks, the flow channels of oil and gas can be significantly increased, thereby greatly increasing the oil production of the oil well.

[0050] In this embodiment, in order to accurately monitor the change of casing pressure of the oil well during the fracturing process, a pressure gauge is installed at the valve of the casing of the Christmas tree, that is, the position where the casing of the Christmas tree is connected to the annular space formed between the oil pipe and the casing, to collect the casing pressure of the oil well. In this embodiment, the time interval of the collection is 0.1s, and the collection time is 10min.

[0051] The collected casing pressure is preprocessed. Since there may be data missing when collecting casing pressure using a pressure gauge, the third-order polynomial interpolation method is used in this application to interpolate the missing part, complete the casing pressure data of the missing part, and arrange the completed data in the order of collection time, and record the arrangement result as the oil well casing pressure sequence. Since polynomial interpolation is a well-known technology, the specific calculation process will not be repeated.

[0052] So far, the casing pressure sequence of the oil well can be obtained through the above method.

[0053] The second step is to construct a casing pressure distribution trend sequence based on the maximum distribution, maximum difference and differential distribution around each acquisition moment in the oil well casing pressure sequence.

[0054] When monitoring the fracturing of an oil well, the fracturing of the oil well requires the continuous input of fracturing fluid, and the casing pressure of the oil well will increase with the input of fracturing fluid. The huge pressure will cause new cracks to appear in the oil well, and the fracturing fluid will enter the new cracks, causing the casing pressure of the oil well to drop suddenly.

[0055] When no new cracks appear, the casing pressure of the oil well continues to increase, and the increasing trend has a certain monotonic relationship, that is, the values ​​of casing pressure increase are similar within the same period of time.

[0056] Based on this, the present application takes each element in the oil well casing pressure sequence as the center, obtains a 9×1 window, and uses the mean filling method to fill the insufficient elements in the window. The mean filling method is a well-known technology and will not be described in detail. Other window sizes can also be set in other embodiments of the present application. Then, the elements in the window are combined into a sequence, recorded as a casing pressure subsequence, and the casing pressure subsequence is used as the input of the first-order difference method, and the output is a casing pressure difference numerator sequence.

[0057] Therefore, the casing pressure distribution trend of the casing pressure subsequence of each element in the oil well casing pressure sequence is calculated to characterize the changing state of the casing pressure at each acquisition moment and distinguish the changes in casing pressure before and after the occurrence of fractures.

[0058] Taking a casing pressure subsequence as an example, the expression of the casing pressure distribution trend quantity of the casing pressure subsequence is: Zf=Sgn(MN)×(mC×vR); where Zf represents the casing pressure distribution trend quantity of the casing pressure subsequence; mC represents the mean of the casing pressure difference numerator sequence of the casing pressure subsequence; vR represents the range value of the casing pressure subsequence; M and N represent the position numbers of the maximum and minimum values ​​in the casing pressure subsequence respectively; Sgn represents the sign function.

[0059] It should be understood that when the elements in the casing pressure subsequence have only a monotonically increasing trend, it indicates that the data of the casing pressure subsequence is before the cracks appear during the fracturing process of the oil well, which makes the range value vR of the casing pressure subsequence larger; at the same time, the elements in the first-order difference sequence of the casing pressure subsequence are all positive, which makes the mean value mC of the casing pressure difference numerator sequence larger. Because there is monotonic growth before the cracks appear in the oil well, the minimum value appears earlier than the maximum value in a local area, so the value of Sgn(MN) is positive, which makes the value of the casing pressure distribution trend quantity Zf of the casing pressure subsequence larger.

[0060] The casing pressure distribution trend quantities of all casing pressure subsequences are arranged according to the order of the casing pressure subsequences to obtain the casing pressure distribution trend sequence.

[0061] The third step is to obtain the extreme values ​​in the casing pressure distribution trend sequence; to form a fracturing identification sequence for the elements in a window of a preset size where each extreme value in the casing pressure distribution trend sequence is located; and to determine the fracturing identification degree of the fracturing identification sequence based on the numerical differences between the elements in the fracturing identification sequence and the central element, as well as the numerical differences on both sides of the central element.

[0062] When new cracks appear in an oil well, if there is no vibration interference from the casing, there will be an extreme value in the casing pressure distribution trend sequence, and the difference between the extreme value and the local value is very large. Under normal circumstances, the casing pressure of the oil well has a certain monotonic trend change, so the calculated casing pressure distribution trend also has a monotonic change.

[0063] When affected by pipeline vibration, the monotonic trend fluctuates, causing vibration deviation in the casing pressure distribution trend sequence, resulting in extreme values ​​at the time when no cracks appear, but the extreme values ​​are slightly different from other values ​​in their local area. Therefore, the casing pressure distribution trend sequence is analyzed.

[0064] The casing pressure distribution trend sequence is used as the input of the AMPD (Automatic Multiscale-based Peak Detection) peak detection algorithm, and the output is all the extreme values ​​of the casing pressure distribution trend sequence. The AMPD algorithm is a well-known technology, and the specific calculation process is not repeated here.

[0065] Furthermore, a 11×1 window is obtained with each extreme value in the casing pressure distribution trend sequence as the center. The mean filling method is used to fill the insufficient elements in the window, and the data in the window are combined into a fracturing identification sequence.

[0066] When the fracturing identification sequence is formed by the casing pressure data of the fracturing state, the central element differs greatly from the elements at other positions and has obvious differences.

[0067] Based on this, for any fracturing identification sequence, the fracturing vibration amplitude value is calculated, and the fracturing vibration amplitude value G of the i-th fracturing identification sequence is i For example, the expression is: In the formula, G i represents the fracturing vibration amplitude value of the i-th fracturing identification sequence; J represents the number of all elements in the fracturing identification sequence; Fh i,j represents the jth element value in the i-th fracturing identification sequence; Fh i represents the central element value of the ith fracturing identification sequence, which is the sixth value in the fracturing identification sequence in this embodiment.

[0068] It should be understood that the change of casing pressure data before fracturing has the same pattern; after fracturing, the change of casing pressure at a certain time also has the same pattern. Therefore, when the fracturing identification sequence is formed by the casing pressure data of the fracturing state, the change pattern of casing pressure is changed, so that the absolute value of the difference between the central element and its neighboring element of the fracturing identification sequence of the oil well at the time of fracture generation|Fh i,j -Fh i | increases, so that the fracturing vibration amplitude value G of the fracturing identification sequence i increase.

[0069] When the oil well is temporarily plugged and fracturing, the casing pressure data before the cracks appear tends to increase overall; after the cracks appear, the fracturing fluid is used to crack, causing the casing pressure data to decrease, and the overall trend is decreasing. For the extreme values ​​caused by pipeline vibration, since the extreme values ​​of this part are in a normal state, although the extreme values ​​caused by pipeline vibration have certain characteristics, the data on both sides of the extreme values ​​belong to the same mode, and the difference between the values ​​is small.

[0070] The left-right imbalance degree of each fracturing identification sequence is calculated, and the left-right imbalance degree of the i-th fracturing identification sequence H is taken as i For example, the expression is:

[0071] H i =|mFl i -mFr i |, where H i represents the left-right imbalance of the fracturing of the i-th fracturing identification sequence; mFl i represents the mean of all elements to the left of the central element of the i-th fracturing identification sequence; mFr i Represents the mean of all elements to the right of the central element of the i-th fracturing identification sequence.

[0072] It should be understood that when the fracturing identification sequence is generated by the fracturing moment, the value on the left side of the central element is the casing pressure distribution trend formed by the continuous increase of casing pressure, and the value on the right side of the central element is the casing pressure distribution trend formed by the continuous decrease of casing pressure; the casing pressure distribution trend on both sides of the central element is positive on the left and negative on the right, which makes the two sides of the central element of the fracturing identification sequence have obvious differences. The absolute value of the difference between the mean values ​​of the elements on both sides of the central element |mFl i -mFr i The larger the value of |, the greater the left-right imbalance degree H of the fracturing identification sequence. i If the extreme value is caused by vibration noise, the values ​​of the neighborhoods on both sides of the central element are normal, and the absolute value of the difference between the mean values ​​of the neighborhoods on both sides of the central element |mFl i -mFr i |Comparatively smaller.

[0073] The fracturing recognition degree of the fracturing recognition sequence is calculated by the fracturing vibration amplitude value and the left-right imbalance degree of the fracturing recognition sequence in the above steps.

[0074] In this embodiment, the product of the fracturing vibration amplitude value of the fracturing identification sequence and the left-right imbalance of the fracturing is used as the fracturing identification degree of the fracturing identification sequence. In other embodiments of the present application, the sum of the fracturing vibration amplitude value of the fracturing identification sequence and the left-right imbalance of the fracturing can also be used as the fracturing identification degree of the fracturing identification sequence.

[0075] It should be understood that if the fracturing identification sequence is formed when cracks appear in the oil well, the absolute value of the difference between the central element of the fracturing identification sequence and its neighboring elements is relatively large, so the fracturing vibration amplitude value G of the fracturing identification sequence is i The value of is large. At the same time, before the crack appears, the change pattern of casing pressure over time is not much different; after the crack appears, the change pattern of casing pressure over time is not much different. However, due to the obvious difference in the change pattern of casing pressure before and after the crack appears, the casing pressure distribution trend quantity is positive on the left and negative on the right, which makes the left and right imbalance degree H of the fracturing identification sequence i The value of is large, which makes the fracturing recognition degree K of the fracturing recognition sequence i The value of is larger.

[0076] In one embodiment of the present application, a flow chart of a method for determining the fracturing recognition degree of a fracturing recognition sequence is shown in the attached figure. Figure 2 shown.

[0077] The fourth step is to perform threshold segmentation on the fracturing recognition degree, dividing it into a basic judgment class and a fracture recognition class; calculating the recognition gap between the basic judgment class and the fracture recognition class; comparing the recognition gap with the preset judgment threshold to determine the moment when the fracture appears when the oil well is temporarily plugged and turned to repeated fracturing.

[0078] When no cracks appear, the casing pressure of the oil well increases with time. If the fluctuation state of the fracturing recognition calculated by the above steps is the same, they belong to the same category. When cracks appear, the casing pressure changes from increasing to decreasing, and the fluctuation mode changes. There is a clear difference between the fracturing recognition when cracks occur and other fracturing recognitions.

[0079] Therefore, all the fracturing recognition degrees are used as the input of the OTSU method, and the output is the segmentation threshold of the fracturing recognition degree. The OTSU method is a well-known technology, and the specific calculation process is not repeated here.

[0080] The fracturing recognition degrees less than the segmentation threshold are grouped into the basic judgment class, denoted as P; the fracturing recognition degrees greater than or equal to the segmentation threshold are grouped into the fracture recognition class, denoted as Q.

[0081] The fracturing recognition degree in the judgment base class is the time when the fracturing recognition sequence does not have cracks, and the fracturing recognition degree in the fracture recognition class is the time when the fracturing recognition sequence may have cracks.

[0082] Further, the standard deviation of the judgment basis class is calculated and recorded as the judgment threshold to.

[0083] When no cracks appear, the distribution of all fracturing recognition degrees is relatively uniform, that is, they belong to the same category. After all fracturing recognition degrees are divided into two categories by the Otsu method, the fluctuation state of the elements in the two categories is the same. The recognition gap between the basic class and the crack recognition class is calculated and judged as follows:

[0084] R = min(Q) - max(P), where R represents the recognition gap between the judgment basis class and the crack identification class; max and min represent the maximum and minimum functions, respectively; P is the judgment basis class, and Q is the crack identification class.

[0085] It should be understood that when the recognition gap R between the basic class and the fracture identification class is less than the judgment threshold to, it means that the difference in the values ​​between the basic class and the fracture identification class is relatively small, and they belong to the same category, and no cracks have appeared in the oil well at the current moment; when the recognition gap R between the basic class and the fracture identification class is greater than or equal to the judgment threshold to, it means that a fracturing identification degree that is significantly different from the overall fracturing identification degree has appeared, and the moments corresponding to all elements in the fracture identification class are respectively regarded as the moments when cracks appear in the oil well.

[0086] The detection result is transmitted to the fracturing fluid control module, and the fracturing fluid control module controls the injection of the fracturing fluid. When cracks appear, the injection of the fracturing fluid is stopped, otherwise the injection continues.

[0087] Based on the same inventive concept as the above method, an embodiment of the present application also provides a composite temporary plugging and diverting repeated fracturing system, including a memory, a processor, and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the steps of a composite temporary plugging and diverting repeated fracturing method described in any one of the above methods are implemented.

[0088] The various embodiments in the present application are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0089] It should be noted that, unless otherwise specified and limited, terms such as "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a circuit structure, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, an element defined by the sentence "including one..." does not exclude the existence of other identical elements in the article or device including the element. In addition, the term "and\or" used herein includes any and all combinations of one or more related listed items.

[0090] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not invented by the present application.

[0091] It will be appreciated that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A composite temporary plugging and diverting repeated fracturing method, characterized in that: The method comprises the following steps: Acquire casing pressure data of the oil well at each acquisition moment to form an oil well casing pressure sequence; All elements around each acquisition moment in the casing pressure sequence of the oil well are combined into a casing pressure subsequence; the sign function value of the position difference of the two maximum values ​​of the casing pressure subsequence, the numerical difference of the maximum value and the differential mean of the casing pressure subsequence are multiplied to obtain the element value corresponding to each acquisition moment in the casing pressure distribution trend sequence; Obtain extreme values ​​in the casing pressure distribution trend sequence; form a fracturing identification sequence for the elements in a window of a preset size where each extreme value in the casing pressure distribution trend sequence is located; record the difference between the numerical mean on the left side and the numerical mean on the right side of the central element in the fracturing identification sequence as the left-right imbalance degree of the fracturing; multiply the mean of the numerical differences between the elements in the fracturing identification sequence and the central element by the left-right imbalance degree of the fracturing to obtain the fracturing identification degree of the fracturing identification sequence; The fracturing recognition degree is segmented by threshold value, and divided into a basic judgment class and a fracture recognition class; the recognition gap between the basic judgment class and the fracture recognition class is calculated; the recognition gap is compared with the preset judgment threshold to determine the time when the fracture appears when the oil well is temporarily plugged and turned to repeated fracturing.

2. A composite temporary plugging and diverting repeated fracturing method according to claim 1, characterized in that: The construction process of the casing pressure distribution trend sequence includes: The elements in the window centered at each acquisition moment in the casing pressure sequence of the oil well are used to form a casing pressure subsequence at each acquisition moment; Get the sign function value of the difference between the position numbers of the maximum value and the minimum value in the casing pressure subsequence; Get the range of the casing pressure subsequence and the mean of the difference sequence; The product of the sign function value, the range and the mean of the difference sequence is taken as the casing pressure distribution trend of the casing pressure subsequence; The casing pressure distribution trend quantities of the casing pressure subsequences at all acquisition moments are combined into a casing pressure distribution trend sequence.

3. A composite temporary plugging and diverting repeated fracturing method according to claim 1, characterized in that: The method for determining the fracturing recognition degree of the fracturing recognition sequence includes: determining a fracturing vibration amplitude value of the fracturing identification sequence based on a numerical difference between the elements in the fracturing identification sequence and the central element; Based on the numerical difference between the two sides of the central element of the fracturing identification sequence, the left-right imbalance of the fracturing identification sequence is determined; The fracturing recognition degree of the fracturing recognition sequence is determined based on the fracturing vibration amplitude value and the left-right imbalance degree of the fracturing.

4. A composite temporary plugging and diverting repeated fracturing method as claimed in claim 3, characterized in that: The method for determining the fracturing vibration amplitude value of the fracturing identification sequence includes: The numerical difference between each element in the fracturing identification sequence and the central element is calculated respectively, and the average value of all the differences calculated in the fracturing identification sequence is taken as the fracturing vibration amplitude value of the fracturing identification sequence.

5. A composite temporary plugging and diverting repeated fracturing method as claimed in claim 3, characterized in that: The left-right imbalance of the fracturing identification sequence is the difference between the mean values ​​of the elements on both sides of the central element of the fracturing identification sequence.

6. A composite temporary plugging and diverting repeated fracturing method as claimed in claim 3, characterized in that: The fracturing recognition degree of the fracturing recognition sequence is obtained by multiplying the fracturing vibration amplitude value by the left-right imbalance degree of the fracturing.

7. A composite temporary plugging and diverting repeated fracturing method according to claim 1, characterized in that: The division method is: Obtaining the segmentation threshold of the fracturing recognition degree of all fracturing recognition sequences; The fracturing recognition degrees less than the segmentation threshold are grouped into the basic judgment class; the fracturing recognition degrees greater than or equal to the segmentation threshold are grouped into the fracture recognition class.

8. A composite temporary plugging and diverting repeated fracturing method according to claim 1, characterized in that: The calculation process of the identification gap is: Get the maximum value in the judgment base class; get the minimum value in the crack identification class; The difference between the minimum and maximum values ​​is used as the identification gap between the basic class and the crack identification class.

9. A composite temporary plugging and diverting repeated fracturing method according to claim 1, characterized in that: The method for determining the crack occurrence time includes: When the identification gap is smaller than the preset judgment threshold, it is determined that no cracks occur in the oil well; Otherwise, the time corresponding to all elements in the fracture identification class is taken as the time when the fractures of the oil wells appear.

10. A composite temporary plugging and diverting re-fracturing system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of a composite temporary plugging and re-fracturing method as described in any one of claims 1 to 9 are implemented.

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