Method for predicting lost circulation length of cement sheath interface, program product and equipment

Abstract

The application discloses a cementing cement sheath interface seal loss length prediction method, a program product and equipment, and the method comprises the following steps: determining interface cracking toughness based on mechanical parameters and fracturing fluid performance parameters; determining interface crack propagation rate in each unit well section based on interface crack propagation time in the unit well section and unit well section length; determining interface fracture toughness of the unit well section based on the mechanical parameters and the interface crack propagation rate in the unit well section; determining cementing cement sheath interface seal loss length in the unit well section based on microseismic data, the interface cracking toughness and the interface fracture toughness of the unit well section; and summing up the cementing cement sheath interface seal loss length in each unit well section to obtain the cementing cement sheath interface seal loss length of the to-be-measured fracturing section. The technical scheme provided by the application can improve the accuracy of cementing cement sheath interface seal loss length prediction.

Description

Technical Field

[0001] This application belongs to the field of cement sheath interface unsealing length detection technology, and particularly relates to a method, program product and equipment for predicting cement sheath interface unsealing length. Background Technology

[0002] Cement sheaths are the core barrier ensuring the sealing of the target well. The cement sheath interface, as the weakest unit in the cemented annulus sealing barrier, directly affects the safe and long-term operation of oil and gas wells during fracturing and other operations. However, during fracturing, the fluid load of the fracturing fluid acts on the cement sheath interface, potentially causing interface cracks that continuously propagate along the wellbore axis. If these interface cracks connect to adjacent fracturing sections or the cemented annulus, it significantly reduces the effectiveness of fracturing operations and impacts wellbore safety. Therefore, accurately predicting the unsealing length of the cement sheath interface (i.e., the length of the cracks at the cement sheath interface) is crucial for adjusting operational parameters promptly based on the unsealing status, preventing further deterioration. Thus, improving the accuracy of predicting the unsealing length of the cement sheath interface is a pressing technical problem that needs to be solved. Summary of the Invention

[0003] The embodiments of this application provide a method, program product, and equipment for predicting the unsealing length of the cement sheath interface, thereby improving the accuracy of predicting the unsealing length of the cement sheath interface.

[0004] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0005] According to a first aspect of the present application, a method for predicting the unsealing length of the cement sheath interface is provided. The method comprises: acquiring fracturing fluid performance parameters of a target well and mechanical parameters of a fracturing section to be tested in the target well, and determining the interface fracture initiation toughness based on the mechanical parameters and the fracturing fluid performance parameters; acquiring the interface fracture propagation time within each unit segment of the fracturing section to be tested, and determining the interface fracture propagation rate within each unit segment based on the interface fracture propagation time within each unit segment and the length of the unit segment; determining the interface fracture toughness within each unit segment based on the mechanical parameters and the interface fracture propagation rate within each unit segment; acquiring microseismic data of the fracturing section to be tested under the condition of interface fracture, and determining the unsealing length of the cement sheath interface within each unit segment based on the microseismic data, the interface fracture initiation toughness, and the interface fracture toughness within each unit segment; and summing the unsealing lengths of the cement sheath interface in each unit segment to obtain the unsealing length of the cement sheath interface in the fracturing section to be tested.

[0006] In some embodiments of this application, based on the aforementioned scheme, the mechanical parameters include the shear modulus, elastic modulus, and Poisson's ratio of the casing and cement sheath on both sides of the cement sheath interface, the shear modulus, elastic modulus, and Poisson's ratio of the cement sheath and formation on both sides of the cement sheath interface, the cement bond strength at the cement sheath interface, the contact pressure at the cement sheath interface, the effective elastic modulus, and the effective shear modulus; the fracturing fluid performance parameters include fracturing flow rate, fracturing fluid viscosity, and fracturing fluid fluid load.

[0007] In some embodiments of this application, based on the foregoing scheme, the interface crack initiation toughness is determined by the following formula:

[0008]

[0009]

[0010]

[0011] Where K1 represents the interfacial crack initiation toughness, p represents the fracturing fluid load, and σ r ε represents the stress perpendicular to the cement sheath interface, r represents the initial length of the interface crack, i represents the imaginary unit, ε is a dual material constant, and μ1 and μ2 represent the shear moduli of the casing and cement sheath on both sides of the cement sheath interface, or the shear moduli of the cement sheath and formation on both sides of the cement sheath interface.

[0012] In some embodiments of this application, based on the foregoing scheme, obtaining the interface fracture propagation time within each unit well segment of the fracturing section to be tested includes: determining the initial time when the interface fracture propagates to the starting point of each unit well segment and the ending time when the interface fracture propagates to the ending point of each unit well segment; calculating the time difference between the ending time and the initial time as the interface fracture propagation time within each unit well segment.

[0013] In some embodiments of this application, based on the foregoing scheme, the interfacial fracture toughness of each unit well section is determined by the following formula:

[0014]

[0015] δ2=v t t

[0016]

[0017]

[0018] Where K2 represents the interfacial fracture toughness, δ2 is the unit propagation length of the interfacial crack along the wellbore axis, δ1 is the normal propagation dimension of the interfacial crack, i represents the imaginary unit, ε is the dual material constant, and E* For the effective elastic modulus, v t q represents the interfacial fracture propagation rate within each unit well section, t represents the interfacial fracture propagation time within each unit well section, and q represents the interfacial fracture propagation time. f Where μ is the fracturing fluid displacement, and μ is the fracturing fluid viscosity. Let be the differential of the initial length of the interface crack. E1 and E2 represent the elastic moduli of the casing and cement sheath on both sides of the cement sheath interface, respectively, or the elastic moduli of the cement sheath and formation on both sides of the cement sheath interface, respectively. v1 and v2 represent the Poisson's ratios of the casing and cement sheath on both sides of the cement sheath interface, respectively, or the Poisson's ratios of the cement sheath and formation on both sides of the cement sheath interface, respectively.

[0019] In some embodiments of this application, based on the foregoing scheme, the unsealing length of the cement sheath interface within each unit well section is determined by the following formula:

[0020]

[0021]

[0022]

[0023] Where l represents the length of the cement sheath interface loss within each unit well section, K1 represents the interface crack initiation toughness, K2 represents the interface fracture toughness, and μ * For the effective shear modulus, δ1 is the normal propagation size of the interface crack, and C l C represents the P-wave velocity in the microseismic data. s v is the shear wave velocity in the microseismic data. t This represents the rate of interface fracture propagation within each unit well section.

[0024] In some embodiments of this application, based on the foregoing scheme, the method further includes: determining the unsealing length of the cement sheath interface of an adjacent fracturing section, wherein the adjacent fracturing section is adjacent to the fracturing section to be tested; determining the perforation cluster spacing between the perforation cluster of the fracturing section to be tested and the perforation cluster of the adjacent fracturing section; and determining whether the unsealing length of the cement sheath interface of the fracturing section to be tested is accurate based on the unsealing length of the cement sheath interface of the adjacent fracturing section and the perforation cluster spacing.

[0025] In some embodiments of this application, based on the aforementioned scheme, determining the accuracy of the unsealing length of the cement sheath interface of the fractured section to be tested based on the unsealing length of the cement sheath interface of the adjacent fractured sections and the perforation cluster spacing includes: if the difference between the sum of the unsealing length of the cement sheath interface of the adjacent fractured sections and the unsealing length of the cement sheath interface of the fractured section to be tested and the perforation cluster spacing is less than or equal to a preset threshold, then the unsealing length of the cement sheath interface of the fractured section to be tested is accurate; if the difference between the sum of the unsealing length of the cement sheath interface of the adjacent fractured sections and the unsealing length of the cement sheath interface of the fractured section to be tested and the perforation cluster spacing is greater than a preset threshold, then the unsealing length of the cement sheath interface of the fractured section to be tested is inaccurate.

[0026] According to a second aspect of the embodiments of this application, a computer program product is provided, the computer program product including computer instructions stored in a computer-readable storage medium and adapted to be read and executed by a processor to cause a computer device having the processor to perform an operation as described in any of the embodiments of the first aspect above.

[0027] According to a third aspect of the embodiments of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing at least one computer program instruction, the at least one computer program instruction being loaded and executed by a processor to perform the operation performed by the method described in any of the embodiments of the first aspect above.

[0028] According to a fourth aspect of the present application, an electronic device is provided, the electronic device including one or more processors and one or more memories, the one or more memories storing at least one computer program instruction, the at least one computer program instruction being loaded and executed by the one or more processors to perform the operation performed by the method as described in any of the embodiments of the first aspect above.

[0029] In this application, the interfacial fracture initiation toughness is first determined by the fracturing fluid performance parameters of the target well and the mechanical parameters of the fracturing section to be tested. Then, the interfacial fracture propagation rate within each unit well section is determined based on the interfacial fracture propagation time and the unit well section length. This avoids the impact of different propagation rates of interfacial fractures in different unit well sections on subsequent data processing. By measuring the propagation rate in each unit well section separately, the accuracy of the obtained interfacial fracture propagation rate can be improved, thereby improving the accuracy of predicting the cement sheath interface unsealing length. The interfacial fracture propagation rate within each unit well section and the mechanical parameters are used to determine the interfacial fracture initiation toughness. The parameters determine the interface fracture toughness of each unit well section. Then, using the microseismic data, the interface fracture initiation toughness, and the interface fracture toughness of each unit well section, the cement sheath interface unsealing length within each unit well section is determined. This further improves the accuracy of the data processing. Finally, the cement sheath interface unsealing lengths within each unit well section are summed to obtain the cement sheath interface unsealing length of the fractured section to be tested. In this way, the interference of different propagation rates of interface fractures within each unit well section on the prediction results of the cement sheath interface unsealing length can be avoided, ultimately improving the accuracy of the prediction results.

[0030] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0032] Figure 1 A schematic diagram of a target well is shown in one embodiment of this application;

[0033] Figure 2 A schematic diagram of the fracturing section in a target well is shown in one embodiment of this application;

[0034] Figure 3 A flowchart of a method for predicting the unsealing length of cement sheath interface in a cementing application according to one embodiment is shown;

[0035] Figure 4 This paper illustrates a schematic diagram of the microseismic acoustic signal of the fractured segment under test in one embodiment of this application.

[0036] Figure 5This paper illustrates a schematic diagram of the microseismic acoustic signal of the fractured segment under test in one embodiment of this application.

[0037] Figure 6 This paper illustrates a schematic diagram of the microseismic acoustic signal of the fractured segment under test in one embodiment of this application.

[0038] Figure 7 This paper illustrates a schematic diagram of the microseismic acoustic signal of the fractured segment under test in one embodiment of this application.

[0039] Figure 8 A schematic diagram of the interface fracture propagation rate of a portion of a unit well section in one embodiment of this application is shown;

[0040] Figure 9 A schematic diagram showing the relationship between interfacial fracture toughness and interfacial crack propagation rate in one embodiment of this application is shown.

[0041] Figure 10 A schematic diagram of the structure of an electronic device according to one embodiment of this application is shown. Detailed Implementation

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

[0043] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0044] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0045] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0046] It should also be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of these terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described.

[0047] To enable those skilled in the art to better understand this application, the following will be combined with Figure 1 and Figure 2 This paper provides a brief explanation of the unsealing length of the cement sheath interface proposed in this application.

[0048] See Figure 1 The diagram shows a target well in one embodiment of this application.

[0049] See Figure 2 The diagram shows a schematic of the fracturing section in a target well according to one embodiment of this application.

[0050] like Figure 1 As shown, the target well is located in formation 102 and contains casing 101 and cementing sheath 103. The cementing sheath interface can be the interface between the inner side of formation 102 and the outer side of cementing sheath 103, or it can be the interface between the inner side of cementing sheath 103 and the outer side of casing 101. Furthermore, the fracturing section 105 is a well section centered on perforation cluster 104, details of which are as follows... Figure 2 As shown, each fracturing section 105 may include multiple unit well sections 106.

[0051] The cement sheath is the core barrier ensuring the sealing of the target well. The cement sheath interface, as the weakest unit in the cemented annulus sealing barrier, is crucial for the safe and long-term operation of oil and gas wells. Effective bonding of the cement sheath interface during fracturing and other operations ensures its sealing. However, during fracturing, the fracturing fluid load on the cement sheath interface can cause interface cracks that continuously extend along the wellbore axis. If these cracks connect to adjacent fracturing sections or the cemented annulus, the fracturing effect will be significantly reduced, impacting wellbore safety. Therefore, accurately predicting the unsealing length of the cement sheath interface (i.e., the length of the cracks at the interface) is essential to adjust operational parameters promptly based on the unsealing status and prevent further deterioration. Based on this, the inventors of this application propose a method for predicting the unsealing length of the cement sheath interface to improve its accuracy.

[0052] Next, we will combine Figure 3 This paper elaborates on the method for predicting the unsealing length of the cement sheath interface proposed in this application.

[0053] See Figure 3 The figure shows a flowchart of a method for predicting the unsealing length of the cement sheath interface in a cementing application according to one embodiment of the present application. As shown, the method may include at least steps 310 to 350:

[0054] Step 310: Obtain the fracturing fluid performance parameters of the target well and the mechanical parameters of the fracturing section to be tested in the target well, and determine the interface fracturing toughness based on the mechanical parameters and the fracturing fluid performance parameters.

[0055] Step 320: Obtain the interface fracture propagation time in each unit well segment of the fracturing section to be tested, and determine the interface fracture propagation rate in each unit well segment based on the interface fracture propagation time in each unit well segment and the length of the unit well segment.

[0056] Step 330: Determine the interface fracture toughness of each unit well section based on the mechanical parameters and the interface crack propagation rate within each unit well section.

[0057] Step 340: Obtain microseismic data of the fractured section under test when interface cracks occur, and based on the microseismic data, the interface crack initiation toughness and the interface fracture toughness of each unit well section, determine the cement sheath interface unsealing length in each unit well section.

[0058] Step 350: Sum the unsealed lengths of the cement sheath interface in each unit well section to obtain the unsealed length of the cement sheath interface in the fracturing section to be tested.

[0059] In this application, the unit well section length can be 5m or 10m, or other lengths depending on actual needs. This application does not make any specific limitation on this.

[0060] In this application, the mechanical parameters may include at least the shear modulus, elastic modulus, and Poisson's ratio of the casing on both sides of the cement sheath interface, the shear modulus, elastic modulus, and Poisson's ratio of the cement sheath and the formation, the cement sheath interface bonding strength, the cement sheath interface contact pressure, the effective elastic modulus, and the effective shear modulus; the fracturing fluid performance parameters may include at least the fracturing flow rate, the fracturing fluid viscosity, and the fracturing fluid fluid load; the microseismic data may include at least the shear wave velocity and the P-wave velocity of the microseismic data.

[0061] In this application, the interfacial fracture initiation toughness is first determined by the fracturing fluid performance parameters of the target well and the mechanical parameters of the fracturing section to be tested. Then, the interfacial fracture propagation rate within each unit well section is determined based on the interfacial fracture propagation time and the unit well section length. This avoids the impact of different propagation rates of interfacial fractures in different unit well sections on subsequent data processing. By measuring the propagation rate in each unit well section separately, the accuracy of the obtained interfacial fracture propagation rate can be improved, thereby improving the accuracy of predicting the cement sheath interface unsealing length. The interfacial fracture propagation rate within each unit well section and the mechanical parameters are used to determine the interfacial fracture initiation toughness. The parameters determine the interface fracture toughness of each unit well section. Then, using the microseismic data, the interface fracture initiation toughness, and the interface fracture toughness of each unit well section, the cement sheath interface unsealing length within each unit well section is determined. This further improves the accuracy of the data processing. Finally, the cement sheath interface unsealing lengths within each unit well section are summed to obtain the cement sheath interface unsealing length of the fractured section to be tested. In this way, the interference of different propagation rates of interface fractures within each unit well section on the prediction results of the cement sheath interface unsealing length can be avoided, ultimately improving the accuracy of the prediction results.

[0062] In step 310 above, the interfacial crack initiation toughness can be determined using the following formulas (1) to (3):

[0063]

[0064]

[0065]

[0066] Where K1 represents the interfacial crack initiation toughness, p represents the fracturing fluid load, and σ rε represents the stress perpendicular to the cement sheath interface, r represents the initial length of the interface crack, i represents the imaginary unit, ε is a dual material constant, and μ1 and μ2 represent the shear moduli of the casing and cement sheath on both sides of the cement sheath interface, or the shear moduli of the cement sheath and formation on both sides of the cement sheath interface.

[0067] In this application, σ r The stress perpendicular to the cement sheath interface is numerically equal to the sum of the cement sheath interface bonding strength and the interface contact pressure. r represents the initial length of the interface crack, which can be determined based on the historical cement sheath interface unsealing length.

[0068] In one specific embodiment, the fracturing displacement of the fracturing section to be tested can be 12m³. 3 The target well has a fracturing fluid pressure of 70 MPa / min, a casing pressure of 45 MPa, and parameters including a wellbore pressure of 46 MPa during solidification, a maximum fracturing pressure of 85 MPa, and a fracturing fluid density of 1.04 g / cm³. 3 The viscosity can be 50 mPa·s. Based on formulas (1) to (3), the crack initiation toughness of the cement sheath interface to be tested can be obtained as 1.2 MPa·m. 0.5 .

[0069] In step 320 above, obtaining the interface fracture propagation time within each unit well section of the fracturing segment to be tested can be specifically performed according to steps 321 to 322 as follows:

[0070] Step 321: Determine the initial time when the interface crack extends to the starting point of each unit well segment and the ending time when the interface crack extends to the ending point of each unit well segment.

[0071] Step 322: Calculate the time difference between the end time and the initial time, as the interface fracture propagation time within each unit well section.

[0072] In this application, please refer to Figure 4 , Figure 5 , Figure 6 ,as well as Figure 7 Each of these illustrations shows a schematic diagram of the microseismic acoustic signal of the fractured segment under test in one embodiment of this application. Figure 4 At 13:07:22, no interface cracks were observed in well section 2945. Figure 5 In the 2945m well section, 13:17:46 marks the initial time of the interface fracture propagation to the starting point of the 2945m well section. Figure 6In the process, the interface fracture extended to the starting point of well section 2940 at 13:35:37, which is also the ending point of well section 2945. This time is the end time of the fracture extension to the end point of well section 2945. The time difference between 13:35:37 and 13:17:46 is the interface fracture extension time in well section 2945. Finally, in Figure 7 If the interface fracture extends to well section 2935 at 14:00:28, then the time difference between 14:00:28 and 13:35:37 is the interface fracture extension time of well section 2940.

[0073] In this application, please refer to Figure 8 The diagram shows the interface crack propagation rate of a portion of a unit well section in one embodiment of this application. It can be seen from the diagram that the interface crack propagation rate is different in different unit well sections. Therefore, calculating the interface crack propagation rate in each unit well section can improve the accuracy of the interface crack propagation rate calculation, and thus improve the accuracy of the prediction result of the cement sheath interface unsealing length.

[0074] In step 330 above, the interfacial fracture toughness of each unit well section can be determined by the following formulas (4) to (7):

[0075]

[0076] δ2=v t t (5)

[0077]

[0078]

[0079] Where K2 represents the interfacial fracture toughness, δ2 is the unit propagation length of the interfacial crack along the wellbore axis, δ1 is the normal propagation dimension of the interfacial crack, i represents the imaginary unit, ε is the dual material constant, and E * For the effective elastic modulus, v t q represents the interfacial fracture propagation rate within each unit well section, t represents the interfacial fracture propagation time within each unit well section, and q represents the interfacial fracture propagation time. f Where μ is the fracturing fluid displacement, and μ is the fracturing fluid viscosity. Let be the differential of the initial length of the interface crack. E1 and E2 represent the elastic moduli of the casing and cement sheath on both sides of the cement sheath interface, respectively, or the elastic moduli of the cement sheath and formation on both sides of the cement sheath interface, respectively. v1 and v2 represent the Poisson's ratios of the casing and cement sheath on both sides of the cement sheath interface, respectively, or the Poisson's ratios of the cement sheath and formation on both sides of the cement sheath interface, respectively.

[0080] For details, please refer to this application. Figure 9 The diagram illustrates the relationship between interfacial fracture toughness and interfacial crack propagation rate in one embodiment of this application. It shows that different interfacial crack propagation rates allow for the calculation of the corresponding interfacial fracture toughness per unit well section. For example, when the interfacial crack propagation rate is 0.5 m / min, the corresponding unit well section is 2950 well sections, and the corresponding interfacial fracture toughness is 0.34 MPa·m. 0.5 This ensures the accuracy of the calculation of interface fracture toughness in different well sections, thereby improving the accuracy of the prediction results of the cement sheath interface unsealing length.

[0081] In step 340 above, the length of the cement sheath interface loss within each unit well section can be determined using the following formulas (8) to (10):

[0082]

[0083]

[0084]

[0085] Where l represents the length of the cement sheath interface loss within each unit well section, K1 represents the interface crack initiation toughness, K2 represents the interface fracture toughness, and μ * For the effective shear modulus, δ1 is the normal propagation size of the interface crack, and C l C represents the P-wave velocity in the microseismic data. s v is the shear wave velocity in the microseismic data. t This represents the rate of interface fracture propagation within each unit well section.

[0086] In one specific embodiment, the interfacial fracture toughness of each unit well section of the fracturing section to be tested is 0.34 MPa·m. 0.5 0.46 MPa·m 0.5 0.58 MPa·m 0.5 The interfacial crack initiation toughness of the fractured section under test is 1.2 MPa·m. 0.5 The shear wave velocity of the microseismic wave is 3.5 km / s and the longitudinal wave velocity is 6.5 km / s. Based on formulas (8) to (10), the unsealed length of the cement sheath interface of each unit well section can be calculated. After summing them, the unsealed length of the cement sheath interface of the fractured section to be tested is 16.8 m.

[0087] In this application, by calculating the unsealing length of the cement sheath interface in each unit well section, the accuracy of data processing can be improved, and the influence of the different propagation rates of interface cracks in different unit well sections on the calculation results can be avoided, thereby improving the accuracy of the unsealing length of the cement sheath interface in each unit well section, and thus improving the accuracy of the prediction results of the unsealing length of the cement sheath interface.

[0088] The method for predicting the unsealing length of the cement sheath interface proposed in this application can also be performed according to the following steps 360 to 380:

[0089] Step 360: Determine the unsealed length of the cement sheath interface of the adjacent fracturing section, wherein the adjacent fracturing section is adjacent to the fracturing section to be tested.

[0090] Step 370: Determine the perforation cluster spacing between the perforation cluster of the fractured section to be tested and the perforation cluster of the adjacent fractured section.

[0091] Step 380: Determine whether the length of the cement sheath interface loss in the fractured section to be tested is accurate based on the length of the cement sheath interface loss in the adjacent fractured section and the perforation cluster spacing.

[0092] In step 380 above, the accuracy of determining the unsealing length of the cement sheath interface of the fractured section to be tested based on the unsealing length of the cement sheath interface of the adjacent fractured section and the perforation cluster spacing can be specifically performed according to steps 381 to 382 as follows:

[0093] Step 381: If the difference between the sum of the unsealed length of the cement sheath interface of the adjacent fracturing section and the unsealed length of the cement sheath interface of the fracturing section to be tested and the perforation cluster spacing is less than or equal to a preset threshold, it indicates that the unsealed length of the cement sheath interface of the fracturing section to be tested is accurate.

[0094] Step 382: If the difference between the sum of the unsealed length of the cement sheath interface of the adjacent fracturing section and the unsealed length of the cement sheath interface of the fracturing section to be tested and the perforation cluster spacing is greater than a preset threshold, it indicates that the unsealed length of the cement sheath interface of the fracturing section to be tested is inaccurate.

[0095] In this application, the determination of the unsealed length of the cement sheath interface between adjacent fracturing sections can be specifically performed according to the method described in steps 310 to 350.

[0096] In this application, the preset threshold can be 1.5m, or other parameters as needed. This application does not impose any specific limitations on this.

[0097] In one specific embodiment, pressure fluctuations occurred between adjacent fracturing sections during the fracturing process. The fracturing operation time was 15:20:11, and the fracturing displacement was 12.6 m³. 3 The casing pressure was 62 MPa; the interface fracture propagation rates of each unit section in adjacent fracturing sections were 0.6 m / min, 0.55 m / min, and 0.38 m / min, respectively; the interface unsealing length of adjacent fracturing sections was calculated to be 21.9 m using the above method. Further measurements showed that the perforation cluster spacing between the tested fracturing section and the adjacent fracturing section was 40 m. The sum of the cement sheath interface unsealing length of the adjacent fracturing section and the cement sheath interface unsealing length of the tested fracturing section was calculated to be 38.7 m, with a difference of 1.3 m, which is less than the preset threshold of 1.5 m, indicating that the calculation of the cement sheath interface unsealing length of the tested fracturing section was accurate.

[0098] In this application, it is necessary to analyze the pressure fluctuation during the fracturing process of adjacent fracturing sections. If pressure fluctuation exists, it indicates that fracturing fluid crosstalk has occurred between the current fracturing section and the adjacent fracturing section. That is, the fracturing fluid of the fracturing section under test may enter the adjacent fracturing section through the interface fracture. At this time, the sum of the unsealing length of the cement sheath interface between the fracturing section under test and the adjacent fracturing section is the perforation cluster spacing between the fracturing section under test and the adjacent fracturing section. Based on this, the prediction result of the unsealing length of the cement sheath interface of the fracturing section under test can be judged, which can improve the accuracy of the prediction of the unsealing length of the cement sheath interface.

[0099] In this application, the interfacial fracture initiation toughness is first determined by the fracturing fluid performance parameters of the target well and the mechanical parameters of the fracturing section to be tested. Then, the interfacial fracture propagation rate within each unit well section is determined based on the interfacial fracture propagation time and the unit well section length. This avoids the impact of different propagation rates of interfacial fractures in different unit well sections on subsequent data processing. By measuring the propagation rate in each unit well section separately, the accuracy of the obtained interfacial fracture propagation rate can be improved, thereby improving the accuracy of predicting the cement sheath interface unsealing length. The interfacial fracture propagation rate within each unit well section and the mechanical parameters are used to determine the interfacial fracture initiation toughness. The parameters determine the interface fracture toughness of each unit well section. Then, using the microseismic data, the interface fracture initiation toughness, and the interface fracture toughness of each unit well section, the cement sheath interface unsealing length within each unit well section is determined. This further improves the accuracy of the data processing. Finally, the cement sheath interface unsealing lengths within each unit well section are summed to obtain the cement sheath interface unsealing length of the fractured section to be tested. In this way, the interference of different propagation rates of interface fractures within each unit well section on the prediction results of the cement sheath interface unsealing length can be avoided, ultimately improving the accuracy of the prediction results.

[0100] Based on the same inventive concept, embodiments of this application provide a computer program product, the computer program product including computer instructions stored in a computer-readable storage medium and adapted to be read and executed by a processor to cause a computer device having the processor to perform the operations performed as described above.

[0101] Based on the same inventive concept, embodiments of this application provide a computer-readable storage medium storing at least one computer program instruction, which is loaded and executed by a processor to perform the operations described above.

[0102] Figure 10 A schematic diagram of the structure of an electronic device according to one embodiment of this application is shown.

[0103] Based on the same inventive concept, embodiments of this application also provide an electronic device. (Reference) Figure 10 The diagram shows a schematic of the structure of an electronic device according to an embodiment of this application. The electronic device includes one or more memories 1004, one or more processors 1002, and at least one computer program (program code) stored in the memory 1004 and executable on the processor 1002. When the processor 1002 executes the computer program, it implements the method described above.

[0104] Among them, Figure 10 In this document, a bus architecture (represented by bus 1000) is used. Bus 1000 may include any number of interconnected buses and bridges, linking various circuits including one or more processors represented by processor 1002 and memory represented by memory 1004. Bus 1000 may also link various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. Bus interface 1005 provides an interface between bus 1000 and receiver 1001 and transmitter 1003. Receiver 1001 and transmitter 1003 may be the same element, i.e., a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 1002 is responsible for managing bus 1000 and general processing, while memory 1004 can be used to store data used by processor 1002 during operation.

[0105] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and embodiments are within the scope and spirit of this application and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Furthermore, the functional units may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit.

[0106] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0107] The units described as separate components may or may not be physically separate. Similarly, the components of the control device may or may not be physical units; they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0108] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard drive, magnetic disk, or optical disk.

[0109] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for predicting the unsealing length of the cement sheath interface in well cementing, characterized in that, The method includes: Obtain the fracturing fluid performance parameters of the target well and the mechanical parameters of the fracturing section to be tested in the target well, and determine the interface fracturing toughness based on the mechanical parameters and the fracturing fluid performance parameters; The interface fracture propagation time in each unit well section of the fracturing section to be tested is obtained, and the interface fracture propagation rate in each unit well section is determined based on the interface fracture propagation time in each unit well section and the length of the unit well section. The interfacial fracture toughness of each unit well section is determined based on the mechanical parameters and the interfacial crack propagation rate within each unit well section. Acquire microseismic data of the fractured section under test when interface cracks occur, and based on the microseismic data, the interface crack initiation toughness and the interface fracture toughness of each unit well section, determine the cement sheath interface unsealing length in each unit well section. The unsealed length of the cement sheath interface in each unit well section is summed to obtain the unsealed length of the cement sheath interface in the fracturing section to be tested.

2. The method according to claim 1, characterized in that, The mechanical parameters include the shear modulus, elastic modulus and Poisson's ratio of the casing, cement sheath and formation on both sides of the cement sheath interface, the cement bond strength at the cement sheath interface, the contact pressure at the cement sheath interface, the effective elastic modulus and the effective shear modulus; the fracturing fluid performance parameters include fracturing flow rate, fracturing fluid viscosity and fracturing fluid fluid load.

3. The method according to claim 1, characterized in that, The interfacial crack initiation toughness is determined by the following formula: Where K1 represents the interfacial crack initiation toughness, p represents the fracturing fluid load, and σ r ε represents the stress perpendicular to the cement sheath interface, r represents the initial length of the interface crack, i represents the imaginary unit, ε is a dual material constant, and μ1 and μ2 represent the shear moduli of the casing and cement sheath on both sides of the cement sheath interface, or the shear moduli of the cement sheath and formation on both sides of the cement sheath interface.

4. The method according to claim 1, characterized in that, The process of obtaining the interface fracture propagation time within each unit well section of the fracturing segment to be tested includes: Determine the initial time when the interface fracture extends to the starting point of each unit well segment and the ending time when the interface fracture extends to the ending point of each unit well segment; The time difference between the end time and the initial time is calculated as the interface fracture propagation time within each unit well section.

5. The method according to claim 1, characterized in that, The interfacial fracture toughness of each unit well section is determined by the following formula: δ2=v t t Where K2 represents the interfacial fracture toughness, δ2 is the unit propagation length of the interfacial crack along the wellbore axis, δ1 is the normal propagation dimension of the interfacial crack, i represents the imaginary unit, ε is the dual material constant, and E * For the effective elastic modulus, v t q represents the interfacial fracture propagation rate within each unit well section, t represents the interfacial fracture propagation time within each unit well section, and q represents the interfacial fracture propagation time. f Where μ is the fracturing fluid displacement, and μ is the fracturing fluid viscosity. Let be the differential of the initial length of the interface crack. E1 and E2 represent the elastic moduli of the casing and cement sheath on both sides of the cement sheath interface, respectively, or the elastic moduli of the cement sheath and formation on both sides of the cement sheath interface, respectively. v1 and v2 represent the Poisson's ratios of the casing and cement sheath on both sides of the cement sheath interface, respectively, or the Poisson's ratios of the cement sheath and formation on both sides of the cement sheath interface, respectively.

6. The method according to claim 1, characterized in that, The length of the cement sheath interface loss within each unit well section is determined by the following formula: Where l represents the length of the cement sheath interface loss within each unit well section, K1 represents the interface crack initiation toughness, K2 represents the interface fracture toughness, and μ * For the effective shear modulus, δ1 is the normal propagation size of the interface crack, and C l C represents the P-wave velocity in the microseismic data. s v is the shear wave velocity in the microseismic data. t This represents the rate of interface fracture propagation within each unit well section.

7. The method according to claims 1 to 6, characterized in that, The method further includes: Determine the unsealing length of the cement sheath interface of adjacent fracturing sections, wherein the adjacent fracturing sections are adjacent to the fracturing section to be tested; Determine the perforation cluster spacing between the perforation cluster of the fractured section to be tested and the perforation cluster of the adjacent fractured section; The accuracy of determining the length of the cement sheath interface loss in the fractured section to be tested based on the length of the cement sheath loss between adjacent fractured sections and the perforation cluster spacing is questionable.

8. The method according to claim 7, characterized in that, The determination of the accuracy of the cement sheath interface loss length of the fractured section under test based on the cement sheath interface loss length of the adjacent fractured sections and the perforation cluster spacing includes: If the difference between the sum of the unsealed length of the cement sheath interface of the adjacent fracturing section and the unsealed length of the cement sheath interface of the fracturing section to be tested and the perforation cluster spacing is less than or equal to a preset threshold, it indicates that the unsealed length of the cement sheath interface of the fracturing section to be tested is accurate. If the difference between the sum of the unsealed length of the cement sheath interface of the adjacent fracturing section and the unsealed length of the cement sheath interface of the fracturing section to be tested and the perforation cluster spacing is greater than a preset threshold, it indicates that the unsealed length of the cement sheath interface of the fracturing section to be tested is inaccurate.

9. A computer program product, characterized in that, The computer program product includes computer instructions stored in a computer-readable storage medium and adapted to be read and executed by a processor to cause a computer device having the processor to perform the method of any one of claims 1 to 8.

10. An electronic device, characterized in that, The electronic device includes one or more processors and one or more memories, wherein at least one piece of program code is stored in the one or more memories, and the at least one piece of program code is loaded and executed by the one or more processors to perform the operation performed by the method as described in any one of claims 1 to 8.

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