Nuclear magnetic resonance logging T2 spectrum borehole expanding correction method, device, equipment and medium
By analyzing the relationship between the borehole diameter curve and the T2 spectrum morphology changes in nuclear magnetic resonance logging, the T2 value of mud filtrate was determined and the echo train signal was corrected, thus solving the T2 spectrum error problem caused by borehole enlargement and improving the accuracy of reservoir parameter interpretation.
Patent Information
- Application Number
- CN202410925880.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-11
- Publication Date
- 2026-01-13
AI Technical Summary
In nuclear magnetic resonance logging, the mud filtrate signal caused by wellbore enlargement affects T2 spectrum measurement, leading to errors in reservoir parameter calculation, and a correction method is urgently needed.
By analyzing the relationship between the wellbore curve and the T2 spectrum morphology changes of nuclear magnetic resonance logging, the T2 value of mud filtrate was determined, the echo train was re-inverted to calculate the porosity of mud filtrate, and the echo train signal was corrected to obtain the corrected T2 spectrum.
It improves the accuracy of reservoir parameter interpretation in nuclear magnetic resonance logging, reduces porosity error in the enlarged wellbore section, and enhances the effectiveness of reservoir evaluation.
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Figure CN121322010A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of geophysical logging technology in oil and gas exploration, in particular to a nuclear magnetic resonance logging T2 spectrum borehole enlargement correction method, device, equipment and medium. BACKGROUND
[0002] The T2 spectrum measured by nuclear magnetic resonance logging is independent of lithology, which can provide accurate porosity and pore structure information for reservoirs, and has achieved extensive and good application effects in unconventional reservoir and complex reservoir evaluation.
[0003] During nuclear magnetic resonance logging, affected by borehole enlargement, the nuclear magnetic logging signal contains part of the mud filtrate signal, and the measured T2 spectrum cannot reflect the true formation condition, which brings huge error to the calculation of reservoir parameters based on nuclear magnetic T2 spectrum. For example, due to the existence of mud filtrate signal in T2 spectrum, the calculated nuclear magnetic porosity will increase, and there will be large error in the reservoir parameters such as bound fluid volume, free fluid volume and permeability calculated by T2 spectrum. The existence of mud filtrate signal in T2 spectrum seriously affects the accuracy of nuclear magnetic resonance logging reservoir parameter interpretation and evaluation. In order to solve the above problems, it is urgent to study the correction method of mud filtrate signal in T2 spectrum. SUMMARY
[0004] Therefore, the present application provides a nuclear magnetic resonance logging T2 spectrum borehole enlargement correction method, device, equipment and medium, by analyzing the change relationship between well diameter and nuclear magnetic resonance logging T2 spectrum form, determining the mud filtrate T2 value and porosity, realizing the borehole enlargement correction of T2 spectrum to eliminate the influence of mud filtrate, and providing more accurate T2 spectrum for logging interpretation personnel for logging reservoir interpretation and evaluation.
[0005] In a first aspect, the embodiments of the present application provide a nuclear magnetic resonance logging T2 spectrum borehole enlargement correction method, comprising:
[0006] determining the mud filtrate T2 value according to the change relationship between the well diameter curve and the nuclear magnetic resonance logging T2 spectrum form;
[0007] re-inverting the measured echo train based on the mud filtrate T2 value, calculating the mud filtrate porosity P mf ;
[0008] calculating the mud filtrate corrected echo train according to the mud filtrate T2 value and the mud filtrate porosity P mf ;
[0009] inverting the corrected echo train to calculate the mud filtrate corrected T2 spectrum.
[0010] In one possible implementation, the step of re-inverting the measured echo train based on the T2 value of the mud filtrate to calculate the porosity of the mud filtrate includes:
[0011] The component distribution of the T2 spectrum is set to obtain the distribution method of the T2 spectrum;
[0012] Based on the distribution of the T2 spectrum, the echo train b of the original measurement is... o Inversion was performed to obtain the T2 spectrum before correction. uc Located in T 2,mf f at the location uc The component is the porosity P of the mud filtrate. mf The calculation formula is as follows:
[0013] P mf =f uc,n
[0014] Among them, f uc,n For T 2,mf f at the location uc Quantity.
[0015] In one possible implementation, the point placement rules for the components of the T2 spectrum are as follows:
[0016] T 2,i =T 2,mf *2 i-n
[0017] Among them, T 2,i The i-th point of the T2 spectral component; T 2,mf Let mf be the T2 value of the mud filtrate; i, m, and n be integers, i = 1, 2, 3, ..., m, where m is the total number of pre-selected T2 spectral components, and m and n satisfy the following conditions:
[0018] T 2,mf *2 -n <T 2,min ≤T 2,mf *2 1-n
[0019] T 2,mf *2 m-1-n <T 2,max ≤T 2,mf *2 m-n
[0020] Among them, T 2,min The minimum value of T2 points, T 2,max This represents the maximum value of the T2 distribution point.
[0021] In one possible implementation, the step is based on the T2 value of the mud filtrate and the porosity P of the mud filtrate.mf Calculate the corrected echo train of the mud filtrate, including:
[0022] Calculate the echo train signal b of the measured mud filtrate mf ;
[0023] Original measurement echo train b o Subtract mud filtrate echo train b mf Obtain echo train b after mud filtrate correction mfc The calculation formula is as follows:
[0024] b mfc,j =b o,j -b mf,j
[0025] Among them, b mfc,j Indicates echo train b mfc The j-th echo, b o,j Indicates echo train b o The j-th echo, b mf,j Indicates echo train b mf The j-th echo.
[0026] In one possible implementation, the echo train signal b mf The calculation formula is as follows:
[0027]
[0028] Among them, b mf,j Indicates echo train b mf The j-th echo; TE is the echo interval of the echo train; T 2,mf The T2 value of the determined mud filtrate; P mf Porosity of mud filtrate.
[0029] In one possible implementation, the step of inverting the corrected echo train to calculate the corrected T2 spectrum of the mud filtrate includes:
[0030] The proportion of mud volume to total volume within the detection area of the calculation instrument is s. mf ;
[0031] According to the ratio s of the mud volume to the total volume mf Calculate the final corrected echo train b c The calculation formula is as follows:
[0032]
[0033] Among them, b c,j Indicates echo train b c The j-th echo, b mfc,j Indicates echo train bmfc The j-th echo, s mf The proportion of mud volume to the total volume;
[0034] The final corrected echo train b c Perform inversion to obtain the corrected T2 spectrum f c .
[0035] In one possible implementation, the proportion s of the mud volume to the total volume is... mf The calculation formula is as follows:
[0036]
[0037] Among them, P mf P represents the porosity of the mud filtrate. mf,t The porosity was measured when the probe area was 100% mud.
[0038] Secondly, embodiments of this application provide a wellbore enlargement correction device for nuclear magnetic resonance logging T2 spectrum, comprising:
[0039] The mud filtrate T2 value calculation module is used to determine the mud filtrate T2 value based on the relationship between the wellbore curve and the morphological changes of the nuclear magnetic resonance logging T2 spectrum.
[0040] The mud filtrate porosity calculation module is used to re-invert the measurement echo train based on the mud filtrate T2 value and calculate the mud filtrate porosity P. mf ;
[0041] The corrected echo train calculation module is used to calculate the echo train based on the T2 value and porosity P of the mud filtrate. mf Calculate the corrected echo train of the mud filtrate;
[0042] The corrected T2 spectrum calculation module is used to invert the corrected echo train and calculate the corrected T2 spectrum of the mud filtrate.
[0043] Thirdly, embodiments of this application provide an electronic device, including:
[0044] processor;
[0045] Memory;
[0046] And a computer program, wherein the computer program is stored in the memory, the computer program including instructions that, when executed by the processor, cause the electronic device to perform the method described in any one of the first aspects.
[0047] Fourthly, embodiments of this application provide a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to perform the method described in any one of the first aspects.
[0048] This application discloses a method for wellbore enlargement correction of T2 spectrum in nuclear magnetic resonance logging, comprising: first, determining the T2 value of mud filtrate based on the relationship between the wellbore diameter curve and the morphological changes of the T2 spectrum in nuclear magnetic resonance logging; then, re-inverting the measured echo train based on the T2 value of mud filtrate to determine the porosity of mud filtrate; next, calculating the corrected echo train based on the T2 value and porosity of mud filtrate; and finally, inverting the corrected echo train and calculating the T2 spectrum after wellbore enlargement correction. By determining the T2 value of mud filtrate through the relationship between the wellbore diameter curve and the T2 spectrum in nuclear magnetic resonance logging, and subtracting the echo train signal of mud filtrate from the original echo train to obtain the echo train after wellbore enlargement correction, and finally inverting the corrected echo train to obtain the corrected T2 spectrum, this method provides logging interpreters with accurate reservoir parameters calculated based on the nuclear magnetic resonance T2 spectrum. Attached Figure Description
[0049] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0050] Figure 1 A schematic flowchart illustrating the wellbore enlargement correction method for T2 spectrum in nuclear magnetic resonance logging provided in this application embodiment;
[0051] Figure 2 This is a schematic diagram illustrating the determination of the T2 value of mud filtrate provided in an embodiment of this application;
[0052] Figure 3 The application effect diagram of the nuclear magnetic resonance logging T2 spectrum wellbore enlargement correction method provided in the embodiments of this application in well A of a tight sandstone gas reservoir in a certain study area;
[0053] Figure 4 This is a structural block diagram of the wellbore enlargement correction device for nuclear magnetic resonance logging T2 spectrum provided in the embodiments of this application;
[0054] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation
[0055] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0056] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.
[0057] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0058] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.
[0059] See Figure 1 This is a schematic flowchart of the wellbore enlargement correction method for T2 spectrum in nuclear magnetic resonance logging provided in this application embodiment. Figure 1 As shown, it mainly includes the following steps.
[0060] Step S1: Determine the T2 value of mud filtrate based on the relationship between the wellbore curve and the T2 spectrum morphology change of nuclear magnetic resonance logging.
[0061] Nuclear magnetic resonance (NMR) logging has a shallow detection depth. If the wellbore is severely enlarged, the echo train signal measured by NMR logging will contain signals from both formation fluids and mud filtrate. This results in the reservoir parameters calculated from the T2 spectrum obtained by echo train inversion failing to reflect the true formation conditions. See also Figure 2 This is a schematic diagram illustrating the determination of the T2 value of mud filtrate provided in an embodiment of this application. Figure 2 As shown, by studying the T2 spectrum morphology characteristics of the enlarged section of the wellbore, the T2 value of the mud filtrate was determined by the T2 spectrum peak. The T2 value is relatively fixed. In this embodiment, the T2 spectrum of the relatively severe enlargement section was analyzed, and the T2 value of the mud filtrate was determined to be around 7ms.
[0062] Step S2: Based on the T2 value of the mud filtrate, the measured echo train is re-inverted to calculate the porosity of the mud filtrate. Specifically:
[0063] Step S2.1: Set the distribution of the components of the T2 spectrum to obtain the distribution method of the T2 spectrum.
[0064] The T2 spectrum in nuclear magnetic resonance logging is obtained by inverting the measurement echo train. Before inversion, the T2 spectrum components need to be pre-selected, i.e., the distribution points of the T2 spectrum components need to be set. The distribution point range of the T2 spectrum components is set to [T 2,min ,T 2,max ], T 2,min The minimum value of T2 points, T 2,max This represents the maximum value of the T2 distribution point.
[0065] Because the T2 value of the mud filtrate is located at T 2,mf To better determine the porosity of the mud filtrate, the distribution rule of its T2 spectrum is considered as follows:
[0066] T 2,i =T 2,mf *2 i-n (1)
[0067] Among them, T 2,i The i-th point of the T2 spectral component is represented in milliseconds (ms); T 2,mf The T2 value of the mud filtrate is defined in milliseconds (ms); mf represents the mud filtrate; i, m, and n are integers, i = 1, 2, 3, ..., m, where m is the total number of pre-selected T2 spectral components, and m and n satisfy the following conditions:
[0068] T 2,mf *2 -n <T 2,min ≤T 2,mf *2 1-n (2)
[0069] T 2,mf *2 m-1-n <T 2,max ≤T 2,mf *2 m-n (3)
[0070] Among them, T 2,min The minimum value of T2 points, T 2,max The maximum value of point T2.
[0071] Step S2.2: Based on the distribution of the T2 spectrum, process the original measured echo train b. o Inversion was performed to obtain the T2 spectrum before correction. uc Located in T 2,mf f at the location uc The component is the porosity P of the mud filtrate. mf Mud filtrate porosity P mf The formula is as follows:
[0072] P mf =f uc,n (4)
[0073] Among them, f uc,n For T 2,mf f at the location uc Quantity.
[0074] Step S3: Based on the T2 value and porosity P of the mud filtrate mf Calculate the echo train of the corrected mud filtrate. Specifically:
[0075] Step S3.1: Calculate the echo train signal b of the measured mud filtrate. mf The calculation formula is as follows:
[0076]
[0077] Among them, b mf,j For echo train b mf The j-th echo; TE is the echo interval of the echo train, in milliseconds.
[0078] Step S3.2: Original measurement echo train b o Subtract mud filtrate echo train b mf Obtain echo train b after mud filtrate correction mfc The calculation formula is as follows:
[0079] b mfc,j =b o,j -b mf,j (6)
[0080] Among them, b mfc,j For echo train b mfc The j-th echo, b o,j For echo train b o The j-th echo, b mf,j For echo train b mf The j-th echo.
[0081] Step S4: Invert the corrected echo train to calculate the corrected T2 spectrum of the mud filtrate. Specifically:
[0082] Step S4.1: Calculate the proportion s of mud volume to the total volume within the instrument's detection area. mf The calculation formula is as follows:
[0083]
[0084] Among them, P mf P represents the porosity of the mud filtrate. mf,t The porosity was measured when the probe area was 100% mud.
[0085] Step S4.2: Based on the ratio s of the mud volume to the total volume mfCalculate the final corrected echo train b c The calculation formula is as follows:
[0086]
[0087] Among them, b c,j For echo train b c The j-th echo.
[0088] Step S4.3: For the final corrected echo train b... c Perform inversion to obtain the corrected T2 spectrum f c At this point, the placement of points for inverting T2 can be set arbitrarily by the user.
[0089] Taking a tight sandstone gas reservoir in a certain study area as an example, the wellbore enlargement correction method for the T2 spectrum of nuclear magnetic resonance logging in this embodiment is used to correct the wellbore enlargement of the T2 spectrum measured by nuclear magnetic resonance logging in the tight sandstone gas reservoir in the study area. See also... Figure 3 The image shows the application effect of the nuclear magnetic resonance logging T2 spectrum wellbore enlargement correction method provided in this application embodiment in well A of a tight sandstone gas reservoir in a certain study area. Figure 3 As shown, the T2 value of the mud filtrate was determined to be 7 ms by analyzing the T2 spectrum morphology of the reservoir nuclear magnetic resonance logging. The porosity of the mud filtrate was recalculated by re-inverting the measured echo train. The inverted T2 spectrum is located in channel 6 of the figure, and the mud filtrate porosity is located in channel 7. The corrected echo train of the mud filtrate was calculated based on the T2 value and porosity of the mud filtrate. The mud filtrate echo train is located in channel 8 of the figure, and the corrected echo train is located in channel 9. The corrected T2 spectrum of the mud filtrate was obtained by inverting the corrected echo train and is located in channel 10 of the figure. The corrected formation porosity was calculated based on the corrected T2 spectrum of the mud filtrate and is located in the last channel of the figure. Compared with the porosity before correction, the corrected porosity is significantly reduced in the enlarged section and basically the same in the non-enlarged section, which effectively improves the accuracy and effectiveness of nuclear magnetic resonance logging porosity evaluation.
[0090] In this embodiment, the T2 value of the mud filtrate is determined by the relationship between the wellbore curve and the T2 spectrum of nuclear magnetic resonance logging. The echo string after wellbore enlargement correction is obtained by subtracting the echo string signal of the mud filtrate from the original echo string. Finally, the corrected T2 spectrum is obtained by inverting the corrected echo string, providing accurate reservoir parameters calculated based on the nuclear magnetic resonance T2 spectrum for logging interpreters.
[0091] Corresponding to the above embodiments, this application also provides a wellbore enlargement correction device for nuclear magnetic resonance logging T2 spectrum.
[0092] See Figure 4 This is a structural block diagram of the wellbore enlargement correction device for T2 spectrum nuclear magnetic resonance logging provided in this embodiment of the application. Figure 4As shown, it mainly includes the following modules.
[0093] The mud filtrate T2 value calculation module 401 is used to determine the mud filtrate T2 value based on the relationship between the wellbore curve and the morphological change of the nuclear magnetic resonance logging T2 spectrum.
[0094] The mud filtrate porosity calculation module 402 is used to re-invert the measurement echo train based on the mud filtrate T2 value and calculate the mud filtrate porosity P. mf ;
[0095] The corrected echo train calculation module 403 is used to calculate the echo train based on the T2 value of the mud filtrate and the porosity P of the mud filtrate. mf Calculate the corrected echo train of the mud filtrate;
[0096] The corrected T2 spectrum calculation module 404 is used to invert the corrected echo train and calculate the corrected T2 spectrum of the mud filtrate.
[0097] It should be noted that the specific content involved in the embodiments of this application can be found in the description of the above method embodiments, and will not be repeated here for the sake of brevity.
[0098] Corresponding to the above embodiments, this application also provides an electronic device.
[0099] See Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 5 As shown, the electronic device 500 may include a processor 501, a memory 502, and a communication unit 503. These components communicate via one or more buses. Those skilled in the art will understand that the electronic device structure shown in the figure does not constitute a limitation on the embodiments of this application. It may be a bus topology or a star topology, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.
[0100] The communication unit 503 is used to establish a communication channel, thereby enabling the electronic device to communicate with other devices.
[0101] Processor 501 serves as the control center of the electronic device, connecting various parts of the device via various interfaces and lines. It executes software programs and / or modules stored in memory 502, and calls data stored in memory to perform various functions and / or process data. The processor may be composed of integrated circuits (ICs), such as a single packaged IC or multiple packaged ICs with the same or different functions connected together. For example, processor 501 may consist only of a central processing unit (CPU). In this embodiment, the CPU may have a single processing core or include multiple processing cores.
[0102] Memory 502 is used to store the execution instructions of processor 501. Memory 502 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.
[0103] When the execution instructions in memory 502 are executed by processor 501, the electronic device 500 is able to perform some or all of the steps in the above method embodiments.
[0104] Corresponding to the above embodiments, this application also provides a computer-readable storage medium, wherein the computer-readable storage medium may store a program, wherein when the program runs, it can control the device where the computer-readable storage medium is located to execute some or all of the steps in the above method embodiments. Specifically, the computer-readable storage medium may be a magnetic disk, an optical disk, read-only memory (ROM), or random access memory (RAM), etc.
[0105] Corresponding to the above embodiments, this application also provides a computer program product containing executable instructions that, when executed on a computer, cause the computer to perform some or all of the steps in the above method embodiments.
[0106] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, the simultaneous existence of A and B, or the existence of B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.
[0107] Those skilled in the art will recognize that the units and algorithm steps described in the embodiments disclosed herein can be implemented using electronic hardware, computer software, or a combination of electronic hardware and software. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0108] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0109] In the several embodiments provided in this application, any function, if implemented as a software functional unit and sold or used as an independent product, 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 a 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 USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0110] The above description is merely a specific embodiment of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. The protection scope of this application should be determined by the protection scope of the claims.
Claims
1. A method for correcting wellbore enlargement using T2 spectrum from nuclear magnetic resonance logging, characterized in that, include: The T2 value of mud filtrate was determined based on the relationship between the wellbore curve and the morphological changes of the T2 spectrum in nuclear magnetic resonance logging. Based on the T2 value of the mud filtrate, the measured echo train is re-inverted to calculate the porosity P of the mud filtrate. mf ; Based on the T2 value and porosity P of the mud filtrate mf Calculate the corrected echo train of the mud filtrate; The corrected echo train is inverted to calculate the corrected T2 spectrum of the mud filtrate.
2. The wellbore enlargement correction method for T2 spectrum of nuclear magnetic resonance logging according to claim 1, characterized in that, The process of re-inverting the measured echo train based on the T2 value of the mud filtrate and calculating the porosity of the mud filtrate includes: The component distribution of the T2 spectrum is set to obtain the distribution method of the T2 spectrum; Based on the distribution of the T2 spectrum, the echo train b of the original measurement is... o Inversion was performed to obtain the T2 spectrum before correction. uc Located in T 2，mf f at the location uc The component is the porosity P of the mud filtrate. mf The calculation formula is as follows: P mf =f uc，n Among them, f uc，n For T 2，mf f at the location uc Quantity.
3. The wellbore enlargement correction method for T2 spectrum of nuclear magnetic resonance logging according to claim 2, characterized in that, The point placement rules for the components of the T2 spectrum are as follows: T 2，i =T 2，mf *2 i-n Among them, T 2，i The i-th point of the T2 spectral component; T 2，mf Let T2 be the determined value of the mud filtrate; mf be the mud filtrate; i, m, and n be integers, i = 1, 2, 3, ..., m, where m is the total number of pre-selected T2 spectral components, and m and n satisfy the following conditions: T 2，mf *2 -n <T 2，min ≤T 2，mf *2 1-n T 2，mf *2 m-1-n <T 2，max ≤T 2，mf *2 m-n Among them, T 2,min The minimum value of T2 points, T 2,max This represents the maximum value of the T2 distribution point.
4. The wellbore enlargement correction method for T2 spectrum of nuclear magnetic resonance logging according to claim 1, characterized in that, The T2 value and porosity P of the mud filtrate are used as the basis. mf Calculate the corrected echo train of the mud filtrate, including: Calculate the echo train signal b of the measured mud filtrate mf ; Original measurement echo train b o Subtract mud filtrate echo train b mf Obtain echo train b after mud filtrate correction mfc The calculation formula is as follows: b mfc，j =b o，j -b mf，j Among them, b mfc，j Indicates echo train b mfc The j-th echo, b o，j Indicates echo train b o The j-th echo, b mf，j Indicates echo train b mf The j-th echo.
5. The wellbore enlargement correction method for T2 spectrum of nuclear magnetic resonance logging according to claim 4, characterized in that, echo train signal b mf The calculation formula is as follows: Among them, b mf，j Indicates echo train b mf The j-th echo; TE is the echo interval of the echo train; T 2，mf The T2 value of the determined mud filtrate; P mf Porosity of mud filtrate.
6. The wellbore enlargement correction method for T2 spectrum of nuclear magnetic resonance logging according to claim 1, characterized in that, The step of inverting the corrected echo train and calculating the corrected T2 spectrum of the mud filtrate includes: The proportion of mud volume to total volume within the detection area of the calculation instrument is s. mf ; According to the ratio s of the mud volume to the total volume mf Calculate the final corrected echo train b c The calculation formula is as follows: Among them, b c，j Indicates echo train b c The j-th echo, b mfc，j Indicates echo train b mfc The j-th echo, s mf The proportion of mud volume to the total volume; The final corrected echo train b c Perform inversion to obtain the corrected T2 spectrum f c .
7. The wellbore enlargement correction method for T2 spectrum of nuclear magnetic resonance logging according to claim 6, characterized in that, The proportion of mud volume to total volume s mf The calculation formula is as follows: Among them, P mf P represents the porosity of the mud filtrate. mf，t The porosity was measured when the probe area was 100% mud.
8. A wellbore enlargement correction device for T2 spectrum of nuclear magnetic resonance logging, characterized in that, include: The mud filtrate T2 value calculation module is used to determine the mud filtrate T2 value based on the relationship between the wellbore curve and the morphological changes of the nuclear magnetic resonance logging T2 spectrum. The mud filtrate porosity calculation module is used to re-invert the measurement echo train based on the mud filtrate T2 value and calculate the mud filtrate porosity P. mf ; The corrected echo train calculation module is used to calculate the echo train based on the T2 value and porosity P of the mud filtrate. mf Calculate the corrected echo train of the mud filtrate; The corrected T2 spectrum calculation module is used to invert the corrected echo train and calculate the corrected T2 spectrum of the mud filtrate.
9. An electronic device, characterized in that, include: processor; Memory; And a computer program, wherein the computer program is stored in the memory, the computer program including instructions that, when executed by the processor, cause the electronic device to perform the method of any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the method according to any one of claims 1 to 7.