Nuclear magnetism T2 spectrum inversion anomaly correction method and system based on echo string preprocessing

Abstract

The invention discloses a nuclear magnetic T2 spectrum inversion anomaly correction method and system based on echo string preprocessing, and belongs to the field of petroleum logging. By contrastive analysis of T2 spectrum inversion abnormal data and combination of an inversion algorithm, specific reasons for inversion anomalies such as spectrum loss of T2 spectrum argillaceous bound water part or high amplitude anomaly are found, and the inversion anomalies are mainly influenced by the relationship of values of the first two points of a C component echo string, so that after a first correction coefficient and a second correction coefficient are obtained, the inversion anomalies of the T2 spectrum argillaceous bound water part can be corrected, and the reliability of the T2 spectrum argillaceous bound water part can be improved. When the amplitude of the first point is smaller than the amplitude of the second point and the difference value reaches a first correction coefficient, or the amplitude of the first point of the C group of echoes is larger than the amplitude of the second point and the difference value reaches a second correction coefficient, echo inversion is started from the second point of the C group of echoes, and T2 spectrum inversion anomaly correction can be realized; according to the method, the problem that T2 spectrum inversion is abnormal due to partial spectrum loss of T2 spectrum argillaceous bound water or higher amplitude anomaly can be well solved, and the low-quality data processing effect is improved.

Description

Technical Field

[0001] The invention belongs to the field of petroleum well logging and relates to a nuclear magnetic T2 spectrum inversion anomaly correction method and system based on echo train preprocessing. Background Art

[0002] Nuclear magnetic resonance logging has advantages in the reservoir evaluation process that other logging methods do not have and is currently widely used in various oil fields.

[0003] The centered nuclear magnetic resonance logging tool (MRT) and the eccentric nuclear magnetic resonance logging tool (iMRT) have achieved good application results in terms of actual logging data quality and processing effects. In terms of data processing and interpretation software, it can well support the processing and interpretation of logging data of the two nuclear magnetic resonance logging tools. From data preprocessing, echo inversion, standard T2 spectrum analysis, comprehensive oil and gas evaluation to processing modules with independent characteristics, it has reached the processing level of other software (such as Petrosite and Insite) and can meet the needs of field data processing.

[0004] However, as the scope of application expands, some problems still exist. After processing, it is found that the shale bound water part (before 4ms) in the T2 spectrum of some wells is lost or the amplitude is abnormally high, such as Figure 1 As shown, this also causes the calculation of NMR porosity to be too low or too high, affecting the normal application of NMR logging data. Summary of the invention

[0005] The purpose of the present invention is to solve the inversion anomaly problem in the prior art that after well data is processed, it is found that the T2 spectrum of mud bound water is partially lost or the amplitude is abnormally high / low, and to provide a nuclear magnetic T2 spectrum inversion anomaly correction method and system based on echo string preprocessing.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention proposes a method for correcting abnormalities in nuclear magnetic T2 spectrum inversion based on echo train preprocessing, comprising the following steps:

[0008] Invert the C group echo to obtain the reference porosity; continuously change the amplitude of the first point of the C group echo to invert and obtain the porosity group; obtain the first correction coefficient and the second correction coefficient according to the reference porosity and the porosity group;

[0009] If the amplitude of the first point of the C group echo is less than the amplitude of the second point and the difference reaches the first correction coefficient, or if the amplitude of the first point of the C group echo is greater than the amplitude of the second point and the difference reaches the second correction coefficient, echo inversion starts from the second point of the C group echo, where the amplitude of the first point and the amplitude of the second point are both positive values;

[0010] When the amplitude of the first point of the C group echo is positive and the amplitude of the second point is negative, the C group echo is preprocessed and then the echo inversion calculation is performed to realize the T2 spectrum inversion anomaly correction.

[0011] Preferably, the method for obtaining the first correction coefficient is as follows:

[0012] Step 1: Keep the value V2 of the second point of the echo of group C unchanged, and subtract 1 / 5 of the value V2 of the second point from the value V1 of the first point to form the first echo string group, which is named ECHO_X1, ECHO_X2, ... ECHO_Xn, until the value of the first point is less than 0;

[0013] Step 2, invert the first echo string groups ECHO_X1, ECHO_X2, ...ECHO_Xn respectively, and calculate the first porosity groups MSIG_X1, MSIG_X2, ...MSIG_Xn;

[0014] Step 3, calculate the difference between the first porosity group MSIG_X1, MSIG_X2, ... MSIG_Xn and the reference porosity. When the difference is closest to 1, the difference between the first point and the second point in the first echo string group ECHO_Xi is Xj; wherein i = 1, 2, 3, ...; j = 1, 2, 3, ...;

[0015] Step 4: Obtain X1, X2, ..., Xm for M C component echo trains according to steps 1 to 3. The average value of X1, X2, ..., Xm is the first correction coefficient.

[0016] Preferably, the method for obtaining the second correction coefficient is as follows:

[0017] Step 1, keep the value V2 of the second point of the echo of group C unchanged, add 1 / 5 of the value of the second point to the value of the first point, and form the second echo string group, named ECHO_P1, ECHO_P2, ... ECHO_Pn, until the value of the first point is greater than 3 times the value of the second point;

[0018] Step 2, invert the second echo string groups ECHO_P1, ECHO_P2, ... ECHO_Pn respectively, and calculate the second porosity groups MSIG_P1, MSIG_P2, ... MSIG_Pn;

[0019] Step 3, calculate the difference between the second porosity MSIG_P1, MSIG_P2, ..., MSIG_Pn and the reference porosity. When the difference is closest to 1, the difference between the first point and the second point in the corresponding second echo string group ECHO_Pi is Pj; wherein, i = 1, 2, 3, ...; j = 1, 2, 3, ...;

[0020] Step 4: Obtain P1, P2, ..., Pm for M C component echo trains according to steps 1 to 3. The average value of P1 / V2, P2 / V2, ..., Pm / V2 is the second correction coefficient.

[0021] Preferably, the maximum likelihood restoration method is used to pre-process the echoes of group C, and then the echo inversion calculation is performed. The implementation method is as follows:

[0022] Step 1: Take out all positive values ​​in the entire echo string and record their positions; if the last point is a negative number, assign the last point a positive number close to 0;

[0023] Step 2: Fit all positive values, recalculate the points with negative values ​​in the entire echo string and replace the original values. If the original value is a positive number, keep it unchanged to obtain the restored echo string, and perform echo inversion on the restored echo string.

[0024] Preferably, a logarithmic fit, exponential fit or linear fit is used for all positive values.

[0025] The present invention proposes a nuclear magnetic T2 spectrum inversion anomaly correction system based on echo train preprocessing, comprising:

[0026] A parameter acquisition module, the parameter acquisition module is used to invert the C group echo to obtain the reference porosity; continuously change the amplitude of the first point of the C group echo to invert and obtain the porosity group; obtain the first correction coefficient and the second correction coefficient according to the reference porosity and the porosity group;

[0027] A first inversion module, wherein the first inversion module is used for starting echo inversion from the second point of the C group echo when the amplitude of the first point of the C group echo is less than the amplitude of the second point and the difference reaches the first correction coefficient, or when the amplitude of the first point of the C group echo is greater than the amplitude of the second point and the difference reaches the second correction coefficient, wherein the amplitude of the first point and the amplitude of the second point are both positive values;

[0028] The second inversion module is used for preprocessing the C group echoes and then performing echo inversion calculation to realize T2 spectrum inversion anomaly correction when the amplitude of the first point of the C group echoes is positive and the amplitude of the second point is negative.

[0029] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of a method for correcting abnormalities in nuclear magnetic T2 spectrum inversion based on echo train preprocessing are implemented.

[0030] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for correcting abnormalities in nuclear magnetic T2 spectrum inversion based on echo train preprocessing.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention proposes a nuclear magnetic T2 spectrum inversion anomaly correction method based on echo train preprocessing. By comparing and analyzing T2 spectrum inversion anomaly data and combining the inversion algorithm, the specific cause of the inversion anomaly such as the partial spectrum loss of T2 spectrum mud bound water or the abnormally high amplitude is found. The inversion anomaly is mainly affected by the numerical value relationship of the first two points of the C component echo train. Therefore, after obtaining the first correction coefficient and the second correction coefficient, the amplitude of the first point is less than the amplitude of the second point and the difference reaches the first correction coefficient, or the amplitude of the first point of the C group echo is greater than the amplitude of the second point and the difference reaches the second correction coefficient. The echo inversion is started from the second point of the C group echo, and the T2 spectrum inversion anomaly correction can be realized. The method can well solve the problem of T2 spectrum inversion anomaly such as the partial spectrum loss of T2 spectrum mud bound water or the abnormally high amplitude, and improves the low-quality data processing effect. By preprocessing the NMR logging echo string data, the problem of partial spectrum loss or abnormally high amplitude of mud bound water in the T2 spectrum and the resulting low or high NMR porosity is solved, and the processing and application effect of low-quality NMR logging data is optimized.

[0033] Furthermore, if the last point is a negative number, the last point is assigned a smaller positive number to ensure that the result after fitting is a positive value at the last point.

[0034] The invention proposes a nuclear magnetic T2 spectrum inversion anomaly correction system based on echo train preprocessing, which realizes T2 spectrum inversion anomaly correction by dividing the system into a parameter acquisition module, a first inversion module and a second inversion module. The modular concept is adopted to make each module independent of each other, which is convenient for unified management of each module. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is an example diagram of a T2 spectrum with severe spectrum loss in the prior art.

[0037] Figure 2 The present invention is a flow chart of the abnormal correction method of nuclear magnetic T2 spectrum inversion based on echo train preprocessing.

[0038] Figure 3 This is an example diagram of the abnormally high amplitude of the T2 spectrum of the mud bound water part of the present invention.

[0039] Figure 4 This is an example diagram of the maximum likelihood reduction method of the present invention.

[0040] Figure 5 This is a diagram of the nuclear magnetic T2 spectrum inversion anomaly correction system based on echo train preprocessing of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0044] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0045] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0046] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0048] The present invention proposes a method for correcting abnormalities in nuclear magnetic T2 spectrum inversion based on echo train preprocessing, such as Figure 2 As shown, the following steps are included:

[0049] S1. Invert the C group echo to obtain the reference porosity; continuously change the amplitude of the first point of the C group echo to invert and obtain the porosity group; obtain the first correction coefficient and the second correction coefficient according to the reference porosity and the porosity group;

[0050] The method for obtaining the first correction coefficient is as follows:

[0051] Step 1: Keep the value V2 of the second point of the echo of group C unchanged, and subtract 1 / 5 of the value V2 of the second point from the value V1 of the first point to form the first echo string group, which is named ECHO_X1, ECHO_X2, ... ECHO_Xn, until the value of the first point is less than 0;

[0052] Step 2, invert the first echo string groups ECHO_X1, ECHO_X2, ...ECHO_Xn respectively, and calculate the first porosity groups MSIG_X1, MSIG_X2, ...MSIG_Xn;

[0053] Step 3, calculate the difference between the first porosity group MSIG_X1, MSIG_X2, ... MSIG_Xn and the reference porosity. When the difference is closest to 1, the difference between the first point and the second point in the first echo string group ECHO_Xi is Xj; wherein i = 1, 2, 3, ...; j = 1, 2, 3, ...;

[0054] Step 4: Obtain X1, X2, ..., Xm for M C component echo trains according to steps 1 to 3. The average value of X1, X2, ..., Xm is the first correction coefficient.

[0055] The method for obtaining the second correction coefficient is as follows:

[0056] Step 1, keep the value V2 of the second point of the echo of group C unchanged, add 1 / 5 of the value of the second point to the value of the first point, and form the second echo string group, named ECHO_P1, ECHO_P2, ... ECHO_Pn, until the value of the first point is greater than 3 times the value of the second point;

[0057] Step 2, invert the second echo string groups ECHO_P1, ECHO_P2, ... ECHO_Pn respectively, and calculate the second porosity groups MSIG_P1, MSIG_P2, ... MSIG_Pn;

[0058] Step 3, calculate the difference between the second porosity MSIG_P1, MSIG_P2, ..., MSIG_Pn and the reference porosity. When the difference is closest to 1, the difference between the first point and the second point in the corresponding second echo string group ECHO_Pi is Pj; wherein, i = 1, 2, 3, ...; j = 1, 2, 3, ...;

[0059] Step 4: Obtain P1, P2, ..., Pm for M C component echo trains according to steps 1 to 3. The average value of P1 / V2, P2 / V2, ..., Pm / V2 is the second correction coefficient.

[0060] The SVD algorithm is used for inversion.

[0061] S2. If the amplitude of the first point of the echo of group C is less than the amplitude of the second point and the difference reaches the first correction coefficient, or the amplitude of the first point of the echo of group C is greater than the amplitude of the second point and the difference reaches the second correction coefficient, echo inversion starts from the second point of the echo of group C, where the amplitude of the first point and the amplitude of the second point are both positive values.

[0062] When the amplitude of the first point of the S3 and C group echoes is positive and the amplitude of the second point is negative, the C group echoes are preprocessed and then the echo inversion calculation is performed to realize the T2 spectrum inversion anomaly correction.

[0063] If the amplitude of the first point of the C group echo is positive and the amplitude of the second point is negative, the maximum likelihood restoration method is used to pre-process the C group echo, and then the echo inversion calculation is performed. The implementation method is as follows:

[0064] Step 1: Take out all positive values ​​in the entire echo string and record their positions; if the last point is a negative number, assign the last point a positive number close to 0;

[0065] Step 2: Fit all positive values, recalculate the points with negative values ​​in the entire echo string and replace the original values. If the original value is a positive number, keep it unchanged to obtain the restored echo string, and perform echo inversion on the restored echo string.

[0066] Use a logarithmic, exponential, or linear fit for all positive values.

[0067] The specific contents of the abnormal correction method for nuclear magnetic T2 spectrum inversion based on echo train preprocessing proposed by the present invention are as follows:

[0068] Problem 1: When the amplitude of the first point of the C group echo is smaller than the amplitude of the second point and both are positive values, the T2 spectrum of the C group will be lost;

[0069] Question 2: When the amplitude of the first point of the C group echo is greater than the amplitude of the second point and both are positive values, the T2 spectrum amplitude of the C group will be abnormally high, such as Figure 3 As shown;

[0070] Question 3: When the first point of the echo of group C is a positive value and the second point is a negative value, both of the above phenomena may occur, but the negative echo value is inconsistent with theoretical understanding.

[0071] Perform the following operations in LEAD4.0 software:

[0072] For problem 1, when the first point of the C group echo is smaller than the second point by X, the echo inversion method is adopted starting from the second point of the echo; for problem 2, when the first point of the C group echo is larger than the second point by P, the echo inversion method is adopted starting from the second point of the echo. Among them, X is the first correction coefficient, and P is the second correction coefficient, which is determined by the theoretical inversion method. The specific method is:

[0073] Step 1: Find a measured C component echo data in the actual data as the reference echo ECHO_Base;

[0074] Step 1: Invert the echo of group C using the common SVD inversion algorithm to obtain the benchmark T2 spectrum T2_Base and the benchmark porosity MSIG_Base;

[0075] The echoes are preprocessed before inversion of the C component data.

[0076] Step 2: Keep the values ​​of the second and subsequent echoes of group C unchanged, and subtract 1 / 5 of the value V2 of the second point from the value V1 of the first point to form a group of echo strings, named ECHO_X1, ECHO_X2, ... ECHO_Xn, until the value of the first point is less than 0;

[0077] Step 3: Keep the values ​​of the second and subsequent echoes of group C unchanged, and add 1 / 5 of the value of the second point to the value of the first point to form a group of echo strings, named ECHO_P1, ECHO_P2, ... ECHO_Pn, until the value of the first point is 3 times greater than that of the second point;

[0078] Step 4, using the SVD algorithm to invert ECHO_X1, ECHO_X2, ...ECHO_Xn and ECHO_P1, ECHO_P2, ...ECHO_Pn respectively, and calculate the porosity MSIG_X1, MSIG_X2, ...MSIG_Xn and MSIG_P1, MSIG_P2, ...MSIG_Pn;

[0079] Step 5, calculate the difference between the porosity MSIG_X1, MSIG_X2, ... MSIG_Xn and MSIG_P1, MSIG_P2, ... MSIG_Pn and the reference porosity MSIG_Base. The difference between the first point and the second point in the echo train ECHO_Xi and ECHO_Pi (i = 1, 2, 3, ...) corresponding to the porosity difference closest to 1 is recorded as Xj and Pj (j = 1, 2, 3, ...) respectively;

[0080] For the M C component echo trains, X1, X2, ...Xm and P1, P2, ...Pm are obtained according to the method of steps 1 to 6, and the average value of X1, X2, ...Xm is calculated to obtain the final first correction coefficient X, and the average value of P1 / V2, P2 / V2, ...Pm / V2 is calculated to obtain the final second correction coefficient P. In the present invention, the first correction coefficient X and the second correction coefficient P obtained according to a block data are 0.48 and 1.93 respectively.

[0081] For question 3, the maximum likelihood restoration method is used to pre-process the echo, and then the inversion calculation is performed. The specific method is as follows: Figure 4 As shown:

[0082] Step 1: Take out all positive values ​​in the entire echo string and record their positions; if the last point is a negative number, assign the last point a smaller positive number, such as 0.001, to ensure that the result after fitting is a positive value at the last point;

[0083] Step 2: Fit all positive values. You can choose logarithmic fitting, exponential fitting or linear fitting. The form of logarithmic fitting is: y = A·ln(x)+B; the form of exponential fitting is: y = A·e B·x ; The form of linear fitting is: y = A x + B. Where A and B are fitting coefficients;

[0084] Step 3: recalculate the points with negative values ​​in the original echo string according to the fitting formula and replace the original values; if the original values ​​are positive, they remain unchanged to obtain the restored echo string;

[0085] Step 4: Use the SVD algorithm to perform inversion calculation on the restored echo string.

[0086] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution and process of the present invention are fully described below in combination with the processing flow of actual well data:

[0087] Embodiment 1:

[0088] Select a well data with problems 1) and 2) and process the following echo train:

[0089] Point location 1 2 3 4 5 6 7 8 9 10 Echo string 1 0.63 1.28 0.12 0.36 -0.58 0.15 0.47 -0.10 -0.41 0.53 Echo string 2 1.63 0.34 0.08 0.37 -0.21 -0.34 0.11 0.28 -0.29 0.41 Echo string 3 1.82 1.61 0.11 0.71 0.73 0.63 0.47 0.25 0.32 0.24

[0090] 1) From the data of echo string 1 and echo string 2, it can be seen that the difference between the second point and the first point of echo string 1 is greater than 0.48, and the data of the first point of echo string 2 is more than 1.93 times greater than the data of the second point, so for these two echo strings, the inversion starts from the second point;

[0091] 2) Echo train 3 does not meet the conditions of the above three problems, so echo train 3 is still inverted from point 1;

[0092] 3) Use the SVD algorithm to invert the echo train.

[0093] Example 2: Maximum Likelihood Restoration Method

[0094] Select the data of a well with problem 3) and process the following sample echo train.

[0095] Point location 1 2 3 4 5 6 7 8 9 10 Echo string 4 3.32 -0.55 -0.17 -0.04 0.29 0.3 0.04 -0.73 0.31 -0.42

[0096] It can be seen from the above echo string that there are negative values ​​in the echo string, and it meets the requirements mentioned in the present invention that the first point value is positive and relatively high, and the second point value is negative, so the following processing is performed:

[0097] 1) Delete all negative numbers in the echo string, and form a new positive echo string with the remaining positive numbers. During the deletion process, keep the positions of all points in the original echo string unchanged. Since the last point is a negative number, replace it with a decimal greater than 0;

[0098] Point location 1 5 6 7 9 10 Echo string 4 positive echo string 3.32 0.29 0.3 0.04 0.31 0.001

[0099] 2) The above echo train 4 positive echo train is exponentially fitted, and the fitting formula is: y = 2.89·e -0.39·x ;

[0100] 3) Recalculate the data at positions 2, 3, 4, 8, and 10 in the original echo string according to the fitting formula to obtain the following restored echo string.

[0101]

[0102] 4) Perform SVD inversion on the restored echo string of echo string 4.

[0103] The present invention proposes a nuclear magnetic T2 spectrum inversion anomaly correction system based on echo train preprocessing, such as Figure 5 As shown, it includes a parameter acquisition module, a first inversion module and a second inversion module;

[0104] The parameter acquisition module is used to invert the C group echo to obtain the reference porosity; continuously change the amplitude of the first point of the C group echo to invert and obtain the porosity group; obtain the first correction coefficient and the second correction coefficient according to the reference porosity and the porosity group;

[0105] The first inversion module is used for starting echo inversion from the second point of the C group echo when the amplitude of the first point of the C group echo is less than the amplitude of the second point and the difference reaches the first correction coefficient, or when the amplitude of the first point of the C group echo is greater than the amplitude of the second point and the difference reaches the second correction coefficient, wherein the amplitude of the first point and the amplitude of the second point are both positive values;

[0106] The second inversion module is used to pre-process the C group echoes and then perform echo inversion calculation when the amplitude of the first point of the C group echoes is positive and the amplitude of the second point is negative, so as to realize T2 spectrum inversion anomaly correction.

[0107] The terminal device provided in an embodiment of the present invention comprises: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0108] The computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to accomplish the present invention.

[0109] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0110] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0111] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0112] If the module / unit integrated in the terminal device is implemented in the form of 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 present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0113] The present invention proposes a nuclear magnetic T2 spectrum inversion anomaly correction method based on echo train preprocessing, which can well solve the problem of T2 spectrum inversion anomalies such as partial spectrum loss of T2 spectrum mud bound water or abnormally high amplitude, and improve the processing effect of low-quality data. By comparing and analyzing the T2 spectrum inversion anomaly data and combining the theoretical inversion algorithm, the causes of inversion anomalies such as partial spectrum loss of T2 spectrum mud bound water or abnormally high amplitude are found. The inversion anomaly is mainly affected by the numerical value relationship of the first two points of the C component echo train. By comparing and analyzing the T2 spectrum inversion anomaly data and combining the theoretical inversion algorithm, the specific causes of inversion anomalies such as partial spectrum loss of T2 spectrum mud bound water or abnormally high amplitude are found, and a solution based on echo train preprocessing is proposed, which is verified by the application of actual well data on site.

[0114] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for correcting abnormalities in nuclear magnetic T2 spectrum inversion based on echo train preprocessing, characterized in that: The steps include: Invert the C group echo to obtain the reference porosity; continuously change the amplitude of the first point of the C group echo to invert and obtain the porosity group; obtain the first correction coefficient and the second correction coefficient according to the reference porosity and the porosity group; If the amplitude of the first point of the C group echo is less than the amplitude of the second point and the difference reaches the first correction coefficient, or if the amplitude of the first point of the C group echo is greater than the amplitude of the second point and the difference reaches the second correction coefficient, echo inversion starts from the second point of the C group echo, where the amplitude of the first point and the amplitude of the second point are both positive values; When the amplitude of the first point of the C group echo is positive and the amplitude of the second point is negative, the C group echo is preprocessed and then the echo inversion calculation is performed to realize the T2 spectrum inversion anomaly correction.

2. The method for correcting abnormality of nuclear magnetic T2 spectrum inversion based on echo train preprocessing according to claim 1 is characterized in that: The method for obtaining the first correction coefficient is as follows: Step 1: Keep the value V2 of the second point of the echo of group C unchanged, and subtract 1 / 5 of the value V2 of the second point from the value V1 of the first point to form the first echo string group, which is named ECHO_X1, ECHO_X2, ... ECHO_Xn, until the value of the first point is less than 0; Step 2, invert the first echo string groups ECHO_X1, ECHO_X2, ... ECHO_Xn respectively, and calculate the first porosity groups MSIG_X1, MSIG_X2, ... MSIG_Xn; Step 3, calculate the difference between the first porosity group MSIG_X1, MSIG_X2, ... MSIG_Xn and the reference porosity. When the difference is closest to 1, the difference between the first point and the second point in the first echo string group ECHO_Xi is Xj; wherein i = 1, 2, 3, ...; j = 1, 2, 3, ...; Step 4: Obtain X1, X2, ..., Xm for the M C component echo trains according to steps 1 to 3. The average value of X1, X2, ..., Xm is the first correction coefficient.

3. The method for correcting abnormality of nuclear magnetic T2 spectrum inversion based on echo train preprocessing according to claim 1, characterized in that: The method for obtaining the second correction coefficient is as follows: Step 1, keep the value V2 of the second point of the echo of group C unchanged, add 1 / 5 of the value of the second point to the value of the first point, and form the second echo string group, named ECHO_P1, ECHO_P2, ... ECHO_Pn, until the value of the first point is greater than 3 times the value of the second point; Step 2, invert the second echo string groups ECHO_P1, ECHO_P2, ... ECHO_Pn respectively, and calculate the second porosity groups MSIG_P1, MSIG_P2, ... MSIG_Pn; Step 3, calculate the difference between the second porosity MSIG_P1, MSIG_P2, ..., MSIG_Pn and the reference porosity. When the difference is closest to 1, the difference between the first point and the second point in the corresponding second echo string group ECHO_Pi is Pj; wherein, i = 1, 2, 3, ...; j = 1, 2, 3, ...; Step 4: Obtain P1, P2, ..., Pm for M C component echo trains according to steps 1 to 3. The average value of P1 / V2, P2 / V2, ..., Pm / V2 is the second correction coefficient.

4. The method for correcting abnormality of nuclear magnetic T2 spectrum inversion based on echo train preprocessing according to claim 1, characterized in that: The maximum likelihood restoration method is used to pre-process the echoes of group C, and then the echo inversion calculation is performed. The implementation method is as follows: Step 1: Take out all positive values ​​in the entire echo string and record their positions; if the last point is a negative number, assign the last point a positive number; Step 2: Fit all positive values, recalculate the points with negative values ​​in the entire echo string and replace the original values. If the original value is a positive number, keep it unchanged to obtain the restored echo string, and perform echo inversion on the restored echo string.

5. The method for correcting abnormality of nuclear magnetic T2 spectrum inversion based on echo train preprocessing according to claim 4, characterized in that: The positive number approaches zero.

6. The method for correcting abnormality of nuclear magnetic T2 spectrum inversion based on echo train preprocessing according to claim 4, characterized in that: Use a logarithmic, exponential, or linear fit for all positive values.

7. A nuclear magnetic T2 spectrum inversion anomaly correction system based on echo train preprocessing, characterized in that: include: A parameter acquisition module, wherein the parameter acquisition module is used to invert the C group echoes to obtain a reference porosity; The amplitude of the first point of the C group echo is continuously changed to perform inversion to obtain the porosity group; the first correction coefficient and the second correction coefficient are obtained according to the reference porosity and the porosity group; A first inversion module, wherein the first inversion module is used for starting echo inversion from the second point of the C group echo when the amplitude of the first point of the C group echo is less than the amplitude of the second point and the difference reaches the first correction coefficient, or when the amplitude of the first point of the C group echo is greater than the amplitude of the second point and the difference reaches the second correction coefficient, wherein the amplitude of the first point and the amplitude of the second point are both positive values; The second inversion module is used for preprocessing the C group echoes and then performing echo inversion calculation to realize T2 spectrum inversion anomaly correction when the amplitude of the first point of the C group echoes is positive and the amplitude of the second point is negative.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for correcting abnormality of nuclear magnetic T2 spectrum inversion based on echo train preprocessing as described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for correcting abnormalities of nuclear magnetic T2 spectrum inversion based on echo train preprocessing as described in any one of claims 1 to 6 are implemented.

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