Pressure-maintaining coring nuclear magnetic porosity measuring method, system and program product

Abstract

The invention belongs to the technical field of nuclear magnetic resonance logging, and particularly discloses a pressure-maintaining coring nuclear magnetic porosity measurement method, system and program product, which are used for estimating pollution semaphore of pressure-maintaining liquid and correcting T2 relaxation distribution of a rock core through a corresponding convex optimization process. The relaxation component of the pressure maintaining liquid in an original signal is removed under the condition that the original relaxation signal of the rock core is not influenced, and the measured T2 relaxation distribution is ensured to be close to the real distribution of the rock core. By offsetting the pressure maintaining liquid signal component in the measurement signal, the interference of the pressure maintaining liquid signal on the measurement of the porosity of the rock core during the pressure maintaining coring can be effectively reduced, the measurement precision of the porosity of the rock core is improved, and the in-situ high-precision porosity measurement of the pressure maintaining coring sample beside the nuclear magnetic well is further realized.

Description

Technical Field

[0001] This invention belongs to the field of nuclear magnetic resonance logging technology, specifically relating to a method, system, and program product for measuring nuclear magnetic porosity using pressure-maintaining coring. Background Technology

[0002] Nuclear magnetic resonance logging requires precise measurement of core porosity to determine the content of oil and gas reservoirs. Conventional coring methods have unavoidable problems such as gas escape and changes in the physicochemical environment. Pressure-holding coring can better preserve the original state of the core, but the pressure-holding fluid in the pressure-holding cylinder can interfere with the porosity measurement.

[0003] Existing well-side measurement techniques typically employ freezing and then extracting cored samples for measurement. This method cannot completely prevent gas escape and changes in the physicochemical environment. On the other hand, if an in-situ measurement scheme is adopted, it is impossible to avoid the interference of the NMR signal of the pressure-holding liquid on porosity measurement. Summary of the Invention

[0004] The purpose of this invention is to provide a method, system, and program for measuring the porosity of nuclear magnetic resonance imaging (NMR) samples obtained by pressure-holding core sampling, in order to solve the aforementioned problems existing in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] Firstly, a method for measuring nuclear magnetic resonance porosity using pressure-holding coring is provided, comprising:

[0007] The magnetic resonance T2 relaxation signal of the core sample was acquired by the nuclear magnetic resonance measurement sequence and the cross-sectional image was constructed using the magnetic resonance T2 relaxation signal;

[0008] Using the center of the cross-sectional image as the center, select the central region with a set radius and the outer ring region outside the central region;

[0009] The average gray level of the central region is used as the first reference signal value, and the average gray level of the outer ring region is used as the second reference signal value.

[0010] Obtain the set prior T2 relaxation time distribution vector, and use the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value to determine the amount of pollution signal that satisfies the set first convex optimization condition;

[0011] The corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition is determined by using the pollution signal quantity, the first reference signal value, and the second signal value.

[0012] The total porosity is calculated based on the corrected T2 relaxation time distribution vector, and the core pore distribution parameters are calculated using the corrected T2 relaxation time distribution vector, the total porosity, and the set positive correlation ratio.

[0013] Construct a core pore distribution curve based on the core pore distribution parameters, and output the overall porosity and core pore distribution curves.

[0014] In one possible design, the method further includes:

[0015] Using the center of the cross-sectional image as the center, a central region with a set radius is selected, and the average gray value of the central region is used as the first reference signal value.

[0016] Obtain the prior relaxation signal value of the pressure-holding coring fluid used in the pressure-holding coring sample, and use the prior relaxation signal value as the second reference signal value.

[0017] In one possible design, determining the amount of contamination signal satisfying a set first convex optimization condition using the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value includes:

[0018] Substituting the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value into the first convex optimization condition, the pollution signal quantity satisfying the first convex optimization condition is obtained. The first convex optimization condition is:

[0019] min{|Ax-(sig-αb0)| 2 +L(α)}

[0020] Where α is the amount of contamination signal, min{·} represents the minimum calculated value, x is the prior T2 relaxation time distribution vector, sig is the first reference signal value, b0 is the second reference signal value, A is the set T2 decay matrix, and L(α) is the loss function that satisfies convexity and decreases with respect to α.

[0021] In one possible design, the loss function L(α) is set as

[0022] L(α)=γ0e -α

[0023] Where γ0 is the first regularization hyperparameter.

[0024] In one possible design, determining the corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition using the contamination signal quantity, the first reference signal value, and the second signal value includes:

[0025] Substituting the pollution signal quantity, the first reference signal value, and the second signal value into the second convex optimization condition, the corrected T2 relaxation time distribution vector satisfying the second convex optimization condition is obtained. The second convex optimization condition is:

[0026] min{|Ax'-(sig-αb0)|2 +γ1|x'|+γ2|x'| 2}

[0027] Where x' is the corrected T2 relaxation time distribution vector, min{·} represents the minimum calculated value, sig is the first reference signal value, b0 is the second reference signal value, A is the set T2 decay matrix, γ1 is the set second regularization hyperparameter, and γ2 is the set third regularization hyperparameter.

[0028] In one possible design, calculating the overall porosity based on the corrected T2 relaxation time distribution vector includes:

[0029] The components of the corrected T2 relaxation time distribution vector are added together to obtain the total T2 relaxation distribution S1;

[0030] Substitute the sum of T2 relaxation distributions S1 into the preset overall porosity calculation formula to obtain the overall porosity P. The overall porosity calculation formula is P = (S1 / S0) × P0, where S0 is the set standard value of the sum of relaxation distributions and P0 is the set standard porosity.

[0031] In one possible design, the calculation of core pore distribution parameters using the corrected T2 relaxation time distribution vector, total porosity, and a set positive correlation ratio includes:

[0032] Substitute each component of the corrected T2 relaxation time distribution vector into the preset core porosity scatter plot formula K. i =(x i The calculation is performed in ×P×β) / S1 to obtain the scatter plot parameters of core porosity corresponding to each component, where x i To correct the corresponding components of the T2 relaxation time distribution vector, where i is the component index and K is the component number. i Here are the corresponding scatter plot parameters for core porosity, and β is the set positive correlation ratio value.

[0033] Core porosity distribution parameters are obtained by combining the scattered parameters of porosity from each core sample.

[0034] Secondly, a pressure-holding coring nuclear magnetic resonance porosity measurement system is provided, comprising a signal acquisition unit, a region selection unit, a signal determination unit, a first optimization unit, a second optimization unit, a porosity calculation unit, and a measurement output unit, wherein:

[0035] The signal acquisition unit is used to acquire the magnetic resonance T2 relaxation signal of the core sample based on the nuclear magnetic resonance measurement sequence, and to construct a cross-sectional image using the magnetic resonance T2 relaxation signal;

[0036] The region selection unit is used to select a central region with a set radius and an outer ring region outside the central region, with the center of the cross-sectional image as the center.

[0037] The signal determination unit is used to take the average gray value of the image in the central region as the first reference signal value and the average gray value of the image in the outer ring region as the second reference signal value.

[0038] The first optimization unit is used to obtain the set prior T2 relaxation time distribution vector, and use the prior T2 relaxation time distribution vector, the first reference signal value and the second reference signal value to determine the amount of pollution signal that satisfies the set first convex optimization condition.

[0039] The second optimization unit is used to determine the corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition by using the pollution signal quantity, the first reference signal value and the second signal value.

[0040] The porosity calculation unit is used to calculate the overall porosity based on the corrected T2 relaxation time distribution vector, and to calculate the core pore distribution parameters using the corrected T2 relaxation time distribution vector, the overall porosity, and the set positive correlation ratio.

[0041] The measurement output unit is used to construct a core pore distribution curve based on the core pore distribution parameters, and output the overall porosity and core pore distribution curve.

[0042] Thirdly, a pressure-holding coring nuclear magnetic resonance porosity measurement system is provided, comprising:

[0043] Memory, used to store instructions;

[0044] A processor is configured to read instructions stored in the memory and execute the method described in any one of the first aspects above, according to the instructions.

[0045] Fourthly, a computer-readable storage medium is provided, on which instructions are stored, which, when executed on a computer, cause the computer to perform any of the methods described in the first aspect. A computer program product is also provided, which, when executed on a computer, performs any of the methods described in the first aspect.

[0046] Beneficial effects: By canceling the pressure-holding fluid signal component in the measurement signal, this invention can effectively reduce the interference of the pressure-holding fluid signal on the core porosity measurement during pressure-holding coring, improve the accuracy of core porosity measurement, and thus realize in-situ high-precision porosity measurement of pressure-holding cored samples near nuclear magnetic resonance wells. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of the steps in the method of Embodiment 1 of the present invention;

[0049] Figure 2 This is a schematic diagram of the system configuration in Embodiment 2 of the present invention;

[0050] Figure 3 This is a schematic diagram of the system configuration in Embodiment 3 of the present invention. Detailed Implementation

[0051] It should be noted that the descriptions of these embodiments are intended to aid in understanding the invention and do not constitute a limitation thereof. The specific structural and functional details disclosed herein are merely for describing exemplary embodiments of the invention. However, the invention may be embodied in many alternative forms and should not be construed as being limited to the embodiments described herein.

[0052] It should be understood that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. 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 an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments according to the specific circumstances.

[0053] Specific details are provided in the following description to provide a complete understanding of the exemplary embodiments. However, those skilled in the art will understand that the exemplary embodiments can be implemented without these specific details. For example, apparatus may be shown in block diagrams to avoid obscuring the examples with unnecessary details. In other embodiments, well-known processes, structures, and techniques may be omitted with non-essential details to avoid obscuring the embodiments.

[0054] Example 1:

[0055] This embodiment provides a method for measuring porosity in pressure-holding coring nuclear magnetic resonance imaging, such as... Figure 1 As shown, the method includes the following steps:

[0056] S1. The magnetic resonance T2 relaxation signal of the core sample was acquired based on the nuclear magnetic resonance measurement sequence, and the cross-sectional image was constructed using the magnetic resonance T2 relaxation signal.

[0057] In practice, NMR sequences can be used to acquire the T2 relaxation signals of cored samples obtained during pressure holding. NMR logging typically uses CPMG pulse sequences, and the measured data is the T2 relaxation signal of the excited object over time. Based on this signal, the content of components with different T2 decay rates within the object can be determined. NMR sequences with or without spatial resolution can be used for acquisition. Spatially resolved NMR sequences provide a set of T2 relaxation image signals of the object over time; each frame represents the relaxation state of the object's cross-section at the current moment, containing richer information than ordinary CPMG sequences. After acquiring the T2 relaxation signals of the cored samples, cross-sectional images can be constructed using these signals. Typically, a non-uniform Fourier transform or CT projection method corresponding to the k-space acquisition trajectory of the pulse sequence is used to reconstruct the cross-sectional image from the k-space NMR signal. For NMR sequences with spatial resolution, each echo time corresponds to one cross-sectional image.

[0058] S2. Using the center of the cross-sectional image as the center, select the central region with a set radius and the outer ring region outside the central region.

[0059] In practice, after obtaining the cross-sectional image, a central region with a set radius can be selected with the center of the cross-sectional image as the center. When step S1 uses an NMR measurement sequence with spatial resolution to acquire T2 relaxation signals, it is also necessary to select the region outside the central region that contains the pressure-holding fluid signal as the outer ring region.

[0060] S3. Take the average gray value of the central region as the first reference signal value, and take the average gray value of the outer ring region as the second reference signal value.

[0061] In specific implementation, the grayscale value of each pixel in the central region is determined, and then the average grayscale value of the central region image is used as the first reference signal value sig. When step S1 uses an NMR measurement sequence with spatial resolution to acquire T2 relaxation signals, the average grayscale value of the outer ring region image is used as the second reference signal value b0, which is the NMR T2 relaxation signal of the pressure-holding fluid. When step S1 uses an NMR measurement sequence without spatial resolution to acquire T2 relaxation signals, the prior relaxation signal value of the pressure-holding core sample used in the pressure-holding core sampling can be directly obtained, and the prior relaxation signal value is used as the second reference signal value b0.

[0062] S4. Obtain the set prior T2 relaxation time distribution vector, and use the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value to determine the amount of pollution signal that satisfies the set first convex optimization condition.

[0063] In specific implementation, firstly, the prior T2 relaxation time distribution vector is obtained. This prior T2 relaxation time distribution vector can be an empirical vector pre-defined based on prior knowledge. Then, the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value are substituted into the first convex optimization condition for calculation, resulting in the pollution signal quantity that satisfies the first convex optimization condition. The first convex optimization condition is...

[0064] min{|ax-(sig-αb0)| 2 +L(α)}

[0065] Where α is the amount of contamination signal; min{·} represents the minimum calculated value; x is the prior T2 relaxation time distribution vector; sig is the first reference signal value; b0 is the second reference signal value; A is the set T2 attenuation matrix, A=exp(-t_i / T2_j), which is a forward discrete Laplace transform that converts the pore component distribution into a time-domain T2 attenuation signal, t_i represents the echo time series, and T2_j represents the discretized T2 relaxation time sampling point sequence. This linear transformation can be regarded as an attenuation matrix; L(α) is a loss function that satisfies convexity and decreases with respect to α. For example, the loss function L(α) is set as follows:

[0066] L(α)=γ0e -α

[0067] Here, γ0 is the first regularization hyperparameter. Since the pressure-holding fluid signal is relatively high compared to the core signal, this loss function is used to make α tend to be as large as possible in the optimization fitting, thereby improving the optimization accuracy.

[0068] S5. Determine the corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition using the pollution signal quantity, the first reference signal value, and the second signal value.

[0069] In practice, the pollution signal quantity, the first reference signal value, and the second signal value can be substituted into the second convex optimization condition for calculation to obtain the corrected T2 relaxation time distribution vector that satisfies the second convex optimization condition. The second convex optimization condition is:

[0070] min{|Ax'-(sig-αb0)| 2 +γ1|x'|+γ2|x'| 2}

[0071] Where x' is the corrected T2 relaxation time distribution vector, min{·} represents the minimum calculated value, sig is the first reference signal value, b0 is the second reference signal value, A is the set T2 decay matrix, γ1 is the set second regularization hyperparameter, and γ2 is the set third regularization hyperparameter.

[0072] S6. Calculate the overall porosity based on the corrected T2 relaxation time distribution vector, and calculate the core pore distribution parameters using the corrected T2 relaxation time distribution vector, the overall porosity, and the set positive correlation ratio.

[0073] In practice, the components of the corrected T2 relaxation time distribution vector can be added together to obtain the total T2 relaxation distribution S1. Then, the total T2 relaxation distribution S1 is substituted into a preset overall porosity calculation formula to obtain the overall porosity P. The overall porosity calculation formula is P = (S1 / S0) × P0, where S0 is the set standard value for the total relaxation distribution, and P0 is the set standard porosity. For example, the total T2 relaxation distribution S0 of a copper sulfate solution standard sample with a determined overall porosity P0 can be used as the standard value. For pure solution samples, P0 = 100%.

[0074] After calculating the overall porosity P, the components of the corrected T2 relaxation time distribution vector can be substituted into the preset core porosity scatter plot formula K. i =(x i The calculation is performed in ×P×β) / S1 to obtain the scatter plot parameters of core porosity corresponding to each component, where x i To correct the corresponding components of the T2 relaxation time distribution vector, where i is the component index and K is the component number. i Here, represents the corresponding scatter plot parameter of core porosity, and β is a set positive correlation ratio value. Then, the core porosity distribution parameters are obtained by combining the scatter plot parameters of each core.

[0075] S7. Construct a core pore distribution curve based on the core pore distribution parameters, and output the overall porosity and core pore distribution curves.

[0076] In practice, a scatter plot of core pore distribution can be constructed using core pore distribution parameters, and curve fitting can be performed on the scatter plot to obtain a core pore distribution curve. Finally, the overall porosity and core pore distribution curve are output to achieve pressure-controlled core sampling and nuclear magnetic resonance porosity measurement.

[0077] Typically, during pressure-holding coring, the core sample is stored in a pressure-holding cylinder filled with pressure-holding fluid. Therefore, the NMR signal is the sum of the interference signal from the pressure-holding fluid and the pore fluid in the core sample, resulting in an inflated NMR relaxation signal. Furthermore, abnormal interference peaks appear in the pressure-holding fluid signal region during T2 relaxation (which may overlap with the core signal and cannot be directly removed), leading to an inflated porosity measurement. The method described in this embodiment can partially or completely remove the pressure-holding fluid relaxation component from the original signal without affecting the original relaxation signal of the core sample. This ensures that the measured T2 relaxation distribution closely approximates the true distribution of the core sample, resulting in a more accurate porosity measurement and improved core porosity measurement precision. Ultimately, this enables in-situ, high-precision porosity measurement of pressure-holding cored samples near the well site using NMR.

[0078] Example 2:

[0079] This embodiment provides a pressure-holding coring nuclear magnetic resonance porosity measurement system, such as... Figure 2 As shown, it includes a signal acquisition unit, a region selection unit, a signal determination unit, a first optimization unit, a second optimization unit, a porosity calculation unit, and a measurement output unit, wherein:

[0080] The signal acquisition unit is used to acquire the magnetic resonance T2 relaxation signal of the core sample based on the nuclear magnetic resonance measurement sequence, and to construct a cross-sectional image using the magnetic resonance T2 relaxation signal;

[0081] The region selection unit is used to select a central region with a set radius and an outer ring region outside the central region, with the center of the cross-sectional image as the center.

[0082] The signal determination unit is used to take the average gray value of the image in the central region as the first reference signal value and the average gray value of the image in the outer ring region as the second reference signal value.

[0083] The first optimization unit is used to obtain the set prior T2 relaxation time distribution vector, and use the prior T2 relaxation time distribution vector, the first reference signal value and the second reference signal value to determine the amount of pollution signal that satisfies the set first convex optimization condition.

[0084] The second optimization unit is used to determine the corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition by using the pollution signal quantity, the first reference signal value and the second signal value.

[0085] The porosity calculation unit is used to calculate the overall porosity based on the corrected T2 relaxation time distribution vector, and to calculate the core pore distribution parameters using the corrected T2 relaxation time distribution vector, the overall porosity, and the set positive correlation ratio.

[0086] The measurement output unit is used to construct a core pore distribution curve based on the core pore distribution parameters, and output the overall porosity and core pore distribution curve.

[0087] Example 3:

[0088] This embodiment provides a pressure-holding coring nuclear magnetic resonance porosity measurement system, such as... Figure 3 As shown, at the hardware level, it includes:

[0089] The data interface is used to establish data communication between the processor and external data terminals;

[0090] Memory, used to store instructions;

[0091] The processor is used to read the instructions stored in the memory and execute the pressure-holding core sampling nuclear magnetic porosity measurement method in Embodiment 1 according to the instructions.

[0092] Optionally, the system also includes an internal bus, through which the processor, memory, and data interface can be interconnected. This internal bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0093] The memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out (FIFO) memory, and / or first-in-last-out (FILO) memory. The processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0094] Example 4:

[0095] This embodiment provides a computer-readable storage medium storing instructions. When these instructions are executed on a computer, the computer performs the pressure-holding core sampling NMR porosity measurement method described in Embodiment 1. The computer-readable storage medium refers to a data storage medium, which may include, but is not limited to, floppy disks, optical disks, hard disks, flash memory, USB flash drives, and / or Memory Sticks. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0096] This embodiment also provides a computer program product that, when run on a computer, executes the pressure-holding coring NMR porosity measurement method described in Embodiment 1. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0097] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for pressure- preserving core magnetic porosimetry, comprising: include: The magnetic resonance T2 relaxation signal of the core sample was acquired by the nuclear magnetic resonance measurement sequence and the cross-sectional image was constructed using the magnetic resonance T2 relaxation signal; Using the center of the cross-sectional image as the center, select the central region with a set radius and the outer ring region outside the central region; The average gray level of the central region is used as the first reference signal value, and the average gray level of the outer ring region is used as the second reference signal value. Obtain the set prior T2 relaxation time distribution vector, and use the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value to determine the amount of pollution signal that satisfies the set first convex optimization condition; The corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition is determined by using the pollution signal quantity, the first reference signal value, and the second signal value. The total porosity is calculated based on the corrected T2 relaxation time distribution vector, and the core pore distribution parameters are calculated using the corrected T2 relaxation time distribution vector, the total porosity, and the set positive correlation ratio. Construct a core pore distribution curve based on the core pore distribution parameters, and output the overall porosity and core pore distribution curves.

2. The method of claim 1, wherein, The method further includes: Using the center of the cross-sectional image as the center, a central region with a set radius is selected, and the average gray value of the central region is used as the first reference signal value. Obtain the prior relaxation signal value of the pressure-holding coring fluid used in the pressure-holding coring sample, and use the prior relaxation signal value as the second reference signal value.

3. The method of claim 1, wherein, The step of determining the amount of contamination signal that satisfies the set first convex optimization condition using the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value includes: Substituting the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value into the first convex optimization condition, the pollution signal quantity satisfying the first convex optimization condition is obtained. The first convex optimization condition is: min{|Ax-(sig-αb0)| 2 +L(α)} Where α is the amount of contamination signal, min{·} represents the minimum calculated value, x is the prior T2 relaxation time distribution vector, sig is the first reference signal value, b0 is the second reference signal value, A is the set T2 decay matrix, and L(α) is the loss function that satisfies convexity and decreases with respect to α.

4. The method of claim 3, wherein, The loss function L(α) is set as follows: L(a) = y0e -α Where γ0 is the first regularization hyperparameter.

5. The method of claim 1, wherein, The step of determining the corrected T2 relaxation time distribution vector that satisfies the set second convex optimization condition using the pollution signal quantity, the first reference signal value, and the second signal value includes: Substituting the pollution signal quantity, the first reference signal value, and the second signal value into the second convex optimization condition, the corrected T2 relaxation time distribution vector satisfying the second convex optimization condition is obtained. The second convex optimization condition is: min{|Ax' - (sig - ab0)| 2 + y1|x'| + y2|x'| 2} Where x' is the corrected T2 relaxation time distribution vector, min{·} represents the minimum calculated value, sig is the first reference signal value, b0 is the second reference signal value, A is the set T2 decay matrix, γ1 is the set second regularization hyperparameter, and γ2 is the set third regularization hyperparameter.

6. The method of claim 1, wherein, The calculation of total porosity based on the corrected T2 relaxation time distribution vector includes: The components of the corrected T2 relaxation time distribution vector are added together to obtain the total T2 relaxation distribution S1; The preset bulk porosity calculation formula is P=(S1 / S0)×P0, wherein S0 is a preset standard value of the relaxation distribution sum, and P0 is a preset standard porosity.

7. A method of pressure preserving core magnetic porosimetry according to claim 6, wherein, The core porosity distribution parameter is calculated by using the corrected T2 relaxation time distribution vector, the bulk porosity, and the preset positive correlation ratio value. The components of the corrected T2 relaxation time distribution vector are substituted into the preset core porosity scatter plot formula Ki=(x i ×P×β) / Si to calculate the core porosity scatter plot parameters corresponding to the components, wherein x i is the corresponding component of the corrected T2 relaxation time distribution vector, i is the component serial number, Ki is the corresponding core porosity scatter plot parameter, and β is a set positive correlation ratio value. The core porosity distribution parameter is obtained by using the core porosity scatter point parameter combination.

8. A pressure-holding core-magnetic porosimetry system, comprising: The method comprises the following steps: The signal acquisition unit is configured to acquire the magnetic resonance T2 relaxation signal of the pressure-maintained coring sample based on a nuclear magnetic measurement sequence, and construct a cross-sectional image by using the magnetic resonance T2 relaxation signal; The region selection unit is configured to select a center region with a preset radius and an outer ring region outside the center region, with the center of the cross-sectional image as the center; The signal determination unit is configured to take the image gray mean value of the center region as a first reference signal value, and take the image gray mean value of the outer ring region as a second reference signal value; The first optimization unit is configured to obtain a preset prior T2 relaxation time distribution vector, and determine a pollution signal amount that satisfies a preset first convex optimization condition by using the prior T2 relaxation time distribution vector, the first reference signal value, and the second reference signal value; The second optimization unit is configured to determine a corrected T2 relaxation time distribution vector that satisfies a preset second convex optimization condition by using the pollution signal amount, the first reference signal value, and the second reference signal value; The porosity calculation unit is configured to calculate a bulk porosity according to the corrected T2 relaxation time distribution vector, and calculate a core porosity distribution parameter by using the corrected T2 relaxation time distribution vector, the bulk porosity, and a preset positive correlation ratio value; The measurement output unit is configured to construct a core porosity distribution curve according to the core porosity distribution parameter, and output the bulk porosity and the core porosity distribution curve.

9. A pressure-holding core-magnetic porosimetry system, comprising: The computer program product comprises: The memory is configured to store instructions; The processor is configured to read the instructions stored in the memory, and execute the pressure-maintained coring nuclear magnetic porosity measurement method according to any one of claims 1-7.

10. A computer program product, characterised in that, When the computer program product runs on the computer, the pressure-maintained coring nuclear magnetic porosity measurement method according to any one of claims 1-7 is executed.

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