A multidimensional nuclear magnetic resonance method and device for characterizing shale organic matter content

Abstract

The present invention proposes a multidimensional nuclear magnetic resonance (NMR) method for characterizing the organic matter content of shale. The method comprises the following steps: acquiring multidimensional NMR data according to a preset multidimensional NMR pulse sequence, the multidimensional NMR data comprising multiple echo trains and multiple FID signals; and processing the multidimensional NMR data to obtain multidimensional NMR results. Furthermore, a multidimensional NMR device for characterizing the organic matter content of shale is proposed. This application significantly improves the accuracy of obtaining shale porosity and permeability parameters, calculates the organic matter content within shale, and identifies the oil and water components within shale. It has the potential for field applications in biomedicine and materials analysis.

Description

Technical Field

[0001] The present invention relates to the field of nuclear magnetic resonance, and in particular to a multidimensional magnetic resonance method and device for characterizing the organic matter content of shale. Background Art

[0002] As an advanced non-destructive detection method, nuclear magnetic resonance (NMR) technology has been widely used in a variety of fields, including medicine, biology, energy, materials, agriculture, forestry, food, safety monitoring, and chemical engineering. In the field of geology, especially rock physics, NMR technology, because it is sensitive only to fluids and unaffected by the rock skeleton, can provide important information for reservoir evaluation, such as porosity, permeability, saturation, and pore size distribution.

[0003] Shale oil is an unconventional oil sourced from oil shale reservoirs. It exists in organic pores and therefore has a short relaxation time. Conventional methods have poor detection effects on shale, and the T1-T2 method is limited by long echo intervals. Furthermore, as the echo interval increases, the information about the short relaxation components of the shale is gradually lost, and the total porosity measured decreases. The applicant previously applied for a Chinese patent (CN107102020A, Invention Name: Multidimensional Nuclear Magnetic Resonance Measurement Method), designed a series of pulse sequences for data acquisition, and proposed a method for processing nuclear magnetic resonance data. However, the aforementioned patent is a groundbreaking invention for multidimensional nuclear magnetic resonance measurement, not a targeted design for shale geology. Although it can analyze important parameters such as the porosity, pore structure, saturated fluid type, skeleton magnetic susceptibility, and heterogeneity of the test material, the measurement accuracy is insufficient, and the detection effect on the organic matter content in shale is poor.

[0004] Therefore, providing a nuclear magnetic resonance method that can accurately characterize the organic matter content in shale to ensure the detection effect and accuracy of shale has become an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The present application provides a multidimensional magnetic resonance method for characterizing the organic matter content of shale to address the first aspect of the poor shale detection effect of the existing technology. The multidimensional nuclear magnetic resonance method for characterizing the organic matter content of shale includes:

[0006] S1: acquiring multidimensional nuclear magnetic resonance data according to a preset multidimensional nuclear magnetic resonance pulse sequence, wherein the multidimensional nuclear magnetic resonance data includes multiple echo train signals and multiple FID signals;

[0007] S2: Processing the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

[0008] Furthermore, step S1 specifically includes:

[0009] S1.1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test through the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane and obtain the transverse plane magnetization vector;

[0010] S1.2: Waiting time T W Then, a 90° radio frequency pulse is applied to the spin system on the TRS channel to rotate the magnetization vector M'0 that has recovered through thermal equilibrium in the longitudinal direction to the transverse plane. After the 90° radio frequency pulse is turned off, the FID signal is collected on the ACQ channel;

[0011] S1.3: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0012] S1.4: Wait for half the echo interval T E , collect a complete discrete spin echo signal in the ACQ channel;

[0013] S1.5: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0014] S1.6: Repeat S1.4 and S1.5 until n spin echo signals and one FID signal are acquired in the ACQ channel, where the n spin echo signals form an echo train signal.

[0015] S1.7. Change the waiting time T W Repeat S1.1 to S1.6 m times to acquire m echo train signals and m FID signals, thereby obtaining multi-dimensional NMR data.

[0016] Furthermore, step S1 may further specifically include:

[0017] S1.1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test through the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane and obtain the transverse plane magnetization vector;

[0018] S1.2: After waiting time T W Then, a 90° radio frequency pulse is applied to the spin system on the TRS channel to rotate the magnetization vector M'0 that has recovered through thermal equilibrium in the longitudinal direction to the transverse plane. After the 90° radio frequency pulse is turned off, the FID signal is collected on the ACQ channel;

[0019] S1.3: Wait for half the echo interval T E, applying a 180° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0020] S1.4: Wait for half the echo interval T E , collect a complete discrete spin echo signal in the ACQ channel;

[0021] S1.5: Wait for half the echo interval T E After +n*τ time, a 180° radio frequency pulse is applied to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector, where τ represents the echo interval time added each time, and n represents the number of refocusing times, n=0, 1, ...N;

[0022] S1.6: Repeat S1.4 and S1.5 until N+1 spin echo signals and one FID signal are acquired in the ACQ channel, where the N+1 spin echo signals form an echo train signal.

[0023] S1.7: Change waiting time T W Repeat S1.1 to S1.6 m times to acquire m echo train signals and m FID signals, thereby obtaining multi-dimensional NMR data.

[0024] Furthermore, step S1 may further specifically include:

[0025] S1.1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test through the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane and obtain the transverse plane magnetization vector;

[0026] S1.2: After waiting time T W Then, a 90° radio frequency pulse is applied to the spin system on the TRS channel to rotate the magnetization vector M'0 that has recovered through thermal equilibrium in the longitudinal direction to the transverse plane. After the 90° radio frequency pulse is turned off, the FID signal is collected on the ACQ channel;

[0027] S1.3: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0028] S1.4: Wait for half the echo interval T E , collect a complete discrete spin echo signal in the ACQ channel;

[0029] S1.5: Wait for half the echo interval T EAfter +n*τ time, a 90° radio frequency pulse is applied to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector, where τ represents the echo interval time added each time, and n represents the number of refocusing times, n=0, 1, ...N;

[0030] S1.6: Repeat S1.4 and S1.5 until N+1 spin echo signals and one FID signal are acquired in the ACQ channel, where the N+1 spin echo signals form an echo train signal.

[0031] S1.7: Change waiting time T W Repeat S1.1 to S1.6 m times to acquire m echo train signals and m FID signals, thereby obtaining multi-dimensional NMR data.

[0032] Furthermore, the response formula of the multidimensional nuclear magnetic resonance data is as follows:

[0033]

[0034] Among them, F(T1,T2) is the two-dimensional T1-T2 characteristic matrix of the sample under test, T1 is the longitudinal relaxation time, T2 is the transverse relaxation time, T W is the waiting time, and t is the time corresponding to the acquisition of FID signal and spin echo signal.

[0035] Furthermore, the echo interval T E Greater than or equal to 0.2ms.

[0036] In a second aspect, a multi-dimensional nuclear magnetic resonance device for characterizing the organic matter content of shale is provided, the device mainly comprising the following modules:

[0037] A data acquisition module is used to acquire multi-dimensional nuclear magnetic resonance data according to a preset multi-dimensional nuclear magnetic pulse sequence, wherein the multi-dimensional nuclear magnetic resonance data includes multiple echo train signals and multiple FID signals;

[0038] The data processing module is used to process the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

[0039] According to a third aspect, an electronic device includes:

[0040] processor;

[0041] A memory stores executable instructions, wherein the executable instructions are executed by the processor to cause the electronic device to perform the steps of the multi-dimensional nuclear magnetic resonance method.

[0042] In a fourth aspect, a computer-readable storage medium stores executable instructions, which implement the steps of the multi-dimensional nuclear magnetic resonance method when executed.

[0043] Based on the above technical solutions, this application achieves the following technical effects.

[0044] (1) The multi-dimensional nuclear magnetic resonance method of the present application adds FID measurement to the traditional T1-T2 measurement method sequence. Compared with the conventional T1-T2 measurement method, since the CPMG operation for transverse magnetization vector measurement is limited by the echo interval, the above method can complete the T1-T2 measurement in combination with FID and obtain more short relaxation component information, which can overcome the effects of low measured porosity and loss of short relaxation components caused by long echo intervals. Laboratory measurement results show that at an echo interval of 0.2ms, compared with the traditional pulse sequence, the pulse sequence of the present application can obtain more organic matter content information, greatly improve the accuracy of obtaining the porosity and permeability parameters of shale, calculate the organic matter content in shale, identify the oil and water components in shale, and have important practical value in biomedicine and material analysis.

[0045] (2) This application starts from the perspective of quantum mechanics, explains the basic theory, rationally arranges and optimizes the corresponding pulses in different time periods of the pulse sequence, combines Solid-Echo and FID, and then introduces the characteristics of FID being sensitive to short relaxation components and Solid-Echo being sensitive to organic matter signals, so as to better obtain the organic matter information in shale and provide a solution for the application of nuclear magnetic resonance technology in the field of shale evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0047] Figure 1 This is a schematic flow chart of a multidimensional nuclear magnetic resonance method for characterizing the organic matter content of shale provided in an embodiment of the present application;

[0048] Figure 2 This is a nuclear magnetic resonance pulse sequence designed for a multidimensional magnetic resonance method for characterizing the organic matter content of shale provided in Example 1 of the present application;

[0049] Figure 3 This is a nuclear magnetic resonance pulse sequence designed for a multidimensional magnetic resonance method for characterizing the organic matter content of shale provided in Example 2 of the present application;

[0050] Figure 4This is a nuclear magnetic resonance pulse sequence designed for a multidimensional magnetic resonance method for characterizing the organic matter content of shale provided in Example 3 of the present application;

[0051] Figure 5 This is the 2D spectrum result of the SR-CPMG sequence used as a comparison in the examples of this application;

[0052] Figure 6 This is a sequential two-dimensional spectrum result achieved by a multidimensional magnetic resonance method for characterizing the organic matter content of shale provided in an embodiment of the present application;

[0053] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0054] Among them, TRS is a pulse transmission channel; ACQ is a signal receiving channel, 700 is an electronic device, 701 is a processor, 702 is a memory, and 703 is a communication unit. DETAILED DESCRIPTION

[0055] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0056] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0057] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0058] First, the definitions and physical meanings of the relevant technical terms involved in this application are introduced as follows.

[0059] Static magnetic field B0. This field, provided by a magnet, determines the signal-to-noise ratio of the NMR signal. When the sample being measured is placed in a static magnetic field, energy levels within the spin system split, generating a macroscopic magnetization vector M0 along the direction of the static magnetic field. M0 is determined by parameters such as the static magnetic field strength B0 and temperature. Magnetic materials are typically permanent magnets and superconductors. Permanent magnets are primarily used for low-field NMR measurements; superconductors are typically used in medical imaging and high-field instrumental chemical spectroscopy in laboratories, requiring the use of liquid helium and liquid nitrogen to maintain a constant magnet temperature.

[0060] RF magnetic field B1 and pulse. RF pulses are electromagnetic signals, typically generated by a coil. The magnetic field generated by RF pulses is called an RF magnetic field. The direction of the RF magnetic field is perpendicular to the direction of the static magnetic field, rotating the magnetization vector formed in the static magnetic field. The rotation angle θ is: θ = γB1t p . Where γ is the magnetic gyroscopic ratio, B1 is the radio frequency magnetic field intensity, t p is the duration of the RF pulse. Therefore, the deflection angle can be varied by controlling the amplitude or duration of the RF pulse. An NMR pulse sequence consists of RF pulses of varying numbers and frequency properties, arranged in a set sequence. By adjusting the inter-pulse interval, pulse angle, and pulse frequency selectivity, measurements of spin system relaxation and diffusion can be achieved.

[0061] Spin echo. Spin echo is the most common signal in nuclear magnetic resonance measurement. First, a 90° pulse is applied to the sample to be measured to rotate the magnetization vector M0 to a transverse plane perpendicular to the direction of the static magnetic field. Due to the diffusion of molecules and the spatial inhomogeneity of the static magnetic field, the magnetization vector M0 is dephased. During this period, if the signal acquisition channel is opened to collect the signal, a free decay signal is obtained. After a certain time τ, a 180° pulse is applied. The dephased magnetization vector will reunite after the same time τ to form an echo signal. The changed echo signal is called a spin echo signal. Spin echo has the following three main aspects in the application of nuclear magnetic resonance: (1) By applying a series of 180° radio frequency pulses, spin echoes are repeatedly formed and the echo train signal is recorded. This pulse sequence is a CPMG pulse sequence. This signal is extremely important for studying the transverse relaxation characteristics of porous media. Under certain conditions, information related to the pore size can be obtained; (2) by changing the gradient amplitude or gradient duration in a gradient magnetic field and recording the change in the spin echo amplitude, the self-diffusion coefficient of the fluid molecules can be obtained; (3) by applying paired frequency encoding or phase encoding gradients, the spatial spin density information of the sample under test can be analyzed to achieve nuclear magnetic resonance imaging.

[0062] Relaxation. The process of a spin system recovering from a resonant state to a thermal equilibrium state. This process is characterized by the longitudinal relaxation time T1 or the transverse relaxation time T2 in different directions. T1 is also called the spin-lattice relaxation time, which reflects the energy exchange between the spin system and the external environment. T2 is also called the spin-spin relaxation time, which reflects the internal energy loss of the spin system. The relaxation process of the spin system can be described by the Bloch equation. The longitudinal relaxation time T1 can be measured using a saturation recovery pulse sequence. By changing the time interval T between the two pulses W , record the signal amplitude, reflecting the evolution of the longitudinal magnetization vector at different editing times:

[0063]

[0064] The above method takes a long time. Each step T W In both cases, the proton spin system needs to wait for a long time and reach thermal equilibrium before the next experiment can be carried out, so the acquisition process is extremely slow.

[0065] This application embodiment provides a multi-dimensional nuclear magnetic resonance method for characterizing the organic matter content of shale. Figure 1 The flowchart of a multi-dimensional nuclear magnetic resonance method for characterizing the organic matter content of shale according to an embodiment of the present application is shown. The multi-dimensional nuclear magnetic resonance method for characterizing the organic matter content of shale provided in an embodiment of the present application may include the following steps when implemented.

[0066] Acquire multidimensional nuclear magnetic resonance data according to a preset multidimensional nuclear magnetic pulse sequence, wherein the multidimensional nuclear magnetic resonance data includes multiple echo train signals and multiple FID signals;

[0067] The multidimensional nuclear magnetic resonance data are processed to obtain multidimensional nuclear magnetic resonance results.

[0068] Example 1

[0069] Combine Figure 2 The present invention provides a multidimensional nuclear magnetic resonance pulse sequence and proposes a multidimensional nuclear magnetic resonance method for characterizing the organic matter content of shale using the pulse sequence. The method includes the following steps:

[0070] S1: Acquire multi-dimensional nuclear magnetic resonance data according to a preset multi-dimensional nuclear magnetic pulse sequence, wherein the multi-dimensional nuclear magnetic resonance data includes a plurality of echo train signals and a plurality of FID signals.

[0071] Specifically, the collecting of multidimensional nuclear magnetic resonance data according to a preset multidimensional nuclear magnetic resonance pulse sequence includes:

[0072] Step 1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test on the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane, thereby obtaining the transverse plane magnetization vector;

[0073] Step 2: Waiting time T W Then, a 90° radio frequency pulse is applied to the spin system on the TRS channel to rotate the magnetization vector M'0 that has recovered through thermal equilibrium in the longitudinal direction to the transverse plane. After the 90° radio frequency pulse is turned off, the FID signal is collected on the ACQ channel;

[0074] Step 3: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0075] Step 4: Wait for half the echo interval T E, collect a complete discrete spin echo signal in the ACQ channel;

[0076] Step 5: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0077] Step 6: Repeat steps 4 and 5 until n spin echo signals and one FID signal are acquired in the ACQ channel, wherein the n spin echo signals form an echo train signal.

[0078] It is worth noting that the spin echo signal collected in step 4 gradually weakens as the number of repetitions increases.

[0079] Step 7. Change the waiting time T W Repeat steps 1 to 6 m times to acquire m echo train signals and m FID signals.

[0080] The response formula of the m echo train signals and the m FID signals is as follows:

[0081]

[0082] Among them, F(T1,T2) is the two-dimensional T1-T2 characteristic matrix of the sample under test, T1 is the longitudinal relaxation time, T2 is the transverse relaxation time, T W is the waiting time, and t is the time corresponding to the acquisition of FID signal and spin echo signal.

[0083] S2: Processing the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

[0084] The collected signal is subjected to data inversion to obtain the T1-T2 spectrum of the sample being tested.

[0085] Preferably, the echo interval T E Greater than or equal to 0.2ms.

[0086] Preferably, T w This is the recovery time of the magnetization vector. In specific operation, it is usually set from a very short time to 3-5 times the T1 time.

[0087] Example 2

[0088] Combine Figure 3 The present invention provides another multidimensional nuclear magnetic resonance pulse sequence and proposes a multidimensional nuclear magnetic resonance method for characterizing the organic matter content of shale using the pulse sequence. The method includes the following steps:

[0089] S1: Acquire multi-dimensional nuclear magnetic resonance data according to a preset multi-dimensional nuclear magnetic pulse sequence, wherein the multi-dimensional nuclear magnetic resonance data includes a plurality of echo train signals and a plurality of FID signals.

[0090] Specifically, the collecting of multidimensional nuclear magnetic resonance data according to a preset multidimensional nuclear magnetic resonance pulse sequence includes:

[0091] Step 1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test on the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane, thereby obtaining the transverse plane magnetization vector;

[0092] Step 2: After waiting time T W Then, a 90° radio frequency pulse is applied to the spin system on the TRS channel to rotate the magnetization vector M'0 that has recovered through thermal equilibrium in the longitudinal direction to the transverse plane. After the 90° radio frequency pulse is turned off, the FID signal is collected on the ACQ channel;

[0093] Step 3: Wait for half the echo interval T E , applying a 180° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0094] Step 4: Wait for half the echo interval T E , collect a complete discrete spin echo signal in the ACQ channel;

[0095] Step 5: Wait for half the echo interval T E After +n*τ time, a 180° radio frequency pulse is applied to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector, where τ represents the echo interval time added each time, and n represents the number of refocusing times, n=0, 1, ...N;

[0096] Preferably, τ is related to the number of pulses used, and the time length is usually 0.5-10 μs.

[0097] Step 6: Repeat steps 4 and 5 until N+1 spin echo signals and one FID signal are collected in the ACQ channel, wherein the N+1 spin echo signals form an echo train signal.

[0098] It is worth noting that the spin echo signal collected in step 4 gradually weakens as the number of repetitions increases.

[0099] Step 7. Change the waiting time T W Repeat steps 1 to 6 m times to acquire m echo train signals and m FID signals.

[0100] The response formula of the m echo train signals and the m FID signals is as follows:

[0101]

[0102] Among them, F(T1,T2) is the two-dimensional T1-T2 characteristic matrix of the sample under test, T1 is the longitudinal relaxation time, T2 is the transverse relaxation time, T W is the waiting time, t is the time corresponding to the acquisition of FID signal and spin echo signal, such as T E +τ,T E +2τ...etc.

[0103] S2: Processing the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

[0104] The collected signal is subjected to data inversion to obtain the T1-T2 spectrum of the sample being tested.

[0105] Preferably, the echo interval T E Greater than or equal to 0.2ms.

[0106] Preferably, T w This is the recovery time of the magnetization vector. In specific operation, it is usually set from a very short time to 3-5 times the T1 time.

[0107] Example 3

[0108] Combine Figure 4 The present invention provides another multidimensional nuclear magnetic resonance pulse sequence and proposes a multidimensional nuclear magnetic resonance method for characterizing the organic matter content of shale using the pulse sequence. The method includes the following steps:

[0109] S1: Acquire multi-dimensional nuclear magnetic resonance data according to a preset multi-dimensional nuclear magnetic pulse sequence, wherein the multi-dimensional nuclear magnetic resonance data includes a plurality of echo train signals and a plurality of FID signals.

[0110] Specifically, the collecting of multidimensional nuclear magnetic resonance data according to a preset multidimensional nuclear magnetic resonance pulse sequence includes:

[0111] Step 1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test on the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane, thereby obtaining the transverse plane magnetization vector;

[0112] Step 2: After waiting time T W Then, a 90° radio frequency pulse is applied to the spin system on the TRS channel to rotate the magnetization vector M'0 that has recovered through thermal equilibrium in the longitudinal direction to the transverse plane. After the 90° radio frequency pulse is turned off, the FID signal is collected on the ACQ channel;

[0113] Step 3: Wait for half the echo interval T E, applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector;

[0114] Step 4: Wait for half the echo interval T E , collect a complete discrete spin echo signal in the ACQ channel;

[0115] Step 5: Wait for half the echo interval T E After +n*τ time, a 90° radio frequency pulse is applied to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector, where τ represents the echo interval time added each time, and n represents the number of refocusing times, n=0, 1, ...N;

[0116] Preferably, τ is related to the number of pulses used, and the time length is usually 0.5-10 μs.

[0117] Step 6: Repeat steps 4 and 5 until N+1 spin echo signals and one FID signal are collected in the ACQ channel, wherein the N+1 spin echo signals form an echo train signal.

[0118] It is worth noting that the spin echo signal collected in step 4 gradually weakens as the number of repetitions increases.

[0119] Step 7. Change the waiting time T W Repeat steps 1 to 6 m times to acquire m echo train signals and m FID signals.

[0120] The response formula of the m echo train signals and the m FID signals is as follows:

[0121]

[0122] Among them, F(T1,T2) is the two-dimensional T1-T2 characteristic matrix of the sample under test, T1 is the longitudinal relaxation time, T2 is the transverse relaxation time, T W is the waiting time, t is the time corresponding to the acquisition of FID signal and spin echo signal, such as T E +τ,T E +2τ...etc.

[0123] S2: Processing the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

[0124] The collected signal is subjected to data inversion to obtain the T1-T2 spectrum of the sample being tested.

[0125] Preferably, the echo interval T E Greater than or equal to 0.2ms.

[0126] Preferably, T w This is the recovery time of the magnetization vector. In specific operation, it is usually set from a very short time to 3-5 times the T1 time.

[0127] The multi-dimensional nuclear magnetic resonance method for characterizing the organic matter content of shale in Example 1 is used as an example to illustrate the technical effect of the present application. The T1-T2 spectrum results of the multi-dimensional nuclear magnetic resonance data collected in Example 1 are as follows: Figure 6 As shown, the T1-T2 spectrum results of the conventional CPMG sequence in the prior art are as follows: Figure 5 From the comparison between the two, it can be seen that the T1-T2 spectrum results of the multidimensional nuclear magnetic resonance method in the embodiment of the present application have more information, and integrating different regions of the spectrum can obtain more organic matter content information.

[0128] The full-diameter NMR core analyzer allows for in-situ, non-destructive, and rapid testing of cores at the drilling site. Due to the large sample size, the equipment's minimum echo interval is 0.2ms. The pulse sequence used in this application effectively compensates for the effects of long echo intervals, providing accurate data support for reservoir evaluation.

[0129] Example 4

[0130] Corresponding to Examples 1 to 3, the present application also provides a multi-dimensional nuclear magnetic resonance device for characterizing the organic matter content of shale, which mainly includes the following modules:

[0131] A data acquisition module is used to acquire multi-dimensional nuclear magnetic resonance data according to a preset multi-dimensional nuclear magnetic pulse sequence, wherein the multi-dimensional nuclear magnetic resonance data includes multiple echo train signals and multiple FID signals;

[0132] The data processing module is used to process the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

[0133] It should be noted that the specific content involved in this embodiment can be found in the description of the above method embodiment. For the sake of brevity, it will not be repeated here.

[0134] See also Figure 7 , is a structural diagram of an electronic device provided in an embodiment of the present application. Figure 7 As shown, the electronic device 700 may specifically include a processor 701, a memory 702, and a communication unit 703. These components communicate via one or more buses. Those skilled in the art will appreciate that the electronic device structure shown in the figure does not limit the embodiments of the present application. It may be a bus structure or a star structure, and may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0135] The communication unit 703 is used to establish a communication channel so that the electronic device can communicate with other devices.

[0136] The processor 701 is the control center of the electronic device. It uses various interfaces and lines to connect various parts of the entire electronic device. It runs or executes software programs and / or modules stored in the memory 702, and calls data stored in the memory to perform various functions of the electronic device and / or process data. The processor can be composed of an integrated circuit (IC), for example, it can be composed of a single packaged IC, or it can be composed of multiple packaged ICs with the same or different functions. For example, the processor 701 can include only a central processing unit (CPU). In the embodiment of the present application, the CPU can be a single computing core or multiple computing cores.

[0137] The memory 702 is used to store execution instructions of the processor 701. The memory 702 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 memory, flash memory, magnetic disk or optical disk.

[0138] When the execution instructions in the memory 702 are executed by the processor 701 , the electronic device 700 is enabled to execute part or all of the steps in the above method embodiments.

[0139] Corresponding to the above embodiment, an embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium may store a program, wherein, when the program is executed, the device containing the computer-readable storage medium may be controlled to perform some or all of the steps in the above method embodiment. In a specific implementation, the computer-readable storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0140] Corresponding to the above embodiment, an embodiment of the present application further provides a computer program product, which includes executable instructions. When the executable instructions are executed on a computer, the computer executes some or all of the steps in the above method embodiment.

[0141] Those skilled in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented using a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians 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.

[0142] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0143] In the several embodiments provided in this application, if any function 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 technical solution of this application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of this application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program code.

[0144] The above description is merely a specific embodiment of the present application. Any person skilled in the art may easily conceive of variations or substitutions within the technical scope disclosed in this application, and such variations or substitutions shall be within the scope of protection of this application. The scope of protection of this application shall be subject to the scope of protection of the claims.

Claims

1. A multidimensional nuclear magnetic resonance method for characterizing the organic matter content of shale, characterized in that: include: S1: acquiring multidimensional nuclear magnetic resonance data according to a preset multidimensional nuclear magnetic pulse sequence, wherein the multidimensional nuclear magnetic resonance data includes a plurality of echo train signals and a plurality of FID signals; S2: Processing the multidimensional nuclear magnetic resonance data to obtain a multidimensional nuclear magnetic resonance result; Step S1 specifically includes: S1.1: Apply a 90° radio frequency pulse to the hydrogen proton spin system of the sample under test through the TRS channel to rotate the macroscopic magnetization vector M0 to the transverse plane and obtain the transverse plane magnetization vector; S1.2: Waiting time T W Then, a 90° radio frequency pulse is applied to the spin system through the TRS channel to restore the magnetization vector M0 in the longitudinal direction after thermal equilibrium recovery. ’ Turn to the transverse plane, turn off the 90° RF pulse, and collect FID signals on the ACQ channel; S1.3: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector; S1.4: Wait for half the echo interval T E , collect a complete discrete spin echo signal in the ACQ channel; S1.5: Wait for half the echo interval T E , applying a 90° radio frequency pulse to the spin system on the TRS channel to refocus the dephased transverse plane magnetization vector; S1.6: Repeat S1.4 and S1.5 until n spin echo signals and one FID signal are acquired in the ACQ channel, where the n spin echo signals form an echo train signal. S1.

7. Change the waiting time T W Repeat S1.1 to S1.6 m times to acquire m echo train signals and m FID signals, thus obtaining multi-dimensional NMR data; The response formula of the multidimensional NMR data is as follows: Among them, F(T1,T2) is the two-dimensional T1-T2 characteristic matrix of the sample under test, T1 is the longitudinal relaxation time, T2 is the transverse relaxation time, T W is the waiting time, and t is the time corresponding to the acquisition of FID signal and spin echo signal.

2. The method according to claim 1, characterized in that The echo interval T E Greater than or equal to 0.2ms.

3. A multidimensional nuclear magnetic resonance device for characterizing shale organic matter content used in the multidimensional nuclear magnetic resonance method for characterizing shale organic matter content according to claim 1, characterized in that: The device mainly includes the following modules: A data acquisition module is used to acquire multi-dimensional nuclear magnetic resonance data according to a preset multi-dimensional nuclear magnetic pulse sequence, wherein the multi-dimensional nuclear magnetic resonance data includes multiple echo train signals and multiple FID signals; The data processing module is used to process the multidimensional nuclear magnetic resonance data to obtain multidimensional nuclear magnetic resonance results.

4. An electronic device, characterized in that: The device comprises: processor; A memory having executable instructions stored thereon, wherein the executable instructions are executed by the processor to cause the electronic device to execute the steps of the multi-dimensional nuclear magnetic resonance method according to any one of claims 1 to 2.

5. A computer-readable storage medium, characterized in that The storage medium stores executable instructions, which, when executed, implement the steps of the multi-dimensional nuclear magnetic resonance method according to any one of claims 1 to 2.

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