A spectrum measurement method, device, equipment and storage medium in nuclear magnetic resonance

Abstract

The present invention relates to the field of nuclear magnetic resonance technology, and discloses a spectrum measurement method, device, equipment and storage medium in nuclear magnetic resonance. The target sample is set in a uniform magnetic field, the target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is set on the target sample. The method includes: applying a linear gradient magnetic field in the target direction of the target sample; determining the uniform area of ​​the radio frequency coil according to the bandwidth of the radio frequency pulse signal; during the reception of the nuclear magnetic resonance echo signal, adjusting the magnetic field size of the linear gradient magnetic field based on the target turning angle until the area of ​​the nuclear magnetic resonance echo signal is constrained within the uniform area of ​​the radio frequency coil to obtain the target linear gradient magnetic field; obtaining the target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field; inverting the target nuclear magnetic resonance echo signal to obtain the T1-T2 spectrum. The problem of T1 end tailing caused by traditional T1-T2 measurement is solved, and the measurement accuracy is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of nuclear magnetic resonance technology, and in particular to a spectrum measurement method, device, equipment and storage medium in nuclear magnetic resonance. Background Art

[0002] As a non-destructive analytical method, nuclear magnetic resonance (NMR) technology has been widely used in the fields of materials science, biomedicine, geological exploration, etc. In NMR technology, the radio frequency coil contains a uniform area and an inhomogeneous area. The uniform area of ​​the radio frequency coil refers to the area where the radio frequency magnetic field intensity is relatively uniform and has little variation in the NMR experiment; corresponding to the uniform area, the inhomogeneous area of ​​the radio frequency coil refers to the area where the radio frequency magnetic field intensity varies greatly.

[0003] In the inhomogeneous area, due to the inhomogeneity of the radio frequency magnetic field, atomic nuclei at different positions will be excited by radio frequencies of different frequencies, resulting in frequency broadening and resolution reduction of the NMR signal, which seriously causes data distortion and affects the quantitative test results. In addition, there is also the T1 tailing problem. For example, when the core length is greater than the coil detection range during core measurement, the linear and nonlinear regions simultaneously produce signal contributions, but in two-dimensional measurements, the flip angle of the nonlinear region is inconsistent with the linear region. Therefore, after inversion, T1 often does not converge, which will cause certain errors in the identification of unconventional reservoir fluids. Traditional nuclear magnetic resonance T1-T2 measurements are performed in a uniform field, which has certain requirements and restrictions on the sample length. For magnetic resonance measurements of long samples, it is often necessary to cut the sample to a specified length and then place it in the uniform area for measurement.

[0004] Therefore, there is an urgent need for a spectrum measurement method in NMR for long samples, which can solve the problems of signal distortion in the inhomogeneous area and T1 tailing existing in the traditional spectrum measurement method in NMR. Summary of the invention

[0005] In view of this, the present application provides a spectrum measurement method, device, equipment and storage medium in nuclear magnetic resonance, which can solve the problems of non-uniform area signal distortion and T1 tailing in traditional spectrum measurement methods in nuclear magnetic resonance. The technical solution is as follows.

[0006] In a first aspect, the present invention provides a spectrum measurement method in nuclear magnetic resonance, wherein a target sample is arranged in a uniform magnetic field, a target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is arranged on the target sample, the method comprising:

[0007] applying a linear gradient magnetic field in a target direction of the target sample;

[0008] Transmitting a radio frequency pulse signal to a target sample through a radio frequency coil, and determining a uniform area of ​​the radio frequency coil according to a bandwidth of the radio frequency pulse signal;

[0009] During the reception of the nuclear magnetic resonance echo signal, the gradient value of the linear gradient magnetic field is adjusted based on the target turning angle until the region of the nuclear magnetic resonance echo signal is constrained within the uniform region of the radio frequency coil to obtain the target linear gradient magnetic field;

[0010] According to the target linear gradient magnetic field, a target nuclear magnetic resonance echo signal is obtained;

[0011] The target nuclear magnetic resonance echo signal is inverted to obtain a T1-T2 spectrum.

[0012] In an optional embodiment, the gradient coil is composed of a plurality of current coils; and the target direction includes an axial direction of the target sample.

[0013] In an optional embodiment, applying a linear gradient magnetic field in a target direction of the target sample includes: adjusting the current direction of the current coil so that a linear gradient magnetic field is applied in an axial direction of the target sample. Adjusting the gradient value of the linear gradient magnetic field includes: adjusting the gradient value of the linear gradient magnetic field by adjusting the current value of the current coil.

[0014] In an optional embodiment, the inverting the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum includes:

[0015] According to the target turning angle, a T1-T2 data response model is determined;

[0016] Based on the target nuclear magnetic resonance echo signal, the T1-T2 data response model is inverted to obtain a T1-T2 spectrum.

[0017] In an optional implementation, the expression of the T1-T2 data response model is:

[0018] ;

[0019] Where, T 1 is the longitudinal relaxation time, T 2 is the transverse relaxation time, TR waiting time, TE echo interval, b ij It represents the signal amplitude at time j in the i-th echo train with TR waiting time and TE echo interval.

[0020] In an optional embodiment, the turning angle is 90 degrees.

[0021] The spectrum measurement method in nuclear magnetic resonance provided by the present invention has the following advantages.

[0022] The spectrum measurement method in nuclear magnetic resonance of the present invention is applied to the measurement of long target samples. A gradient coil is arranged on the target sample, and the gradient coil is composed of a plurality of current coils. First, the target sample to be measured is placed in the main magnetic field so that the axial direction of the target sample is consistent with the direction of the main magnetic field, and the main magnetic field is set to a uniform magnetic field. Then, the current coil is energized to generate a linear gradient magnetic field, the direction of which is consistent with the main magnetic field, and the magnitude of the linear gradient magnetic field is controlled by the magnitude of the current in the current coil. A radio frequency pulse signal is emitted to the target sample through the radio frequency coil to excite the nuclear resonance of the target sample, generate a nuclear magnetic resonance signal, and collect the nuclear magnetic resonance signal generated by the target sample through the radio frequency coil. The spectrum measurement method in nuclear magnetic resonance of the present invention needs to constrain the region of the nuclear magnetic resonance signal to the uniform region of the radio frequency coil, so that it can be confirmed that the turning angle of the T1-T2 data response model is 90 degrees. Based on this target turning angle, the gradient value of the linear gradient magnetic field is adjusted, that is, the current of the current coil is adjusted, so that the region of the nuclear magnetic resonance signal is constrained to the uniform region of the radio frequency coil, and the gradient value of the linear gradient magnetic field at this time is recorded. The determination of the homogeneous area of ​​the radio frequency coil is that the excitation and receiving thickness of the nuclear magnetic resonance signal can be calculated according to the bandwidth of the radio frequency pulse signal, and the homogeneous area of ​​the radio frequency coil can be obtained according to the excitation and receiving thickness. According to the gradient value of the linear gradient magnetic field set at this time, the target nuclear magnetic resonance signal is collected. Since the turning angle is constrained to be 90 degrees, the expression of the T1-T2 data response model is consistent with the expression of the T1-T2 inversion model, which solves the tailing problem caused by the inconsistency between the response model and the inversion model in the conventional test method. Therefore, by inverting the target nuclear magnetic resonance signal, the T1-T2 spectrum can be obtained. The spectrum measurement method in the nuclear magnetic resonance of the present invention constrains the nuclear magnetic resonance signal within the homogeneous area of ​​the radio frequency coil by applying a linear gradient magnetic field to the sample, adjusting the gradient output size, matching the bandwidth of the radio frequency pulse signal, and solving the non-uniform area signal distortion and T1 tailing problems caused by the traditional T1-T2 measurement of long samples, and greatly improving the measurement accuracy.

[0023] In a second aspect, the present invention provides a spectrum measurement device in nuclear magnetic resonance, wherein a target sample is arranged in a uniform magnetic field, a target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is arranged on the target sample, the device comprising:

[0024] A linear gradient magnetic field application module, used for applying a linear gradient magnetic field in a target direction of a target sample;

[0025] A uniform area determination module is used to transmit a radio frequency pulse signal to a target sample through a radio frequency coil, and determine a uniform area of ​​the radio frequency coil according to a bandwidth of the radio frequency pulse signal;

[0026] A linear gradient magnetic field adjustment module is used to adjust the gradient value of the linear gradient magnetic field based on the target turning angle during the reception of the nuclear magnetic resonance echo signal, until the area of ​​the nuclear magnetic resonance echo signal is constrained within the uniform area of ​​the radio frequency coil, thereby obtaining the target linear gradient magnetic field;

[0027] An acquisition module, used for obtaining a target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field;

[0028] The inversion module is used to invert the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum.

[0029] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the spectrum measurement method in nuclear magnetic resonance of the above-mentioned first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0030] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the spectrum measurement method in nuclear magnetic resonance according to the first aspect or any corresponding embodiment thereof.

[0031] In a fifth aspect, the present invention provides a computer program product, comprising computer instructions for causing a computer to execute the spectrum measurement method in nuclear magnetic resonance according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 The figure is a flowchart of a spectrum measurement method in nuclear magnetic resonance according to an exemplary embodiment.

[0034] Figure 2 It is a schematic diagram of an SR-CPMG sequence diagram according to an exemplary embodiment.

[0035] Figure 3 It is a schematic diagram of an SR-CPMG-G sequence diagram according to an exemplary embodiment.

[0036] Figure 4 is a schematic diagram of a turning angle according to an exemplary embodiment.

[0037] Figure 5 It is a schematic diagram showing the results of a traditional SR-CPMG test on a long water film sample according to an exemplary embodiment.

[0038] Figure 6 It is a schematic diagram showing the results of SR-CPMG-G testing a long water film sample according to an exemplary embodiment.

[0039] Figure 7 It is a schematic diagram showing the results of conventional SR-CPMG testing of a shale (long) sample according to an exemplary embodiment.

[0040] Figure 8 It is a schematic diagram showing the results of SR-CPMG-G testing a shale (long) sample according to an exemplary embodiment.

[0041] Fig. 9 It is a structural schematic diagram of a spectrum measurement device in nuclear magnetic resonance provided in an embodiment of the present application.

[0042] Fig.10 It is a structural schematic diagram of a computer device provided by an optional embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0044] It should be understood that the "indication" mentioned in the embodiments of the present application can be a direct indication, an indirect indication, or an indication of an association relationship. For example, A indicates B, which can mean that A directly indicates B, for example, B can be obtained through A; it can also mean that A indirectly indicates B, for example, A indicates C, and B can be obtained through C; it can also mean that there is an association relationship between A and B.

[0045] In the description of the embodiments of the present application, the term "corresponding" may indicate a direct or indirect correspondence between two items, or an association relationship between the two items, or a relationship between indication and being indicated, configuration and being configured, and the like.

[0046] In an embodiment of the present application, "predefinition" may be implemented by pre-saving corresponding codes, tables or other methods that can be used to indicate relevant information in a device (for example, including a terminal device and a network device). The present application does not limit its specific implementation method.

[0047] As a non-destructive analytical method, nuclear magnetic resonance (NMR) technology has been widely used in materials science, biomedicine, geological exploration and other fields. Magnetic resonance technology can avoid the skeleton response of porous media and directly obtain the hydrogen-containing signal in the porous fluid. It has achieved very good application results in the evaluation of fluid properties in petroleum geology and materials science. One-dimensional NMR can obtain the porosity and pore size distribution of porous media, and two-dimensional NMR can obtain fluid type and saturation information.

[0048] In NMR technology, the RF coil contains a uniform area and an inhomogeneous area. The uniform area of ​​the RF coil refers to the area where the RF magnetic field intensity is relatively uniform and varies little in the NMR experiment; corresponding to the uniform area, the inhomogeneous area of ​​the RF coil refers to the area where the RF magnetic field intensity varies greatly. In this area, due to the inhomogeneity of the RF magnetic field, the nuclei at different positions will be excited by RF of different frequencies, resulting in frequency broadening and resolution reduction of the NMR signal, which seriously causes data distortion and affects the quantitative test results. In addition, when the core length is greater than the coil detection range during core measurement, the linear and nonlinear regions simultaneously generate signal contributions, but in two-dimensional measurement, the flip angle of the nonlinear region is inconsistent with the linear region, so T1 often does not converge after inversion, which will bring certain errors to the identification of unconventional reservoir fluids. Traditional nuclear magnetic resonance porous media measurements are completed in a uniform field, which has certain requirements and restrictions on the sample length. For magnetic resonance measurements of long cores, it is often necessary to cut the sample to a specified length and then put it into the uniform area for measurement.

[0049] In nuclear magnetic resonance (NMR), T1 (longitudinal relaxation time) and T2 (transverse relaxation time) are important parameters for describing the relaxation process of nuclear spins in samples or tissues. The tailing effect in T1 and T2 measurements will affect the accuracy of the data and cause errors in the measurement results. Tailing refers to the fact that during the signal acquisition process, the decay curve of the signal has a non-ideal tail after the ideal exponential decay, that is, the signal decay process becomes slower, or the curve does not completely decay to zero at the end. This phenomenon often results in the fitting curve in the measurement of T1 and T2 not accurately reflecting the actual relaxation process, affecting the accuracy of the measurement results.

[0050] The occurrence of tailing phenomenon may be caused by multiple factors, common reasons include: in NMR experiments, the inhomogeneity of local magnetic field may cause different relaxation characteristics of magnetization vectors in different regions, resulting in signal tailing. In addition, the inhomogeneity of magnetic field may come from interference from the sample itself, container, equipment or external environment. The non-ideal performance of the hardware of NMR instrument (such as RF pulses, probes and receiving systems) may lead to incomplete signal attenuation. In particular, the bandwidth limitation of the receiving system or the incomplete time domain response of the pulse may lead to signal tailing.

[0051] Therefore, the problems of signal distortion in the inhomogeneous area and T1 tailing in the T1-T2 measurement of nuclear magnetic resonance of long samples need to be solved urgently. The embodiment of the present invention provides a spectrum measurement method in nuclear magnetic resonance, which can effectively and selectively excite and detect the information of a certain layer in the sample by applying a specific linear gradient magnetic field in the axial direction of the sample, and solve the problem of signal distortion in the inhomogeneous area. At the same time, by changing the gradient value, the nuclear magnetic resonance signal contribution area is constrained to solve the T1 non-convergence problem caused by the signal contribution of the inhomogeneous area. At the same time, high-resolution T1-T2 measurement data of the sample can be obtained, which solves the problem of signal distortion in the inhomogeneous area and T1 tailing in the spectrum measurement method of the traditional nuclear magnetic resonance of long samples.

[0052] In the spectrum measurement method in nuclear magnetic resonance of this embodiment, the target sample is placed in a uniform magnetic field, the target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is placed on the target sample. Figure 1 As shown, the following steps are included.

[0053] S101. Apply a linear gradient magnetic field in a target direction of a target sample.

[0054] Specifically, in step S101, the target sample is a long sample, and a long core sample can be selected. The target direction is the axial direction of the target sample, and for the long core sample, it is the core length direction of the long core sample. The linear gradient magnetic field is applied by a gradient coil, and the gradient coil is composed of a plurality of current coils. The direction and gradient value of the linear gradient magnetic field can be changed by changing the direction and magnitude of the current in the current coil.

[0055] S102 , transmitting a radio frequency pulse signal to a target sample through a radio frequency coil, and determining a uniform area of ​​the radio frequency coil according to a bandwidth of the radio frequency pulse signal.

[0056] Specifically, in step S102, a radio frequency pulse signal is transmitted to the target sample through the radio frequency coil to excite the nuclear resonance of the target sample, thereby generating a nuclear magnetic resonance signal, and the generated nuclear magnetic resonance signal is collected by the radio frequency coil.

[0057] Optionally, in the traditional NMR method, the NMR echo signal is generally collected through the SR-CPMG (Steady-State Refocusing CPMG) sequence. The SR-CPMG sequence diagram is as follows: Figure 2 As shown, the SR-CPMG sequence is a pulse sequence commonly used in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI), mainly used to improve the steady-state response of the signal and reduce signal attenuation in the experiment.

[0058] This embodiment introduces a gradient pulse on the basis of the SR-CPMG sequence, that is, the SR-CPMG-G sequence (Steady-State Refocusing CPMG with Gradient) is used to collect nuclear magnetic resonance echo signals. The SR-CPMG-G sequence is shown in FIG. Figure 3 As shown in the figure, the SR-CPMG-G sequence combines the advantages of the steady-state refocusing CPMG (SR-CPMG) sequence and achieves spatial encoding or other optimization purposes by introducing gradient pulses. Its main application areas generally include improving spatial resolution in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) and enhancing specific signals. The SR-CPMG-G sequence maintains steady-state magnetization and refocuses transverse magnetization through periodic 180° pulses. This helps to reduce the impact of transverse relaxation and improve signal stability.

[0059] In the above steps, since a linear gradient magnetic field is applied, there is a linear difference in the H nuclear resonance frequency at each position of the sample in the gradient direction. The limited bandwidth of the RF pulse in the frequency domain determines the excitation and receiving thickness of the NMR signal, that is, the uniform area of ​​the RF coil. The expressions for the excitation and receiving thickness are:

[0060] ;

[0061] Where P 2 is the pulse width, i.e. the pulse application time; G △B represents the magnitude of the applied gradient, γ is the H nuclear gyromagnetic ratio, 42.58 MHz / T.

[0062] S103. During the reception of the nuclear magnetic resonance echo signal, the gradient value of the linear gradient magnetic field is adjusted based on the target turning angle until the region of the nuclear magnetic resonance echo signal is constrained within the uniform region of the radio frequency coil, thereby obtaining the target linear gradient magnetic field.

[0063] Specifically, in step S103, the region of the nuclear magnetic resonance signal needs to be constrained within the uniform region of the radio frequency coil, so that the expression of the T1-T2 signal response model and the T1-T2 inversion model can be consistent, that is, the turning angle is 90 degrees. Figure 4As shown in the figure, taking a long core sample as an example, the core length is greater than the length of the uniform zone of the RF coil. In addition to the signal contributed by the uniform zone, there is also a signal contribution from the non-uniform zone. In actual conditions, the angle of the resonant zone is 90°, and the angle of the non-resonant zone is less than 90°. The turning angle of the non-resonant zone is not a constant and cannot be determined. Therefore, in its inversion model, only the 90° turning angle can be selected as the inversion response model, and the turning angle of the non-uniform zone cannot be measured. Therefore, based on the target turning angle of 90 degrees, the current of the current coil is adjusted, thereby adjusting the gradient value of the gradient magnetic field until the area of ​​the nuclear magnetic resonance signal is constrained within the uniform zone of the RF coil. When adjusting the gradient value of the gradient magnetic field, in order to achieve the measurement effect, the gradient climbing time is set to 1~3ms, and the gradient stabilization time is set to 10~30ms. The combination of the gradient field pulse sequence and the SR-CPMG sequence can solve the T1 tailing problem of the traditional T1-T2 measurement method of long samples.

[0064] In the above steps, the expression of the gradient value of the linear gradient magnetic field is:

[0065] ;

[0066] Where h is the excitation and receiving thickness; G max is the maximum value of the gradient; G A0 is the gradient output amplitude; γ is the H nuclear gyromagnetic ratio, 42.58MHz / T.

[0067] The expression of the traditional T1-T2 data response model is as follows:

[0068] ;

[0069] Setting the turning angle , the T1-T2 data response model of this embodiment can be obtained, and the expression is:

[0070] ;

[0071] The T1-T2 inversion model is also based on this formula, thus ensuring the consistency between the inversion model and the response model and solving the tailing problem caused by model inconsistency in conventional testing methods.

[0072] S104. Obtain a target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field.

[0073] Specifically, in step S104, the current of the current coil is adjusted to adjust the gradient value of the gradient magnetic field until the region of the nuclear magnetic resonance signal is confined within the uniform region of the radio frequency coil, and the gradient value at this time is recorded, i.e., the target linear gradient magnetic field. Under this target linear gradient magnetic field, a radio frequency pulse signal is emitted to obtain a target nuclear magnetic resonance signal.

[0074] S105 , inverting the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum.

[0075] Specifically, in step S105, after obtaining the target nuclear magnetic resonance signal, the T1-T2 spectrum can be obtained by performing inversion using the above-mentioned T1-T2 inversion model.

[0076] In summary, the spectrum measurement method in the nuclear magnetic resonance provided by the embodiment of the present invention is applied to the measurement of long target samples. A gradient coil is arranged on the target sample, and the gradient coil is composed of a plurality of current coils. First, the target sample to be measured is placed in the main magnetic field so that the axial direction of the target sample is consistent with the direction of the main magnetic field, and the main magnetic field is set to a uniform magnetic field. Then, the current coil is energized to generate a linear gradient magnetic field, the direction of which is consistent with the main magnetic field, and the magnitude of the linear gradient magnetic field is controlled by the magnitude of the current in the current coil. A radio frequency pulse signal is transmitted to the target sample through the radio frequency coil to excite the nuclear resonance of the target sample, generate a nuclear magnetic resonance signal, and collect the nuclear magnetic resonance signal generated by the target sample through the radio frequency coil. The spectrum measurement method in the nuclear magnetic resonance of the present invention needs to constrain the area of ​​the nuclear magnetic resonance signal to the uniform area of ​​the radio frequency coil, so it can be confirmed that the turning angle of the T1-T2 data response model is 90 degrees. Based on this target turning angle, the gradient value of the linear gradient magnetic field is adjusted, that is, the current of the current coil is adjusted, so that the area of ​​the nuclear magnetic resonance signal is constrained to the uniform area of ​​the radio frequency coil, and the gradient value of the linear gradient magnetic field at this time is recorded. The determination of the homogeneous area of ​​the radio frequency coil is that the excitation and receiving thickness of the nuclear magnetic resonance signal can be calculated according to the bandwidth of the radio frequency pulse signal, and the homogeneous area of ​​the radio frequency coil can be obtained according to the excitation and receiving thickness. According to the gradient value of the linear gradient magnetic field set at this time, the target nuclear magnetic resonance signal is collected. Since the turning angle is constrained to be 90 degrees, the expression of the T1-T2 data response model is consistent with the expression of the T1-T2 inversion model, which solves the tailing problem caused by the inconsistency between the response model and the inversion model in the conventional test method. Therefore, by inverting the target nuclear magnetic resonance signal, the T1-T2 spectrum can be obtained. The spectrum measurement method in the nuclear magnetic resonance of the present invention constrains the nuclear magnetic resonance signal within the homogeneous area of ​​the radio frequency coil by applying a linear gradient magnetic field to the sample, adjusting the gradient output size, matching the bandwidth of the radio frequency pulse signal, and solving the non-uniform area signal distortion and T1 tailing problems caused by the traditional T1-T2 measurement of long samples, and greatly improving the measurement accuracy.

[0077] Exemplarily, here, a long water film sample and a mud shale sample (long) are used as test samples to illustrate the spectrum measurement method in the above-mentioned nuclear magnetic resonance. The long water film sample and the mud shale sample (long) are used as test samples to cover the entire test area. The internal gradient field of the mud shale sample is large and is greatly affected by the radio frequency non-uniformity. The long water film sample and the mud shale sample (long) are measured by the spectrum measurement method in the nuclear magnetic resonance provided by the above embodiment.

[0078] The results of testing the long water film sample using the traditional SR-CPMG sequence are as follows Figure 5 As shown, the results of testing the long water film sample using the method of this embodiment, that is, using SR-CPMG-G, are as follows Figure 6 As shown, Figure 5 and Figure 6 Intensity (au) indicates the signal amplitude value. The results of using the traditional SR-CPMG sequence to test shale (long) are as follows Figure 7 As shown, the results of using the method of this embodiment, that is, using SR-CPMG-G to test shale (long) are as follows Figure 8 It can be seen that the spectrum measurement method in NMR provided by the embodiment of the present invention solves the T1 tailing problem of the spectrum measurement method in NMR of long samples, and can achieve high-precision and high-efficiency measurement of specific layers inside the sample.

[0079] In the embodiments of the present application, a spectrum measuring device in nuclear magnetic resonance is also provided, which is used to implement the above embodiments and preferred embodiments, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0080] The present application provides a spectrum measurement device in nuclear magnetic resonance. Fig. 9 : is a schematic structural diagram of a spectrum measurement device in a nuclear magnetic resonance provided by an embodiment of the present application, wherein a target sample is set in a uniform magnetic field, a target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is set on the target sample. The device comprises:

[0081] A linear gradient magnetic field applying module 901 is used to apply a linear gradient magnetic field in a target direction of a target sample;

[0082] A uniform area determination module 902 is used to transmit a radio frequency pulse signal to a target sample through a radio frequency coil, and determine a uniform area of ​​the radio frequency coil according to a bandwidth of the radio frequency pulse signal;

[0083] The linear gradient magnetic field adjustment module 903 is used to adjust the gradient value of the linear gradient magnetic field based on the target turning angle during the reception of the nuclear magnetic resonance echo signal, until the area of ​​the nuclear magnetic resonance echo signal is constrained within the uniform area of ​​the radio frequency coil, thereby obtaining the target linear gradient magnetic field;

[0084] An acquisition module 904 is used to obtain a target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field;

[0085] The inversion module 905 is used to invert the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum.

[0086] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0087] The spectrum measurement device in the nuclear magnetic resonance in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0088] The embodiment of the present invention also provides a computer device having the above Fig. 9 The spectrum measurement device in nuclear magnetic resonance is shown.

[0089] See also Fig.10 , Fig.10 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Fig.10 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process instructions executed in the computer device, including instructions stored in or on the memory to display graphic information in a graphical user interface on an external input / output device (such as a display device coupled to an interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Fig.10 A processor 10 is taken as an example.

[0090] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0091] The memory 20 stores instructions executable by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0092] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0093] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0094] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Fig.10 The example of connecting through bus is taken in the following.

[0095] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0096] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0097] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A spectrum measurement method in nuclear magnetic resonance, characterized in that: The target sample is arranged in a uniform magnetic field, the target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is arranged on the target sample. The method comprises: applying a linear gradient magnetic field in a target direction of the target sample; Transmitting a radio frequency pulse signal to a target sample through a radio frequency coil, and determining a uniform area of ​​the radio frequency coil according to a bandwidth of the radio frequency pulse signal; During the reception of the nuclear magnetic resonance echo signal, the gradient value of the linear gradient magnetic field is adjusted based on the target turning angle until the region of the nuclear magnetic resonance echo signal is constrained within the uniform region of the radio frequency coil to obtain the target linear gradient magnetic field; Obtaining a target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field; Inverting the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum; Wherein, the gradient coil is composed of a plurality of current coils; the target direction includes the axial direction of the target sample; Applying a linear gradient magnetic field in a target direction of the target sample comprises: adjusting the current direction of the current coil so as to apply a linear gradient magnetic field in the axial direction of the target sample; The step of adjusting the gradient value of the linear gradient magnetic field comprises: By adjusting the current of the current coil, the gradient value of the linear gradient magnetic field is adjusted; The turning angle is 90 degrees.

2. The method according to claim 1, characterized in that The inverting the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum comprises: Determining a T1-T2 data response model according to the target turning angle; Based on the target nuclear magnetic resonance echo signal, the T1-T2 data response model is inverted to obtain a T1-T2 spectrum.

3. The method according to claim 2, characterized in that The expression of the T1-T2 data response model is: ； Where, T1 is the longitudinal relaxation time, T2 is the transverse relaxation time, TR is the waiting time, TE is the echo interval, b is ij It represents the signal amplitude at time j in the i-th echo train with TR waiting time and TE echo interval.

4. A spectrum measuring device in nuclear magnetic resonance, characterized in that: The target sample is arranged in a uniform magnetic field, the target direction of the target sample is consistent with the uniform magnetic field, and a gradient coil is arranged on the target sample. The device comprises: A linear gradient magnetic field application module, used for applying a linear gradient magnetic field in a target direction of a target sample; A uniform area determination module, used for transmitting a radio frequency pulse signal to a target sample through a radio frequency coil, and determining a uniform area of ​​the radio frequency coil according to a bandwidth of the radio frequency pulse signal; A linear gradient magnetic field adjustment module is used to adjust the gradient value of the linear gradient magnetic field based on the target turning angle during the reception of the nuclear magnetic resonance echo signal, until the area of ​​the nuclear magnetic resonance echo signal is constrained within the uniform area of ​​the radio frequency coil, thereby obtaining a target linear gradient magnetic field; An acquisition module, used to obtain a target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field; An inversion module, used to invert the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum; Wherein, the gradient coil is composed of a plurality of current coils; the target direction includes the axial direction of the target sample; Applying a linear gradient magnetic field in a target direction of the target sample comprises: adjusting the current direction of the current coil so as to apply a linear gradient magnetic field in the axial direction of the target sample; The step of adjusting the gradient value of the linear gradient magnetic field comprises: By adjusting the current of the current coil, the gradient value of the linear gradient magnetic field is adjusted; The turning angle is 90 degrees.

5. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the spectrum measurement method in nuclear magnetic resonance according to any one of claims 1 to 3 by executing the computer instructions.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the spectrum measurement method in nuclear magnetic resonance according to any one of claims 1 to 3.

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