Method for obtaining physical properties of rock core and nuclear magnetic resonance equipment

Abstract

The invention provides a method for obtaining physical properties of a rock core and nuclear magnetic resonance equipment, and the method for obtaining the physical properties of the rock core comprises the following steps: measuring transverse relaxation time T2 of a to-be-measured rock core at different depth positions through nuclear magnetic resonance, and recording first echo data corresponding to each depth position; performing inversion processing on the first echo data at the different depth positions to obtain T2 distribution spectrums at the different depth positions; and obtaining the physical properties of the to-be-tested rock core based on the T2 distribution spectrum. According to the method for obtaining the physical properties of the rock core, the transverse relaxation time T2 is measured through nuclear magnetic resonance, the physical properties and fluid distribution of unconventional reservoirs can be comprehensively and accurately represented, and the method is suitable for different types of unconventional reservoirs. Multi-scale information from the surface to the deep layer can be provided through measurement of different depth positions, and the overall accuracy and reliability of data are improved. According to the inversion processing method, key physical property information can be extracted from complex signals, and the resolution and accuracy of data are improved.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas field exploitation, and in particular to a method for obtaining core physical properties and a nuclear magnetic resonance device. Background Art

[0002] In the process of oil and gas field exploration and development, it is crucial to conduct a comprehensive and detailed evaluation of the reservoir. By deeply understanding the pore structure and fluid properties inside the reservoir, it is not only possible to optimize the mining strategy and increase oil and gas production, but also to effectively evaluate the distribution of remaining oil, providing a key basis for the study of remaining oil distribution and comprehensive reservoir evaluation, which is of great significance for improving the development efficiency of oil and gas fields and ensuring energy supply.

[0003] At present, field measurement technologies mainly include conventional logging methods (such as acoustic logging, density logging and element logging). These logging methods can capture changes in fluid-related information in a timely manner. In addition, they can be measured in real time on site, and data can be quickly obtained without complex subsequent processing procedures. The required equipment is relatively simple and easy to operate.

[0004] However, the applicant discovered during the implementation of the present invention that the basic mathematical model of conventional logging methods is mainly designed for medium-high porosity and medium-high permeability reservoirs, which is inconsistent with the low porosity and low permeability characteristics of unconventional reservoirs, resulting in a mismatch in theoretical basis. Therefore, when testing unconventional oil and gas reservoirs, the test results have large deviations and are difficult to meet the needs of practical applications. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a method for obtaining core physical properties and a nuclear magnetic resonance device to solve the technical problem of large deviation in test results of conventional well logging technology in unconventional oil and gas reservoir measurements.

[0006] In order to solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0007] The first aspect of the present application provides a method for obtaining physical properties of a core, comprising:

[0008] The transverse relaxation time T2 of the core to be tested at different depths is measured by using nuclear magnetic resonance, and the first echo data corresponding to each depth is recorded;

[0009] Performing inversion processing on the first echo data at different depths to obtain T2 distribution spectra at different depths;

[0010] The physical properties of the core to be tested are obtained based on the T2 distribution spectrum.

[0011] In some embodiments, the method of measuring the transverse relaxation time T2 of the core to be measured at different depths using nuclear magnetic resonance includes:

[0012] Continuously measuring T2 of the core to be measured at continuous depth positions using the nuclear magnetic resonance;

[0013] The method of performing inversion processing on the first echo data at different depth positions to obtain T2 distribution spectra at different depth positions includes:

[0014] The first echo data at continuous depth positions are inverted to obtain the T2 distribution spectrum at continuous depth positions.

[0015] In some embodiments, before obtaining the physical properties of the core to be tested based on the T2 distribution spectrum, the method further includes:

[0016] Measuring the longitudinal relaxation time T1 of the core to be measured by using the nuclear magnetic resonance, and recording the second echo data;

[0017] Using the nuclear magnetic resonance to measure the two-dimensional relaxation characteristics T2-T1 of the core to be measured, and recording the third echo data;

[0018] performing joint inversion on the second echo data, the third echo data and the first echo train at continuous depth positions to obtain a T2-T1 two-dimensional distribution spectrum at continuous depth positions;

[0019] The method for obtaining the physical properties of the core to be tested based on the T2 distribution spectrum includes:

[0020] The physical properties of the core to be measured are obtained based on the T2 distribution spectrum and the T2-T1 two-dimensional distribution spectrum.

[0021] In some embodiments, before obtaining the physical properties of the core to be tested based on the T2 distribution spectrum, the method further includes:

[0022] Measuring the fluid diffusion coefficient D of the core to be measured by using the nuclear magnetic resonance, and recording the fourth echo data;

[0023] Using the nuclear magnetic resonance to measure the two-dimensional relaxation characteristic T2-D of the core to be measured, and recording the fifth echo data;

[0024] performing joint inversion on the fourth echo data, the fifth echo data and the first echo train at continuous depth positions to obtain a T2-D two-dimensional distribution spectrum at continuous depth positions;

[0025] The method for obtaining the physical properties of the core to be tested based on the T2 distribution spectrum includes:

[0026] The physical properties of the core to be measured are obtained based on the T2 distribution spectrum and the T2-D two-dimensional distribution spectrum.

[0027] In some embodiments, before measuring the transverse relaxation time T2 of the core to be tested at different depths using nuclear magnetic resonance, the method further includes:

[0028] Obtain the core to be tested from the drilling site; wherein the diameter of the core to be tested is greater than or equal to 8 cm and less than or equal to 12 cm; and / or the length of the core to be tested is less than or equal to 110 cm;

[0029] The core to be measured is measured at the drilling site.

[0030] In some embodiments, before performing inversion processing on the first echo data at different depth positions, the method further includes:

[0031] All the collected first echo data are calibrated.

[0032] A second aspect of the present application provides a nuclear magnetic resonance device, comprising:

[0033] frame;

[0034] A magnet chamber, arranged on the frame;

[0035] A driving mechanism is arranged on the frame spaced apart from the magnet chamber along a first horizontal direction;

[0036] A support frame connected to the driving mechanism, wherein the driving mechanism is used to drive the support frame to enter the magnet chamber along a first horizontal direction; the support frame has an initial position;

[0037] A first limiting assembly connected to the initial position of the support frame;

[0038] The second limiting assembly is arranged on the support frame; the first limiting assembly and the second limiting assembly are respectively used to contact with two ends of the core to be measured along the first horizontal direction to jointly limit the movement of the core to be measured along the first horizontal direction.

[0039] In some embodiments, it also includes:

[0040] A locking assembly connected to the second limiting assembly and the support frame;

[0041] Wherein, the second limiting component is movably connected to the support frame to adjust the distance between it and the first limiting component; and the locking component is used to limit the movement of the second limiting component.

[0042] In some embodiments, the second limit assembly is slidably connected to the support frame along the first horizontal direction; the support frame has a bar-shaped through hole, and the length direction of the through hole is the same as the first horizontal direction;

[0043] The locking assembly comprises:

[0044] A screw rod, a first end of which is connected to the limiting plate, and a second end of which extends out of the through hole;

[0045] A nut is threadedly connected to the second end of the screw rod, and the nut can abut against the support frame.

[0046] In some embodiments, the second limiting component includes:

[0047] A lead screw, wherein the length direction of the lead screw is the same as the first horizontal direction;

[0048] The support frame is provided with a threaded hole, the first end of the lead screw is threadedly connected to the support frame through the threaded hole, and the second end of the lead screw is used to contact the core to be measured; the lead screw and the threaded hole together form the locking assembly.

[0049] Compared with the prior art, the method for obtaining the physical properties of the core provided in this application first uses nuclear magnetic resonance to measure the transverse relaxation time T2. Nuclear magnetic resonance technology can comprehensively and accurately characterize the physical properties and fluid distribution of unconventional reservoirs, and is applicable to different types of unconventional reservoirs, such as shale oil, shale gas and tight sandstone. Measurements at different depths can provide multi-scale information from the surface to the deep layer. Multi-depth measurements can ensure the representativeness of the data, avoid deviations caused by local characteristics, and improve the overall accuracy and reliability of the data. Then, by recording the first echo data at each depth position, detailed T2 information is obtained; finally, the inversion processing method can extract key physical property information from complex signals and improve the resolution and accuracy of the data. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0051] Figure 1 The T2 distribution spectrum of the continuous depth of Example 1 of the present application is schematically shown;

[0052] Figure 2 A schematic diagram schematically shows the cut-off time setting of the T2 distribution spectrum of Example 1 of the present application;

[0053] Figure 3 A schematic diagram of the structure of an implementation method of Example 2 of the present application is schematically shown;

[0054] Figure 4 The structural diagram of another implementation method of Example 2 of the present application is schematically shown;

[0055] Figure 5 The structural diagram of another implementation method of Example 2 of the present application is schematically shown;

[0056] Figure 6 The structural diagram of another implementation method of Example 2 of the present application is schematically shown;

[0057] Figure 7 A structural diagram of another implementation method of Example 2 of the present application is schematically shown.

[0058] Description of Figure Numbers:

[0059] 1. Frame; 11. Carrying member; 12. Mounting member; 13. Fixing member; 2. Magnet chamber; 21. Control panel; 3. Driving mechanism; 31. Control system; 4. Support frame; 41. Support member; 42. Connecting member; 5. First limit assembly; 6. Second limit assembly; 61. Lead screw; 62. Spring; 63. First limit plate; 64. Second limit plate; 7. Third limit member; 8. Measuring part; 9. Distance sensor; 10. Controller; 20. Protection cabin; 201. Operation window; 30. Core to be measured; A. First horizontal direction; B. Second horizontal direction. DETAILED DESCRIPTION

[0060] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0061] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by technicians in the field to which this application belongs.

[0062] Example 1

[0063] Embodiment 1 of the present application provides a method for obtaining physical properties of a core, comprising:

[0064] The transverse relaxation time T2 of the core to be tested at different depths is measured by using nuclear magnetic resonance, and the first echo data corresponding to each depth is recorded;

[0065] Before measuring the transverse relaxation time T2 of the core to be tested at different depths by using nuclear magnetic resonance, the method further includes:

[0066] Obtain the core to be tested from the drilling site; wherein the diameter of the core to be tested is greater than or equal to 8 cm and less than or equal to 12 cm; and / or the length of the core to be tested is less than or equal to 110 cm;

[0067] The core to be measured is measured at the drilling site.

[0068] The diameter of the core to be tested can be 8cm, 9cm, 10cm, 11cm or 12cm, etc. The length of the core to be tested can be 110cm, 100cm, 90cm, 80cm or 70cm, etc. The larger core to be tested can fully reflect the physical properties and fluid distribution of the reservoir, reduce the impact of local geological characteristics (such as cracks, mineral composition changes, etc.) on the measurement results, and improve the representativeness of the data. Through measurements at different depths, the overall characteristics of the reservoir can be more accurately evaluated.

[0069] The core to be tested can be transferred to the laboratory for measurement; alternatively, the core to be tested can be measured at the drilling site to omit the processing steps required for the preservation and transfer of the core to be tested (such as the preparation of dry rock samples, the preparation of saturated rock samples, the preparation of dehydrated rock samples, etc.), thereby ensuring the accuracy of the final measurement results.

[0070] Before measurement, different depth positions to be measured can be marked on the core to be measured, for example, by a ruler or other marking tool. Then the prepared core to be measured can be packed in a non-magnetic container (such as a glass test tube) without hydrogen and placed in the magnet chamber of the nuclear magnetic resonance device. Then, a pulse sequence of the transverse relaxation time T2 is selected, and relevant parameters are set. The setting of the parameters is mastered by those skilled in the art and will not be repeated here.

[0071] During the measurement process, after one depth position is measured, the first echo data corresponding to the current depth position is recorded using the data acquisition and recording function of the nuclear magnetic resonance equipment. Then the core to be measured is moved along the depth direction (i.e., length direction) of the core to be measured to measure the next depth position and record the data until all measurements and records are completed.

[0072] By analyzing the initial signal intensity and signal attenuation rate of the first echo data, the porosity and fluid type of the core to be tested can be preliminarily estimated.

[0073] In order to ensure the accuracy of the final measurement result, the method of measuring the transverse relaxation time T2 of the core to be measured at different depths by using nuclear magnetic resonance includes:

[0074] Continuously measuring T2 of the core to be measured at continuous depth positions using the nuclear magnetic resonance;

[0075] The method of performing inversion processing on the first echo data at different depth positions to obtain T2 distribution spectra at different depth positions includes:

[0076] The first echo data at continuous depth positions are inverted to obtain the T2 distribution spectrum at continuous depth positions.

[0077] Specifically, the driving mechanism of the nuclear magnetic resonance equipment of Example 2 of the present application can be used to drive the core to be measured to move 0.1 mm, and then measure it. After the data is collected, the next measurement is performed, and then the driving mechanism is used to drive the core to be measured to move 0.1 mm until all measurements are completed, so as to obtain multi-scale information from the surface to the deep layer, avoid deviations caused by local characteristics, and improve the overall accuracy and reliability of the data.

[0078] In order to ensure accurate physical properties of the core to be measured, before the inversion processing of the first echo data at different depths, the following steps are further included:

[0079] All the collected first echo data are calibrated.

[0080] First, a standard sample with known porosity and known volume can be selected. The porosity and fluid properties of the standard sample can be accurately measured by other methods (such as mercury intrusion, CT scanning, etc.). Then, the same NMR equipment can be used with the same parameter settings to measure the standard sample and obtain the echo data of the standard sample. Next, a linear regression or polynomial fitting method is used to establish a scale relationship between the NMR signal amplitude and porosity, and then the NMR signal amplitude is converted into NMR porosity. The conversion formula is as follows:

[0081]

[0082] Where M i represents the NMR signal amplitude of the i-th relaxation component in the core to be tested;

[0083] M b Represents the total amplitude of the NMR signal of the standard sample;

[0084] S b Indicates the number of superpositions set when the standard sample is subjected to NMR scanning;

[0085] S represents the number of stacking times set when performing nuclear magnetic resonance scanning on the core to be tested;

[0086] G bIt indicates the signal receiving gain when the standard sample is subjected to NMR scanning;

[0087] G represents the signal receiving gain when the core to be tested is subjected to nuclear magnetic resonance scanning;

[0088] V b Indicates the volume of the standard sample;

[0089] V represents the volume of the core to be tested.

[0090] In order to ensure accurate physical properties of the core to be tested, multiple standard samples with known porosity and known volume can be used for multi-standard sample fitting calibration to obtain the fitting result of the nuclear magnetic resonance relaxation signal amplitude and porosity. The fitting relationship is:

[0091] y=ax

[0092] In the formula, y represents the nuclear magnetic porosity value;

[0093] X represents the echo signal amplitude;

[0094] A represents the conversion coefficient between the echo signal amplitude and the nuclear magnetic porosity, that is, the porosity calibration factor.

[0095] Performing inversion processing on the first echo data at different depths to obtain T2 distribution spectra at different depths;

[0096] Specifically, in order to obtain key parameters for core or reservoir pore structure evaluation (such as porosity, permeability, saturation, etc.), it is necessary to perform multi-exponential inversion processing on the first echo data of nuclear magnetic resonance to obtain a one-dimensional T2 distribution. The inversion formula is as follows:

[0097]

[0098] Where y(t) represents t i The echo signal amplitude measured at each moment;

[0099] T 2j represents the transverse relaxation time corresponding to the jth NMR relaxation component;

[0100] p j Represents the distribution spectrum amplitude corresponding to the jth relaxation component.

[0101] Then, the above method is used to invert the first echo data at different depths, that is, to obtain the T2 distribution spectrum at continuous depths. The first echo data at different depths are processed by multi-exponential inversion to obtain the following: Figure 1 T2 distribution spectra at consecutive depth positions are shown.

[0102] Before obtaining the physical properties of the core to be tested based on the T2 distribution spectrum, the method further includes:

[0103] Measuring the longitudinal relaxation time T1 of the core to be measured by using the nuclear magnetic resonance, and recording the second echo data;

[0104] Using the nuclear magnetic resonance to measure the two-dimensional relaxation characteristics T2-T1 of the core to be measured, and recording the third echo data;

[0105] performing joint inversion on the second echo data, the third echo data and the first echo train at continuous depth positions to obtain a T2-T1 two-dimensional distribution spectrum at continuous depth positions;

[0106] The method for obtaining the physical properties of the core to be tested based on the T2 distribution spectrum includes:

[0107] The physical properties of the core to be measured are obtained based on the T2 distribution spectrum and the T2-T1 two-dimensional distribution spectrum.

[0108] The second echo data reflects the longitudinal relaxation time T1 of the core, which can evaluate the fluid mobility, rock mineral composition, etc. The third echo data reflects the two-dimensional relaxation characteristics T2-T1 of the core, which is used to more comprehensively characterize the microstructure and fluid properties of the core, including porosity, permeability and fluid saturation.

[0109] Before measurement, a pulse sequence with a longitudinal relaxation time T1 is selected and relevant parameters are set. The setting of the parameters is known to those skilled in the art and will not be described in detail here.

[0110] The coupling relationship expression of T2 and T1 is as follows:

[0111]

[0112] Where b ik Indicates that the i-th echo has a waiting time of TW k The echo signal amplitude at time ;

[0113] m represents the transverse relaxation time T which is pre-set in logarithmic equal intervals 2j Number;

[0114] r represents the longitudinal relaxation time T which is pre-set in logarithmic equal intervals. 1p Number;

[0115] f jp Denotes the transverse relaxation time T 2j , longitudinal relaxation time T 1p The two-dimensional distribution function of

[0116] Represents the polarization factor term. For the inversion recovery method, α=2; for the saturation recovery method, α=1.

[0117] In the joint inversion, in order to perform joint inversion on k groups of echo train signals with different waiting times and obtain the same solution f jp , requiring different echo trains to satisfy the least squares fitting condition:

[0118]

[0119] In the formula,

[0120] Represents the signal-to-noise ratio of the kth group of echo trains.

[0121] When performing nuclear magnetic resonance measurements, different waiting times (such as different T1 and T2 measurement conditions) will result in different signal-to-noise ratios of the measured echo train data. In order to ensure the accuracy of the inversion results, normalization or weighted processing can be used to balance the signal-to-noise ratios of each group of echo trains, and then the inversion formula can be written in matrix form for solution to obtain the T2-T1 two-dimensional distribution spectrum.

[0122] Before obtaining the physical properties of the core to be tested based on the T2 distribution spectrum, the method further includes:

[0123] Measuring the fluid diffusion coefficient D of the core to be measured by using the nuclear magnetic resonance, and recording the fourth echo data;

[0124] Using the nuclear magnetic resonance to measure the two-dimensional relaxation characteristic T2-D of the core to be measured, and recording the fifth echo data;

[0125] performing joint inversion on the fourth echo data, the fifth echo data and the first echo train at continuous depth positions to obtain a T2-D two-dimensional distribution spectrum at continuous depth positions;

[0126] The method for obtaining the physical properties of the core to be tested based on the T2 distribution spectrum includes:

[0127] The physical properties of the core to be measured are obtained based on the T2 distribution spectrum and the T2-D two-dimensional distribution spectrum.

[0128] Specifically, the fourth echo data mainly reflects the fluid diffusion coefficient D of the core, which can be used to evaluate the fluid properties in the core, such as fluid viscosity, pore connectivity and fluid migration capacity. The fifth echo data mainly reflects the two-dimensional relaxation characteristics T2-D of the core, which can more comprehensively characterize the microstructure and fluid properties of the core, such as porosity, permeability, fluid saturation and pore connectivity.

[0129] By measuring multiple groups of spin echo train data with different echo intervals through the CPMG sequence, the echo signal amplitude can be expressed as:

[0130]

[0131] Where b ik Indicates that the i-th echo has a waiting time of TE K The echo signal amplitude at time ;

[0132] m represents the transverse relaxation time T which is pre-set in logarithmic equal intervals 2j Number;

[0133] n represents the diffusion relaxation D pre-set in logarithmic equal intervals p Number;

[0134] Denotes the transverse relaxation time T 2j , diffusion relaxation D p The two-dimensional distribution function of .

[0135] because,

[0136] It is concluded that

[0137] By jointly inverting the echo string data measured at different echo intervals through the above formula, the two-dimensional distribution spectrum of T2-D can be obtained.

[0138] The physical properties of the core to be tested are obtained based on the T2 distribution spectrum.

[0139] Specifically, the physical properties of the core to be tested may include classical nuclear magnetic porosity, interval porosity and nuclear magnetic permeability.

[0140] In the T2 distribution spectrum, for rock samples saturated with a single fluid, most of the fluids in small pores or micropores are in a bound state, and there are fewer free-flowing fluids. In these tiny pores, the interaction between the fluid and the inner wall of the rock skeleton is strong, so that the relaxation process is mainly affected by surface relaxation, which significantly increases the relaxation rate of the fluid. The fluid in the large pores exhibits relaxation characteristics similar to those of the free fluid, and its relaxation mechanism is mainly bulk relaxation, resulting in a longer relaxation time. Therefore, the short relaxation time in the T2 distribution spectrum reflects the small-sized pores in the rock, while the long relaxation time corresponds to the larger-sized pores.

[0141] The signal intensity of the original echo attenuation curve at the initial moment or the area covered by the T2 distribution curve is proportional to the number of polarizations of hydrogen nuclei within the detection range. The specific value of the NMR porosity can be determined by calibrating the scale using standard samples. for:

[0142]

[0143] In the formula, represents the nuclear magnetic porosity;

[0144] T 2max Indicates the end time of T2 spectrum distribution;

[0145] T 2min Indicates the starting time of T2 spectrum distribution;

[0146] Represents the distribution function of the T2 spectrum curve.

[0147] In order to distinguish between capillary bound fluid and movable fluid, a specific T2 cutoff value T2c can be set. At this time, the movable fluid porosity can be calculated as:

[0148]

[0149] In the formula, represents the movable fluid porosity;

[0150] T 2c Represents the T2 cutoff value that divides movable fluid and capillary-bound fluid.

[0151] An MRI device with an echo interval of 0.15 ms and a high signal-to-noise ratio can be used to accurately detect clay-bound fluid signals with T2 < 0.5 ms. It is basically equal to the total NMR porosity m. In order to distinguish between capillary bound fluid and clay bound fluid, a specific T2 cutoff value T can be set. 2CC , at this time, the porosity of capillary bound fluid can be calculated as:

[0152]

[0153] In the formula, represents the porosity of capillary bound fluid;

[0154] T 2CC represents the T2 cutoff time for classifying capillary bound fluid, clay bound fluid, and movable fluid,

[0155] The calculation formula of clay bound fluid porosity is:

[0156]

[0157] In the formula, represents the clay-bound fluid porosity.

[0158] like Figure 2As shown in the figure, by setting multiple different T2 distribution spectrum cutoff times, the interval porosity in different T2 time ranges can be calculated. The calculation formula is as follows:

[0159]

[0160] …

[0161]

[0162] In the formula, It represents the interval porosity corresponding to the time range of T2;

[0163] T 2c1 , T 2C2 …T 2CN It is the cut-off time of multiple T2 intervals set.

[0164] The nuclear magnetic permeability can be calculated using the free fluid model and the average T2 model. The specific calculation method is known to those skilled in the art and will not be described in detail here.

[0165] Compared with the prior art, the method for obtaining the physical properties of the core provided in Example 1 of the present application first uses nuclear magnetic resonance to measure the transverse relaxation time T2. Nuclear magnetic resonance technology can comprehensively and accurately characterize the physical properties and fluid distribution of unconventional reservoirs, and is applicable to different types of unconventional reservoirs, such as shale oil, shale gas, and tight sandstone. Measurements at different depths can provide multi-scale information from the surface to the deep layer. Multi-depth measurements can ensure the representativeness of the data, avoid deviations caused by local characteristics, and improve the overall accuracy and reliability of the data. Then, by recording the first echo data at each depth position, detailed T2 information is obtained; finally, the inversion processing method can extract key physical property information from complex signals and improve the resolution and accuracy of the data.

[0166] Example 2

[0167] like Figures 3 to 7 Embodiment 2 of the present application provides a nuclear magnetic resonance device, including:

[0168] Rack 1;

[0169] A magnet chamber 2, arranged on the frame 1;

[0170] A driving mechanism 3 is arranged on the frame 1 and spaced apart from the magnet chamber 2 along a first horizontal direction A;

[0171] A support frame 4 connected to the driving mechanism 3, wherein the driving mechanism 3 is used to drive the support frame 4 to enter the magnet chamber 2 along the first horizontal direction A; the support frame 4 has an initial position;

[0172] A first limiting component 5 is connected to the initial position of the supporting frame 4;

[0173] The second limiting assembly 6 is arranged on the support frame 4; the first limiting assembly 5 and the second limiting assembly 6 are respectively used to contact with the two ends of the core 30 to be tested along the first horizontal direction A to jointly limit the movement of the core 30 to be tested along the first horizontal direction A.

[0174] The first horizontal direction A of the present application is the axial direction (ie, the depth direction) of the rock sample 30 to be tested, and the second horizontal direction B is the radial direction of the rock sample 30 to be tested.

[0175] Specifically, the frame 1 is used to provide a stable support platform to ensure the fixation of various components (such as the magnet chamber 2, the driving mechanism 3, the support frame 4, etc.). The frame 1 may include a bearing member 11, a mounting member 12 and two fixing members 13. The bearing member 11 may have a horizontal placement surface, and the magnet chamber 2, the mounting member 12 and the two fixing members 13 may all be arranged on the placement surface. The two fixing members 13 are arranged at intervals along the first horizontal direction A, and the two fixing members 13 may be arranged on the placement surface by bolts or clamping, and the magnet chamber 2 is located between the two fixing members 13. A fixing member 13 is arranged between the mounting member 12 and the magnet chamber 2, and the driving mechanism 3 is arranged on the mounting member 12, and the mounting member 12 may be fixedly arranged on the bearing surface by bolts or clamping.

[0176] The magnet chamber 2 is used to provide a highly uniform static magnetic field so that the nuclear magnetic moment in the core 30 to be tested can be effectively excited and detected. The magnet chamber 2 can be located in the middle of the support 11 along the first horizontal direction A to make the overall device more stable. The magnet chamber 2 can be connected to the placement surface by bolts or other fasteners. The magnet chamber 2 can be located in the middle of the two fixing members 13 along the first horizontal direction A, and the magnet chamber 2 can be spaced from the two fixing members 13. The specific structure of the magnet chamber 2 is known to those skilled in the art and will not be repeated here. The control panel 21 of the magnet chamber 2 is configured on the frame 1, and is used to set and adjust various parameters of the magnet chamber 2, such as magnetic field strength, radio frequency pulse parameters, temperature control, etc.

[0177] The driving mechanism 3 is used to drive the support frame 4 to move precisely along the first horizontal direction A, ensuring that the core 30 to be measured on the support frame 4 can accurately enter and exit the magnet chamber 2. The driving mechanism 3 can be connected to the mounting member 12 by bolts or rivets, and the driving mechanism 3 can be connected to the support frame 4 by clamping or bonding. The driving mechanism 3 can be selected from a stepper motor, a servo motor or a hydraulic cylinder, etc., wherein a stepper motor with a large driving force and high precision is preferred. The control system 31 of the driving mechanism 3 can be arranged on the frame 1, and the step distance of each drive can be set by the control system 31 of the driving mechanism 3. For example, in continuous depth measurement, each drive can be set to 0.1mm, and the interval time between each drive can be set to ensure the accuracy and stability of the measurement. For example, it can be set to wait for 1 second after each drive before the next drive.

[0178] The support frame 4 is used to support the core 30 to be tested, ensuring that the core 30 to be tested remains stable during the measurement process, and ensuring the accuracy and repeatability of the final test result. The two fixing members 13 can be both equipped with a slideway extending along the first horizontal direction A, and the support frame 4 can be slidably connected with the two fixing members 13 along the first horizontal direction A through the slideway. The support frame 4 can be in the shape of a strip extending along the first horizontal direction A. The support frame 4 can be made of non-magnetic metal, such as aluminum or copper, or the support frame 4 can be made of non-metallic materials, such as plastic or carbon fiber, to ensure the accuracy of the final test result of the core 30 to be tested.

[0179] The first limit assembly 5 is used to contact at least part of the first end face of the core 30 to be measured. The first limit assembly 5 is located at the initial position of the support frame 4, which is the reference position of the support frame 4 when it does not enter the magnet chamber 2, and is used to determine the starting position of the core 30 to be measured, so as to ensure that the starting position of the core 30 to be measured is consistent each time the measurement is made, and to improve the repeatability and accuracy of the measurement. By setting the initial position, it is ensured that the starting position of the core 30 to be measured is the same each time the measurement is made. When the measurement starts, the support frame 4 can be driven by the driving mechanism 3 to drive a preset distance along the first horizontal direction A, so that the first end of the core 30 to be measured enters the magnet chamber 2 for measurement, and then continuous depth measurement is performed to comprehensively evaluate the physical properties of the core 30 to be measured, and provide richer data support. The preset distance can be obtained by the design parameters of the equipment; or, a standard sample of known size can be placed on the support frame 4, the driving mechanism 3 is started, the support frame 4 is driven step by step, and the distance of each movement is recorded. When the first end of the standard sample just enters the magnet chamber 2, the moving distance is taken as the preset distance. The nuclear magnetic resonance device also includes a display connected to the magnet chamber 2 signal. When the first end of the standard sample just enters the magnet chamber 2, the detection result of the magnet chamber 2 is displayed on the display, and the reading can confirm that the measurement has started.

[0180] A fixing hole can be set at the initial position of the support frame 4, and the first limit assembly 5 can be fixedly connected to the support frame 4 through bolts and the fixing hole; or, a slot can be set at the initial position of the support frame 4, and the first limit assembly 5 can be plugged into the support frame 4 through the slot. The first limit assembly 5 can be in the shape of a plate, a strip or other shapes, wherein the plate-shaped first limit assembly 5 can increase the contact area with the core 30 to be measured and enhance the limiting effect. The size of the first limit assembly 5 in the vertical direction is smaller than the size of the magnet chamber 2 in the vertical direction to ensure that the first limit assembly 5 can enter the magnet chamber 2.

[0181] The second limit assembly 6 is used to contact at least part of the second end of the core 30 to be measured, so that the second limit assembly 6 and the first limit assembly 5 can clamp the core 30 to be measured, and then jointly limit the movement of the core 30 to be measured along the first horizontal direction A. The second limit assembly 6 can be fixedly connected to the support frame 4 by bolts or other fasteners; or, the second limit assembly 6 can be plugged into the support frame 4. The second limit assembly 6 can be in the shape of a plate, a strip or other shapes, wherein the plate shape can increase the contact area with the core 30 to be measured and enhance the limiting effect. The size of the second limit assembly 6 in the vertical direction is smaller than the size of the magnet chamber 2 in the vertical direction to ensure that the second limit assembly 6 can enter the magnet chamber 2.

[0182] The material selection of the first limiting component 5 and the second limiting component 6 may refer to the supporting frame 4 .

[0183] Compared with the prior art, the nuclear magnetic resonance device provided in Example 2 of the present application drives the support frame 4 to move precisely along the first horizontal direction A through the driving mechanism 3, ensuring that the core 30 to be measured on the support frame 4 can accurately enter and exit the magnet chamber 2, and realize the measurement of different positions in the depth direction of the core 30 to be measured. The first limit assembly 5 is located at the initial position of the support frame 4, providing a fixed reference point for the starting position of the core 30 to be measured, ensuring that the starting position of the core 30 to be measured is consistent each time the measurement is made, thereby improving the repeatability of the measurement, and at the same time laying the foundation for the accurate measurement of different positions in the depth direction of the core 30 to be measured. The first limit assembly 5 and the second limit assembly 6 jointly limit the movement of the core 30 to be measured along the first horizontal direction A, prevent the displacement of the core 30 to be measured during the measurement process, ensure the accurate measurement of different positions in the depth direction of the core 30 to be measured, and ensure the accuracy of the final distribution spectrum drawing, thereby ensuring the accuracy of the measurement results.

[0184] like Figure 4 As shown, in some embodiments, it also includes:

[0185] A locking assembly (not shown in the figure), connected to the second limiting assembly 6 and the support frame 4;

[0186] The second limiting assembly 6 is movably connected to the support frame 4 to adjust the distance between the second limiting assembly 6 and the first limiting assembly 5 ; the locking assembly is used to limit the movement of the second limiting assembly.

[0187] Specifically, the locking assembly is used to fix the second limit assembly 6 to prevent the second limit assembly 6 from being displaced during the measurement process. The movable connection of the second limit assembly 6 and the cooperation of the locking assembly enable the device to adapt to the cores 30 to be measured of different sizes, thereby improving the versatility and flexibility of the device and being applicable to a variety of different measurement tasks.

[0188] like Figure 4 As shown, in some embodiments, the second limiting assembly 6 is slidably connected to the support frame 4 along the first horizontal direction A; the support frame 4 has a bar-shaped through hole, and the length direction of the through hole is the same as the first horizontal direction A;

[0189] The locking assembly comprises:

[0190] A screw rod (not shown in the figure), the first end of which is connected to the limiting plate, and the second end of which extends out of the through hole;

[0191] A nut (not shown in the figure) is threadedly connected to the second end of the screw rod, and the nut can abut against the support frame 4.

[0192] Specifically, the support frame 4 is penetrated in the vertical direction to form a through hole. The support frame 4 can be configured with a slide groove extending along the first horizontal direction A, and the second limit assembly 6 is slidably connected to the support frame 4 along the first horizontal direction A through the slide groove to adjust the spacing between the first limit assembly 5 and the second limit assembly 6, and the first end of the screw can be interference fit or bonded with the limit plate.

[0193] Before starting the measurement, the nut is unscrewed, and the second limit assembly 6 slides along the first horizontal direction A, and the screw moves in the through hole along the first horizontal direction A. When the second limit assembly 6 contacts the second end of the core 30 to be measured, the nut is screwed in, so that the nut abuts against the support frame 4, limiting the movement of the second limit assembly 6. It is suitable for multi-size measurement, has strong practicality, and is easy to operate.

[0194] like Figure 4 As shown, in some embodiments, the second limiting component 6 includes:

[0195] A lead screw 61, wherein the length direction of the lead screw 61 is the same as the first horizontal direction A;

[0196] The support frame 4 is provided with a threaded hole, the first end of the lead screw 61 is threadedly connected to the support frame 4 through the threaded hole, and the second end of the lead screw 61 is used to contact the core 30 to be measured; the lead screw 61 and the threaded hole together form the locking assembly.

[0197] Specifically, the support frame 4 may include a support member 41 and a connecting member 42, the support member 41 is slidably connected to the two fixing members 13 along the first horizontal direction A, the support member 41 has a support surface, the connecting member 42 and the first limiting assembly 5 are both arranged on the support surface, and the connecting member 42 and the first limiting assembly 5 are arranged at intervals along the first horizontal direction A. The driving mechanism 3 is connected to the support member 41 and / or the connecting member 42.

[0198] The connecting member 42 can be connected to the supporting member 41 by means of bolts or interference fit, the connecting member 42 is provided with a threaded hole, and the first end of the lead screw 61 is connected to the connecting member 42 through the threaded hole; the spacing between the first limiting assembly 5 and the lead screw 61 is adjusted by rotating the lead screw 61. The second limiting assembly 6 can also include a first limiting plate 63, the first limiting plate 63 and the second end of the lead screw 61 are interference fit or bonded, and the second end of the lead screw 61 contacts the second end of the core 30 to be measured through the first limiting plate 63, so as to increase the contact area between the two and ensure the limiting effect.

[0199] like Figure 5 As shown, in some embodiments, the second limiting component 6 includes:

[0200] A first end of the spring 62 is connected to the support frame 4 , and a second end of the spring 62 is used to contact the core 30 to be measured.

[0201] Specifically, the spring 62 is extended and retracted along the first horizontal direction A. The first end of the spring 62 can be connected to the connecting member 42 by bolts or clamping. The second limiting assembly 6 can also include a second limiting plate 64, the second limiting plate 64 is interference fit or bonded to the second end of the lead screw 61, and the second end of the spring 62 can be clamped or bolted to the second limiting plate 64. The spring 62 can contact the second end of the core 30 to be measured through the second limiting plate 64 to increase the contact area between the two and ensure the limiting effect.

[0202] like Figure 6 As shown, in some embodiments, it also includes:

[0203] Two third limiting members 7, both located between the first limiting assembly 5 and the second limiting assembly 6, and the two third limiting members 7 are spaced apart on the support frame 4 along the second horizontal direction B;

[0204] The two third limit members 7 are respectively used to contact the two sides of the core 30 to be tested along the second horizontal direction B to jointly limit the movement of the core 30 to be tested along the first horizontal direction A, and the second horizontal direction B is perpendicular to the first horizontal direction A.

[0205] Specifically, the first limiting assembly 5, the second limiting assembly 6 and the two third limiting members 7 together form a limiting space, and the core 30 to be measured is located in the limiting space. The third limiting member 7 can be in a plate shape, a strip shape or other shapes. The third limiting member 7 can be fixedly arranged on the support member 41 by bolts or clamping.

[0206] The third limiting member 7 can be spaced apart from the first limiting member 5 and the second limiting member 6 respectively; or, when the second limiting member 6 is fixedly arranged on the support member 41, the third limiting member 7 can be connected to the first limiting member 5 and the second limiting member 6 respectively to enhance the stability of the overall structure; or, when the second limiting member 6 is movably arranged on the support member 41, the third limiting member 7 can be connected to the first limiting member 5 and spaced apart from the second limiting member 6.

[0207] like Figure 6 As shown, in some embodiments, the third limiting member 7 includes:

[0208] The elastic member has two ends connected to the first limiting assembly 5 and the second limiting assembly 6 respectively.

[0209] Specifically, the elastic member is in the shape of a strip, for example, the elastic member can be a rubber strip or a spring, etc. The length direction of the elastic member can be the same as the first horizontal direction A, and the two ends of the elastic member can be connected to the two limit members by hooks or buckles, etc. Due to its deformation characteristics, the elastic member can adapt to the way in which the second limit assembly 6 is movably connected to the frame 1, and the elastic member can produce a slight deformation in the second horizontal direction B, which can adapt to different sizes of the core 30 to be tested along the second horizontal direction B, and has stronger adaptability.

[0210] like Figures 3 to 6 As shown, in some embodiments, the support frame 4 has an arc-shaped bearing surface for bearing the core 30 to be tested, the axis of the bearing surface is the same as the first horizontal direction A, and the bearing surface forms two third limit members 7; and / or,

[0211] The support frame 4 is provided with a measuring part 8 , and the measuring part 8 is used to measure the size of the core 30 to be measured along the first horizontal direction A.

[0212] Specifically, the support member 41 has an arc-shaped bearing surface, and the shape of the arc-shaped bearing surface matches the outer contour of the core 30 to ensure that the core 30 to be tested can fit the bearing surface when placed to reduce shaking and displacement. The support member 41 can be formed into an arc-shaped bearing surface by injection molding or molding.

[0213] The measuring part 8 can be engraved on the surface of the support member 41 by a laser etching machine; or the measuring part 8 can be printed on the surface of the support member 41 by printing. The starting position of the measuring part 8 can be aligned with the end surface of the first end of the core 30 to be measured, and the operator can intuitively see the size and position of the core 30 to be measured during measurement, providing a real-time feedback mechanism, enhancing the control ability of the driving mechanism 3, and ensuring the smooth progress of the measurement.

[0214] like Figure 3 As shown, in some embodiments, it also includes:

[0215] A distance sensor 9 is arranged on the frame 1 along the first horizontal direction A with a spacing from the support frame 4; the detection end of the distance sensor 9 is used to face the end surface of the core 30 to be tested;

[0216] The controller 10 is connected to the distance sensor 9 signal. The distance sensor 9 can convert the detected distance signal into a first signal. The controller 10 is used to obtain the first signal.

[0217] Specifically, the distance sensor 9 can be arranged on the mounting member 12 by bolts or bonding, and the detection end of the distance sensor 9 can face the first end face or the second end face of the core 30 to be measured. For example, the second limit assembly 6 contacts a part of the second end face of the core 30 to be measured, and the detection end of the distance sensor 9 faces another part of the second end face of the core 30 to be measured. The distance sensor 9 can be an infrared distance sensor 9 or a laser sensor.

[0218] The controller 10 can be embedded in the carrier 11. The controller 10 can be a controller 10 configured for a nuclear magnetic resonance device in the prior art, which is connected to the magnet chamber 2 by signal, and can obtain and store the result of each measurement, ensuring accurate recording and processing of the measurement data. The controller 10 is configured with a display screen for displaying the measurement results.

[0219] During the continuous measurement process, the distance sensor 9 can monitor the moving position of the core 30 to be measured in real time, ensuring the accuracy of the moving position during each measurement and the accuracy of the final detection result.

[0220] like Figure 7 As shown, in some embodiments, it also includes:

[0221] The protection cabin 20 is connected to the frame 1 to form a accommodating space, and the magnet chamber 2, the driving mechanism 3, the support frame 4, the first limit assembly 5 and the second limit assembly 6 are all arranged in the accommodating space; the protection cabin 20 has an operating window 201, and the operating window 201 is used to open or close the accommodating space.

[0222] Specifically, the protection cabin 20 is used to maintain the cleanliness of the interior of the accommodating space, prevent the entry of dust and impurities from the outside, and increase safety, so that the nuclear magnetic resonance equipment is suitable for measurement at the drilling site. The protection cabin 20 can be made of non-magnetic, corrosion-resistant materials, such as aluminum or plastic. The operating window 201 can be rectangular or circular, etc. The operating window 201 can be opposite to the support frame 4 to facilitate the operation of the operator. The operating window 201 can be rotatably or slidably connected to the protection cabin 20, and the edge of the operating window 201 can be provided with a sealing strip to ensure sealing.

[0223] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for obtaining core physical properties, characterized in that: include: The transverse relaxation time T2 of the core to be tested at different depths is measured by using nuclear magnetic resonance, and the first echo data corresponding to each depth is recorded; Performing inversion processing on the first echo data at different depths to obtain T2 distribution spectra at different depths; The physical properties of the core to be tested are obtained based on the T2 distribution spectrum.

2. The method for obtaining core physical properties according to claim 1, characterized in that: The method for measuring the transverse relaxation time T2 of the core to be measured at different depths by using nuclear magnetic resonance comprises: Continuously measuring T2 of the core to be measured at continuous depth positions using the nuclear magnetic resonance; The method of performing inversion processing on the first echo data at different depth positions to obtain T2 distribution spectra at different depth positions includes: The first echo data at continuous depth positions are inverted to obtain the T2 distribution spectrum at continuous depth positions.

3. The method for obtaining core physical properties according to claim 2, characterized in that: Before obtaining the physical properties of the core to be tested based on the T2 distribution spectrum, the method further includes: Measuring the longitudinal relaxation time T1 of the core to be measured by using the nuclear magnetic resonance, and recording the second echo data; Using the nuclear magnetic resonance to measure the two-dimensional relaxation characteristics T2-T1 of the core to be measured, and recording the third echo data; performing joint inversion on the second echo data, the third echo data and the first echo train at continuous depth positions to obtain a T2-T1 two-dimensional distribution spectrum at continuous depth positions; The method for obtaining the physical properties of the core to be tested based on the T2 distribution spectrum includes: The physical properties of the core to be measured are obtained based on the T2 distribution spectrum and the T2-T1 two-dimensional distribution spectrum.

4. The method for obtaining core physical properties according to claim 2, characterized in that: Before obtaining the physical properties of the core to be tested based on the T2 distribution spectrum, the method further includes: Measuring the fluid diffusion coefficient D of the core to be measured by using the nuclear magnetic resonance, and recording the fourth echo data; Using the nuclear magnetic resonance to measure the two-dimensional relaxation characteristic T2-D of the core to be measured, and recording the fifth echo data; performing joint inversion on the fourth echo data, the fifth echo data and the first echo train at continuous depth positions to obtain a T2-D two-dimensional distribution spectrum at continuous depth positions; The method for obtaining the physical properties of the core to be tested based on the T2 distribution spectrum includes: The physical properties of the core to be measured are obtained based on the T2 distribution spectrum and the T2-D two-dimensional distribution spectrum.

5. The method for obtaining core physical properties according to claim 1, characterized in that: Before measuring the transverse relaxation time T2 of the core to be tested at different depths by using nuclear magnetic resonance, the method further includes: Obtain the core to be tested from the drilling site; wherein the diameter of the core to be tested is greater than or equal to 8 cm and less than or equal to 12 cm; and / or the length of the core to be tested is less than or equal to 110 cm; The core to be measured is measured at the drilling site.

6. The method for obtaining core physical properties according to claim 1, characterized in that: Before the inversion processing is performed on the first echo data at different depth positions, the method further includes: All the collected first echo data are calibrated.

7. A nuclear magnetic resonance device, characterized in that: include: frame; A magnet chamber, arranged on the frame; A driving mechanism is arranged on the frame spaced apart from the magnet chamber along a first horizontal direction; A support frame connected to the driving mechanism, wherein the driving mechanism is used to drive the support frame to enter the magnet chamber along a first horizontal direction; The support frame has an initial position; A first limiting assembly connected to the initial position of the support frame; The second limiting assembly is arranged on the support frame; the first limiting assembly and the second limiting assembly are respectively used to contact with two ends of the core to be measured along the first horizontal direction to jointly limit the movement of the core to be measured along the first horizontal direction.

8. The nuclear magnetic resonance apparatus according to claim 7, characterized in that: Also includes: A locking assembly connected to the second limiting assembly and the support frame; Wherein, the second limiting component is movably connected to the support frame to adjust the distance between it and the first limiting component; and the locking component is used to limit the movement of the second limiting component.

9. The nuclear magnetic resonance apparatus according to claim 8, characterized in that: The second limit assembly is slidably connected to the support frame along the first horizontal direction; the support frame has a bar-shaped through hole, and the length direction of the through hole is the same as the first horizontal direction; The locking assembly comprises: A screw rod, a first end of which is connected to the limiting plate, and a second end of which extends out of the through hole; A nut is threadedly connected to the second end of the screw rod, and the nut can abut against the support frame.

10. The nuclear magnetic resonance device according to claim 8, characterized in that: The second limiting component includes: A lead screw, wherein the length direction of the lead screw is the same as the first horizontal direction; The support frame is provided with a threaded hole, the first end of the lead screw is threadedly connected to the support frame through the threaded hole, and the second end of the lead screw is used to contact the core to be measured; the lead screw and the threaded hole together form the locking assembly.

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