A rock sample measurement system and measurement method with high vertical resolution

Abstract

The present invention discloses a rock sample measurement system and a measurement method with high longitudinal resolution. The present invention utilizes a multi-channel radio frequency probe composed of multiple coils with different sensitivities to collect the magnetic resonance signal of the rock sample, and thereby obtains the real rock sample signal. Based on this, compared with the traditional single-channel measurement, the multi-channel measurement of the present invention can better reflect the local characteristics of the rock sample, improve the longitudinal resolution of the signal, and can more accurately measure the fluid and occurrence state of the rock sample. Therefore, the multi-channel measurement of the present invention is suitable for large-scale application and promotion in the field of rock sample measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear magnetic resonance, and in particular relates to a rock sample measurement system and a measurement method with high longitudinal resolution. Background Art

[0002] As the exploration and development focus of the oil and gas industry shifts from conventional reservoirs to unconventional reservoirs, a comprehensive understanding of the rock properties and microstructure of unconventional reservoirs is of great significance for the implementation of efficient production construction, production increase, and production stabilization measures; in the face of the diversification of oil and gas storage space and the complexity of the seepage mechanism of fluids in rock porous media, traditional rock property testing and rock static microstructure description can no longer meet the research needs of oil and gas seepage and reservoir production increase; nuclear magnetic resonance technology (NMR) is non-destructive and harmless, and can directly reflect the distribution of rock pore fluids and indirectly reflect the changes in rock pore structure through resonance signals. Therefore, it has outstanding advantages in rock physics testing, pore structure characterization, and pore fluid identification.

[0003] Nuclear magnetic resonance is sensitive to fluids and their occurrence states in porous rocks, and can provide information such as oil and gas content and their occurrence states. Among them, rock physical properties are one of the important parameters for understanding the oil and gas storage conditions of oil and gas layers, dividing the physical boundaries of main layers, effective reservoirs and interlayers, and evaluating reservoirs and calculating oil and gas reserves. Therefore, nuclear magnetic resonance rock physics is an important method for oil and gas detection and has been widely used.

[0004] Existing nuclear magnetic resonance logging technologies mainly include downhole detectors and laboratory benchtop nuclear magnetic resonance instruments. Among them, downhole detectors can test in-situ cores at the bottom of the well, as well as move and measure the core physical properties of different layers. However, due to hardware limitations, the logging instrument has low accuracy and low vertical resolution (generally greater than 0.5m), which can no longer meet the perforation requirements of the well site.

[0005] Laboratory benchtop NMR instruments can be used to detect full-size cores, with short echo times and high test accuracy, and can also be used in conjunction with trend replacement equipment for multi-dimensional measurements. However, due to the limited effective signal receiving range of the radio frequency coil of the NMR instrument, the coring samples need to be truncated, and the longest sample length that can be collected cannot exceed the effective signal receiving range of the radio frequency coil. This will result in it being unable to meet the needs of long-length coring sampling. Based on this, wellside core magnetic resonance measurement equipment that can measure long-length cores has appeared on the market. It moves the core through a transmission device and measures various positions of the core, thereby improving the longitudinal resolution to a few centimeters.

[0006] At present, the magnetic resonance measurement equipment for well cores all use solenoid probes. The solenoid probes have a high signal-to-noise ratio, but they are mostly single-channel. The rock core has a certain longitudinal dimension, generally 5 to 8 cm. Therefore, the longitudinal resolution of the real signal obtained by magnetic resonance measurement of the entire rock sample with a single channel is difficult to reach the 1 cm level. This will make it impossible to accurately measure the fluid and its occurrence state of the rock sample. Based on this, how to provide a rock sample measurement system with high longitudinal resolution has become an urgent problem to be solved. Summary of the invention

[0007] The purpose of the present invention is to provide a rock sample measurement system and measurement method with high longitudinal resolution, so as to solve the problem that the longitudinal resolution of the radio frequency probe in the prior art using a single channel for rock sample magnetic resonance measurement is not high, resulting in the inability to accurately measure the fluid and its occurrence state of the rock sample.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, a rock sample measurement system with high vertical resolution is provided, comprising:

[0010] A magnetic device, a mobile device and a radio frequency device, wherein the magnetic device is used to generate a uniform static magnetic field, and a rock sample to be tested is placed on the mobile end of the mobile device;

[0011] The radio frequency device comprises a radio frequency probe, wherein a plurality of receiving coils are arranged in the radio frequency probe, the radio frequency probe and the rock sample to be measured are both arranged in the static magnetic field generated by the magnet device, and the sensitivity of each receiving coil is different from each other in the axial direction of the rock sample to be measured;

[0012] The rock sample measurement system further includes: a workstation and a nuclear magnetic resonance device, wherein the workstation and the nuclear magnetic resonance device are respectively electrically connected to the mobile device, and are used to send a movement control signal to the mobile device, so that the mobile device drives the rock sample to be measured to pass through the detection area of ​​the radio frequency probe based on the movement control signal;

[0013] The nuclear magnetic resonance device is electrically connected to the radio frequency device, and is used to send a plurality of radio frequency transmission pulses to the radio frequency device in sequence when the rock sample to be tested passes through the detection area of ​​the radio frequency probe, so that after the radio frequency device receives each radio frequency transmission pulse, it transmits the received radio frequency transmission pulse to the rock sample to be tested through the radio frequency probe, so as to perform multiple sampling on the rock sample to be tested by using multiple radio frequency transmission pulse signals;

[0014] The radio frequency device is also used to receive the nuclear magnetic resonance echo signal generated by the rock sample to be tested when excited by the radio frequency transmission pulse through the multiple receiving coils in the radio frequency probe at each sampling, so as to obtain the rock sample sampling signal at each sampling based on the nuclear magnetic resonance echo signal received by the multiple receiving coils;

[0015] The radio frequency device is also used to send each rock sample sampling signal to the workstation via the nuclear magnetic resonance device;

[0016] The workstation is used to determine the real rock sample signal of the rock sample to be tested according to each received rock sample sampling signal, and obtain the fluid and occurrence state of the rock sample to be tested based on the real rock sample signal.

[0017] Based on the above disclosed content, the measurement system provided by the present invention has a plurality of receiving coils arranged in the radio frequency probe, and the sensitivity of each receiving coil is different in the longitudinal direction of the rock sample; thus, it is equivalent to providing a plurality of receiving channels with greatly different sensitivities; at the same time, the present invention is provided with a moving device, which drives the rock sample to pass through the detection range of the radio frequency probe, and in the process of movement, transmits radio frequency pulses to the rock sample in sequence through the radio frequency probe; based on this, multiple sampling can be performed during the movement, and in each sampling, multiple receiving coils are used to simultaneously receive the nuclear magnetic resonance echo signal of the rock sample, so as to form a sampling signal corresponding to this sampling based on the nuclear magnetic resonance echo signal received by each receiving coil; finally, the real signal of the rock sample can be determined based on the multiple sampling signals, and the fluid and occurrence state of the rock sample can be obtained based on the real signal.

[0018] Through the above design, the present invention uses a multi-channel radio frequency probe composed of multiple coils with different sensitivities to collect the magnetic resonance signal of the rock sample, and thereby obtain the real rock sample signal; based on this, compared with the traditional single-channel measurement, the multi-channel measurement of the present invention can better reflect the local characteristics of the rock sample, improve the longitudinal resolution of the signal, and can more accurately measure the fluid and occurrence state of the rock sample. Therefore, it is suitable for large-scale application and promotion in the field of rock sample measurement.

[0019] In one possible design, the plurality of receiving line segments include a plurality of saddle-shaped receiving coils and a solenoid coil.

[0020] In one possible design, the plurality of receiving line segments include a plurality of saddle-shaped receiving coils and a solenoid coil;

[0021] The radio frequency device further comprises: a radio frequency power amplifier, a transceiver conversion module and a plurality of preamplifiers, and each preamplifier corresponds to a receiving coil;

[0022] The input end of the radio frequency power amplifier is electrically connected to the transmission channel of the nuclear magnetic resonance device, and the output end of the radio frequency power amplifier is electrically connected to the transceiver conversion module, wherein the transceiver conversion module is electrically connected to the solenoid coil, and the transceiver conversion module is also electrically connected to the corresponding preamplifier;

[0023] Each saddle-shaped receiving coil is electrically connected to a corresponding preamplifier, and each preamplifier is electrically connected to a receiving channel of the nuclear magnetic resonance device.

[0024] In a possible design, the moving device drives the rock sample to be tested to pass through the detection area of ​​the radio frequency probe at a fixed step distance based on the movement control signal, and after the rock sample to be tested moves the fixed step distance for the first time, one end of the rock sample to be tested moves to the boundary of the detection area;

[0025] Correspondingly, the nuclear magnetic resonance device is used to send a radio frequency transmission pulse to the radio frequency device after the rock sample to be tested moves a fixed step distance, so that after receiving the radio frequency transmission pulse, the radio frequency device transmits the received radio frequency transmission pulse to the rock sample to be tested through the radio frequency probe to stimulate and obtain the nuclear magnetic resonance echo signal of the rock sample to be tested.

[0026] In a possible design, the expected resolution of the real rock sample signal is greater than the fixed step distance.

[0027] In a possible design, the mobile device includes: a transmission controller, a drive motor and a transmission mechanism, wherein the nuclear magnetic resonance device and the workstation are electrically connected to the transmission controller respectively, the transmission controller is electrically connected to the drive motor, the drive end of the drive motor is transmission-connected to the transmission mechanism, and the rock sample to be tested is placed on the transmission mechanism.

[0028] In one possible design, the magnet arrangement includes a permanent magnet or a superconducting magnet.

[0029] In a second aspect, a measurement method of the rock sample measurement system with high vertical resolution based on the first aspect or any possible design of the first aspect is provided, wherein the method is performed by a workstation in the rock sample measurement system with high vertical resolution, and the method comprises:

[0030] Acquire a plurality of rock sample sampling signals sent by the nuclear magnetic resonance device, wherein the plurality of rock sample sampling signals are sampled and obtained during the process of the rock sample to be tested passing through the detection area of ​​the radio frequency probe;

[0031] Based on a number of rock sample sampling signals, a real rock sample signal of the rock sample to be tested is determined, and based on the real rock sample signal, the fluid and occurrence state of the rock sample to be tested are obtained.

[0032] In a possible design, based on a number of rock sample sampling signals, a real rock sample signal of the rock sample to be tested is determined, including:

[0033] Obtaining the sensitivity of each receiving coil in the radio frequency probe;

[0034] Based on the sensitivity of each receiving coil, a sensitivity matrix is ​​constructed, and based on a number of rock sample sampling signals, a sampling signal matrix is ​​constructed;

[0035] Using the sensitivity matrix and the sampling signal matrix, a real rock sample signal model is constructed;

[0036] The real rock sample signal model is iteratively solved to obtain the real rock sample signal of the rock sample to be tested after iterative solution.

[0037] In a possible design, the real rock sample signal model is:

[0038] min||Ay-s|| 2 +λ1|y| (1)

[0039] In the above formula (1), A represents the sensitivity matrix, s represents the sampling signal matrix, y represents the real rock sample signal matrix, λ1 represents the regularization factor, and || || represents the second norm;

[0040] in,

[0041]

[0042]

[0043] In the above formula (2), a(-I / 2,c(M)) represents the sensitivity of the Mth receiving coil in the radio frequency probe, and I represents a constant, wherein I=Lc / r, and Lc represents the length of the radio frequency probe, and r is the expected resolution of the real rock sample signal;

[0044] In the above formula (3), S(x(1), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the first sampling, and at the first sampling, the nuclear magnetic resonance echo signals received by all the receiving coils in the radio frequency probe constitute the rock sample sampling signal at the first sampling, and S(x(N), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the Nth sampling;

[0045] In the above formula (4), y() represents the real rock sample signal, and x(1) represents the horizontal coordinate of the target end of the rock sample to be tested in the target coordinate system during the first sampling, wherein the origin of the target coordinate system is the center of the RF probe, the horizontal axis is the axial direction of the RF probe, the vertical axis is the direction perpendicular to the axial direction, and the target end is the end of the rock sample to be tested that first enters the detection area of ​​the RF probe.

[0046] In the third aspect, a rock sample measuring device with high vertical resolution is provided. Taking the device as an electronic device as an example, the device includes a memory, a processor and a transceiver which are communicatively connected in sequence, wherein the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program to execute the measurement method as described in the second aspect or any possible design of the second aspect.

[0047] In a fourth aspect, a storage medium is provided, on which instructions are stored. When the instructions are executed on a computer, the measurement method as in the second aspect or any possible design of the second aspect is executed.

[0048] In a fifth aspect, a computer program product comprising instructions is provided, which, when executed on a computer, causes the computer to execute the measurement method as described in the second aspect or any possible design of the second aspect.

[0049] Beneficial effects:

[0050] (1) The present invention utilizes a multi-channel radio frequency probe composed of multiple coils with different sensitivities to collect the magnetic resonance signal of the rock sample, and thereby obtains the real rock sample signal; based on this, compared with the traditional single-channel measurement, the multi-channel measurement of the present invention can better reflect the local characteristics of the rock sample, improve the longitudinal resolution of the signal, and can more accurately measure the fluid and occurrence state of the rock sample. Therefore, it is suitable for large-scale application and promotion in the field of rock sample measurement.

[0051] (2) Compared with the prior art in which the resolution is lower than or equal to the stepping distance of the rock sample, the present invention sets the resolution to be higher than the stepping distance of the rock sample; thus, the more channels the receiving coil has and the greater the sensitivity difference, the greater the ratio of the stepping distance to the resolution; based on this, the limiting resolution can be improved or the scanning time can be saved under the same resolution requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A schematic diagram of the architecture of a rock sample measurement system with high vertical resolution provided by an embodiment of the present invention;

[0053] Figure 2 A timing diagram of the acquisition of rock sample sampling signals provided by an embodiment of the present invention;

[0054] Figure 3 A schematic diagram of a target coordinate system provided by an embodiment of the present invention;

[0055] Figure 4 A schematic diagram of the steps of a measurement method based on a rock sample measurement system with high vertical resolution provided by an embodiment of the present invention;

[0056] Figure 5 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0058] It should be understood that although the terms first, second, etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another unit. For example, a first unit can be referred to as a second unit, and similarly, a second unit can be referred to as a first unit without departing from the scope of the exemplary embodiments of the present invention.

[0059] It should be understood that the term "and / or" that may appear in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" that may appear in this article describes another type of association object relationship, indicating that two relationships may exist. For example, A / and B can represent two situations: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0060] Example:

[0061] See also Figures 1 to 3As shown, the high longitudinal resolution rock sample measurement system provided in this embodiment may include but is not limited to: a magnet device, a mobile device, a radio frequency device, a nuclear magnetic resonance device and a workstation; wherein, in a specific application, the rock sample to be measured is placed on the mobile end of the mobile device, and the magnet device is used to generate a uniform static magnetic field so as to cooperate with the radio frequency device to perform magnetic resonance measurement on the rock sample to be measured; optionally, the magnet device may include but is not limited to a permanent magnet or a superconducting magnet.

[0062] At the same time, the radio frequency device may include, but is not limited to, a radio frequency probe, wherein, see Figure 1 As shown, a plurality of receiving coils are arranged in the example radio frequency probe, and the radio frequency probe and the rock sample to be tested are both arranged in the static magnetic field generated by the magnet device (in this embodiment, the example radio frequency probe can be placed between the two poles of the permanent magnet or the superconducting magnet), and the sensitivity of each receiving coil is different in the axial direction of the rock sample to be tested; in this way, it is equivalent to using a multi-channel radio frequency probe composed of multiple coils with different sensitivities to collect the magnetic resonance signal of the rock sample, thereby using the collected magnetic resonance signal to solve the real rock sample signal with high longitudinal resolution, and then accurately measure the fluid and occurrence state of the rock sample to be tested.

[0063] In specific applications, the workstation and the nuclear magnetic resonance device are respectively electrically connected to the mobile device for sending a mobile control signal to the mobile device, so that the mobile device drives the rock sample to be tested to pass through the detection area of ​​the radio frequency probe based on the mobile control signal; at the same time, the nuclear magnetic resonance device is electrically connected to the radio frequency device for sending a number of radio frequency transmission pulses to the radio frequency device in sequence during the process of the rock sample to be tested passing through the detection area of ​​the radio frequency probe, so that after receiving each radio frequency transmission pulse, the radio frequency device transmits the received radio frequency transmission pulse to the rock sample to be tested through the radio frequency probe, so as to perform multiple sampling of the rock sample to be tested using multiple radio frequency transmission pulse signals.

[0064] Furthermore, the radio frequency device is also used to receive the nuclear magnetic resonance echo signal generated by the rock sample to be tested when excited by the radio frequency transmission pulse through multiple receiving coils in the radio frequency probe at each sampling, so as to obtain the rock sample sampling signal at each sampling based on the nuclear magnetic resonance echo signal received by multiple receiving coils, and send the rock sample sampling signal obtained at each sampling to the workstation through the nuclear magnetic resonance device, and the workstation is used to determine the real rock sample signal of the rock sample to be tested based on each received rock sample sampling signal, and obtain the fluid and occurrence state of the rock sample to be tested based on the real rock sample signal. In this embodiment, the example nuclear magnetic resonance device can be, but is not limited to, a nuclear magnetic resonance spectrometer.

[0065] In this embodiment, the nuclear magnetic resonance device may be, but is not limited to, a nuclear magnetic resonance spectrometer.

[0066] Through the above explanation, when the rock sample to be tested in this embodiment is moving, the nuclear magnetic resonance device will send several radio frequency transmission pulses to the radio frequency device in sequence, and when the radio frequency device receives each pulse, it will use the radio frequency probe to transmit to the rock sample to be tested, so as to stimulate and obtain the nuclear magnetic resonance echo signal of the rock sample to be tested; then, the multiple receiving coils of the radio frequency probe will simultaneously receive the nuclear magnetic resonance echo signal and transmit it to the radio frequency device; wherein, assuming that there are M receiving coils in the radio frequency probe, then one sampling will obtain M nuclear magnetic resonance echo signals, and the M nuclear magnetic resonance echo signals constitute the rock sample sampling signal of this sampling; therefore, since multiple receiving coils are provided, each receiving coil covers a part of the area in the axial direction of the rock sample to be tested, based on this, multiple receiving coils can collect more local magnetic resonance signals of the rock sample to be tested; thus, the longitudinal resolution of the real rock sample signal obtained based on the collected magnetic resonance signal will inevitably be greatly improved compared with the single-channel measurement.

[0067] In a specific embodiment, the multiple receiving coils in the RF probe may include, but are not limited to, a plurality of saddle-shaped receiving coils and a solenoid coil; see Figure 1 As shown ( Figure 1 Only three receiving coils are shown in the figure, which is only for illustration), wherein the solenoid coil can be used for both transmitting and receiving, while the saddle-shaped receiving coil is only used for receiving magnetic resonance signals.

[0068] At the same time, the RF device may also include, but is not limited to: a RF power amplifier, a transceiver conversion module, and a plurality of preamplifiers, wherein, in this embodiment, each preamplifier corresponds to a receiving coil.

[0069] Furthermore, the input end of the RF power amplifier is electrically connected to the transmitting channel of the nuclear magnetic resonance device, and the output end of the RF power amplifier is electrically connected to the transceiver conversion module, wherein the transceiver conversion module is electrically connected to the solenoid coil, and the transceiver conversion module is also electrically connected to the corresponding preamplifier; similarly, each saddle-shaped receiving coil is electrically connected to the corresponding preamplifier, and each preamplifier is electrically connected to the receiving channel of the nuclear magnetic resonance device.

[0070] Thus, the excitation principle of the radio frequency transmission pulse of the measurement system provided in this embodiment is:

[0071] When it is necessary to transmit a pulse to the rock sample to be tested, the nuclear magnetic resonance spectrometer sends a radio frequency transmission pulse to the radio frequency power amplifier through its corresponding transmission channel. After being amplified by the radio frequency power amplifier, the radio frequency transmission pulse is sent to the radio frequency probe via the transceiver conversion module and transmitted to the rock sample to be tested by the spiral tube coil in the radio frequency probe.

[0072] When it is necessary to receive magnetic resonance signals, the radio frequency device is first adjusted from the transmitting state to the receiving state through the transceiver conversion module, and then the spiral tube coil and each saddle-shaped receiving coil in the radio frequency probe are used to receive the nuclear magnetic resonance echo signal generated by the excitation of the rock sample to be tested. Finally, after being amplified by the corresponding preamplifiers, it is transmitted to the magnetic resonance spectrometer, and then received by the magnetic resonance spectrometer and transmitted to the workstation.

[0073] In a possible design, this embodiment provides a specific moving method of the aforementioned rock sample to be tested, as shown below:

[0074] In this embodiment, for example, the moving device drives the rock sample to be tested to pass through the detection area of ​​the radio frequency probe at a fixed step distance based on the movement control signal, and after the rock sample to be tested moves the fixed step distance for the first time, one end of the rock sample to be tested moves to the boundary of the detection area; at the same time, the nuclear magnetic resonance device is used to send a radio frequency transmission pulse to the radio frequency device after the rock sample to be tested moves the fixed step distance each time, so that after receiving the radio frequency transmission pulse, the radio frequency device transmits the received radio frequency transmission pulse to the rock sample to be tested through the radio frequency probe, so as to excite and obtain the nuclear magnetic resonance echo signal of the rock sample to be tested.

[0075] join Figure 2 As shown, assuming that the moving direction of the rock sample to be tested is horizontal, then, after the first movement (i.e., after the first movement of a fixed step distance), the right end of the rock sample to be tested moves to the left end of the RF probe, thereby entering the boundary of its corresponding detection area; at the same time, when the second movement is performed, the right end of the rock sample to be tested moves a fixed step distance again, and so on, and the cycle continues until the other side of the rock sample moves to the right edge of the RF probe, thereby completing the acquisition process; wherein, assuming that it moves N times, N sampling signals are obtained.

[0076] Optionally, for example, the expected resolution of the real rock sample signal is greater than the fixed step distance; in this way, the ratio of the step distance to the resolution will be larger based on the greater the number of channels of the receiving coil and the greater the sensitivity difference; based on this, the limiting resolution can be improved or the scanning time can be saved under the same resolution requirement.

[0077] In this embodiment, the following provides a specific structure of a mobile device:

[0078] In specific applications, the mobile device may include, but is not limited to: a transmission controller, a drive motor and a transmission mechanism, wherein the nuclear magnetic resonance device and the workstation are electrically connected to the transmission controller respectively, the transmission controller is electrically connected to the drive motor, the drive end of the drive motor is transmission-connected to the transmission mechanism, and the rock sample to be tested is placed on the transmission mechanism; in this embodiment, the transmission mechanism may include, but is not limited to, a conveyor belt.

[0079] Thus, in combination with the aforementioned mobile device and radio frequency device, the collection process of the aforementioned rock sample to be tested is as follows:

[0080] like Figure 2 As shown, the moving device is controlled by the workstation and the radio frequency device so that one side of the rock sample to be tested moves to the left edge of the radio frequency probe, and the transmission controller turns off the motor power supply to start collecting signals; after the first collection is completed, the nuclear magnetic resonance spectrometer sends a step trigger signal, and the transmission controller restores the motor power supply. At the same time, the workstation sends a control signal to control the drive motor to drive the rock sample to be tested to move a fixed step distance Δx. After the movement, the transmission controller turns off the motor power supply, and the radio frequency device starts the second signal collection, and so on and so forth until the other side of the rock sample moves to the right edge of the radio frequency probe and the collection is ended; at this time, during the movement process, a total of N signals can be collected; wherein, the total distance moved by the rock sample to be tested is L=Lc+Lr, Lc is the length of the radio frequency probe, Lr is the total length of the rock sample, and L=N×Δx.

[0081] In this way, after the acquisition process is completed, the workstation can solve the real rock sample signal of the rock sample to be tested based on the collected rock sample sampling signals, and based on this, derive the fluid and occurrence state of the rock sample to be tested.

[0082] In this embodiment, a method for measuring a real rock sample signal is provided as follows:

[0083] Since the radio frequency probe is provided with multiple receiving coils, the rock sample sampling signal obtained by the nth acquisition can be expressed as S(x(n),c), where x(n) represents the horizontal coordinate of the target end of the rock sample to be measured in the target coordinate system (that is, the position of its target end); see Figure 3 As shown, the origin of the target coordinate system is the center of the RF probe, the horizontal axis is the axial direction of the RF probe, the vertical axis is the direction perpendicular to the axial direction, and the target end is the end of the rock sample to be tested that first enters the detection area of ​​the RF probe; based on the above example, the target end is the right end of the rock sample to be tested, that is, x(1)=-0.5Lc during the first acquisition; at the same time, c represents the receiving coil, and there are M receiving coils in total; of course, when the moving direction is different, the principle of determining the target end is the same as the above example, which will not be repeated here.

[0084] Based on this, the signal S(x(n),c) can be expressed as:

[0085]

[0086] In the above formula (4), y() represents the real rock sample signal, x(n) represents the horizontal coordinate of the target end of the rock sample to be tested in the target coordinate system at the nth sampling, a(i,c) represents the sensitivity of the receiving coil in the radio frequency probe, i represents the spatial position of the sensitivity diagram, and the range is [-I / 2, I / 2], where I = Lc / r, Lc represents the length of the radio frequency probe, r is the expected resolution of the real rock sample signal, and n = 1, 2, ..., N, N represents the number of sampling times, that is, the total number of rock sample sampling signals.

[0087] In this way, the above formula (4) can be converted into a matrix form to construct a real rock sample signal model; wherein the matrix form is:

[0088] A·y=S (5)

[0089] In the above formula (5), A represents the sensitivity matrix, s represents the sampling signal matrix, and y represents the real rock sample signal matrix; based on this, the specific process of the workstation determining the real rock sample signal of the rock sample to be tested based on a number of rock sample sampling signals is:

[0090] The first step: obtaining the sensitivity of each receiving coil in the radio frequency probe.

[0091] Step 2: Based on the sensitivity of each receiving coil, a sensitivity matrix is ​​constructed, and based on a number of rock sample sampling signals, a sampling signal matrix is ​​constructed.

[0092] In this embodiment, the sensitivity matrix is ​​shown in the following formula (2):

[0093]

[0094] In the above formula (2), A is a two-dimensional matrix with M*N rows and Lr / r columns, wherein a(-I / 2,c(M)) represents the sensitivity of the Mth receiving coil in the RF probe (whose dimension is I x M,), I represents a constant, I=Lc / r, and Lc represents the length of the RF probe, and r is the expected resolution of the real rock sample signal.

[0095] Similarly, the sampling signal matrix is ​​as shown in the following formula (3):

[0096]

[0097] In the above formula (3), S(x(1), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the first sampling, and at the first sampling, the nuclear magnetic resonance echo signals received by all the receiving coils in the radio frequency probe constitute the rock sample sampling signal at the first sampling, and S(x(N), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the Nth sampling.

[0098] After constructing the aforementioned sensitivity matrix and sampling signal matrix, a real rock sample signal model can be constructed; wherein the construction process is shown in the third step below.

[0099] Step 3: Using the sensitivity matrix and the sampling signal matrix, a real rock sample signal model is constructed.

[0100] Furthermore, the real rock sample signal model is shown in the following formula (1):

[0101] min||Ay-s|| 2 +λ1|y| (1)

[0102] In the above formula (1), A represents the sensitivity matrix, s represents the sampling signal matrix, y represents the real rock sample signal matrix, λ1 represents the regularization factor, and || || represents the binary norm.

[0103] at the same time,

[0104] In the above formula (4), y() represents the real rock sample signal, and x(1) represents the horizontal coordinate of the target end of the rock sample to be measured in the target coordinate system during the first sampling.

[0105] After constructing the real rock sample signal, it is iteratively solved for the optimal solution, and the optimal solution y corresponds to the real rock sample signal of the rock sample to be tested; wherein, the solution process is shown in the fourth step below.

[0106] Step 4: iteratively solve the real rock sample signal model to obtain the real rock sample signal of the rock sample to be tested after iterative solution. In this embodiment, iterative solution can be implemented using an existing iterative solution algorithm, and its principle will not be repeated.

[0107] Therefore, through the above detailed description of the rock sample measurement system with high longitudinal resolution, this embodiment uses a multi-channel radio frequency probe composed of multiple coils with different sensitivities to collect the magnetic resonance signal of the rock sample, and thereby obtain the real rock sample signal; based on this, compared with the traditional single-channel measurement, the multi-channel measurement of the present invention can better reflect the local characteristics of the rock sample, improve the longitudinal resolution of the signal, and can more accurately measure the fluid and occurrence state of the rock sample, and therefore, is suitable for large-scale application and promotion in the field of rock sample measurement.

[0108] In one possible design, see Figure 4 As shown, the second aspect of this embodiment provides a measurement method for a rock sample measurement system with high longitudinal resolution based on the first aspect of the embodiment, wherein the method is executed by a workstation in the rock sample measurement system with high longitudinal resolution, and the method may include but is not limited to the following steps S1 and S2.

[0109] S1. Acquire a plurality of rock sample sampling signals sent by a nuclear magnetic resonance device, wherein the plurality of rock sample sampling signals are sampled when the rock sample to be tested passes through a detection area of ​​a radio frequency probe.

[0110] S2. Based on a number of rock sample sampling signals, determine the real rock sample signal of the rock sample to be tested, and based on the real rock sample signal, derive the fluid and occurrence state of the rock sample to be tested; in this embodiment, for example, but not limited to, the following steps S21 to S24 can be used to determine the real rock sample signal.

[0111] S21. Obtain the sensitivity of each receiving coil in the radio frequency probe.

[0112] S22. A sensitivity matrix is ​​constructed based on the sensitivity of each receiving coil, and a sampling signal matrix is ​​constructed based on a number of rock sample sampling signals.

[0113] S23. Using the sensitivity matrix and the sampling signal matrix, a real rock sample signal model is constructed; in this embodiment, the real rock sample signal model can be but is not limited to the following formula (1).

[0114] min||Ay-s|| 2 +λ1|y| (1)

[0115] In the above formula (1), A represents the sensitivity matrix, s represents the sampling signal matrix, y represents the real rock sample signal matrix, λ1 represents the regularization factor, and || || represents the second norm;

[0116] in,

[0117]

[0118]

[0119] In the above formula (2), a(-I / 2,c(M)) represents the sensitivity of the Mth receiving coil in the RF probe, and I represents a constant, wherein I=Lc / r, and Lc represents the length of the RF probe, and r is the expected resolution of the real rock sample signal.

[0120] In the above formula (3), S(x(1), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the first sampling, and at the first sampling, the nuclear magnetic resonance echo signals received by all the receiving coils in the radio frequency probe constitute the rock sample sampling signal at the first sampling, and S(x(N), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the Nth sampling.

[0121] In the above formula (4), y() represents the real rock sample signal, and x(1) represents the horizontal coordinate of the target end of the rock sample to be tested in the target coordinate system during the first sampling, wherein the origin of the target coordinate system is the center of the RF probe, the horizontal axis is the axial direction of the RF probe, the vertical axis is the direction perpendicular to the axial direction, and the target end is the end of the rock sample to be tested that first enters the detection area of ​​the RF probe.

[0122] After constructing the real rock sample signal model, the real rock sample signal can be obtained by solving the optimal solution of the model; wherein the solution process is shown in the following axis S24.

[0123] S24. Performing iterative solution processing on the real rock sample signal model to obtain the real rock sample signal of the rock sample to be tested after the iterative solution processing.

[0124] The working process, working details and technical effects of the method provided in the second aspect of this embodiment can be found in the first aspect of the embodiment and will not be described in detail here.

[0125] like Figure 5 As shown, the third aspect of this embodiment provides a rock sample device with high vertical resolution. Taking the device as an electronic device as an example, it includes: a memory, a processor and a transceiver that are communicatively connected in sequence, wherein the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program to execute the measurement method described in the second aspect of the embodiment.

[0126] For example, the memory may include, but is not limited to, random access memory (RAM), read only memory (ROM), flash memory, first input first output (FIFO) and / or first in last out (FILO), etc. Specifically, the processor may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor may be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). At the same time, the processor may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state.

[0127] In some embodiments, the processor may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the display screen. For example, the processor may not be limited to a microprocessor of the STM32F105 series, a reduced instruction set computer (RISC) microprocessor, an X86 architecture processor, or a processor with an integrated embedded neural network processing unit (NPU); the transceiver may be, but is not limited to, a wireless fidelity (WIFI) wireless transceiver, a Bluetooth wireless transceiver, a general packet radio service technology (General Packet Radio Service, GPRS) wireless transceiver, a ZigBee protocol (a low-power local area network protocol based on the IEEE802.15.4 standard, ZigBee) wireless transceiver, a 3G transceiver, a 4G transceiver and / or a 5G transceiver, etc. In addition, the device may also include, but is not limited to, a power module, a display screen, and other necessary components.

[0128] The working process, working details and technical effects of the electronic device provided in this embodiment can be found in the second aspect of the embodiment and will not be described in detail here.

[0129] The fourth aspect of this embodiment provides a storage medium storing instructions including the measurement method described in the second aspect of the embodiment, that is, the storage medium stores instructions, and when the instructions are run on a computer, the measurement method described in the second aspect of the embodiment is executed.

[0130] The storage medium refers to a carrier for storing data, which may include but is not limited to a floppy disk, a CD, a hard disk, a flash memory, a USB flash drive and / or a memory stick, and the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0131] The working process, working details and technical effects of the storage medium provided in this embodiment can be found in the second aspect of the embodiment and will not be described in detail here.

[0132] The fifth aspect of this embodiment provides a computer program product comprising instructions, which, when executed on a computer, causes the computer to execute the measurement method as described in the second aspect of the embodiment, wherein the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0133] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rock sample measurement system with high vertical resolution, characterized in that: include: A magnetic device, a mobile device and a radio frequency device, wherein the magnetic device is used to generate a uniform static magnetic field, and a rock sample to be tested is placed on the mobile end of the mobile device; The radio frequency device comprises a radio frequency probe, wherein a plurality of receiving coils are arranged in the radio frequency probe, the radio frequency probe and the rock sample to be measured are both arranged in the static magnetic field generated by the magnet device, and the sensitivity of each receiving coil is different from each other in the axial direction of the rock sample to be measured; The rock sample measurement system further includes: a workstation and a nuclear magnetic resonance device, wherein the workstation and the nuclear magnetic resonance device are respectively electrically connected to the mobile device, and are used to send a movement control signal to the mobile device, so that the mobile device drives the rock sample to be measured to pass through the detection area of ​​the radio frequency probe based on the movement control signal; The nuclear magnetic resonance device is electrically connected to the radio frequency device, and is used to send a plurality of radio frequency transmission pulses to the radio frequency device in sequence when the rock sample to be tested passes through the detection area of ​​the radio frequency probe, so that after the radio frequency device receives each radio frequency transmission pulse, it transmits the received radio frequency transmission pulse to the rock sample to be tested through the radio frequency probe, so as to perform multiple sampling on the rock sample to be tested by using multiple radio frequency transmission pulse signals; The radio frequency device is also used to receive the nuclear magnetic resonance echo signal generated by the rock sample to be tested when excited by the radio frequency transmission pulse through the multiple receiving coils in the radio frequency probe at each sampling, so as to obtain the rock sample sampling signal at each sampling based on the nuclear magnetic resonance echo signal received by the multiple receiving coils; The radio frequency device is also used to send each rock sample sampling signal to the workstation via the nuclear magnetic resonance device; The workstation is used to determine the real rock sample signal of the rock sample to be tested according to each received rock sample sampling signal, and obtain the fluid and occurrence state of the rock sample to be tested based on the real rock sample signal; The moving device drives the rock sample to be tested to pass through the detection area of ​​the radio frequency probe according to the fixed step distance based on the movement control signal, and after the rock sample to be tested moves the fixed step distance for the first time, one end of the rock sample to be tested moves to the boundary of the detection area; Correspondingly, the nuclear magnetic resonance device is used to send a radio frequency transmission pulse to the radio frequency device after the rock sample to be tested moves a fixed step distance, so that after receiving the radio frequency transmission pulse, the radio frequency device transmits the received radio frequency transmission pulse to the rock sample to be tested through the radio frequency probe to stimulate and obtain a nuclear magnetic resonance echo signal of the rock sample to be tested; The expected resolution of the real rock sample signal is greater than the fixed step distance; The process of determining the real rock sample signal of the rock sample to be tested based on a number of rock sample sampling signals by the workstation is as follows: Step 1: The workstation obtains the sensitivity of each receiving coil in the radio frequency probe; Step 2: The workstation constructs a sensitivity matrix based on the sensitivity of each receiving coil, and constructs a sampling signal matrix based on a number of rock sample sampling signals, wherein the sensitivity matrix is ​​shown in the following formula (2); In the above formula (2), A is a sensitivity matrix, wherein a(-I / 2,c(M)) represents the sensitivity of the Mth receiving coil in the radio frequency probe, I represents a constant, I=Lc / r, and Lc represents the length of the radio frequency probe, and r is the expected resolution of the real rock sample signal; The sampling signal matrix is ​​shown in the following formula (3): In the above formula (3), S(x(1), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the first sampling, and at the first sampling, the nuclear magnetic resonance echo signals received by all the receiving coils in the radio frequency probe constitute the rock sample sampling signal at the first sampling, and S(x(N), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the Nth sampling; Step 3: The workstation constructs a real rock sample signal model using the sensitivity matrix and the sampling signal matrix; The real rock sample signal model is shown in the following formula (1): min||Ay-s|| 2 +λ1|y| (1) In the above formula (1), A represents the sensitivity matrix, s represents the sampling signal matrix, y represents the real rock sample signal matrix, λ1 represents the regularization factor, and || || represents the second norm; at the same time, In the above formula (4), y() represents the real rock sample signal, and x(1) represents the horizontal coordinate of the target end of the rock sample to be tested in the target coordinate system during the first sampling, wherein the origin of the target coordinate system is the center of the radio frequency probe, the horizontal axis is the axial direction of the radio frequency probe, the vertical axis is the direction perpendicular to the axial direction, and the target end is the end of the rock sample to be tested that first enters the detection area of ​​the radio frequency probe; Step 4: The workstation performs iterative solution processing on the real rock sample signal model to obtain the real rock sample signal of the rock sample to be tested after the iterative solution processing.

2. A rock sample measurement system with high vertical resolution according to claim 1, characterized in that: The plurality of receiving coils include a plurality of saddle-shaped receiving coils and a solenoid coil.

3. A rock sample measurement system with high vertical resolution according to claim 1, characterized in that: The plurality of receiving coils include a plurality of saddle-shaped receiving coils and a solenoid coil; The radio frequency device further comprises: a radio frequency power amplifier, a transceiver conversion module and a plurality of preamplifiers, and each preamplifier corresponds to a receiving coil; The input end of the radio frequency power amplifier is electrically connected to the transmission channel of the nuclear magnetic resonance device, and the output end of the radio frequency power amplifier is electrically connected to the transceiver conversion module, wherein the transceiver conversion module is electrically connected to the solenoid coil, and the transceiver conversion module is also electrically connected to the corresponding preamplifier; Each saddle-shaped receiving coil is electrically connected to a corresponding preamplifier, and each preamplifier is electrically connected to a receiving channel of the nuclear magnetic resonance device.

4. A rock sample measurement system with high vertical resolution according to claim 1, characterized in that: The mobile device includes: a transmission controller, a drive motor and a transmission mechanism, wherein the nuclear magnetic resonance device and the workstation are electrically connected to the transmission controller respectively, the transmission controller is electrically connected to the drive motor, the drive end of the drive motor is transmission-connected to the transmission mechanism, and the rock sample to be tested is placed on the transmission mechanism.

5. A rock sample measurement system with high vertical resolution according to claim 1, characterized in that: The magnet device includes a permanent magnet or a superconducting magnet.

6. A measurement method based on the high vertical resolution rock sample measurement system according to any one of claims 1 to 5, characterized in that: The method is performed by a workstation in the rock sample measurement system with high vertical resolution, and the method comprises: Acquire a plurality of rock sample sampling signals sent by the nuclear magnetic resonance device, wherein the plurality of rock sample sampling signals are sampled and obtained during the process of the rock sample to be tested passing through the detection area of ​​the radio frequency probe; Based on a number of rock sample sampling signals, a real rock sample signal of the rock sample to be tested is determined, and based on the real rock sample signal, the fluid and occurrence state of the rock sample to be tested are obtained.

7. The method according to claim 6, characterized in that Based on a plurality of rock sample sampling signals, determining a real rock sample signal of the rock sample to be tested comprises: Obtaining the sensitivity of each receiving coil in the radio frequency probe; Based on the sensitivity of each receiving coil, a sensitivity matrix is ​​constructed, and based on a number of rock sample sampling signals, a sampling signal matrix is ​​constructed; Using the sensitivity matrix and the sampling signal matrix, a real rock sample signal model is constructed; The real rock sample signal model is iteratively solved to obtain the real rock sample signal of the rock sample to be tested after iterative solution.

8. The method according to claim 7, characterized in that The real rock sample signal model is: min||Ay-s|| 2 +λ1|y| (1) In the above formula (1), A represents the sensitivity matrix, s represents the sampling signal matrix, y represents the real rock sample signal matrix, λ1 represents the regularization factor, and || || represents the second norm; in, In the above formula (2), a(-I / 2,c(M)) represents the sensitivity of the Mth receiving coil in the radio frequency probe, and I represents a constant, wherein I=Lc / r, and Lc represents the length of the radio frequency probe, and r is the expected resolution of the real rock sample signal; In the above formula (3), S(x(1), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the first sampling, and at the first sampling, the nuclear magnetic resonance echo signals received by all the receiving coils in the radio frequency probe constitute the rock sample sampling signal at the first sampling, and S(x(N), c(M)) represents the nuclear magnetic resonance echo signal received by the Mth receiving coil in the radio frequency probe at the Nth sampling; In the above formula (4), y() represents the real rock sample signal, and x(1) represents the horizontal coordinate of the target end of the rock sample to be tested in the target coordinate system during the first sampling, wherein the origin of the target coordinate system is the center of the RF probe, the horizontal axis is the axial direction of the RF probe, the vertical axis is the direction perpendicular to the axial direction, and the target end is the end of the rock sample to be tested that first enters the detection area of ​​the RF probe.

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