CN112834542A - Method for simultaneously measuring layered water content and pore size distribution of rock core - Google Patents
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 116
- 239000011435 rock Substances 0.000 title claims abstract description 89
- 239000011148 porous material Substances 0.000 title claims abstract description 71
- 238000009826 distribution Methods 0.000 title claims abstract description 49
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- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 claims abstract description 18
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
- G01N24/081—Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
Abstract
The invention relates to the technical field of petroleum exploration, in particular to a method for simultaneously measuring water content and pore size distribution of a rock core. The invention discloses a pulse sequence application method for detecting the water content and pore size distribution of a rock core, which is characterized in that the resonance frequencies of water in different layers in a calibration rock sample are different by applying frequency coding gradients among radio frequency pulses, so that the layered detection of the rock core to be detected is realized, a calibration rock sample signal curve with uniform water content is obtained by applying a test of a pulse sequence, and a calculation model of the water content of each calibration layer is established; obtaining the water content of the saturated rock core to be detected at different layers by using the calculation model, and obtaining the pore size distribution of the rock core to be detected; compared with the conventional test method, the method has the advantages of simple test flow, short test time and capability of realizing nondestructive test of the sample; the water content and pore size distribution test of any number of layers of the rock core can be realized simultaneously, and the method has great significance for research and analysis with exploration.
Description
Technical Field
The invention relates to the technical field of logging evaluation of oil and gas reservoir reservoirs in petroleum exploration, in particular to a method for simultaneously measuring the layered water content and the pore size distribution of a rock core.
Background
In the process of oil and gas exploration and development, the water content and the pore size distribution of the rock core are important indexes for evaluating the economic development of the oil field. During secondary recovery in an oil field, the recovery rate of the oil well is increased by injecting water into the production well, i.e. the oil well. However, as shown in fig. 1, the process of injecting water to push the crude oil in the formation to the production well is not piston type, but is pointed at a certain angle, and the water content is different at different positions in the formation. Therefore, how to accurately measure the water content and the pore size distribution of the rock core has important significance for the efficient development of oil and gas fields.
The conventional method for measuring the water content of the rock core mainly comprises a distillation extraction method, a chromatography method, a microwave method, an ethanol closed heating extraction-chromatography measurement method, a vacuum dry distillation method and a drying method; the conventional method for measuring the pore size distribution of the rock core mainly adopts a mercury intrusion method. Toluene in the distillation extraction method and mercury in the mercury pressing method cause pollution to the environment; the conventional water content method only tests the water content of the whole rock core, but cannot test the water content of different positions of the rock core, and is not beneficial to research and analysis. And the test method for the water content and the pore size distribution of the rock core has long test time and high cost, and is not suitable for the conventional physical property parameter test of the rock core.
The conventional Chinese patent document CN105401937 discloses a saturation index prediction method based on a pore system structure, which comprises the steps of selecting a representative core sample of a target layer, saturating the representative core sample with a saline solution with a certain concentration, measuring a nuclear magnetic resonance T2 spectrum of a saturated core and nuclear magnetic resonance T2 spectra of cores in different centrifugal states, and obtaining a core void structure index and a core saturation index by calculating the geometric mean value of the nuclear magnetic resonance T2 spectrum and the water saturation of the core in different centrifugal states so as to determine the target layer index. However, the method has complex flow and long testing time, and can not simultaneously realize the water content and pore size distribution test of any number of layers of the rock core.
Disclosure of Invention
Therefore, the invention aims to solve the technical problem that the prior art cannot simultaneously realize the water content and pore size distribution test of any number of layers of the rock core. The invention provides a method for simultaneously measuring layered water content and pore size distribution in a water-saturated rock core by utilizing a nuclear magnetic resonance technology, which is used for quantitatively characterizing the water content and the pore size distribution of each position of the rock core and testing the multi-layer water content and the pore size distribution of the rock core. The test method is simple to operate and high in test speed, and can realize nondestructive test of water content and pore size distribution of each position of the core.
The invention discloses a pulse sequence application method for detecting water content and pore size distribution of a rock core, which sequentially comprises the following operations:
applying 90-degree radio frequency pulse with the pulse width of P1 to the radio frequency pulse applying channel;
applying an amplitude G on a gradient pulse application channela0The frequency encoding compensation gradient of (a);
applying N180-degree radio-frequency pulses with the pulse width of P2 on a radio-frequency pulse applying channel; and applying an amplitude G to the gradient pulse application channel between every two 180 DEG radio frequency pulsesa1The frequency encoding gradient.
Optionally, the frequency of the radio frequency pulse is 50kHz to 5000kHz, Ga0The value range is 0-0.05T/m, Ga1The value range is 0-0.05T/m, and the value range of N is 1000-12000.
Optionally, the time interval between the corresponding 90 ° rf pulse peak and the corresponding 180 ° rf pulse peak is TE/2, and the time interval between every two 180 ° rf pulses is TE.
Optionally, the TE is 0.2ms to 1 ms.
Optionally, the value range of P1 is 8us-12us, and the value range of P2 is 18us-22 us.
The invention also discloses a method for measuring the water content and the pore size distribution of the rock core, which comprises the following steps,
s1, selecting a core calibration sample with uniform water content, and obtaining the water content of the core to be tested when the core is saturated with water;
s2 applying to the calibration sample rock by the pulse sequence applying method according to any one of claims 1 to 5, stopping for a time Tw, performing n cycles for one cycle, and collecting echo peak signals; connecting echo peaks of each layer of the calibration sample rock at different times to obtain a transverse relaxation time T2 attenuation spectrum of the corresponding layer; obtaining the pore diameters of different layers, namely the pore diameter distribution of the rock to be detected, according to the transverse relaxation time T2 attenuation spectrums of different layers of the calibration sample rock, and utilizing the following formula:
wherein, T2 is the transverse relaxation time of each layer of the core, Fs is the pore shape factor, and when the pores are spherical, Fs is 3; when the pores are columnar pores, Fs is 2;
rcis the pore diameter;
s3, establishing a core layered water content calculation model according to the nuclear magnetic semaphore corresponding to the water content of each layer of the calibration sample rock;
s4, applying the same pulse sequence as that applied to the sample to the rock core to be tested, circulating for m times to obtain nuclear magnetic signal quantity corresponding to the water content of each layer of the rock to be tested, and obtaining the water content and the pore diameter of each layer of the rock to be tested according to the rock core layered water content calculation model.
Optionally, n and m are both powers of 2, and the range is 2-1024.
Optionally, the value range of Tw is 1000ms to 10000 ms.
Optionally, in step S1, the core to be tested is dried and weighed, and the weight M of the dry core is recorded0(ii) a Vacuumizing the dry rock core, adding formation water, vacuumizing until the rock core is completely saturated with water, and weighing to obtain a weight M1Obtaining the total water content M of the core to be measured when the core is saturated with water1-M0。
Optionally, the model for calculating the layered water content of the core is a linear relationship between the nuclear magnetic signal quantity of each layer of the core and the water content of each layer of the core, and the following formula is shown:
y＝ax+b
wherein x represents the moisture content of each layer;
y represents the nuclear magnetic signal quantity corresponding to the water content of each layer;
a is the slope and b is the intercept.
The invention also discloses a pulse sequence application method for detecting the water content and the pore size distribution of the rock core, or a measurement method for the water content and the pore size distribution of the rock core, and the application of the method in the field of petroleum exploration.
The technical scheme of the invention has the following advantages:
1. the invention discloses a pulse sequence application method for detecting water content and pore size distribution of a rock core, which is characterized in that a frequency coding gradient is applied among radio frequency pulses, and a gradient field is applied along the direction of a magnetic field, so that the resonance frequencies of water at different positions in a calibration rock sample are different, thus realizing the layered detection of the rock core to be detected, not only obtaining the water content of each layer of the rock core, but also obtaining the pore size distribution of the rock core to be detected, and realizing the simultaneous detection of the water content distribution and the pore size distribution of the rock core.
2. The invention discloses a method for measuring the water content and pore size distribution of a rock core, which is characterized in that a signal curve of a calibration sample rock with uniform water content is obtained by a pulse sequence application method, and a calculation model of the water content of each layer of the calibration sample is established; because nuclear magnetic resonance inside the rock only measures the signal of hydrogen in water, substances without hydrogen do not have signals; therefore, the signal quantity and the water content of each layer are in a linear relation, the water content of the saturated rock core to be detected at different layers is obtained by utilizing the calculation model, and the pore diameter of each layer is measured at the same time to obtain the pore diameter distribution of the rock core to be detected; compared with the conventional test method, the method has the advantages of simple test flow, short test time and capability of realizing nondestructive test of the sample; the water content and pore size distribution test of any number of layers of the rock core can be realized simultaneously, and the method has great significance for research and analysis with exploration.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of water injection from an oil well as described in the background of the invention;
FIG. 2 is a sequence diagram of a GR-CPMG pulse sequence used in an embodiment of the present invention;
FIG. 3 is a graph of GR-CPMG echo signal acquisition of the present invention;
FIG. 4 is a GR-CPMG collection curve for a calibration sample rock of the present invention;
FIG. 5 is a linear relationship fit curve of the horizons of a rock portion of a calibration sample according to the present invention;
FIG. 6 is a GR-CPMG acquisition curve of a water-saturated core to be tested in the embodiment of the invention;
fig. 7 is a graph showing pore size distribution of a core to be measured.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
Example 1
selecting five groups of rock core calibration samples with uniform water content, wherein the water content is respectively 0.1g, 0.5g, 1g, 2g and 3g, and the water content is respectively 1%, 5%, 10%, 20% and 30% in sequence;
preparing a core to be measured with the diameter of 25mm and the length of 25mm, namely standard sandstone, placing the core to be measured in a drying oven at 105 ℃ for drying for 24 hours, and then weighing 46.6448g of dry weight of the core to be measured; then placing the core to be tested in a vacuumizing water saturation device, adding formation water, vacuumizing and saturating for 48 hours to ensure that the pores of the core to be tested are completely saturated with the formation water, and weighing 45.8968g of the water-saturated core to be tested to obtain the water content of the core of 0.748 g;
Placing the calibration sample rock in a sample chamber of a nuclear magnetic resonance instrument, applying a GR-CPMG pulse sequence as shown in FIG. 2, first applying 90 DEG radio frequency pulses with a pulse width of 10us and a frequency of 200Hz to the calibration sample in a radio frequency pulse applying channel (RF channel, X direction), then applying a frequency encoding compensation gradient with an amplitude of 0.05T/m in a gradient pulse applying channel (GR channel, Y direction), and subsequently applying 7000 radio frequency pulses with a pulse width of 20us and 180 DEG to the calibration sample in the RF channel, wherein the time interval between the peak of the 90 DEG radio frequency pulse and the peak of the first 180 DEG radio frequency pulse is 0.5 ms; the time interval between every two 180 DEG radio frequency pulse wave crests is 1ms, a frequency coding gradient with the amplitude of 0.05T/m is applied between every two 180 DEG pulses, and echo signals are collected in the gradient application process, namely signal signals in figure 2; as shown in fig. 3, the 90 ° pulse application time is zero, the corresponding time at the echo peak is t, the value is equal to 1ms, the time interval between every two 180 ° rf pulse peaks is the same, the echo peak points of different layers of the sample at the t time are obtained, and then the echo peaks of different times on each layer are connected to obtain the transverse relaxation time attenuation spectra of different layers;
in order to obtain a proper signal-to-noise ratio, after the GR-CPMG sequence is applied, the GR-CPMG sequence is applied for 5000ms, the cycle of applying the GR-CPMG sequence is repeated for 1024 times, and the time is set to be one cycle;
in other embodiments of the present invention, the 90 ° RF pulses and 180 ° RF pulses are applied at a frequency in the range of 50-5000kHz, and the frequency and amplitude of the frequency-encoded compensation gradient and the frequency-encoded gradient in the same GR-CPMG sequence are 0-0.05T/m, and in other embodiments are 0.04T/m,0.03T/m, 0.02T/m, or 0.01T/m, but are not limited thereto.
In other embodiments of the present invention, the time interval between every two 180 ° rf pulse peaks may be 0.2ms,0.3ms,0.4ms,0.5ms,0.6ms,0.7ms, 0.8ms or 0.9ms, and is not limited thereto.
In other embodiments of the present invention, the number N of 180 ° rf pulses applied to the rf pulse applying channel per applying the pulse sequence is 1000-.
In other embodiments of the invention, the pulse width of the radio frequency pulse is selectively adjusted according to different instruments and samples, and the pulse width of the 90-degree radio frequency pulse can be adjusted to be 8us,9us, 11us or 12 us; the pulse width of the 180 ° rf pulse may be adjusted to 18us,19us,21us, or 22us, and is not limited thereto.
In this embodiment, as shown in fig. 2, a frequency coding compensation gradient of 0.05T/m is applied to the GR channel to make the phases of all voxels consistent, and a frequency coding gradient of 0.05T/m is applied between every two 180 ° rf pulses to perform one-dimensional positioning, and applying frequency coding positioning will make all voxels in the selected slice out of phase, which is out of phase due to the frequency coding gradient effect, so that the intensity of the signal is reduced; different frequencies correspond to different locations;
storing the collected sample signal data to obtain a T2 attenuation spectrum; the most basic formula of T2 relaxation is shown in the following formula 1, wherein S is specific surface area and unit is m2V is the volume of the test sample in m3ρ is the transverse surface relaxation strength of rock, the capacity of surface relaxation generated by collision between hydrogen nuclei in fluid and the surface of a solid inside a reservoir pore, and the unit is m/ms:
the equation for T2 relaxation and pore size distribution is shown in equation 2 below, assuming that the pores consist of ideal spheres, where Fs is the pore shape factor, spherical pores, and Fs ═ 3; columnar pores, Fs ═ 2; rc is the pore diameter, and the pore diameters of different rock core layers are obtained, namely the different pore diameter distributions of the rock core to be detected.
Step 3, establishing a core layered water content calculation model
Testing five groups of calibration stone samples with uniform water content according to the GR-CPMG pulse sequence in the step 2 respectively to obtain a calibration sample rock GR-CPMG acquisition curve, which is shown in figure 4;
according to the GR-CPMG acquisition curve of the sample rock shown in FIG. 4, then, the nuclear magnetic semaphore corresponding to the water content of each layer in the five groups of calibration samples with uniform water content is determined, as shown in Table 1, a fitting relation curve is obtained, and therefore, a core water content calculation model of each layer is obtained, as shown in Table 2, x represents the water content corresponding to each layer, and y represents the nuclear magnetic semaphore corresponding to the water content of each layer. As can be seen from the linear relation fitting curve of the rock part horizon of the calibration sample shown in FIG. 5, the fitting curve of the selected part of horizons has good linear correlation;
TABLE 1 nuclear magnetic semaphore corresponding to core stratified water content
TABLE 2 core stratified water content calculation model
| Number of layers | Fitting relation curve | Number of layers | Fitting relation curve |
| Layer 1 | y＝9503.4x+25.768 | Layer 21 | y＝9434.8x+47.218 |
| Layer 2 | y＝10009x+21.238 | Layer 22 | y＝9539.9x+30.387 |
| Layer 3 | y＝10109x+16.795 | Layer 23 | y＝9557.5x+34.865 |
| Layer 4 | y＝9965.2x+15.263 | Layer 24 | y＝9611.3x+45.096 |
| Layer 5 | y＝9823x+19.99 | Layer 25 | y＝9661.4x+34.792 |
| Layer 6 | y＝9743.5x+19.987 | Layer 26 | y＝9633.9x+32.175 |
| Layer 7 | y＝9663.6x+33.898 | Layer 27 | y＝9650.5x+25.203 |
| Layer 8 | y＝9659.9x+28.22 | Layer 28 | y＝9662.7x+36.711 |
| Layer 9 | y＝9595.3x+25.783 | Layer 29 | y＝9786x+35.198 |
| Layer 10 | y＝9458.4x+31.814 | Layer 30 | y＝9849.9x+36.143 |
| Layer 11 | y＝9456.3x+27.391 | Layer 31 | y＝9809.4x+33.908 |
| Layer 12 | y＝9507.6x+26.036 | Layer 32 | y＝9782.2x+28.911 |
| Layer 13 | y＝9481.8x+38.494 | Layer 33 | y＝9807.1x+29.416 |
| Layer 14 | y＝9493.9x+35.61 | Layer 34 | y＝10021x+25.512 |
| Layer 15 | y＝9444.2x+34.319 | Layer 35 | y＝10085x+30.284 |
| Layer 16 | y＝9425.9x+31.698 | Layer 36 | y＝10103x+31.219 |
| Layer 17 | y＝9471.4x+31.018 | Layer 37 | y＝10051x+23.023 |
| Layer 18 | y＝9475.6x+40.334 | Layer 38 | y＝10047x+23.085 |
| Layer 19 | y＝9530.6x+40.937 | Layer 39 | y＝10187x+26.331 |
| Layer 20 | y＝9518.3x+37.228 | Layer 40 | y＝10436x+26.824 |
Since the resonance frequencies of all hydrogen protons are the same under the action of the magnetic field, the resonance frequencies of water at different positions in the calibration sample are different by applying a gradient field along the direction of the magnetic field, and the thickness of each layer is calculated by the following formula (formula 3):
wherein, the FOV is the visual field range, the unit is mm, and the FOV is determined according to the sample size (the FOV is more than or equal to 2 multiplied by the sample length); TD represents the number of points, and the numerical value is twice of the cycle number;
nuclear magnetic resonance only measures the signal of H in water, and no signal for hydrogen-free species; therefore, the signal amount of each layer is linear with the water content.
Step 4, nuclear magnetic resonance signals and apertures (r) of the saturated rock core to be tested at different layers are tested simultaneouslyc) A distribution curve;
wrapping the water-saturated rock core to be detected with a preservative film to prevent water loss;
testing a water-saturated core sample to be tested by using a GR-CPMG pulse sequence to obtain a GR-CPMG acquisition curve of the water-saturated core to be tested, as shown in FIG. 6; determining nuclear magnetic resonance signal quantity and a nuclear magnetic resonance T2 spectrum on each layer of the saturated water to-be-detected rock core by utilizing a BRD inversion algorithm according to the measured curve;
calculating the water content of each layer of the rock core by using a layered water content calculation model in the table 1 according to a T2 spectral curve of each layer to obtain the water content components of different layer layers; as shown in table 3;
according to the formula 2, the pore size distribution of the core to be measured is calculated, as shown in fig. 7, it can be seen from fig. 7 that the pore size distribution of each layer of the core is approximately in a three-peak state. The first peak represents the water content of the bound water in the rock core, and the water cannot be exploited in the oil and gas development process; the second peak represents the water content of the mobile water in the core, which is carried out during the oil and gas migration; the third peak represents the water cut of the free water in the core, how much of this water affects the recovery of hydrocarbons.
TABLE 3 Water content calculation results for 40 layers of rock core
Test example
The test method described in example 1 was repeated 6 times for the core to be tested, and the water content was shown in table 4.
Table 4 results of repeated tests on cores to be tested
And (4) test conclusion: the detection method disclosed by the application can simply, effectively and simultaneously measure the water content and the pore size distribution of different rock core layers, has good repeatability and good stability of test results, and can be used in the petroleum exploration process.
It is to be understood that the above examples are illustrative only for the purpose of clarity of description and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (11)
1. A pulse sequence application method for detecting water content and pore size distribution of a rock core is characterized by sequentially comprising the following operations:
applying 90-degree radio frequency pulse with the pulse width of P1 to the radio frequency pulse applying channel;
applying an amplitude G on a gradient pulse application channela0The frequency encoding compensation gradient of (a);
applying N180-degree radio-frequency pulses with the pulse width of P2 on a radio-frequency pulse applying channel; and applying an amplitude G to the gradient pulse application channel between every two 180 DEG radio frequency pulsesa1The frequency encoding gradient.
2. The method for applying the pulse sequence for detecting the water content and the pore size distribution of the rock core according to claim 1, wherein the frequency of the radio frequency pulse is 50kHz-5000kHz, and the G isa0The value range is 0-0.05T/m, Ga1The value range is 0-0.05T/m, and the value range of N is 1000-12000.
3. The pulse sequence application method for detecting the water content and the pore size distribution of the rock core according to claim 1 or 2, wherein the corresponding time of the 90-degree radio frequency pulse peak and the corresponding time interval of the first 180-degree radio frequency pulse peak are TE/2, and the peak time interval of every two 180-degree radio frequency pulses is TE.
4. The method for applying the pulse sequence for detecting the water content and the pore size distribution of the rock core according to claim 3, wherein the TE is 0.2ms-1 ms.
5. The pulse sequence application method for detecting the water content and the pore size distribution of the rock core according to any one of claims 1 to 4, wherein the P1 is in a range of 8us to 12us, and the P2 is in a range of 18us to 22 us.
6. A method for measuring the water content and pore size distribution of a rock core is characterized by comprising the following steps,
s1, selecting a core calibration sample with uniform water content, and obtaining the water content of the core to be tested when the core is saturated with water;
s2 applying to the calibration sample rock by the pulse sequence applying method according to any one of claims 1 to 5, stopping for a time Tw, performing n cycles for one cycle, and collecting echo peak signals; connecting echo peaks of each layer of the calibration sample rock at different times to obtain a transverse relaxation time T2 attenuation spectrum of the corresponding layer; obtaining the pore diameters of different layers, namely the pore diameter distribution of the rock to be detected, according to the transverse relaxation time T2 attenuation spectrums of different layers of the calibration sample rock, and utilizing the following formula:
wherein, T2 is the transverse relaxation time of each layer of the core, Fs is the pore shape factor, and when the pores are spherical, Fs is 3; when the pores are columnar pores, Fs is 2;
rcis the pore diameter;
s3, establishing a core layered water content calculation model according to the nuclear magnetic semaphore corresponding to the water content of each layer of the calibration sample rock;
s4, applying the same pulse sequence as that applied to the sample to the rock core to be tested, circulating for m times to obtain nuclear magnetic signal quantity corresponding to the water content of each layer of the rock to be tested, and obtaining the water content and the pore diameter of each layer of the rock to be tested according to the rock core layered water content calculation model.
7. The method for measuring the water content and the pore size distribution of the rock core according to claim 6, wherein n and m are both powers of 2 and have a range of 2-1024.
8. The method for measuring the water content and the pore size distribution of the rock core according to claim 6, wherein the Tw ranges from 1000ms to 10000 ms.
9. The method for measuring the water content and the pore size distribution of the core according to any one of claims 6 to 8, wherein in step S1, the core to be measured is dried and weighed, and the weight M of the dry core is recorded0(ii) a Vacuumizing the dry rock coreAdding formation water and vacuumizing until the rock core is completely saturated with water and weighing to obtain the weight M1Obtaining the total water content M of the core to be measured when the core is saturated with water1-M0。
10. The method for measuring the water content and the pore size distribution of the core according to any one of claims 6 to 9, wherein the calculation model of the layered water content of the core is a linear relation between the nuclear magnetic signal quantity of each layer of the core and the water content of each layer of the core, and is represented by the following formula:
y＝ax+b
wherein x represents the moisture content of each layer;
y represents the nuclear magnetic signal quantity corresponding to the water content of each layer;
a is the slope and b is the intercept.
11. The application of the pulse sequence application method for detecting the water content and the pore size distribution of the rock core according to any one of claims 1 to 5 or the measurement method for the water content and the pore size distribution of the rock core according to any one of claims 6 to 10 in the field of oil exploration.
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