Full-size pore quantitative characterization method for oil-water occurrence of tight reservoir based on logging nuclear magnetism

Abstract

The invention relates to a full-size pore quantitative characterization method for oil-water occurrence of a tight reservoir based on logging nuclear magnetism, and belongs to the field of unconventional oil-gas exploration and development. Comprising the following steps: step 1, extracting aperture size distribution characteristics of a rock core sample based on a large-vision-field splicing scanning electron microscope; 2, respectively establishing indoor nuclear magnetic T2-aperture conversion models of oil and water; 3, establishing an indoor nuclear magnetism T2-nuclear magnetism logging T2 conversion model; 4, establishing a logging nuclear magnetic transverse relaxation time T2-aperture conversion model of oil and water; 5, fitting the nuclear magnetic logging T2 spectrum into a water T2 spectrum and an oil T2 spectrum based on a frequency division principle; and step 6, realizing full-size fluid identification and distribution evaluation of the oil-water two-phase fluid of the reservoir based on the oil and water logging nuclear magnetic transverse relaxation time T2-aperture conversion model. The method is high in result reliability, sufficient in basis and easy to operate, and has important guiding significance for exploration and development.

Description

Technical Field

[0001] The invention relates to a method for quantitatively characterizing full-size pores of oil and water storage in dense reservoirs based on well logging nuclear magnetic resonance, and belongs to the field of unconventional oil and gas exploration and development. Background Art

[0002] With the continuous advancement of oil and gas exploration and development technology and the increasing demand for energy, the goal of global oil and gas exploration and development has gradually shifted from conventional structural trapped oil and gas reservoirs to tight oil and gas and shale oil and gas in unconventional areas, making tight reservoirs and shale reservoirs a new focus in oil and gas geological research.

[0003] At present, there are published patent documents that establish a conversion model between nuclear magnetic T2 and pore size based on the experimental results of high-pressure mercury injection, nitrogen adsorption, wide-field scanning electron microscopy, etc. combined with indoor nuclear magnetic resonance. First of all, it should be explained that high-pressure mercury injection does not obtain the pore size, but the throat size. The T2-pore size conversion model established based on the results of high-pressure mercury injection experiments is not reasonable; secondly, since nitrogen adsorption can only characterize pores below 100nm, the pore size it characterizes is not complete. High-resolution, large-field-of-view stitching scanning electron microscopes can reveal the distribution of nano- to micro-scale pores well and relatively comprehensively. Existing public patent documents all use nuclear magnetic resonance detection by saturating a single-property fluid (such as water or oil), but there are still three shortcomings. First, only limited core samples can be calibrated and evaluated for pore size, and the pore size distribution of the entire well section reservoir cannot be characterized. Second, the difference in relaxation rates of fluids of different properties will cause different nuclear magnetic T2 values ​​in pores of the same size. In actual formations (especially oil layers), there are generally oil-water miscible phases. The nuclear magnetic T2 spectrum explained by nuclear magnetic logging is often a comprehensive reflection of the distribution of oil and water in different pore sizes. Third, due to differences in instrument parameters and detection environments, logging nuclear magnetic resonance and indoor nuclear magnetic resonance cannot be directly equivalent. It is precisely because of these problems and limitations that how to use nuclear magnetic logging data to achieve pore size characterization of tight reservoirs in the entire well section has become a technical problem facing the evaluation of unconventional reservoir quality and sweet spots. Summary of the invention

[0004] In order to solve the current problems faced with the complex distribution of oil-water pore size in tight reservoirs and oil-water two-phase flow, the present invention provides a method for quantitatively characterizing the full-size pores of oil and water storage in tight reservoirs based on well logging nuclear magnetic resonance.

[0005] The present invention uses a large field of view to splice the pore size distribution extracted by the scanning electron microscope, and establishes the T2-aperture conversion model of pressurized saturated oil and water respectively with the indoor pressurized oil / water saturated nuclear magnetic resonance, and further uses the nuclear magnetic frequency division principle to disassemble the oil / water nuclear magnetic signal obtained by nuclear magnetic logging, and further uses the conversion model to realize the quantitative characterization of the full-scale pores of oil and water occurrence based on the vertical continuous nuclear magnetic logging, and uses the T2-aperture conversion model of oil and water to realize the full-scale fluid distribution evaluation of the oil-water two-phase fluid in the reservoir. This has important guiding significance for revealing the evaluation of the oil content of unconventional reservoirs and the subsequent "sweet spot" optimization.

[0006] The technical solution of the present invention is: The quantitative characterization method of full-scale pores of oil and water in tight reservoirs based on well logging nuclear magnetic resonance includes: Step 1: Extract the pore size distribution characteristics of the core sample based on a large field of view stitching scanning electron microscope; Step 2: Based on the NMR T2 spectra of pressurized saturated oil and saturated water samples, indoor NMR T2-aperture conversion models of oil and water are established respectively; Step 3: Based on the indoor NMR spectrum and NMR logging spectrum of the closed core sampling sample, establish an indoor NMR T2-NMR logging T2 conversion model; Step 4: Establish the well logging NMR transverse relaxation time T2-aperture conversion model for oil and water; Step 5: Fit the nuclear magnetic logging T2 spectrum into water T2 spectrum and oil T2 spectrum based on the frequency division principle; Step 6: Based on the logging NMR transverse relaxation time T2-aperture conversion model of oil and water, full-scale fluid identification and distribution evaluation of reservoir oil-water two-phase fluid is realized.

[0007] Preferably, according to the present invention, in step 1, the distribution of pores is characterized, and the size of the pores is determined as the number of pixels of the area occupied by the pores; the sizes of all pores are extracted, and the total area of ​​pores of the same size is counted, and the frequency of pores of the same size is determined as the ratio of the total area of ​​pores of the same size to the total area of ​​all pores.

[0008] Preferably, in step 2, according to the difference in relaxation rates of oil and water, the same sample is saturated with oil and saturated with water respectively, and nuclear magnetic resonance T2 detection of the core sample is carried out, and the indoor nuclear magnetic resonance T2-aperture conversion model of oil and water is established by using morphological characteristics and the relationship between T2 and aperture corresponding to the peaks and troughs; The indoor NMR T2-aperture conversion model for water is: r 室内-水 =396.15T 2室内-水 1.0049 (1) The indoor NMR T2-aperture conversion model for oil is: r 室内-油 =357.73 T 2室内-油 0.8604 (2) In formula (1) and formula (2), r 室内-水 and r 室内-油 is the pore size of the lithology sample when saturated with water and saturated with oil, nm; T 2室内-水 is the indoor nuclear magnetic T2 of the lithology sample saturated with water, ms; T 2室内-油 This is the indoor NMR T2, ms, of the lithology sample when it is saturated with oil.

[0009] Preferably, in step 3, the indoor nuclear magnetic T2 spectrum of the core sample that has not been developed in the formation and subsequently preserved in a simulated high temperature and high pressure environment of the formation has a similar morphology to the nuclear magnetic logging T2 spectrum of the core sample, and an indoor nuclear magnetic T2-nuclear magnetic logging T2 conversion model is established according to the T2 corresponding to the peaks and troughs, as shown below; When T 2_室内 <0.8ms, T 2_测井 =15.92 T 2_室内 1.62 When T 2_室内 ≥0.8ms, T 2_测井 =7.67 T 2_室内 +2.54 (3) In formula (3), T 2_测井 is the nuclear magnetic logging T2, ms; T 2_室内 This is the indoor nuclear magnetic resonance T2, ms of the core sample that has not been developed in the formation and subsequently preserved in a high temperature and high pressure environment simulating the formation.

[0010] Preferably, in step 4, the well logging nuclear magnetic T2-aperture conversion model is obtained by jointly obtaining the indoor nuclear magnetic T2-aperture conversion model obtained in step 2 and the indoor nuclear magnetic T2-well logging nuclear magnetic T2 conversion model obtained in step 3, including: The well logging nuclear magnetic transverse relaxation time T2-aperture conversion model of water is: r 测井_水 =74.72T 2测井_水 0.92 (4) The oil logging nuclear magnetic transverse relaxation time T2-aperture conversion model is: r 测井_油 =89.247T 2测井_油 0.78 (5) In formula (4) and formula (5):r 测井_水 is the pore size of the lithology sample when saturated with water, nm; r 测井_油 is the pore size of the lithology sample when saturated with oil, nm; T 2测井_水 is the relaxation time T2 when the fluid property is water in NMR logging, ms; T 2测井_油 It is the relaxation time T2 when the fluid property is oil in NMR logging, ms.

[0011] Preferably, according to the present invention, in step 5, the nuclear magnetic frequency division principle is utilized and the Origin software is used to decompose the logging nuclear magnetic T2 spectrum into an oil spectrum and a water spectrum, wherein the nuclear magnetic spectrum in the high T2 value region, i.e., the spectrum peak higher than 5ms, is the oil spectrum, and the nuclear magnetic spectrum in the low T2 value region, i.e., the spectrum peak not higher than 5ms, is the water spectrum, and the nuclear magnetic logging T2 spectrum of the entire well section is frequency-divided in turn to obtain the distribution of the oil spectrum of the entire well section, i.e., the oil T2 spectrum, and the water spectrum, i.e., the water T2 spectrum, to achieve fluid identification of the entire well section.

[0012] Preferably, according to the present invention, in step 6, the logging T2-pore size conversion model of oil and water in step 4 and the identification results of oil and water in step 5 are integrated, the pore size distribution of water is calculated according to formula (4) for the water spectrum, and the pore size distribution of oil is calculated according to formula (5) for the oil spectrum, that is, the quantitative characterization of the full-size pores of the continuous two-phase fluid on the logging is realized.

[0013] The beneficial effects of the present invention are: The present invention realizes a quantitative characterization method of full-scale pores for oil and water occurrence based on well logging nuclear magnetic resonance, and determines the pore size distribution characteristics of reservoir fluids in the study area as well as the full-scale identification and distribution characteristics of fluids. The method and results are highly reliable, well-founded, and easy to operate, and have important guiding significance for exploration and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] When considered in conjunction with the accompanying drawings, the present invention can be more completely and better understood by referring to the detailed description below, and the scientificity and practicality of the present invention can be better explained, but the drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The example description of the present invention is used to explain the present invention and does not constitute an improper limitation of the present invention. Obviously, modifications and changes made by those skilled in the art based on the purpose of the present invention belong to the protection scope of the present invention.

[0015] Figure 1 It is the imaging result of a large field of view stitching scanning electron microscope; Figure 2 This is a schematic diagram of the aperture size distribution characteristics obtained based on a large field of view stitching scanning electron microscope; Figure 3 It is a schematic diagram comparing the indoor nuclear magnetic T2 spectrum and the pore size distribution diagram after pressurized saturated water; Figure 4 It is a schematic diagram of the indoor nuclear magnetic T2-aperture conversion model after pressurized saturated water; Figure 5 This is a schematic diagram of the comparison between the indoor nuclear magnetic T2 spectrum after pressurized saturated water and the pore size distribution after fitting using the conversion model; Figure 6 It is a schematic diagram comparing the indoor NMR T2 spectrum and pore size distribution diagram after pressurized saturated oil; Figure 7 It is a schematic diagram of the indoor nuclear magnetic T2-aperture conversion model after pressurized saturated oil; Figure 8 This is a schematic diagram of the comparison between the indoor nuclear magnetic resonance T2 spectrum after pressurized oil saturation and the pore size distribution after fitting using the conversion model; Fig. 9 It is a schematic diagram comparing the nuclear magnetic T2 spectrum in the reservoir chamber and the nuclear magnetic T2 spectrum in the well logging; Fig.10 It is a schematic diagram of the NMR T2-well logging NMR T2 conversion model in the reservoir chamber; Fig.11 This is a schematic diagram of the comparison between the nuclear magnetic T2 spectrum in the reservoir chamber after fitting with the conversion model and the well logging nuclear magnetic spectrum; Fig.12 This is a schematic diagram comparing the well logging nuclear magnetic T2 spectrum of water and the pore size distribution diagram; Fig.13 This is a schematic diagram of the well logging nuclear magnetic resonance T2-aperture conversion model for water; Fig.14 This is a schematic diagram of the comparison between the well logging nuclear magnetic T2 spectrum of water and the pore size distribution after fitting using the conversion model; Fig.15 This is a schematic diagram comparing the well logging nuclear magnetic T2 spectrum and pore size distribution diagram of oil; Fig.16 This is a schematic diagram of the oil well logging nuclear magnetic T2-aperture conversion model; Fig.17 This is a schematic diagram of the comparison between the well logging nuclear magnetic T2 spectrum of oil and the pore size distribution after fitting with the conversion model; Fig.18 This is a schematic diagram of nuclear magnetic frequency division; Fig.19 This is a schematic diagram of the evaluation results of the continuous oil and water distribution characteristics of the Ke 811 well in the study area; Fig. 20 It is a schematic flow chart of the method for quantitatively characterizing full-size pores of oil and water storage based on well logging nuclear magnetic resonance of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Example 1 Based on logging nuclear magnetic tight reservoir oil and water occurrence full-scale pore quantitative characterization method, such as Fig. 20 As shown, including: Step 1: Extract the pore size distribution characteristics of the core sample based on a large field of view stitching scanning electron microscope; Step 2: Based on the NMR T2 spectra of pressurized saturated oil and saturated water samples, indoor NMR T2-aperture conversion models of oil and water are established respectively; Step 3: Based on the indoor NMR spectrum and NMR logging spectrum of the closed core sampling sample, establish an indoor NMR T2-NMR logging T2 conversion model; Step 4: Establish the well logging NMR transverse relaxation time T2-aperture conversion model for oil and water; Step 5: Fit the nuclear magnetic logging T2 spectrum into water T2 spectrum and oil T2 spectrum based on the frequency division principle; Step 6: Based on the logging NMR transverse relaxation time T2-aperture conversion model of oil and water, full-scale fluid identification and distribution evaluation of reservoir oil-water two-phase fluid is realized.

[0018] Example 2 The method for quantitative characterization of full-size pores of oil and water occurrence in tight reservoirs based on well logging nuclear magnetic resonance described in Example 1 is different in that: In step 1, based on the high-resolution large-field scanning electron microscope, the gray value difference between pores and rock skeleton in the electron microscope photograph is used, such as Figure 1 As shown, the distribution of pores is characterized, and the size of the pores is determined as the number of pixels in the area occupied by the pores; the sizes of all pores are extracted, and the total area of ​​pores of the same size is counted, and the frequency of pores of the same size is determined as the ratio of the total area of ​​pores of the same size to the total area of ​​all pores. Figure 2 shown.

[0019] In step 2, according to the difference in relaxation rate between oil and water, the same sample is saturated with oil and saturated with water respectively, and the nuclear magnetic resonance T2 detection of the core sample is carried out. The nuclear magnetic resonance T2 spectrum of the reservoir is limited by its pore size distribution and fluid properties. The results of the saturated oil nuclear magnetic resonance T2 and the saturated water nuclear magnetic resonance T2 are very similar to the pore size distribution extracted by the large field of view splicing scanning electron microscope in step 1, respectively. Figure 3 and Figure 6As shown; using the morphological characteristics, according to the relationship between T2 and aperture corresponding to the peaks and troughs, the indoor nuclear magnetic T2-aperture conversion model of oil and water is established, as shown in Figure 4 and Figure 7 As shown; the results have a high degree of fit, as shown Figure 5 and Figure 8 As shown. Among them, nuclear magnetic resonance T2 detection, in oil and gas geology, the signal distribution of nuclear magnetic resonance measurement reflects the matrix pore size and fluid properties. For single-phase fluid, the transverse relaxation time T2 has a good positive correlation with the pore size; in the reservoir of oil-water two-phase fluid, water is often distributed in the low T2 interval, while oil is often distributed in the high T2 interval. Among them, large-field-of-view stitching scanning electron microscopy, that is, high-resolution large-field-of-view stitching scanning electron microscopy, is a method of obtaining a larger field of view and extracting a larger range of pore size distribution in sequence based on continuous scanning electron microscope observations. It is a good solution to the problem that the tight reservoir has strong heterogeneity and the scanning electron microscope obtains the pore size distribution of a small field of view with large errors.

[0020] The indoor NMR T2-aperture conversion model for water is: r 室内-水 =396.15T 2室内-水 1.0049 (1) The indoor NMR T2-aperture conversion model for oil is: r 室内-油 =357.73 T 2室内-油 0.8604 (2) In formula (1) and formula (2), r 室内-水 and r 室内-油 is the pore size of the lithology sample when saturated with water and saturated with oil, nm; T 2室内-水 is the indoor nuclear magnetic T2 of the lithology sample saturated with water, ms; T 2室内-油 This is the indoor NMR T2, ms, of the lithology sample when it is saturated with oil.

[0021] In step 3, the indoor nuclear magnetic T2 spectrum of the core sample that has not been developed in the formation and subsequently preserved in a simulated high temperature and high pressure environment of the formation is similar to the nuclear magnetic logging T2 spectrum of the core sample, such as Fig. 9 As shown in the figure, the parameters of nuclear magnetic resonance logging and indoor nuclear magnetic resonance are different. Therefore, the nuclear magnetic resonance logging T2 spectrum and indoor nuclear magnetic resonance T2 spectrum of the same core sample are taken. The results show that their distribution forms are consistent. According to the T2 corresponding to the peaks and troughs, the indoor nuclear magnetic resonance T2-nuclear magnetic resonance logging T2 conversion model is established, as shown in Fig.10 As shown; the results show that the fit is high, such as Fig.11 as shown below; When T 2_室内 <0.8ms, T 2_测井 =15.92 T 2_室内 1.62 When T 2_室内 ≥0.8ms, T 2_测井 =7.67 T 2_室内 +2.54 (3) In formula (3), T 2_测井 is the nuclear magnetic logging T2, ms; T 2_室内 This is the indoor nuclear magnetic resonance T2, ms of the core sample that has not been developed in the formation and subsequently preserved in a high temperature and high pressure environment simulating the formation.

[0022] In step 4, the conversion model between the transverse relaxation time T2 of oil and water and the aperture in the well logging nuclear magnetic T2 spectrum is derived and established by integrating steps 1 to 3; the well logging nuclear magnetic T2-aperture conversion model is obtained by combining the indoor nuclear magnetic T2-aperture conversion model obtained in step 2 and the indoor nuclear magnetic T2-well logging nuclear magnetic T2 conversion model obtained in step 3, such as Fig.12 , Fig.13 , Fig.15 , Fig.16 As shown; the results show that the fit is high, such as Fig.14 and Fig.17 Shown; including: The well logging nuclear magnetic transverse relaxation time T2-aperture conversion model of water is: r 测井_水 =74.72T 2测井_水 0.92 (4) The oil logging nuclear magnetic transverse relaxation time T2-aperture conversion model is: r 测井_油 =89.247T 2测井_油 0.78 (5) In formula (4) and formula (5): r 测井_水 is the pore size of the lithology sample when saturated with water, nm; r 测井_油 is the pore size of the lithology sample when saturated with oil, nm; T 2测井_水 is the relaxation time T2 when the fluid property is water in NMR logging, ms; T 2测井_油 It is the relaxation time T2 when the fluid property is oil in NMR logging, ms.

[0023] In step 5, based on the difference in the distribution of oil / water fluid properties in the nuclear magnetic T2 spectrum, water is often distributed in the low T2 value area, while oil is often distributed in the high T2 value area. Based on the principle of nuclear magnetic frequency division, the logging nuclear magnetic T2 spectrum is decomposed into oil spectrum and water spectrum using Origin software, wherein the nuclear magnetic spectrum with a high T2 value area, i.e., the spectrum peak higher than 5ms, is the oil spectrum, and the nuclear magnetic spectrum with a low T2 value area, i.e., the spectrum peak not higher than 5ms, is the water spectrum. The whole well section nuclear magnetic logging T2 spectrum is frequency-divided in turn to obtain the distribution of the oil spectrum of the whole well section, i.e., the oil T2 spectrum, and the water spectrum, i.e., the water T2 spectrum, as shown in FIG. Fig.18 As shown, fluid identification of the entire well section is achieved.

[0024] In step 6, the logging T2-pore size conversion model of oil and water in step 4 and the identification results of oil and water in step 5 are integrated, and the pore size distribution of water is calculated according to formula (4) for the water spectrum and the pore size distribution of oil is calculated according to formula (5) for the oil spectrum, that is, the quantitative characterization of the full-size pores of the continuous two-phase fluid on the well logging is realized, as shown in Fig.19 shown.

Claims

1. A quantitative characterization method for full-size pores of oil and water in tight reservoirs based on well logging nuclear magnetic resonance, characterized in that: include: Step 1: Extract the pore size distribution characteristics of the core sample based on a large field of view stitching scanning electron microscope; Step 2: Based on the NMR T2 spectra of pressurized saturated oil and saturated water samples, indoor NMR T2-aperture conversion models of oil and water are established respectively; Step 3: Based on the indoor NMR spectrum and NMR logging spectrum of the closed core sampling sample, establish an indoor NMR T2-NMR logging T2 conversion model; Step 4: Establish the well logging NMR transverse relaxation time T2-aperture conversion model for oil and water; Step 5: Fit the nuclear magnetic logging T2 spectrum into water T2 spectrum and oil T2 spectrum based on the frequency division principle; Step 6: Based on the logging NMR transverse relaxation time T2-aperture conversion model of oil and water, full-scale fluid identification and distribution evaluation of reservoir oil-water two-phase fluid is realized.

2. The method for quantitative characterization of full-size pores of oil and water occurrence in dense reservoirs based on well logging nuclear magnetic resonance according to claim 1, characterized in that: In step 1, the distribution of pores is characterized, and the size of the pores is determined as the number of pixels of the area occupied by the pores; the sizes of all pores are extracted, and the total area of ​​pores of the same size is counted, and the frequency of pores of the same size is determined as the ratio of the total area of ​​pores of the same size to the total area of ​​all pores.

3. The method for quantitative characterization of full-size pores of oil and water occurrence in dense reservoirs based on well logging nuclear magnetic resonance according to claim 1, characterized in that: In step 2, according to the difference in relaxation rates of oil and water, the same sample is saturated with oil and saturated with water respectively, and nuclear magnetic resonance T2 detection of the core sample is carried out. Based on the morphological characteristics and the relationship between T2 and aperture corresponding to the peaks and troughs, an indoor nuclear magnetic resonance T2-aperture conversion model of oil and water is established; include: The indoor NMR T2-aperture conversion model for water is: r 室内-水 =396.15T 2室内-水 1.0049 （1） The indoor NMR T2-aperture conversion model for oil is: r 室内-油 =357.73 T 2室内-油 0.8604 （2） In formula (1) and formula (2), r 室内-水 and r 室内-油 is the pore size of the lithology sample when saturated with water and saturated with oil, nm; T 2室内-水 is the indoor nuclear magnetic T2 of the lithology sample saturated with water, ms; T 2室内-油 This is the indoor NMR T2, ms, of the lithology sample when it is saturated with oil.

4. The method for quantitative characterization of full-size pores of oil and water occurrence in dense reservoirs based on well logging nuclear magnetic resonance according to claim 3 is characterized in that: In step 3, the indoor nuclear magnetic T2 spectrum of the core sample that has not been developed in the formation and subsequently preserved in the high temperature and high pressure environment of the simulated formation has similar morphology to the nuclear magnetic logging T2 spectrum of the core sample. According to the T2 corresponding to the peaks and valleys, the indoor nuclear magnetic T2-nuclear magnetic logging T2 conversion model is established, as shown below; When T 2_室内 <0.8ms, T 2_测井 =15.92 T 2_室内 1.62 When T 2_室内 ≥0.8ms, T 2_测井 =7.67 T 2_室内 +2.54 (3) In formula (3), T 2_测井 is the nuclear magnetic logging T2, ms; T 2_室内 This is the indoor nuclear magnetic resonance T2, ms of the core sample that has not been developed in the formation and subsequently preserved in a high temperature and high pressure environment simulating the formation.

5. The method for quantitative characterization of full-size pores of oil and water occurrence in dense reservoirs based on well logging nuclear magnetic resonance according to claim 4, characterized in that: In step 4, the well logging nuclear magnetic T2-aperture conversion model is jointly obtained by using the indoor nuclear magnetic T2-aperture conversion model obtained in step 2 and the indoor nuclear magnetic T2-well logging nuclear magnetic T2 conversion model obtained in step 3, including: The well logging nuclear magnetic transverse relaxation time T2-aperture conversion model of water is: r 测井_水 =74.72T 2测井_水 0.92 （4） The oil logging nuclear magnetic transverse relaxation time T2-aperture conversion model is: r 测井_油 =89.247T 2测井_油 0.78 （5） In formula (4) and formula (5): r 测井_水 is the pore size of the lithology sample when saturated with water, nm; r 测井_油 is the pore size of the lithology sample when saturated with oil, nm; T 2测井_水 is the relaxation time T2 when the fluid property is water in NMR logging, ms; T 2测井_油 It is the relaxation time T2 when the fluid property is oil in NMR logging, ms.

6. The method for quantitative characterization of full-size pores of oil and water occurrence in tight reservoirs based on well logging nuclear magnetic resonance according to any one of claims 1 to 5, characterized in that: In step 5, the nuclear magnetic frequency division principle is used to decompose the logging nuclear magnetic T2 spectrum into oil spectrum and water spectrum using Origin software, wherein the nuclear magnetic spectrum in the high T2 value region, i.e., the spectrum peak higher than 5ms, is the oil spectrum, and the nuclear magnetic spectrum in the low T2 value region, i.e., the spectrum peak not higher than 5ms, is the water spectrum. The nuclear magnetic logging T2 spectrum of the entire well section is frequency-divided in turn to obtain the distribution of the oil spectrum of the entire well section, i.e., the oil T2 spectrum, and the water spectrum, i.e., the water T2 spectrum, to achieve fluid identification of the entire well section.

7. The method for quantitative characterization of full-size pores of oil and water occurrence in dense reservoirs based on well logging nuclear magnetic resonance according to claim 5, characterized in that: In step 6, the logging T2-pore size conversion model of oil and water in step 4 and the identification results of oil and water in step 5 are integrated, and the pore size distribution of water is calculated according to formula (4) for the water spectrum, and the pore size distribution of oil is calculated according to formula (5) for the oil spectrum, that is, the quantitative characterization of the full-size pores of the continuous two-phase fluid on the logging is realized.

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