Quantitative determination method and system for oil saturation of shale

Abstract

The invention provides a shale oil saturation quantitative determination method and system. The quantitative determination method comprises the following steps: preparing a shale plunger sample; washing the shale plunger sample with oil, drying, vacuumizing, pressurizing and saturating deionized water, and carrying out a one-dimensional nuclear magnetic resonance test to obtain the pore volume of the shale plunger sample; 3, drying the shale plunger sample again to obtain the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plunger sample, and measuring the oil outlet amount of the tail end of the displacement device by using a measuring cylinder; determining an oil and water distribution area according to the shale plunger sample and dividing a boundary value of the oil and water distribution area; respectively calculating the oil saturation in different displacement stages of the oil shale plunger samples with oil discharged through displacement and oil shale plunger samples without oil discharged through displacement; feature parameters are extracted according to the shale plunger sample, an oil saturation calculation model is established based on a least square method, and a chart is constructed. The invention provides a shale oil saturation interpretation chart based on different displacement stage nuclear magnetic characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to a method and system for quantitatively determining shale oil saturation. Background Art

[0002] With the reduction of conventional oil and gas resources and the transformation of the global energy structure, unconventional oil and gas resources, especially shale oil resources, have gradually become the focus of exploration and development. The quantitative calculation of oil saturation in shale oil reservoirs is of great significance for the division of sweet spots, evaluation of movable resources and improvement of oil recovery. Compared with conventional sandstone and conglomerate reservoirs, the conductivity mechanism of shale reservoirs has become extremely complex due to the presence of clay minerals, TOC and pyrite, resulting in large errors in the calculation results of saturation calculation models such as Archie's formula, Indonesian equation and Simon equation. In addition, conventional distillation and retorting methods are difficult to apply due to the dense shale samples, complex pore structure and kerogen content. For example, kerogen cracking will occur under high temperature conditions during the retorting process. Therefore, considering the shortcomings of the existing quantitative calculation methods for shale oil saturation, it is necessary to design a shale oil saturation interpretation chart based on nuclear magnetic characteristics at different displacement stages.

[0003] Prior art 1 related to the present invention:

[0004] Chinese invention patent, patent number: CN202010403810.7, title: A method for calculating oil saturation in shale. The invention includes the following steps: S1: sample preparation; S2: apparent density determination; S3: helium porosity determination; S4: calculation of porosity occupied by hydrocarbons;

[0005] S5: Calculation of total porosity; S6: Calculation of current oil saturation of shale samples; S7: Calculation of original oil saturation of shale samples. This method as a whole has the advantages of clear thinking, easy operation, and simple calculation, but it has the following shortcomings: (1) The invention uses the pyrolysis parameter S1 as an approximation of the liquid hydrocarbon content in the shale sample to calculate the oil saturation, but this parameter needs to be corrected for both light hydrocarbons and heavy hydrocarbons, that is, some liquid hydrocarbons have too high boiling points and cannot evaporate below 300°C; (2) The pore space occupied by heavy hydrocarbons, non-hydrocarbons, and asphaltene is missed during the calculation of total porosity.

[0006] Prior art 2 related to the present invention:

[0007] Chinese invention patent, patent number: CN202011374966.3, named: A shale oil saturation evaluation model, evaluation method, and application. This invention conducts nuclear magnetic resonance T2 spectrum measurement on the basis of oil washing and low-temperature drying of shale samples in the mature stage; then, vacuum pressurize and saturate the oil and age it, carry out heavy water absorption experiment, and perform nuclear magnetic resonance T2 spectrum measurement in the process until the nuclear magnetic spectrum line basically does not change, and invert the oil content in the pore throat based on the sample nuclear magnetic signal. Finally, the oil saturation of the rock sample is obtained using the oil-containing volume and pore volume. However, the oil saturation obtained by this method is the residual oil saturation in the sample after the saturated oil sample reaches equilibrium after the absorption of heavy water. At this time, the type and content of fluids stored in the sample are somewhat different from those of the original untreated sample. Summary of the invention

[0008] In view of the above problems, the present invention is proposed to provide a method and system for quantitatively determining shale oil saturation that overcomes the above problems or at least partially solves the above problems.

[0009] According to one aspect of the present invention, a method for quantitatively determining oil saturation in shale is provided, the method comprising:

[0010] Step 1: preparing a shale plug sample;

[0011] Step 2: washing the shale plug sample with oil, drying it, evacuating and pressurizing it with saturated deionized water, and conducting a one-dimensional nuclear magnetic resonance test to obtain the pore volume of the shale plug sample;

[0012] Step 3: drying the shale plug sample again, obtaining the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample and measuring the oil output at the end of the displacement device with a measuring cylinder;

[0013] Step 4: Determine the oil and water distribution areas and divide the boundary values ​​between the two according to the shale plug sample;

[0014] Step 5: Calculate the oil saturation of shale plug samples at different displacement stages for oil-producing and oil-free shale plug samples;

[0015] Step 6: Extract characteristic parameters from shale plug samples and establish an oil saturation calculation model based on the least squares method and construct a chart.

[0016] Optionally, the step 3: drying the shale plug sample again, obtaining the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample and measuring the oil output at the end of the displacement device with a measuring cylinder specifically includes:

[0017] Step 3: The shale plug sample is dried again, vacuumed and pressurized to be saturated with oil, and then displaced with deionized water. During the displacement process, one-dimensional and two-dimensional nuclear magnetic resonance tests are carried out to obtain the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample, and the oil output at the end of the displacement device is measured with a measuring cylinder.

[0018] Optionally, the oil used in the vacuum pressurized saturated oil is n-dodecane.

[0019] Optionally, the step 4: determining the oil and water distribution areas and dividing the boundary values ​​thereof according to the shale plunger sample specifically includes:

[0020] According to the dynamic change characteristics of the signal intensity of the two-dimensional nuclear magnetic resonance T1-T2 spectrum of the shale plug sample at different displacement stages, the oil and water distribution areas are determined and the boundary values ​​between the two are divided.

[0021] Optionally, the step 6: extracting characteristic parameters according to the shale plug sample and establishing an oil saturation calculation model based on the least squares method and constructing a chart specifically includes:

[0022] According to the dynamic change characteristics of one-dimensional nuclear magnetic T2 spectra of shale plug samples in different displacement stages, characteristic parameters are extracted and an oil saturation calculation model is established based on the least squares method, and a chart is constructed.

[0023] Optionally, the one-dimensional nuclear magnetic resonance test specifically includes:

[0024] During the displacement process, one-dimensional nuclear magnetic resonance experimental measurements of shale plug samples were carried out to obtain the dynamic change characteristics of the one-dimensional nuclear magnetic T2 spectra of the samples at different displacement stages.

[0025] Optionally, the two-dimensional nuclear magnetic resonance test specifically includes:

[0026] During the displacement process, two-dimensional nuclear magnetic resonance experimental measurements of shale plug samples were carried out to obtain the dynamic change characteristics of the two-dimensional nuclear magnetic T1-T2 spectra of the samples at different displacement stages.

[0027] Optionally, the step 5: respectively calculating the oil saturation of the shale plug samples at different displacement stages for oil-producing and oil-free shale plug samples specifically includes:

[0028] S501: Calculate the oil saturation of the displaced oil shale plug samples at different displacement stages. Take water flooding stage 1 as an example. The calculation method of oil saturation in other stages is similar to that of water flooding stage 1:

[0029]

[0030]

[0031] Where: The oil saturation of the shale plug sample after the water flooding stage 1 is calculated, %; V 饱油 is the original oil-bearing volume of the oil-saturated shale plug sample, ml; V 水驱阶段1出油 V is the volume of oil measured in the measuring cylinder after the end of water flooding stage 1, ml; 孔隙 The pore volume measured in step 2 of the oil shale plug sample is displaced, ml; m 饱油前 The mass of the oil shale plunger sample before vacuum saturation, g; m 饱油后 is the mass of the oil shale plug sample after vacuum saturation, g; ρ 油 is the oil density, g / cm 3 .

[0032] Step S502: Calculate the signal intensity ratio of the 2D NMR oil distribution area at different displacement stages for all shale plug samples:

[0033]

[0034] Where: is the signal intensity ratio of 2D NMR oil distribution area in water flooding stage 1, decimal; is the signal intensity of the 2D NMR oil distribution area in water flooding stage 1, au; is the total signal intensity of the 2D NMR T1-T2 spectrum in water flooding stage 1, au.

[0035] Step S503: using the least squares method to fit the relationship between the signal intensity ratio of the two-dimensional nuclear magnetic resonance oil distribution area and the measured oil saturation at different displacement stages of all shale plug samples displaced with oil, and establishing an oil saturation calculation model based on the signal intensity ratio of the two-dimensional nuclear magnetic resonance oil distribution area.

[0036] Step S504: using the fitting model established in S3 and combining the signal intensity ratio of the 2D NMR oil distribution area of ​​the non-oiled sample at different displacement stages, calculate the oil saturation of the non-oiled sample at different displacement stages.

[0037] Optionally, the step 6: extracting characteristic parameters according to the shale plug sample and establishing an oil saturation calculation model based on the least squares method and constructing a chart specifically includes:

[0038] Extraction of characteristic parameters of nuclear magnetic T2 spectrum:

[0039] NMR T2 geometric mean:

[0040]

[0041] Where: T 2gm is the geometric mean value of NMR T2; T 2i is the i-th NMR transverse relaxation time; is the corresponding porosity component; is the porosity value of the NMR test; N is the number of sampling points of the NMR T2 spectrum;

[0042] The first peak amplitude of the nuclear magnetic T2 spectrum: the longitudinal amplitude component corresponding to the first peak of the T2 spectrum;

[0043] The relationship between characteristic parameters and measured oil saturation was fitted by the least squares method, and an oil saturation calculation model based on one-dimensional nuclear magnetic resonance T2 spectrum characteristic parameters was established and a chart was constructed.

[0044] Optionally, the drying of the shale plug sample specifically includes: placing the oil-washed shale plug sample into a drying device, and drying it at 100° C. for about 12 hours.

[0045] The present invention also provides a shale oil saturation quantitative determination system, which is applied to the above-mentioned shale oil saturation quantitative determination method, and the determination system comprises:

[0046] Plug sample preparation module, used to prepare shale plug samples;

[0047] A one-dimensional nuclear magnetic resonance module is used to wash the shale plug sample with oil, dry it, evacuate and pressurize it with saturated deionized water, and conduct a one-dimensional nuclear magnetic resonance test to obtain the pore volume of the shale plug sample;

[0048] An oil output calculation module is used to dry the shale plug sample again, obtain the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample, and measure the oil output at the end of the displacement device with a measuring cylinder;

[0049] A boundary value division module, used to determine the oil and water distribution areas and divide the boundary values ​​of the two according to the shale plunger sample;

[0050] Saturation calculation module, used to calculate the oil saturation of shale plug samples at different displacement stages, including those that have produced oil and those that have not produced oil;

[0051] The chart construction module is used to extract characteristic parameters according to the shale plug sample and establish an oil saturation calculation model based on the least squares method and construct a chart.

[0052] The present invention provides a method and system for quantitatively determining oil saturation in shale, the method comprising: step 1: preparing a shale plunger sample; step 2: washing oil and drying the shale plunger sample, vacuuming and pressurizing saturated deionized water, carrying out a one-dimensional nuclear magnetic resonance test, and obtaining the pore volume of the shale plunger sample; step 3: drying the shale plunger sample again, obtaining the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plunger sample, and measuring the oil output at the end of the displacement device with a measuring cylinder; step 4: determining the oil and water distribution areas according to the shale plunger sample and dividing the boundary values ​​of the two; step 5: respectively calculating the oil saturation of the shale plunger sample at different displacement stages of the oil-producing and non-oil-producing shale plunger samples; step 6: extracting characteristic parameters according to the shale plunger sample, establishing an oil saturation calculation model based on the least squares method, and constructing a chart. A shale oil saturation interpretation chart based on nuclear magnetic characteristics at different displacement stages is provided.

[0053] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0055] Figure 1 A flow chart of a method for quantitatively determining oil saturation in shale provided in an embodiment of the present invention;

[0056] Figure 2 A dynamic change characteristic diagram of the one-dimensional nuclear magnetic resonance test results of the F15 sample at different displacement stages provided by an embodiment of the present invention;

[0057] Figure 3 A dynamic change characteristic diagram of the two-dimensional nuclear magnetic T1-T2 spectrum of the F15 sample at different displacement stages provided by an embodiment of the present invention;

[0058] Figure 4 A relationship diagram between the signal intensity of the two-dimensional nuclear magnetic oil region and the measured oil saturation provided in an embodiment of the present invention;

[0059] Figure 5 An analysis diagram of the relationship between the nuclear magnetic characteristic parameters and the measured oil saturation provided in an embodiment of the present invention;

[0060] Figure 6A test diagram of the oil saturation fitting effect provided by an embodiment of the present invention;

[0061] Figure 7 A shale sample oil saturation estimation chart provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0063] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0064] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0065] like Figure 1 As shown, a method for quantitatively determining oil saturation of shale oil formations based on two-dimensional nuclear magnetic resonance experiments includes the following steps:

[0066] Step 1: Shale plug sample preparation;

[0067] Step 2: Wash the shale plug sample with oil, dry it, evacuate and pressurize it with saturated deionized water, and conduct a one-dimensional nuclear magnetic resonance test to obtain the pore volume of the shale plug sample;

[0068] Step 3: The shale plug sample is dried again, vacuumed and pressurized to be saturated with oil (n-dodecane), and then displaced with deionized water under pressure. One-dimensional and two-dimensional nuclear magnetic resonance tests are carried out during the displacement process to obtain the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample and measure the oil output at the end of the displacement device with a measuring cylinder;

[0069] Step 4: According to the dynamic change characteristics of the signal intensity of the two-dimensional nuclear magnetic resonance T1-T2 spectrum of the shale plug sample at different displacement stages, the oil and water distribution areas are determined and the boundary values ​​between the two are divided;

[0070] Step 5: Calculate the oil saturation of shale plug samples at different displacement stages for oil-producing and oil-free shale plug samples;

[0071] Step 6: According to the dynamic change characteristics of the one-dimensional nuclear magnetic resonance T2 spectrum of the shale plug samples at different displacement stages, the characteristic parameters are extracted and the oil saturation calculation model is established based on the least squares method and a chart is constructed.

[0072] The shale plug sample preparation process in step 1 is as follows:

[0073] The blocky shale samples to be analyzed were cut into plugs with a diameter of about 2.5 cm and a height of about 4 cm.

[0074] The treatment in step 2 includes washing oil from shale plug samples, drying, vacuuming and pressurizing saturated deionized water, and one-dimensional nuclear magnetic resonance experimental testing:

[0075] Shale plug sample oil washing: put the shale plug sample into the Soxhlet extraction device and soak it in oil washing in a cycle. The solvent is toluene and the oil washing time is 7 days.

[0076] Drying of shale plug samples: put the washed shale plug samples into a drying device and dry them at 100°C for about 12 hours;

[0077] Vacuum and pressurize saturated deionized water: Place the shale plug sample after oil washing and drying into a vacuum and pressurized saturation device, vacuum (about -0.1MPa) for about 2h, and then pressurize saturated deionized water (15MPa, 12h);

[0078] One-dimensional NMR test: One-dimensional NMR test was carried out on shale plug samples saturated with deionized water to obtain the pore volume of the shale plug samples, referring to the standard SY / T 6490-2014.

[0079] The treatment in step 3 includes drying of shale plug samples, vacuuming and pressurizing to saturate oil, pressurized displacement, one-dimensional nuclear magnetic resonance testing, two-dimensional nuclear magnetic resonance testing, and terminal oil output measurement;

[0080] Drying of shale plunger samples: Place the shale sample in a drying device and dry it at 100°C for about 12 hours;

[0081] Vacuuming and pressurizing oil saturation: Place the dried shale plug sample into a vacuuming and pressurizing saturation device, vacuum (about -0.1MPa) for about 2h, and then pressurize and saturate with n-dodecane (15MPa, 12h);

[0082] Pressurized displacement: Place the pressurized shale plug sample saturated with oil into the displacement device and carry out displacement experiments with deionized water (displacement pressure is about 40MPa);

[0083] One-dimensional NMR test: During the displacement process, one-dimensional NMR experimental measurement of shale plug samples was carried out to obtain the dynamic change characteristics of the one-dimensional NMR T2 spectrum of the samples at different displacement stages;

[0084] Two-dimensional nuclear magnetic resonance test: During the displacement process, two-dimensional nuclear magnetic resonance experimental measurement of shale plug samples was carried out to obtain the dynamic change characteristics of the two-dimensional nuclear magnetic T1-T2 spectrum of the samples at different displacement stages;

[0085] Measuring the oil output at the end of the displacement device: Use a measuring cylinder to measure the oil output at the outlet of the displacement device.

[0086] In step 4, the oil and water distribution areas are determined and the boundary values ​​of the two are divided according to the dynamic change characteristics of the signal intensity of the two-dimensional nuclear magnetic T1-T2 spectrum of the shale plug sample at different displacement stages. The specific operations are as follows:

[0087] The 2D NMR measurement results of shale plug samples at different displacement stages (oil-saturated state, water flooding stage 1, water flooding stage 2, ...) were analyzed, and the oil and water distribution areas were divided according to the change characteristics of the 2D NMR T1-T2 spectrum signal intensity, and the boundary value was determined.

[0088] The calculation process of oil saturation at different displacement stages of shale plug samples with and without oil in step 5 is as follows:

[0089] S1: Calculate the oil saturation of the shale plug sample at different displacement stages (taking water flooding stage 1 as an example, the calculation method of oil saturation in other stages is similar to that of water flooding stage 1):

[0090]

[0091]

[0092] Where: The oil saturation of the shale plug sample after the water flooding stage 1 is calculated, %; V 饱油 is the original oil-bearing volume of the oil-saturated shale plug sample, ml; V 水驱阶段1出油 V is the volume of oil measured in the measuring cylinder after the end of water flooding stage 1, ml; 孔隙 The pore volume measured in step 2 of the oil shale plug sample is displaced, ml; m 饱油前 The mass of the oil shale plunger sample before vacuum saturation, g; m 饱油后 is the mass of the oil shale plug sample after vacuum saturation, g; ρ 油 is the oil density, g / cm 3 .

[0093] S2: Calculate the signal intensity ratio of 2D NMR oil distribution area in different displacement stages of all shale plug samples (taking water flooding stage 1 as an example, the calculation method of oil saturation in other stages is similar to that of water flooding stage 1):

[0094]

[0095] Where: is the signal intensity ratio of 2D NMR oil distribution area in water flooding stage 1, decimal; is the signal intensity of the 2D NMR oil distribution area in water flooding stage 1, au; is the total signal intensity of the 2D NMR T1-T2 spectrum in water flooding stage 1, au.

[0096] S3: The least squares method is used to fit the relationship between the signal intensity ratio of the two-dimensional nuclear magnetic resonance oil distribution area and the measured oil saturation at different displacement stages of all shale plug samples that have been displaced to produce oil, and an oil saturation calculation model based on the signal intensity ratio of the two-dimensional nuclear magnetic resonance oil distribution area is established.

[0097] S4: Using the fitting model established in S3, combined with the signal intensity ratio of the 2D NMR oil distribution area of ​​the non-oiled samples at different displacement stages, the oil saturation of the non-oiled samples at different displacement stages is calculated:

[0098] The operation in step 6 includes extracting characteristic parameters, establishing a relationship model between characteristic parameters and oil saturation, and constructing a chart based on the dynamic change characteristics of the one-dimensional nuclear magnetic T2 spectrum of the shale plug sample at different displacement stages:

[0099] S1: Extraction of characteristic parameters of nuclear magnetic T2 spectrum:

[0100] NMR T2 geometric mean:

[0101]

[0102] Where: T 2gm is the geometric mean value of NMR T2; T 2i is the i-th NMR transverse relaxation time; is the corresponding porosity component; is the porosity value of the NMR test; N is the number of sampling points of the NMR T2 spectrum.

[0103] The first peak amplitude of the nuclear magnetic T2 spectrum: the longitudinal amplitude component corresponding to the first peak of the T2 spectrum.

[0104] S2: The relationship between characteristic parameters and measured oil saturation is fitted using the least squares method, and an oil saturation calculation model based on one-dimensional nuclear magnetic resonance T2 spectrum characteristic parameters is established and a chart is constructed.

[0105] Beneficial effects: A shale oil saturation interpretation chart based on nuclear magnetic characteristics at different displacement stages is provided.

[0106] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for quantitatively determining oil saturation in shale, characterized in that: The quantitative determination method comprises: Step 1: preparing a shale plug sample; Step 2: washing the shale plug sample with oil, drying it, evacuating and pressurizing it with saturated deionized water, and conducting a one-dimensional nuclear magnetic resonance test to obtain the pore volume of the shale plug sample; Step 3: drying the shale plug sample again, obtaining the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample and measuring the oil output at the end of the displacement device with a measuring cylinder; Step 4: Determine the oil and water distribution areas and divide the boundary values ​​between the two according to the shale plug sample; Step 5: Calculate the oil saturation of shale plug samples at different displacement stages for oil-producing and oil-free shale plug samples; Step 6: Extract characteristic parameters from shale plug samples and establish an oil saturation calculation model based on the least squares method and construct a chart.

2. A method for quantitatively determining shale oil saturation according to claim 1, characterized in that: The step 3: drying the shale plug sample again, obtaining the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample and measuring the oil output at the end of the displacement device with a measuring cylinder specifically includes: Step 3: The shale plug sample is dried again, vacuumed and pressurized to be saturated with oil, and then displaced with deionized water. During the displacement process, one-dimensional and two-dimensional nuclear magnetic resonance tests are carried out to obtain the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample, and the oil output at the end of the displacement device is measured with a measuring cylinder.

3. A method for quantitatively determining shale oil saturation according to claim 2, characterized in that: The oil used in the vacuum pressurized saturated oil is n-dodecane.

4. The method for quantitatively determining shale oil saturation according to claim 1, characterized in that: The step 4: determining the oil and water distribution areas and dividing the boundary values ​​of the oil and water distribution areas according to the shale plug samples specifically includes: According to the dynamic change characteristics of the signal intensity of the two-dimensional nuclear magnetic resonance T1-T2 spectrum of the shale plug sample at different displacement stages, the oil and water distribution areas are determined and the boundary values ​​between the two are divided.

5. The method for quantitatively determining shale oil saturation according to claim 1, characterized in that: The step 6: extracting characteristic parameters according to the shale plug sample and establishing an oil saturation calculation model based on the least square method and constructing a chart specifically includes: According to the dynamic change characteristics of one-dimensional nuclear magnetic T2 spectra of shale plug samples in different displacement stages, characteristic parameters are extracted and an oil saturation calculation model is established based on the least squares method, and a chart is constructed.

6. A method for quantitatively determining shale oil saturation according to claim 5, characterized in that: The one-dimensional nuclear magnetic resonance test specifically includes: During the displacement process, one-dimensional nuclear magnetic resonance experimental measurements of shale plug samples were carried out to obtain the dynamic change characteristics of the one-dimensional nuclear magnetic T2 spectrum of the samples at different displacement stages.

7. A method for quantitatively determining shale oil saturation according to claim 4, characterized in that: The two-dimensional nuclear magnetic resonance test specifically includes: During the displacement process, two-dimensional nuclear magnetic resonance experimental measurements of shale plug samples were carried out to obtain the dynamic change characteristics of the two-dimensional nuclear magnetic T1-T2 spectra of the samples at different displacement stages.

8. The method for quantitatively determining shale oil saturation according to claim 1, characterized in that: The step 5: calculating the oil saturation of the shale plug samples at different displacement stages, including: S501: Calculate the oil saturation of the displaced oil shale plug samples at different displacement stages. Take water flooding stage 1 as an example. The calculation method of oil saturation in other stages is similar to that of water flooding stage 1: Where: The oil saturation of the shale plug sample after the water flooding stage 1 is calculated, %; V 饱油 is the original oil-bearing volume of the oil-saturated shale plug sample, ml; V 水驱阶段1出油 V is the volume of oil measured in the measuring cylinder after the end of water flooding stage 1, ml; 孔隙 The pore volume measured in step 2 of the oil shale plug sample is displaced, ml; m 饱油前 The mass of the oil shale plunger sample before vacuum saturation, g; m 饱油后 is the mass of the oil shale plug sample after vacuum saturation, g; ρ 油 is the oil density, g / cm 3 . Step S502: Calculate the signal intensity ratio of the 2D NMR oil distribution area at different displacement stages for all shale plug samples: Where: is the signal intensity ratio of 2D NMR oil distribution area in water flooding stage 1, decimal; is the signal intensity of the 2D NMR oil distribution area in water flooding stage 1, au; is the total signal intensity of the 2D NMR T1-T2 spectrum in water flooding stage 1, au. Step S503: using the least squares method to fit the relationship between the signal intensity ratio of the two-dimensional nuclear magnetic resonance oil distribution area and the measured oil saturation at different displacement stages of all shale plug samples displaced with oil, and establishing an oil saturation calculation model based on the signal intensity ratio of the two-dimensional nuclear magnetic resonance oil distribution area. Step S504: using the fitting model established in S3 and combining the signal intensity ratio of the 2D NMR oil distribution area of ​​the non-oiled sample at different displacement stages, calculate the oil saturation of the non-oiled sample at different displacement stages.

9. The method for quantitatively determining shale oil saturation according to claim 1, characterized in that: The step 6: extracting characteristic parameters according to the shale plug sample and establishing an oil saturation calculation model based on the least square method and constructing a chart specifically includes: Extraction of characteristic parameters of nuclear magnetic T2 spectrum: NMR T2 geometric mean: Where: T 2gm is the geometric mean value of NMR T2; T 2i is the i-th NMR transverse relaxation time; is the corresponding porosity component; is the porosity value of the NMR test; N is the number of sampling points of the NMR T2 spectrum; The first peak amplitude of the nuclear magnetic T2 spectrum: the longitudinal amplitude component corresponding to the first peak of the T2 spectrum; The relationship between characteristic parameters and measured oil saturation was fitted by the least squares method, and an oil saturation calculation model based on one-dimensional nuclear magnetic resonance T2 spectrum characteristic parameters was established and a chart was constructed.

10. The method for quantitatively determining shale oil saturation according to claim 1, characterized in that: The drying of the shale plug sample specifically includes: placing the oil-washed shale plug sample into a drying device, and drying it at 100° C. for about 12 hours.

11. A shale oil saturation quantitative determination system, applied to a shale oil saturation quantitative determination method according to any one of claims 1 to 10, characterized in that: The determination system comprises: Plug sample preparation module, used to prepare shale plug samples; A one-dimensional nuclear magnetic resonance module is used to wash the shale plug sample with oil, dry it, evacuate and pressurize it with saturated deionized water, and conduct a one-dimensional nuclear magnetic resonance test to obtain the pore volume of the shale plug sample; An oil output calculation module is used to dry the shale plug sample again, obtain the dynamic change characteristics of the one-dimensional and two-dimensional nuclear magnetic resonance test results of the shale plug sample, and measure the oil output at the end of the displacement device with a measuring cylinder; A boundary value division module, used to determine the oil and water distribution areas and divide the boundary values ​​of the two according to the shale plunger sample; Saturation calculation module, used to calculate the oil saturation of shale plug samples at different displacement stages, including those that have produced oil and those that have not produced oil; The chart construction module is used to extract characteristic parameters according to the shale plug sample and establish an oil saturation calculation model based on the least squares method and construct a chart.

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