Shale oil reservoir space characterization method, chart construction method and measurement method

Abstract

The invention discloses a shale oil reservoir space characterization method, a chart construction method and a measurement method, and the characterization method comprises the following steps: carrying out linear cutting treatment on a shale sample to obtain a plunger sample with a regular shape; helium gas injection measurement is carried out on the plunger sample in the regular shape, and the effective porosity of the shale sample is determined; performing nuclear magnetic porosity measurement on the plunger sample to determine the total porosity of the shale sample; and characterizing the shale oil reservoir space of the shale sample based on the effective porosity and the total porosity of the shale sample. According to the method, by carrying out linear cutting treatment on a shale sample and optimizing pretreatment steps, on the premise of ensuring the accuracy of an experimental result, the influence of residual oil in the sample on a test process and a test result is avoided, and on the basis, the effective porosity and the total porosity of the shale sample are determined based on helium gas injection measurement and nuclear magnetic resonance measurement; and further establishing a comprehensive representation mode of the shale oil storage space.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum exploration, and in particular to a method for characterizing a shale oil reservoir space, a plate construction method and a measurement method. Background Art

[0002] The global shale oil resources are abundant, and the rapid development of unconventional oil and gas resources has made oil and gas exploration move from "outside the source" to "inside the source" scale exploration and development stage. Porosity is one of the key parameters for oil and gas resource evaluation, and it is of great significance for determining the reservoir space, fluid saturation and geological reserves of rocks. Shale pores can be divided into open pores and closed pores according to whether they are connected. Open pores are often characterized by effective porosity, which is an important parameter for proven reserves of reservoirs; total porosity is the basic parameter for calculating geological reserves, which consists of connected open pores and closed pores. In the actual production process, helium, nitrogen and other fluids are often used to fill plunger samples for porosity evaluation. The measured porosity only reflects the characteristics of connected pores and ignores the unconnected pores in shale. The effective development of shale oil resources must rely on large-scale hydraulic fracturing technology. After fracturing, unconnected pores may be opened; and after fracturing, the self-absorption of water in shale will produce a large number of microcracks, which also greatly increases the chance of unconnected pores being connected, making unconnected pores recoverable.

[0003] In addition, due to the extremely low permeability and complex mineral composition of shale, especially the characteristics of developed micro-nano pores and lamellae, coupled with the differences in pore types characterized by different testing methods, and different laboratories have different understandings of the testing methods and poor repeatability of test results, it is difficult to accurately characterize the porosity of shale.

[0004] Helium porosity and saturated liquid method are selected to test the plunger sample. The measured porosity is usually the connected effective porosity. Helium molecules have a small diameter, stable chemical composition and density, and weak adsorption, making them an ideal medium for gas injection measurement. The helium injection method measures the pressure change by filling the sample pores with a known pressure, and indirectly measures the effective porosity of the shale plunger sample. However, before using the helium injection method to measure, it is necessary to wash the oil and dry the pretreatment under the specified drying temperature and humidity environment to calculate the apparent volume. However, for samples with different clay contents, the drying environmental conditions and drying time are difficult to control, and excessive drying will lead to large differences in the measurement results. The mis-saturated liquid method is divided into the WIP method (deionized water as the medium), the KIP method (kerosene as the medium) and the DLP method (water-kerosene). For low-porosity and low-permeability shale reservoir samples, the mineral composition and pore wettability are complex and diverse, especially when they contain a large number of easily swellable clay minerals, and when the diameter of the liquid molecule is larger than the pore throat diameter, the liquid cannot fully fill the porous medium, resulting in a large deviation in the measurement results. At the same time, if the sample is saturated with kerosene, it needs to be cleaned with an organic solvent after the test, which will affect the pore structure of the rock and thus affect the accuracy of subsequent experimental results. The plunger sample mercury injection test can also be used to characterize the effective porosity of shale, but most of them can only characterize the information of large pores (>50nm) in shale: the theoretical lower limit of effective pores reflected by ordinary mercury injection (30MPa) is about 24.5nm, high-pressure mercury injection (413MPa) can reach 1.8nm, and constant-rate mercury injection technology (about 6MPa) can simultaneously reflect pore and throat information. Due to the low porosity and low permeability characteristics of shale, high displacement pressure is required to promote mercury injection into the sample, but artificial fractures are easily generated in the process and the overall mercury removal efficiency of shale is low, resulting in the destructiveness of the experiment and the test samples cannot be used for other tests.

[0005] In addition, North America proposed to use crushed samples for total porosity measurement. The GRI (Gas Research Institute) method measures the total porosity of shale. This method also uses helium injection to measure, but the rock needs to be crushed. Although the gas filling pressure during the measurement is reduced, the contact area between the gas and the rock pores is increased, and the test time is shortened, the degree of crushing affects the range of released pores, and at the same time changes the original water saturation of the core or the water absorption of the core, causing the density of the core to change, resulting in differences in measurement results. The CO2 / N2 adsorption method quantitatively characterizes the powder sample, but it mainly reflects the pore size distribution of shale in the micropore (<2nm) and mesopore (2~50nm) range, which is mainly controlled by the size relationship between the molecular diameter and the pore diameter. The gas adsorption effect of shale pores is difficult to quantify.

[0006] Nuclear magnetic resonance can obtain information such as effective porosity, total porosity, pore size distribution, pore connectivity and movable fluid of shale without damaging the sample. However, it is affected by many factors such as the test environment, instrument parameters, micropores of the sample, paramagnetic substances and fluid types. In addition, the porosity, permeability and pore size in mud shale are usually smaller than those in conventional reservoirs, resulting in a low signal-to-noise ratio in nuclear magnetic experiments and a longer time to obtain data. The relaxation time of nanoscale pores is very short and may be below the detection limit of the instrument and cannot be detected. At the same time, due to the presence of a large number of organic pores in mud shale, the water and organic matter in the pores are of the same core and are difficult to distinguish, which increases the difficulty of data interpretation.

[0007] In addition, imaging methods such as optical microscopy, scanning electron microscopy, FIB-SEM, and micro-nano CT can be used to conduct qualitative analysis of shale reservoirs. Combined with statistical methods, quantitative information such as shale porosity and pore size distribution can be obtained, but the credibility and accuracy of imaging analysis are limited by sample characteristics on imaging quality and instrument resolution. In addition, whether the sample pretreatment correctly retains the original information and whether the micro-area analysis is sufficiently representative are also important issues. Summary of the invention

[0008] In order to accurately establish a characterization system for shale oil reservoir space, avoid being affected by permeability and complex mineral composition, and at the same time solve the defects of harsh drying conditions, low efficiency of high-pressure pumps, and easy destruction of samples when measuring the apparent volume, thereby enriching the technical route and increasing the selection space, a characterization method, a plate construction method and a measurement method for shale oil reservoir space are provided in the embodiments of the present invention.

[0009] In a first aspect, an embodiment of the present invention provides a method for characterizing a shale oil reservoir space, which may include:

[0010] The shale samples were processed by wire cutting to obtain plug samples with regular shapes;

[0011] Conducting helium injection measurements on the regularly shaped plug samples to determine the effective porosity of the shale samples;

[0012] Performing nuclear magnetic porosity measurement on the plug sample to determine the total porosity of the shale sample;

[0013] The shale oil reservoir space of the shale sample is characterized based on the effective porosity and total porosity of the shale sample.

[0014] Optionally, the performing nuclear magnetic porosity measurement on the plunger sample to determine the total porosity of the shale sample may include:

[0015] Conducting two-dimensional nuclear magnetic resonance porosity measurement on the plunger sample under normal temperature conditions, drying conditions, saturated water conditions and centrifugal conditions in turn to determine the total porosity of the shale sample;

[0016] Wherein, the drying condition is drying at 70°C for not less than 48h;

[0017] The saturated water condition is 15Mpa saturated water for no less than 15h.

[0018] Optionally, the nuclear magnetic porosity measurement adopts the SR-CPMG sequence, with a TE echo time of 0.06 ms, a NECH value of 18000, an NTI value of 31, an end time of 3000 ms, and NS repeated scanning 32 times.

[0019] Optionally, the performing helium injection measurement on the regularly shaped plunger sample to determine the effective porosity of the shale sample may include:

[0020] Helium gas injection measurements were performed on the regularly shaped plug samples using an injection pressure of 100 psi, and pressure was monitored using a high-precision pressure sensor to determine the effective porosity of the shale samples.

[0021] Optionally, determining the effective porosity of the shale sample may include:

[0022] Obtaining the time-varying value of the effective porosity and the time-varying value of the pressure of the shale sample in a preset time period;

[0023] Based on the power function approximation method, the effective porosity variation with time and the pressure variation with time are used to fit the pre-established correlation equation between porosity and time to determine the effective porosity of the shale sample.

[0024] Optionally, the ambient temperature for carrying out helium gas injection measurement on the regularly shaped plunger sample is 24±0.5°C.

[0025] Optionally, before performing helium injection measurement on a regular shaped plunger sample, the following may also be included:

[0026] Based on electronic vernier caliper measurement, the apparent volume of regularly shaped plunger samples was determined.

[0027] Optionally, the method may further include: performing electron microscope scanning and nano-CT scanning on the plug sample to determine the fracture porosity of the plug sample.

[0028] In a second aspect, an embodiment of the present invention provides a method for constructing a shale porosity identification chart, which may include:

[0029] Obtaining different types of shale samples, and measuring the organic matter abundance of the different types of shale samples;

[0030] Measuring the effective porosity and total porosity of different types of shale samples, wherein the effective porosity and total porosity of the shale samples are measured according to the method for characterizing the shale oil reservoir space described in the first aspect;

[0031] A shale porosity identification chart is constructed based on the organic matter abundance, effective porosity and total porosity of different types of shale samples.

[0032] In a third aspect, an embodiment of the present invention provides a method for quickly measuring effective porosity of shale, which may include:

[0033] Measuring the abundance of organic matter in shale samples from the study area;

[0034] Based on the pre-constructed shale porosity identification plate and the organic matter abundance, the effective porosity and measurement equilibrium time of the shale sample are quickly determined;

[0035] Wherein, the shale porosity identification plate is pre-constructed according to the construction method of the shale porosity identification plate described in the second aspect.

[0036] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0037] The embodiment of the present invention provides a characterization method, a plate construction method and a measurement method for shale oil reservoir space. The characterization method optimizes the pretreatment steps by linear cutting of shale samples, and avoids the influence of residual oil in the sample on the test process and results while ensuring the accuracy of the experimental results. On this basis, based on helium injection measurement and nuclear magnetic resonance measurement, the effective porosity and total porosity of the shale sample are determined, and then a comprehensive characterization method for shale oil reservoir space is established, laying a foundation for actual production and resource evaluation.

[0038] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0039] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 This is a flow chart of the method for characterizing shale oil reservoir space provided in Example 1 of the present invention;

[0042] Figure 2 A flowchart of a detailed method for characterizing shale oil reservoir space provided in Example 1 of the present invention;

[0043] Figure 3 This is a CT scan of the S-1 sample provided in Example 1 of the present invention;

[0044] Figure 4 This is a CT scan of the S-2 sample provided in Example 1 of the present invention;

[0045] Figure 5 This is a schematic diagram of the helium (effective) porosity measurement results of the S-1 sample provided in Example 1 of the present invention;

[0046] Figure 6 This is a schematic diagram of the helium (effective) porosity measurement results of the S-2 sample provided in Example 1 of the present invention;

[0047] Figure 7 This is a schematic diagram of the closed porosity measurement results of the S-1 sample provided in Example 1 of the present invention;

[0048] Figure 8 This is a schematic diagram of the closed porosity measurement results of the S-2 sample provided in Example 1 of the present invention;

[0049] Fig. 9 This is a flow chart of a method for constructing a shale porosity identification chart provided in the second embodiment of the present invention;

[0050] Fig.10 This is one of the examples of the shale porosity identification chart provided in the second embodiment of the present invention;

[0051] Fig.11 This is the second example of the shale porosity identification chart provided in the second embodiment of the present invention. DETAILED DESCRIPTION

[0052] 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.

[0053] The inventors found in actual work that a single porosity test method has limitations and it is difficult to accurately characterize the actual reservoir space of shale. It is necessary to comprehensively compare and analyze multiple test methods to establish a systematic shale oil reservoir space characterization system to meet the needs of large-scale sample testing in industrial production, effectively deal with the anisotropy of mud shale, improve the systematicness and representativeness of test samples, and combine pore oil content research to comprehensively characterize the pore and fracture structure of shale oil reservoirs at multiple scales. In view of this, a characterization method, a plate construction method, and a measurement method for shale oil reservoir space are provided in the embodiments of the present invention.

[0054] Embodiment 1

[0055] In the first embodiment of the present invention, a method for characterizing shale oil reservoir space is provided, referring to Figure 1 As shown,

[0056] The method may include the following steps:

[0057] Step S11, performing wire cutting processing on the shale sample to obtain a plunger sample with a regular shape.

[0058] In this step, the shale sample is pre-processed, that is, it is processed by wire cutting to lay the foundation for determining the apparent volume of the sample. The apparent volume is no longer calculated through drying treatment, that is, no oil washing and drying operations are performed, and the internal structure of the sample is not changed. In this step, the liquid measurement method is no longer used for the apparent volume detection, which avoids the increase in the measurement error of the clay mineral expansion volume.

[0059] Step S12: Perform helium injection measurement on the regularly shaped plunger sample to determine the effective porosity of the shale sample.

[0060] Step S13: perform nuclear magnetic porosity measurement on the plunger sample to determine the total porosity of the shale sample.

[0061] Step S14: characterize the shale oil reservoir space of the shale sample based on the effective porosity and total porosity of the shale sample.

[0062] The above-mentioned shale oil reservoir space characterization method provided in the embodiment of the present invention optimizes the pretreatment steps by linear cutting of shale samples, and avoids the influence of residual oil in the sample on the test process and results while ensuring the accuracy of the experimental results. On this basis, based on helium injection measurement and nuclear magnetic resonance measurement, the effective porosity and total porosity of the shale sample are determined, and then a comprehensive characterization method of shale oil reservoir space is established, laying a foundation for actual production and resource evaluation.

[0063] In a specific embodiment, the present invention provides a detailed method for characterizing shale oil reservoir space, referring to Figure 2 As shown, the method may include the following steps:

[0064] Step S21, performing wire cutting processing on the shale sample to obtain a plunger sample with a regular shape.

[0065] In this step, the shale sample is processed by wire cutting technology to cut it into a regularly shaped plug sample, which is convenient for measuring the apparent volume in the subsequent steps.

[0066] Step S22: Determine the apparent volume of the regularly shaped plunger sample based on the electronic vernier caliper measurement method.

[0067] This step measures the apparent volume of the sample based on the electronic vernier caliper measurement method, and no longer requires oil washing or drying of the sample, thereby avoiding changes in the apparent volume caused by the clay minerals absorbing water and swelling during the liquid measurement method, and reducing errors during the measurement process.

[0068] Step S23: Perform helium injection measurement on the regularly shaped plunger sample to determine the effective porosity of the shale sample.

[0069] In the specific implementation of this step, helium injection measurement is carried out on the regular-shaped plunger sample using an injection pressure of 100 psi, and a high-precision pressure sensor is used for pressure monitoring to determine the effective porosity of the shale sample. The ambient temperature for helium injection measurement of the regular-shaped plunger sample is 24±0.5°C.

[0070] In this step, the equilibrium time is determined according to Boyle's law when conducting helium injection measurement. The specific measurement process is as follows: First, the effective porosity change value and pressure change value of the shale sample in the preset time period are obtained; then, based on the power function approximation method, the effective porosity change value and pressure change value are used to fit the pre-established porosity and time correlation equation to determine the effective porosity of the shale sample. In this step, in order to improve the measurement accuracy, the effective porosity of the shale sample after 50 hours is calculated and recorded according to Boyle's law to achieve the purpose of accurate measurement.

[0071] Step S24: perform nuclear magnetic porosity measurement on the plunger sample to determine the total porosity of the shale sample.

[0072] The plunger samples were subjected to two-dimensional nuclear magnetic resonance (NMR) porosity measurements at room temperature, drying, saturated water and centrifugal conditions, respectively, to determine the total porosity of the shale samples. The drying condition was 70°C for no less than 48 hours, and the saturated water condition was 15 MPa saturated water for no less than 15 hours.

[0073] In this step, the sample was dried at 70°C for 48 hours to remove the fluid that may have existed in the pores of the sample; it was saturated with water at 15 MPa for 15 hours to ensure that the volume of the connected pores was completely occupied by water; and the volume occupied by movable water was removed by centrifugation.

[0074] The specific parameters of NMR in this step are as follows: NMR porosity measurement uses SR-CPMG sequence, TE echo time is 0.06ms, NECH value is 18000, NTI value is 31, end time is 3000ms, and NS is repeated 32 times.

[0075] Step S25: characterize the shale oil reservoir space of the shale sample based on the effective porosity and total porosity of the shale sample. Taking into account the inevitable errors in each experiment, the helium porosity value is selected to characterize the effective porosity, and the closed pores are characterized using the nuclear magnetic resonance results, and a comprehensive characterization process for the porosity and spatial distribution of the shale oil reservoir space is established.

[0076] Step S26: Scan the plunger sample with an electron microscope and a nano-CT scan to determine the fracture porosity of the plunger sample. Fracture porosity, as a type of effective porosity, is an important parameter for describing the internal voids of rocks or soils, and is of great significance for oil and gas migration research.

[0077] The above method provided in the embodiment of the present invention achieves the purpose of quantitative evaluation of the effective porosity and total porosity of shale oil samples by optimizing the sample pretreatment, experimental process and parameter setting of different test experiments, laying a foundation for actual production and resource evaluation.

[0078] In a specific example, shale samples in a certain study area were selected and qualitatively observed by thin section and scanning electron microscopy, and then measured using helium porosity and nuclear magnetic resonance porosity. A total of 2 pure shale plug samples after wire cutting were obtained at the same depth, S-1 and S-2.

[0079] The samples were prepared and observed by thin sections, scanning electron microscopy, and nano-CT. The samples developed felsic laminae, clay laminae, and shell laminae, and the mineral composition was mainly clay minerals, quartz, and carbonate minerals. CT results Figure 3 It shows that the S-1 sample has two relatively straight foliation fractures, which are perpendicular to the cylindrical surface of the plunger, and the fracture porosity is 1.85%; Figure 4 It shows that S-2 has two groups of microcracks, which are generally parallel to the bedding plane, and the fracture porosity is 0.93%.

[0080] The porosity of S-1 and S-2 samples was measured by helium porosimetry, with an initial injection pressure of 100 psi and a test environment of 24±0.5°C. The apparent volume of S-1 was 2.506 cm in diameter, 1.954 cm in length, and 23.44 g in mass; the apparent volume of S-2 was 2.494 cm in diameter, 1.143 cm in length, and 13.49 g in mass. The porosity of the samples was measured over a long period of time and the results showed: Figure 5 The porosity of S-1 is 5.5% at 25 minutes and 8.64% at 53 hours as specified by the national standard. Figure 6 The porosity of S-2 is shown to be 6.68% at 25 minutes and 8.38% at 53 hours as specified by the national standard.

[0081] By means of nuclear magnetic resonance, SR-CPMG sequence was used, TE echo time was 0.06ms, NECH value was 18000, NTI value was 31, end time was 3000ms, and NS was repeated 32 times. The samples were tested at room temperature, dried at 70℃ for 48h, and saturated with water at 15Mpa for 15h. The porosity of S-1 closed pores was 9.43% and that of S-2 closed pores was 4.31%. The test results are respectively as follows: Figure 7 , Figure 8 According to the comprehensive characterization results, under the condition of optimizing sample pretreatment, experimental process and parameters, the effective porosity of S-1 is 8.64%, the total porosity is 18.07%, and the fracture porosity is 1.85%; the effective porosity of S-2 is 8.38%, the total porosity is 12.69%, and the fracture porosity is 0.93%.

[0082] Embodiment 2

[0083] In the second embodiment of the present invention, a method for constructing a shale porosity identification chart is provided, referring to Fig. 9 As shown, the method may include the following steps:

[0084] Step S91: Acquire different types of shale samples, and measure the organic matter abundance of the different types of shale samples.

[0085] Step S92: measuring the effective porosity and total porosity of different types of shale samples, wherein the effective porosity and total porosity of the shale samples are measured according to the method for characterizing the shale oil reservoir space described in Example 1.

[0086] Step S93: construct a shale porosity identification chart based on the organic matter abundance, effective porosity and total porosity of different types of shale samples.

[0087] The embodiment of the present invention uses numerical experiment means to fit the physical experiment results and predict the porosity value at a later time. Helium porosity experiments are conducted on different shale samples to obtain the porosity and pressure variation over time within 60 hours. The power function approximation method is used to establish a general relationship and perform curve fitting. According to the pre-established general relationship between porosity and experimental time, the fitting relationship between the porosity of the rock sample and the experimental time is obtained by fitting the experimental data, and the effective porosity of the rock sample is determined.

[0088] Specifically, the general relationship between porosity and experimental time is: Porosity = a × t b +c; where Porosity is the porosity, t is the experimental time, and a, b and c are constants to be determined.

[0089] Considering the influence of organic matter abundance on reservoir porosity, organic matter abundance tests were conducted on samples from different regions, and helium porosity-time curve fitting charts under different TOC backgrounds were established. It is expected that in the future, when the TOC of a sample in a certain region is known, the helium porosity measurement equilibrium time and the final effective porosity of the sample can be obtained through the chart, thereby improving the accuracy and timeliness of the experiment.

[0090] Based on the same inventive concept, an embodiment of the present invention also provides a method for quickly measuring the effective porosity of shale, which may include:

[0091] First, the organic matter abundance of the shale samples in the study area is measured; then, based on the pre-constructed shale porosity identification map and organic matter abundance, the effective porosity and measurement equilibrium time of the shale samples are quickly determined; wherein, the shale porosity identification map is pre-constructed according to the above-mentioned shale porosity identification map construction method.

[0092] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for characterizing shale oil reservoir space, characterized in that: include: The shale samples were processed by wire cutting to obtain plug samples with regular shapes; Conducting helium injection measurements on the regularly shaped plug samples to determine the effective porosity of the shale samples; Performing nuclear magnetic porosity measurement on the plug sample to determine the total porosity of the shale sample; The shale oil reservoir space of the shale sample is characterized based on the effective porosity and total porosity of the shale sample.

2. The method according to claim 1, characterized in that The step of measuring the nuclear magnetic porosity of the plunger sample to determine the total porosity of the shale sample comprises: Conducting two-dimensional nuclear magnetic resonance porosity measurement on the plunger sample under normal temperature conditions, drying conditions, saturated water conditions and centrifugal conditions in turn to determine the total porosity of the shale sample; Wherein, the drying condition is drying at 70°C for not less than 48h; The saturated water condition is 15Mpa saturated water for no less than 15h.

3. The method according to claim 2, characterized in that The nuclear magnetic porosity measurement adopts the SR-CPMG sequence, with a TE echo time of 0.06 ms, a NECH value of 18000, an NTI value of 31, an end time of 3000 ms, and NS repeated scanning 32 times.

4. The method according to claim 1, characterized in that: The method of carrying out helium injection measurement on the regularly shaped plunger sample to determine the effective porosity of the shale sample comprises: Helium gas injection measurements were performed on the regularly shaped plug samples using an injection pressure of 100 psi, and pressure was monitored using a high-precision pressure sensor to determine the effective porosity of the shale samples.

5. The method according to claim 4, characterized in that Determining the effective porosity of the shale sample comprises: Obtaining the time-varying value of the effective porosity and the time-varying value of the pressure of the shale sample in a preset time period; Based on the power function approximation method, the effective porosity changes with time and the pressure changes with time. The porosity value is fitted to the pre-established correlation equation between porosity and time to determine the effective porosity of the shale sample.

6. The method according to claim 4, characterized in that The ambient temperature for the helium injection measurement of the regularly shaped plunger sample is 24±0.5°C.

7. The method according to claim 1, characterized in that Before starting the helium injection measurement on the regular shaped plunger sample, it also includes: Based on electronic vernier caliper measurement, the apparent volume of regularly shaped plunger samples was determined.

8. The method according to any one of claims 1 to 7, characterized in that: Also includes: The plug samples were subjected to electron microscope scanning and nano-CT scanning to determine the fracture porosity of the plug samples.

9. A method for constructing a shale porosity identification chart, characterized in that: include: Obtaining different types of shale samples, and measuring the organic matter abundance of the different types of shale samples; Measuring the effective porosity and total porosity of different types of shale samples, wherein the effective porosity and total porosity of the shale samples are measured according to the method for characterizing shale oil reservoir space according to any one of claims 1 to 7; A shale porosity identification chart is constructed based on the organic matter abundance, effective porosity and total porosity of different types of shale samples.

10. A method for rapid measurement of effective porosity of shale, characterized in that: include: Measuring the abundance of organic matter in shale samples from the study area; Based on the pre-constructed shale porosity identification plate and the organic matter abundance, the effective porosity and measurement equilibrium time of the shale sample are quickly determined; Wherein, the shale porosity identification plate is pre-constructed according to the method for constructing a shale porosity identification plate according to claim 9.

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