A method for constructing relationship between low-matured continental shale hydrocarbon generation process and pore structure

Abstract

The application provides a kind of low matured continental facies shale hydrocarbon generation process and pore structure relationship construction method, belongs to shale hydrocarbon generation process technical field.The application establishes low matured continental facies shale hydrocarbon generation process by using gold tube thermal simulation of kerogen sample under the same experimental conditions, and the mineral composition, pore structure and morphology characteristics are characterized by using gold tube thermal simulation of water adding plunger sample combined with scanning electron microscope, the corresponding relationship of low matured continental facies shale hydrocarbon generation process and pore evolution is obtained, so as to distinguish the advantage development temperature interval or maturity interval of shale oil and gas, and the reaction stage and pore structure evolution characteristics experienced are clear, which can provide new ideas for future hydrocarbon generation process reproduction, hydrocarbon generation mechanism discussion and resource dynamic evaluation of continental facies shale.Meanwhile, the gold tube thermal simulation of water adding plunger sample is used in the application, which can approximately simulate the real geological conditions, so that the experimental results are closer to the results under real geological conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of shale hydrocarbon generation process, and in particular to a method for constructing the relationship between the hydrocarbon generation process and pore structure of low-maturity continental shale. Background Art

[0002] Shale oil and gas are a key type of unconventional oil and gas, playing a crucial role in transforming the energy mix. Because marine shales generally have a higher degree of organic matter maturity, most have already experienced peak hydrocarbon generation, making it impossible to fully recover their entire hydrocarbon generation process. Continental shales, on the other hand, generally have lower organic matter maturity, making them ideal candidates for hydrocarbon generation research.

[0003] Thermal simulation is commonly used to characterize and characterize the hydrocarbon generation process in shale. Most existing thermal simulation experiments extract kerogen from organic matter in shale, making it difficult to measure changes in pore structure, pore diameter, and pore connectivity at various stages. This results in deficiencies in the study of pore evolution during hydrocarbon generation. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for constructing the relationship between the hydrocarbon generation process and pore structure of low-maturity continental shale. The method provided by the present invention can achieve a detailed characterization of the hydrocarbon generation process of continental shale and the evolution of its pore structure characteristics.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for establishing the relationship between the hydrocarbon generation process and pore structure of low-maturity continental shale, comprising the following steps:

[0007] Provide low-maturity continental shale samples and determine the total organic carbon content, vitrinite reflectance and organic matter type of low-maturity continental shale samples;

[0008] The low-maturity continental shale samples are divided into multiple groups, one group is used to prepare multiple water-added plug samples; the other group is used to prepare multiple kerogen samples;

[0009] In the temperature range of 100-600℃, multiple temperature points were set, and multiple plunger samples with water added and multiple kerogen samples were placed in a gold tube for gold tube thermal simulation. A plunger sample and kerogen sample were taken out at each temperature point.

[0010] The hydrocarbons produced by kerogen samples at different temperatures were collected, and the hydrocarbon production and C, H, or N isotope content of the hydrocarbons were measured. Combined with the total organic carbon content, vitrinite reflectance, and organic matter type of the low-maturity continental shale samples, the hydrocarbon generation process of the low-maturity continental shale was established.

[0011] Micro-nano CT scanning and reconstruction analysis were performed on the plug samples after treatment at different temperature points to obtain the pore structure characteristics of low-maturity continental shale at different temperature points;

[0012] The plunger samples treated at different temperatures were prepared into scanning electron microscope samples and subjected to scanning electron microscope tests to observe the mineral composition and morphological characteristics of low-maturity continental shale at different temperatures.

[0013] The hydrocarbon generation process of the low-maturity continental shale at different temperature points is matched with the pore structure and morphological characteristics of the low-maturity continental shale at different temperature points to obtain the relationship between the hydrocarbon generation process and pore structure of the low-maturity continental shale.

[0014] Preferably, the vitrinite reflectance of the low-maturity continental shale sample is less than 0.7%.

[0015] Preferably, the volume of water in the plunger sample with water added is half the volume of the plunger sample.

[0016] Preferably, the temperature points include 100°C, 200°C, 300°C, 325°C, 350°C, 375°C, 400°C, 450°C, 500°C, 550°C and 600°C.

[0017] Preferably, the heating rate of the gold tube thermal simulation is 0.1-20° C. / h, and the pressure is 0.1-50 MPa.

[0018] Preferably, the hydrocarbon substances produced by the kerogen sample at different temperatures include gaseous hydrocarbons and liquid hydrocarbons;

[0019] The process of establishing hydrocarbon generation from low-maturity continental shale includes:

[0020] Obtaining a "temperature-gas hydrocarbon" relationship curve and a "temperature-liquid hydrocarbon" relationship curve based on the yields of gaseous hydrocarbons and liquid hydrocarbons of the kerogen sample at different temperatures; obtaining the yield and temperature at the peak of hydrocarbon generation and the temperature range for large-scale hydrocarbon generation based on the relationship curves;

[0021] Based on the principle of carbon isotope fractionation, the hydrocarbon generation stage of kerogen at different temperatures is obtained through the changes in the carbon isotope characteristics of gaseous hydrocarbons.

[0022] Preferably, the pore structure parameters obtained by the micro-nano CT scanning and reconstruction analysis include pore distribution, pore size range and pore connectivity.

[0023] Preferably, the preparation process of the scanning electron microscope sample includes argon ion polishing and coating.

[0024] Preferably, the morphological characteristics obtained by the scanning electron microscope test include pore type, pore connectivity, mineral composition and morphology, organic matter morphology and pore development.

[0025] The present invention provides a method for constructing the relationship between the hydrocarbon generation process and pore structure of low-maturity continental shale, comprising the following steps: providing low-maturity continental shale samples, measuring the total organic carbon content, vitrinite reflectance and organic matter type of the low-maturity continental shale samples; dividing the low-maturity continental shale samples into multiple groups, preparing multiple water-added plunger samples in one group; and preparing multiple kerogen samples in another group; setting multiple temperature points in the temperature range of 100-600°C, placing the multiple water-added plunger samples and the multiple kerogen samples in a gold tube, performing a gold tube thermal simulation, and taking out a plunger sample and a kerogen sample at each temperature point; collecting hydrocarbon substances generated by the kerogen samples at different temperature points, and measuring the hydrocarbon substance yield and hydrocarbon content. The hydrocarbon generation process of low-maturity continental shale is established by combining the total organic carbon content, vitrinite reflectance and organic matter type of low-maturity continental shale samples with the C, H or N isotope content of the samples; micro-nano CT scanning and reconstruction analysis are performed on the plug samples after treatment at different temperature points to obtain the pore structure characteristics of the low-maturity continental shale at different temperature points; the plug samples after treatment at different temperature points are prepared into scanning electron microscopy samples, and scanning electron microscopy tests are performed to observe the mineral composition and morphological characteristics of the low-maturity continental shale at different temperatures; the hydrocarbon generation process of the low-maturity continental shale at different temperature points is matched with the pore structure and morphological characteristics of the low-maturity continental shale at different temperature points to obtain the relationship between the hydrocarbon generation process and pore structure of the low-maturity continental shale. Under the same experimental conditions, the present invention uses gold tube thermal simulation of kerogen samples to establish the hydrocarbon generation process of low-maturity continental shale, and uses gold tube thermal simulation of water-added plunger samples combined with micro-nano CT scanning and reconstruction to characterize the pore structure and morphology characteristics, thereby obtaining the correspondence between the hydrocarbon generation process of low-maturity continental shale and pore evolution. This can thus identify the dominant development temperature range or maturity range of shale oil and gas, clarify the reaction stages experienced and the pore change characteristics, and provide new ideas for the future reproduction of the hydrocarbon generation process of continental shale gas, the exploration of hydrocarbon generation mechanisms, and the dynamic evaluation and prediction of resources.

[0026] At the same time, most existing hydrocarbon generation thermal simulation experiments extract kerogen from organic matter in shale. Furthermore, regardless of whether the system is closed, open, or semi-closed / semi-open, most experiments focus on dry samples, with few experiments involving water-added samples. However, water plays a crucial role in mineral transformation and diagenetic reactions, leading to discrepancies between laboratory simulation results and those obtained under real geological conditions. The present invention uses water-added plunger samples for gold tube thermal simulation, which can approximate real geological conditions and ensure that pore evolution characteristics more closely match those obtained under real geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1The gaseous hydrocarbon production characteristics of different types of kerogen at the same heating rate;

[0028] Figure 2 The liquid hydrocarbon production characteristics of different types of kerogen at the same heating rate;

[0029] Figure 3 This is the methane carbon isotope signature of type I kerogen;

[0030] Figure 4 This is the methane carbon isotope signature of type II kerogen;

[0031] Figure 5 It is the methane carbon isotope signature of type III kerogen;

[0032] Figure 6 The scanning electron micrographs of water column samples at different temperatures are shown;

[0033] Figure 7 This is a three-dimensional reconstruction of the core sample with a water column at 350°C;

[0034] Figure 8 This is the pore extraction diagram of the core sample with water column at 350℃;

[0035] Figure 9 This is the pore connectivity diagram of the core sample with water column at 350℃;

[0036] Figure 10 The pore diameter distribution histogram of the water column sample at 350℃;

[0037] Figure 11 This is the pore connectivity diagram of the core sample without water column at 350℃;

[0038] Figure 12 These are the characterization results of the hydrocarbon generation process of continental shale and the corresponding pore structure. DETAILED DESCRIPTION

[0039] The present invention provides a method for establishing the relationship between the hydrocarbon generation process and pore structure of low-maturity continental shale, comprising the following steps:

[0040] Provide low-maturity continental shale samples and determine the total organic carbon content, vitrinite reflectance and organic matter type of low-maturity continental shale samples;

[0041] The low-maturity continental shale samples are divided into multiple groups, one group is used to prepare multiple water-added plug samples; the other group is used to prepare multiple kerogen samples;

[0042] In the temperature range of 100-600°C, multiple temperature points were set, and multiple plunger samples with water added and multiple kerogen samples were placed in a gold tube for gold tube thermal simulation. A plunger sample and a kerogen sample were taken out at each temperature point.

[0043] The hydrocarbons produced by kerogen samples at different temperatures were collected, and the hydrocarbon production and C, H, or N isotope content of the hydrocarbons were measured. Combined with the total organic carbon content, vitrinite reflectance, and organic matter type of the low-maturity continental shale samples, the hydrocarbon generation process of the low-maturity continental shale was established.

[0044] Micro-nano CT scanning and reconstruction analysis were performed on the plug samples after treatment at different temperature points to obtain the pore structure characteristics of low-maturity continental shale at different temperature points;

[0045] The plunger samples treated at different temperatures were prepared into scanning electron microscope samples and subjected to scanning electron microscope tests to observe the mineral composition and morphological characteristics of low-maturity continental shale at different temperatures.

[0046] The hydrocarbon generation process of the low-maturity continental shale at different temperature points is matched with the pore structure and morphological characteristics of the low-maturity continental shale at different temperature points to obtain the relationship between the hydrocarbon generation process and pore structure of the low-maturity continental shale.

[0047] The present invention provides low-maturity continental shale samples, and measures the total organic carbon content, vitrinite reflectance, and organic matter type of the low-maturity continental shale samples. In the present invention, the vitrinite reflectance of the low-maturity continental shale samples is less than 0.7%. In the present invention, total organic carbon content is determined according to the national standard GB / T19145-2022, Determination of Total Organic Carbon in Sedimentary Rocks; vitrinite reflectance is determined according to the industry standard SYT5124-2012, Method for Determination of Vitrinite Reflectance in Sedimentary Rocks; and organic matter type is determined according to the industry standard SYT5125-2014, Method for Identification and Classification of Kerogen Microscopic Components by Transmitted Light-Fluorescence.

[0048] In the present invention, the low-maturity continental shale samples are divided into multiple groups. One group is used to prepare multiple water-added plug samples, and the other group is used to prepare multiple kerogen samples. In the present invention, the volume of water in the water-added plug samples is preferably half the volume of the plug samples. As a specific embodiment of the present invention, the cross-sectional diameter of the plug samples is preferably 5 mm and the length is preferably 1 cm. In the present invention, the water is preferably distilled water, and the added volume of water is preferably 0.2 mL.

[0049] In the present invention, the number of the plunger samples with water added is consistent with the number of experimental temperature points. In the present invention, the number of the plunger samples with water added is preferably 11.

[0050] In the present invention, the kerogen sample preparation method refers to GB / T19144-2010 Method for Isolating Kerogen from Sedimentary Rocks. In the present invention, the number of kerogen samples is consistent with the number of experimental temperature points. In the present invention, the number of kerogen samples is preferably 11.

[0051] The present invention sets multiple temperature points within the 100-600°C temperature range. Multiple water-added plunger samples and multiple kerogen samples are placed in a gold tube for gold tube thermal simulation. A plunger sample and a kerogen sample are removed at each temperature point. In the present invention, the experimental temperature points preferably include 100°C, 200°C, 300°C, 325°C, 350°C, 375°C, 400°C, 450°C, 500°C, 550°C, and 600°C.

[0052] In the present invention, the heating rate of the gold tube thermal simulation is preferably 0.1-20°C / h, more preferably 1-10°C / h, further preferably 2-5°C / h, and the pressure is preferably 0.1-50 MPa, more preferably 1-30 MPa, further preferably 5-18 MPa.

[0053] The present invention collects hydrocarbons produced by kerogen samples at different temperatures, measures hydrocarbon production and the C, H, or N isotope content of the hydrocarbons, and establishes the hydrocarbon generation process of low-maturity continental shale based on the total organic carbon content, vitrinite reflectance, and organic matter type of the low-maturity continental shale samples. In the present invention, the hydrocarbons produced by the kerogen samples at different temperatures include gaseous hydrocarbons and liquid hydrocarbons;

[0054] In the present invention, the process of establishing hydrocarbon generation from low-maturity continental shale includes:

[0055] Obtaining a "temperature-gas hydrocarbon" relationship curve and a "temperature-liquid hydrocarbon" relationship curve based on the yields of gaseous hydrocarbons and liquid hydrocarbons of the kerogen sample at different temperatures; obtaining the yield and temperature at the peak of hydrocarbon generation and the temperature range for large-scale hydrocarbon generation based on the relationship curves;

[0056] Based on the principle of carbon isotope fractionation, the hydrocarbon generation stage of kerogen at different temperatures is obtained through the changes in the carbon isotope characteristics of gaseous hydrocarbons.

[0057] The present invention conducts micro-nano CT scanning and reconstruction analysis on plug samples treated at different temperatures to obtain the pore structure characteristics of low-maturity continental shale at different temperatures. The present invention does not require any specific micro-nano CT scanning and reconstruction analysis methods; these methods, familiar to those skilled in the art, can be used. In the present invention, the pore structure parameters obtained by micro-nano CT scanning and reconstruction analysis include pore distribution, pore size range, and pore connectivity.

[0058] The invention prepares the plunger samples after different temperature points into scanning electron microscope samples, and carries out scanning electron microscope test to observe the mineral components and the morphological characteristics of the low matured continental shale at different temperatures. In the invention, the preparation process of the scanning electron microscope sample includes argon ion polishing and film plating. In the invention, the test method of the scanning electron microscope refers to the petroleum industry standard SY / T 5162-2014 "Rock sample scanning electron microscope analysis method". In the invention, the morphological characteristics obtained by the scanning electron microscope test include pore type, pore connectivity, mineral component and morphology, organic matter morphology and pore development.

[0059] The invention corresponds the hydrocarbon generation process of the low matured continental shale at different temperature points to the pore structure and the morphological characteristics of the low matured continental shale at different temperatures, and obtains the relationship between the hydrocarbon generation process and the pore structure of the low matured continental shale. In the invention, under the same experimental conditions, the hydrocarbon generation process of the low matured continental shale is established by using the gold tube thermal simulation of the kerogen sample, the pore structure and the morphological characteristics are characterized by using the gold tube thermal simulation of the water-added plunger sample combined with micro-nano CT scanning and reconstruction, the corresponding relationship between the hydrocarbon generation process and the pore evolution of the low matured continental shale is obtained, so that the advantage development temperature interval or maturity interval of the shale oil and gas can be distinguished, the reaction stage and the pore change characteristics experienced can be determined, and new ideas can be provided for the reproduction of the hydrocarbon generation process of the continental shale gas, the discussion of the hydrocarbon generation mechanism, and the dynamic evaluation and prediction of the resources in the future.

[0060] The construction method of the relationship between the hydrocarbon generation process and the pore structure of the low matured continental shale provided by the invention will be described in detail in combination with the embodiments below, but they cannot be understood as the limitation on the protection scope of the invention.

[0061] Example 1

[0062] Low matured continental shale samples with different organic matter types in the Qaidam Basin are selected for experiments. The information of the samples is shown in Table 1.

[0063] Table 1 Information of experimental samples

[0064]

[0065] The relationship between the hydrocarbon generation process and the pore structure of the low matured continental shale is characterized by the following method:

[0066] Step 1: Select low maturity (Ro < 0.7%) continental shale samples, prepare 23 sample plungers, select one plunger for TOC (total organic carbon), Ro, and organic matter type determination; select the remaining 22 plungers, divide them into two groups, one group is water-added, and the other group is water-free, the water-free group is a control sample. In addition, extract one kerogen sample into 11 parts for thermal simulation experiment preparation;

[0067] Step 2: Add the sample to the gold tube. According to the hydrocarbon generation characteristics of organic matter, set 11 experimental temperature points, namely 100℃, 200℃, 300℃, 325℃, 350℃, 375℃, 400℃, 450℃, 500℃, 550℃, and 600℃. Set the heating rate to 2℃ / h and the pressure to 18MPa.

[0068] Step 3: Take out one sample at each designed temperature point for subsequent analysis, and continue heating the remaining samples until the last set temperature point is reached, and the heating process is completed;

[0069] Step 4: Collect gaseous and liquid hydrocarbons from the kerogen sample gold tubes, determine their yields, and determine hydrocarbon C, H, and N isotopes. Simultaneously, perform SEM sample preparation (including argon ion polishing and coating), micro-nano CT scanning, and data reconstruction on the plunger samples.

[0070] Step 5: Determine the porosity, pore-throat ratio, organic matter content and distribution characteristics through micro-nano CT scanning and data reconstruction; observe the changes in mineral distribution, organic matter distribution and pore evolution through scanning electron microscopy.

[0071] Step 6: Conduct comprehensive data analysis. First, analyze the hydrocarbon generation characteristics of samples at different temperature stages, including hydrocarbon generation amount and hydrocarbon generation rate, to establish the complete process of hydrocarbon generation of the samples. Second, analyze the pore evolution of samples at corresponding temperature stages, including pore distribution, pore size range and changes in pore connectivity. Finally, form a detailed characterization of the terrestrial shale hydrocarbon generation process and the corresponding pore structure.

[0072] The hydrocarbon generation process and pore evolution, as well as the detailed characterization of the hydrocarbon generation process and corresponding pore structure of continental shale are as follows:

[0073] (1) Hydrocarbon generation process

[0074] The gaseous hydrocarbon production characteristics of different types of kerogen at the same heating rate are as follows: Figure 1 As shown in Figure 2, the liquid hydrocarbon production characteristics of different types of kerogen at the same heating rate are as follows: Figure 2 As shown. Figure 1 、 2 As can be seen, the gas hydrocarbon curves for different kerogen types vary. Type I kerogen gas hydrocarbon production characteristics are divided into three stages: slow, fast, and slow. The gas hydrocarbon production curve for Type II kerogen is similar to that for Type I kerogen, but differs in that Type II kerogen production increases slowly before 300°C, then rapidly increases between 300°C and 470°C. Although gas hydrocarbon yield decreases between 470°C and 600°C, it is still better than that of Type I kerogen. Type III kerogen gas hydrocarbon yield increases rapidly from the outset and remains in this rapid growth phase. Overall, the gas hydrocarbon yield of Type I kerogen > Type III kerogen > Type II kerogen.

[0075] In terms of liquid hydrocarbons, the liquid hydrocarbon production curves of the three types of kerogens show similar trends, but the liquid hydrocarbon production of Type I kerogen is much greater than that of Type II and Type III kerogens. Type II kerogen has a wider temperature range for liquid hydrocarbon generation than Type III kerogen and has a higher yield.

[0076] Carbon isotope characteristics of methane in different types of kerogens Figures 3-5 shown. Figure 3 is the methane carbon isotope characteristic of type I kerogen, Figure 4 is the methane carbon isotope signature of type II kerogen. Figure 5 is the methane carbon isotope characteristic of type III kerogen. Figures 3-5 It can be seen that the carbon isotope values ​​of Type I kerogen are lighter than those of Type II kerogen, which in turn are lighter than those of Type III kerogen. Secondly, with increasing pyrolysis temperature, both types of methane carbon isotopes exhibit an evolutionary pattern of first becoming lighter and then heavier. This pattern is consistent with previous experimental results, but the evolutionary processes differ.

[0077] (2) Pore evolution

[0078] Scanning electron microscopy images of water column samples at different temperatures are shown in Figure 2. Figure 6 As shown. Figure 6 As can be seen, at 20°C, due to the low maturity of organic matter, hydrocarbon generation has yet to occur in significant quantities, and the conversion of clay minerals is limited. The pores in the shale are primarily microfractures, intragranular primary pores, intergranular solution pores, and mineral intercrystalline pores, while organic pores are underdeveloped. As the temperature increases, at 100°C, the porosity within the organic matter begins to increase, primarily macropores, with a small amount of mesopores also developing. Pore connectivity is moderate. At 200°C, the porosity within the organic matter increases significantly, and pore connectivity is established. At 300°C, the porosity within the organic matter increases rapidly, becoming extremely well-developed, from micropores to macropores, with pores interconnected in a network or honeycomb pattern. At 400°C, the porosity within the organic matter further develops, but notably, pore collapse is observed, compromising pore connectivity. At 500°C, while the porosity increases further, pore collapse becomes increasingly severe, and pore connectivity decreases.

[0079] The 350℃ water column sample was cut into 200.1μm×200.1μm×300.1μm samples for micron CT scanning test and reconstruction. The 350℃ water column sample core three-dimensional reconstruction image is shown in Figure 7 As shown in the figure, the pore extraction diagram of the core sample with water column at 350℃ is as follows Figure 8 The pore connectivity diagram of the core sample with water added at 350℃ is shown in Figure 9 The pore diameter distribution histogram of the water column sample at 350℃ is shown in Figure 10 As shown in Figure 2, the porosity of the 350℃ water column sample is 0.95%, the pore connectivity is poor, and the pore diameter distribution is about 1 to 2 μm.

[0080] The pore connectivity diagram of the 350℃ water column-free core sample is shown in the figure below. Figure 11 It can be seen that compared with the pore connectivity of the core sample with water column at 350℃, the porosity of the sample without water column is lower and the pore connectivity is poorer.

[0081] (3) Detailed characterization of the hydrocarbon generation process of continental shales and the corresponding pore structure

[0082] Through comprehensive analysis, the hydrocarbon generation process of continental shale and the corresponding pore structure characterization results are as follows Figure 12 Based on this model, we can identify the dominant temperature range or maturity range for shale oil and gas development, and clearly identify the reaction stages and pore change characteristics experienced.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for establishing the relationship between hydrocarbon generation process and pore structure of low-maturity continental shale, comprising the following steps: Provide low-maturity continental shale samples and determine the total organic carbon content, vitrinite reflectance and organic matter type of low-maturity continental shale samples; The low-maturity continental shale samples are divided into multiple groups, one group is used to prepare multiple water-added plug samples; the other group is used to prepare multiple kerogen samples; the volume of water in the water-added plug samples is half the volume of the plug samples; In the temperature range of 100-600℃, multiple temperature points were set, and multiple water-added plunger samples and multiple kerogen samples were placed in a gold tube for gold tube thermal simulation. A plunger sample and a kerogen sample were taken out at each temperature point. The hydrocarbons produced by kerogen samples at different temperatures were collected, and the hydrocarbon production and C, H, or N isotope content of the hydrocarbons were measured. Combined with the total organic carbon content, vitrinite reflectance, and organic matter type of the low-maturity continental shale samples, the hydrocarbon generation process of the low-maturity continental shale was established. Micro-nano CT scanning and reconstruction analysis were performed on the plug samples after treatment at different temperature points to obtain the pore structure characteristics of low-maturity continental shale at different temperature points; The plunger samples treated at different temperatures were prepared into scanning electron microscope samples and subjected to scanning electron microscope tests to observe the mineral composition and morphological characteristics of low-maturity continental shale at different temperatures. Corresponding the hydrocarbon generation process of the low-maturity continental shale at different temperatures with the pore structure and morphology characteristics of the low-maturity continental shale at different temperatures to obtain the relationship between the hydrocarbon generation process and pore structure of the low-maturity continental shale; The hydrocarbon substances produced by the kerogen sample at different temperatures include gaseous hydrocarbons and liquid hydrocarbons; The process of establishing hydrocarbon generation from low-maturity continental shale includes: Obtaining a "temperature-gas hydrocarbon" relationship curve and a "temperature-liquid hydrocarbon" relationship curve based on the yields of gaseous hydrocarbons and liquid hydrocarbons of the kerogen sample at different temperatures; obtaining the yield and temperature at the peak of hydrocarbon generation and the temperature range for large-scale hydrocarbon generation based on the relationship curves; Based on the principle of carbon isotope fractionation, the hydrocarbon generation stage of kerogen at different temperatures is obtained through the changes in the carbon isotope characteristics of gaseous hydrocarbons.

2. The construction method according to claim 1, characterized in that The vitrinite reflectance of the low-maturity continental shale sample is less than 0.7%.

3. The construction method according to claim 1, characterized in that The temperature points include 100°C, 200°C, 300°C, 325°C, 350°C, 375°C, 400°C, 450°C, 500°C, 550°C and 600°C.

4. The construction method according to claim 1 or 3, characterized in that The heating rate of the gold tube thermal simulation is 0.1~20°C / h, and the pressure is 0.1~50MPa.

5. The construction method according to claim 1, characterized in that The pore structure parameters obtained by the micro-nano CT scanning and reconstruction analysis include pore distribution, pore size range and pore connectivity.

6. The construction method according to claim 1, characterized in that The preparation process of the scanning electron microscope sample includes argon ion polishing and coating.

7. The construction method according to claim 1 or 6, characterized in that: The morphological characteristics obtained by the scanning electron microscope test include pore type, pore connectivity, mineral composition and morphology, organic matter morphology and pore development.

Images