Shale oil-bearing evaluation method and shale oil geological recoverable reserve evaluation method

Abstract

The present application provides a shale-hosted oil evaluation method and a shale oil geological recoverable reserve evaluation method. The shale-hosted oil evaluation method comprises: obtaining a powder sample of a target shale core; extracting the powder sample with chloroform under the condition of 20-30 DEG C to obtain free light oil; performing Soxhlet extraction on the residue after chloroform extraction with a mixture of dichloromethane and methanol under the condition of 60-70 DEG C to obtain free heavy oil; performing chloroform Soxhlet extraction on the residue after Soxhlet extraction with the mixture of dichloromethane and methanol under the condition of 70-80 DEG C to obtain adsorbed oil; determining the content of free oil and the content of adsorbed oil, and / or the composition of free oil and the composition of adsorbed oil based on the free light oil, the free heavy oil and the adsorbed oil. The technical scheme provided by the present application can accurately evaluate the quantity and characteristics of free oil and adsorbed oil in different types of reservoirs in shale sections, and provide support decision basis for selecting sweet spot sections and evaluating shale oil exploitation benefits in the study area.

Description

Technical Field

[0001] This invention relates to a method for evaluating shale oil deposits and a method for evaluating the geologically recoverable reserves of shale oil. Background Technology

[0002] In recent years, previous researchers have classified the occurrence state of oil in shale reservoirs into three end-members: adsorbed oil, miscible oil, and free oil. Based on this, different separation and extraction quantitative techniques and corresponding methods for calculating shale oil resources and geologically recoverable reserves have been proposed. Separation and extraction quantitative techniques can be summarized into two main categories: one is solvent stepwise extraction, which is based on the differences in the size and molecular polarity of different occurrence spaces in shale reservoirs, using different solvents to extract from block and powder samples separately. However, due to the lack of clarity regarding the source, formation process, and interrelationships between crude oil and organic and inorganic minerals in the rock, as well as the activity properties of the crude oil, the extraction process is complex. Most importantly, each step of the extract does not have a clear one-to-one correspondence with the crude oil in different occurrence states within the actual geological body; that is, the extract products lack explicit geological significance. The second method is the thermal release method. The principle is based on the fact that shale oil in different occurrence states has different molecular thermal volatilization capabilities. Shale oil located in fractures and large pores is more easily released thermally than oil located in micropores; smaller molecules are more easily released thermally than larger molecules; and free compounds are more easily released thermally than adsorbed compounds. Therefore, by setting reasonable heating experimental conditions, the oil in different occurrence states in the shale system can be quantitatively characterized. The problem with this method is that heating increases molecular mobility, failing to objectively reflect the magnitude of molecular mobility; furthermore, heating causes insoluble organic matter kerogen to generate some soluble hydrocarbons.

[0003] Therefore, it is still necessary to study new technical solutions to better evaluate shale oil reserves, lay the foundation for better evaluation of geologically recoverable shale oil reserves, and better selection of sweet spots in shale oil. Summary of the Invention

[0004] The purpose of this invention is to provide a method applicable to the evaluation of the quantity and characteristics of oil reserves in different types of shale formations.

[0005] Another objective of this invention is to provide a method for accurately evaluating the geologically recoverable reserves of shale oil.

[0006] To achieve the above objectives, the present invention provides a method for evaluating shale oil reserves, wherein the method includes:

[0007] Obtain powder samples from the target shale core;

[0008] The powder sample was extracted with chloroform (i.e., trichloromethane) at 20℃-30℃ to obtain free light oil;

[0009] The residue obtained after extraction with chloroform at 20℃-30℃ was subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy and light oil.

[0010] The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ was subjected to Soxhlet extraction with chloroform at 70℃-80℃ to obtain adsorbed oil.

[0011] Based on the obtained free light oil, free heavy oil, and adsorbed oil, determine the content of free oil and the content of adsorbed oil (including rock mineral adsorption and kerogen adsorption), and / or determine the composition of free oil and adsorbed oil.

[0012] In the above-mentioned shale oil-bearing evaluation method, preferably, the particle size of the powder sample is 80-120 mesh.

[0013] In the above-mentioned shale oil evaluation method, preferably, the step of extracting the powder sample with chloroform (i.e., trichloromethane) at 20℃-30℃ to obtain free light oil includes:

[0014] Step 1: Immerse the powder sample in chloroform and extract it at 20℃-30℃ to achieve solid-liquid separation;

[0015] Step 2: Observe whether the separated liquid phase is colorless; if the separated liquid phase is colored, proceed to step 3; if the separated liquid phase is colorless (usually, step 3 needs to be repeated at least twice before the separated liquid phase is colorless), proceed to step 4.

[0016] Step 3: Immerse the separated solid phase in chloroform at 20℃-30℃ for extraction, thereby performing solid-liquid separation; and repeat Step 2:

[0017] Step 4: Dry the liquid phase obtained from each solid-liquid separation. The product obtained from the drying is free light oil.

[0018] In the above-mentioned shale oil-bearing evaluation method, preferably, the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7.

[0019] In the above-mentioned shale oil evaluation method, preferably, the step of extracting the residue obtained by chloroform extraction at 20℃-30℃ with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy oil includes:

[0020] The residue obtained after extraction with chloroform at 20℃-30℃ was subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ until colorless. The liquid product was dried, and the dried product was the free heavy oil.

[0021] In the above-mentioned shale oil evaluation method, preferably, the adsorbed oil obtained by Soxhlet extraction of the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ is further obtained by Soxhlet extraction with chloroform at 70℃-80℃.

[0022] The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ is subjected to Soxhlet extraction with chloroform at 70℃-80℃ until it becomes colorless. The liquid product is then dried, and the dried product is the adsorbed oil.

[0023] In the above-mentioned shale oil-bearing evaluation method, preferably, determining the content of free oil and adsorbed oil includes:

[0024] The mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil were determined separately.

[0025] The content of free oil and the content of adsorbed oil are determined using the following formula based on the mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil:

[0026] S f =(m fl +m fh )÷m c

[0027] S a =m a ÷m c

[0028] In the formula, S f The free oil content is expressed in mg / g rock; m fl The mass of free light oil is expressed in mg; m fh The mass of free heavy oil is expressed in mg; m c The mass of the powdered sample from the shale core is expressed in grams (g); S a The content of adsorbed oil is expressed in mg / g rock; m a The mass of the adsorbed oil is expressed in mg.

[0029] In the above-mentioned shale oil evaluation method, preferably, determining the composition of free oil and adsorbed oil includes:

[0030] The free light oil, free heavy oil, and adsorbed oil were analyzed by saturated hydrocarbon chromatography to determine the composition of the free oil and the adsorbed oil.

[0031] This invention also provides a method for evaluating the geologically recoverable reserves of shale oil, wherein the method includes:

[0032] Obtain typical lithological assemblages of each typical lithofacies in the shale strata of the study area;

[0033] For each core sample in the typical lithological combination samples of each typical lithofacies, the shale oil content and adsorbed oil content of each core sample are determined by using the shale oil evaluation method provided in the above specific embodiments of the present invention.

[0034] Based on the content of free oil and adsorbed oil in each core sample of typical lithological assemblage samples of each typical lithofacies, the geological recoverable reserves of shale oil are evaluated.

[0035] In the above-mentioned method for evaluating the geological recoverable reserves of shale oil, preferably, the method of obtaining typical lithological combination samples of each typical lithofacies in the shale strata of the study area includes:

[0036] Core samples of different lithologies corresponding to typical rocks in each shale stratum of the study area were obtained;

[0037] Organic carbon and pyrolysis analyses were performed on each core sample to determine the content of soluble and insoluble organic matter and geochemical characteristics in each core sample.

[0038] Based on the organic carbon content and pyrolysis parameter S1 (i.e., free hydrocarbon content) of each core sample, typical lithological assemblages were selected.

[0039] In the above-mentioned method for evaluating the geologically recoverable reserves of shale oil, preferably, the evaluation of the geologically recoverable reserves of shale oil based on the content of free oil and adsorbed oil in each core sample of a typical lithological combination sample of each typical lithofacies includes:

[0040] Based on the content of free oil and adsorbed oil in each core sample of typical lithological combination samples of each typical lithofacies, the sweet spot lithofacies of shale oil are determined.

[0041] Based on the content of free oil and adsorbed oil in each core sample from typical lithological assemblage samples of various shale oil sweet spot facies, the geologically recoverable reserves of shale oil are determined.

[0042] In the above-mentioned method for evaluating the geologically recoverable reserves of shale oil, preferably, the geologically recoverable reserves of shale oil are determined based on the content of free oil and adsorbed oil in each core sample of a typical lithological assemblage sample of each shale oil sweet spot facies, including:

[0043] Based on the contents of free oil and adsorbed oil in each core sample of typical lithological assemblage samples of each shale oil sweet spot facies, and combined with the oil-bearing characteristics of the source-reservoir relationship, the range of free oil and adsorbed oil contents of each shale oil sweet spot facies is determined.

[0044] Based on the range of free and adsorbed oil content in the sweet spot facies of each shale oil, the geologically recoverable reserves of shale oil are determined.

[0045] More preferably, the geologically recoverable reserves of shale oil are determined by the following formula:

[0046]

[0047] In the formula, Q R Geologically recoverable resources, unit 10 4 t; Q i The geologically recoverable resource quantity of the i-th lithofacies is expressed in units of 10. 4 t; A i Let be the oil-bearing area of ​​the i-th rock facies, in km². 2 H i ρ represents the effective thickness of the i-th lithofacies, in meters. i The density of the i-th lithofacies is t / m³. 3 S i denoted as the free oil content of the i-th facies, in mg / g rock; n is the total number of shale oil sweet spot facies in each shale stratum of the study area; K is the free oil compensation coefficient.

[0048] In the above-mentioned method for evaluating the geological recoverable reserves of shale oil, preferably, the determination of the free oil content and adsorbed oil content of each core sample in the typical lithological combination samples of each typical lithofacies using the above-mentioned shale oil occurrence evaluation method of the present invention includes:

[0049] Obtain powder samples from each core sample; for each core sample powder sample, perform the following steps respectively;

[0050] The powder sample was extracted with chloroform (i.e., trichloromethane) at 20℃-30℃ to obtain free light oil;

[0051] The residue obtained after extraction with chloroform at 20℃-30℃ was subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy oil.

[0052] The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ was subjected to Soxhlet extraction with chloroform at 70℃-80℃ to obtain adsorbed oil.

[0053] Based on the obtained free light oil, free heavy oil, and adsorbed oil, the content of free oil and the content of adsorbed oil (including rock mineral adsorption and kerogen adsorption) are determined.

[0054] In the above-mentioned method for evaluating the geological recoverable reserves of shale oil, preferably, the particle size of the powder sample is 80-120 mesh.

[0055] In the above-mentioned method for evaluating the geologically recoverable reserves of shale oil, preferably, the extraction of free light oil from the powder sample using chloroform (i.e., trichloromethane) at 20℃-30℃ includes:

[0056] Step 1: Immerse the powder sample in chloroform and extract it at 20℃-30℃ to achieve solid-liquid separation;

[0057] Step 2: Observe whether the separated liquid phase is colorless; if the separated liquid phase is colored, proceed to step 3; if the separated liquid phase is colorless (usually, step 3 needs to be repeated at least twice before the separated liquid phase is colorless), proceed to step 4.

[0058] Step 3: Immerse the separated solid phase in chloroform at 20℃-30℃ for extraction, thereby performing solid-liquid separation; and repeat Step 2:

[0059] Step 4: Dry the liquid phase obtained from each solid-liquid separation. The product obtained from the drying is free light oil.

[0060] In the above-mentioned method for evaluating the geological recoverable reserves of shale oil, preferably, the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7.

[0061] In the above-mentioned method for evaluating the geological recoverable reserves of shale oil, preferably, the step of extracting the residue obtained by chloroform extraction at 20℃-30℃ with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy oil includes: extracting the residue obtained by chloroform extraction at 20℃-30℃ with a mixture of dichloromethane and methanol at 60℃-70℃ until colorless, drying the liquid phase product, and obtaining the dried product as free heavy oil.

[0062] In the above-mentioned method for evaluating the geological recoverable reserves of shale oil, preferably, the step of obtaining adsorbed oil by Soxhlet extraction of the residue obtained after Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ and chloroform Soxhlet extraction at 70℃-80℃ includes: Soxhlet extraction of the residue obtained after Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ with chloroform at 70℃-80℃ until colorless, drying the liquid phase product, and the dried product is the adsorbed oil.

[0063] In the above-mentioned method for evaluating the geologically recoverable reserves of shale oil, preferably, determining the content of free oil and adsorbed oil includes:

[0064] The mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil were determined separately.

[0065] The content of free oil and the content of adsorbed oil are determined using the following formula based on the mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil:

[0066] S f =(m fl +m fh )÷m c

[0067] S a =m a ÷m c

[0068] In the formula, S f The free oil content is expressed in mg / g rock; m fl The mass of free light oil is expressed in mg; m fh The mass of free heavy oil is expressed in mg; m c The mass of the powdered sample from the shale core is expressed in grams (g); S a The content of adsorbed oil is expressed in mg / g rock; m a The mass of the adsorbed oil is expressed in mg.

[0069] The evaluation of oil content in shale formations is the core of shale reservoir evaluation. The technical solution provided by this invention can accurately evaluate the quantity and characteristics of free and adsorbed oil in shale, providing a supporting decision-making basis for selecting sweet spots and accurately evaluating geologically recoverable reserves. Compared with traditional methods, it can provide a deeper understanding of the formation and evolution process of crude oil in shale formations, as well as the adsorption forces between crude oil and organic and inorganic matter in the rock, and the activity properties of crude oil. Attached Figure Description

[0070] Figure 1 This is a flowchart of a shale oil evaluation method provided in a specific embodiment of the present invention.

[0071] Figure 2 A flowchart of a method for evaluating the geological recoverable reserves of shale oil provided in a specific embodiment of the present invention.

[0072] Figure 3 This is a comprehensive cross-sectional view of organic matter in sections one, two, and three of the Fengcheng Formation in the study area of ​​Example 1 of the present invention.

[0073] Figure 4This is a correlation diagram of soluble and insoluble organic matter in sections one, two, and three of the Fengcheng Formation in the study area of ​​Example 1 of the present invention.

[0074] Figure 5 This is a correlation diagram of organic carbon and S1 / TOC in sections one, two, and three of the Fengcheng Formation in the study area of ​​Example 1 of the present invention.

[0075] Figure 6 This is a comparison diagram of free oil and adsorbed oil in a typical lithological combination sample of shale strata in the study area of ​​Example 1 of the present invention.

[0076] Figure 7 This is a distribution map of different lithofacies in the shale strata of the key well in the study area of ​​Embodiment 1 of the present invention. Detailed Implementation

[0077] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0078] Current classification schemes do not accurately correspond to the occurrence forms of oil in geological bodies, failing to objectively describe the characteristics of oil occurrence and thus affecting the evaluation of crude oil liquidity. Therefore, this invention classifies the occurrence state of crude oil in shale reservoirs into two end-members: adsorbed oil and free oil, eliminating the "miscible" end-member. This is primarily because the formation process and source of crude oil are considered; crude oil is a product of kerogen thermal degradation and has broken away from the parent structure, thus eliminating the possibility of miscibility between the two substances. Adsorbed crude oil exists based on the principle of "like dissolves like," and the adsorption capacity of organic matter is far greater than that of inorganic minerals. Free crude oil exists because after a large amount of crude oil is adsorbed by kerogen, it diffuses into spaces with lower concentrations; further, after adsorbing surrounding inorganic minerals, a large amount of crude oil and kerogen form an "organic network," resulting in continuous migration. Therefore, there is a clear and definable boundary between adsorbed and free crude oil.

[0079] There are four main differences between free and adsorbed oils: ① Storage space, including size and connectivity: Free oils generally have larger storage spaces, resulting in a larger contact area with the solvent and making them easier to extract. Crude oils located in micropores or enveloped by kerogen macromolecules are difficult to extract due to limited contact with the solvent. ② Molecular polarity: Free oils, after migration and fractionation, generally have lower molecular polarity and are easier to extract. Adsorbed oils, on the other hand, generally have higher molecular polarity and are relatively difficult to extract. ③ Molecular thermal volatility: Free oils, after migration and fractionation, have smaller molecules and are generally more volatile. ④ Molecular mobility: Free oils have less adsorption than adsorbed oils and are easier to extract.

[0080] Based on the requirement that molecular activity (including physical adsorption, chemical adsorption, and crude oil fluidity) is a special factor of free oil, and combined with the study of the "two-end-member" state of crude oil in shale reservoirs, as well as the systematic analysis of extraction solvents and experimental conditions, this invention proposes a stepwise extraction quantitative technique using different solvents and different temperature levels.

[0081] See Figure 1 A specific embodiment of the present invention provides a method for evaluating shale-bearing oil reserves, wherein the method includes:

[0082] Step S1: Obtain powder samples from the target shale core;

[0083] Step S2: Extract the powder sample with chloroform (i.e., chloroform) at 20℃-30℃ to obtain free light oil;

[0084] Step S3: The residue obtained after extraction with chloroform at 20℃-30℃ is subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy and light oil.

[0085] Step S4: The residue obtained by Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ is subjected to Soxhlet extraction with chloroform at 70℃-80℃ to obtain adsorbed oil.

[0086] Step S5: Based on the obtained free light oil, free heavy oil and adsorbed oil, determine the content of free oil and the content of adsorbed oil (including rock mineral adsorption and kerogen adsorption), and / or determine the composition of free oil and adsorbed oil.

[0087] The shale oil evaluation method provided by this invention is based on the inventor's research and understanding of the "dualistic theory" (that is, dividing crude oil in shale reservoirs into only two end-members, adsorbed oil and free oil, without defining the "miscible" end-member), and is proposed on the basis of a renewed understanding of oil content, crude oil flow mechanism, and influencing factors. In this shale oil evaluation method, chloroform is first used for extraction at 20℃-30℃ to extract free light oil. At this time, the free oil of heavier non-hydrocarbon components, asphaltene, etc., has not been completely extracted. A mixture of dichloromethane and methanol, which has stronger polarity and better similarity to these components, is used as a solvent for Soxhlet extraction at 60℃-70℃ to further complete the extraction and extract the free heavy and light components. Finally, chloroform is used for Soxhlet extraction at 70℃-80℃ to extract the adsorbed oil.

[0088] Furthermore, in step S1, the particle size of the powder sample is 80-120 mesh.

[0089] Further, in step S2, the extraction of the powder sample with chloroform (i.e., chloroform) at 20°C-30°C to obtain free light oil includes:

[0090] Step S21: Immerse the powder sample in chloroform and extract it at 20℃-30℃ to perform solid-liquid separation;

[0091] Step S22: Observe whether the separated liquid phase is colorless; if the separated liquid phase is colored, proceed to step S23; if the separated liquid phase is colorless (usually, step S23 needs to be repeated at least twice before the separated liquid phase is colorless), proceed to step S24.

[0092] Step S23: Immerse the separated solid phase in chloroform at 20℃-30℃ for extraction, thereby performing solid-liquid separation; and repeat step S22:

[0093] Step S24: Dry the liquid phase obtained from each solid-liquid separation. The product obtained from the drying is the free light oil.

[0094] Furthermore, the solid-liquid separation is achieved by allowing the liquid phase to stand and then pouring it out;

[0095] Furthermore, in step S24, drying the liquid phase obtained from each solid-liquid separation includes: mixing the liquid phases obtained from each solid-liquid separation and then drying them; mixing the liquid phases obtained from each solid-liquid separation and then drying them helps to reduce quantitative errors.

[0096] Furthermore, during the extraction process, stirring is performed;

[0097] Furthermore, the drying process is carried out by air drying.

[0098] Further, in step S3, the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7.

[0099] Further, in step S3, the extraction of the residue obtained after extraction with chloroform at 20°C-30°C using a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil includes:

[0100] The residue obtained after extraction with chloroform at 20℃-30℃ was subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ until colorless. The liquid product was dried, and the dried product was the free heavy oil.

[0101] Furthermore, the drying process is carried out by air drying.

[0102] Further, in step S4, the process of obtaining adsorbed oil by Soxhlet extraction of the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C, followed by Soxhlet extraction with chloroform at 70°C-80°C, comprises:

[0103] The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ is subjected to Soxhlet extraction of chloroform at 70℃-80℃ until colorless. The liquid product is dried, and the dried product is the adsorbed oil.

[0104] Furthermore, the drying process is carried out by air drying.

[0105] Further, in step S5, determining the content of free oil and adsorbed oil includes:

[0106] The mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil were determined separately.

[0107] The content of free oil and the content of adsorbed oil are determined using the following formula based on the mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil:

[0108] S f =(m fl +m fh )÷m c

[0109] S a =m a ÷m c

[0110] In the formula, S f The free oil content is expressed in mg / g rock; m flThe mass of free light oil is expressed in mg; m fh The mass of free heavy oil is expressed in mg; m c The mass of the powdered sample from the shale core is expressed in grams (g); S a The content of adsorbed oil is expressed in mg / g rock; m a The mass of the adsorbed oil is expressed in mg.

[0111] Further, in step S5, determining the composition of the free oil and the composition of the adsorbed oil includes:

[0112] The free light oil, free heavy oil, and adsorbed oil were analyzed by saturated hydrocarbon chromatography to determine the composition of the free oil and the adsorbed oil.

[0113] See Figure 2 A specific embodiment of the present invention provides a method for evaluating the geologically recoverable reserves of shale oil, wherein the method includes:

[0114] Step A1: Obtain typical lithological assemblage samples of typical lithofacies in each shale stratum of the study area;

[0115] Step A2: For each core sample in the typical lithological combination sample of each typical lithofacies, the content of free oil and adsorbed oil in each core sample is determined by using the shale oil evaluation method provided in the above specific embodiments of the present invention.

[0116] Step A3: Based on the content of free oil and adsorbed oil in each core sample of typical lithological assemblage samples of each typical lithofacies, evaluate the geological recoverable reserves of shale oil.

[0117] Furthermore, in step A1, obtaining typical lithological assemblage samples of typical lithofacies from various shale strata in the study area includes:

[0118] Step A11: Obtain core samples of different lithologies corresponding to each typical rock in the shale strata of the study area;

[0119] Step A12: Perform organic carbon and pyrolysis analysis on each core sample to determine the content of soluble and insoluble organic matter and geochemical characteristics in each core sample;

[0120] Step A13: Based on the organic carbon content and pyrolysis parameter S1 (i.e., free hydrocarbon content) of each core sample, select typical lithological combination samples;

[0121] When screening samples, three main factors are considered: first, the organic carbon content, as higher organic carbon content indicates greater oil production; second, the ratio of pyrolysis parameter S1 to organic carbon content, reflecting oil storage capacity and crude oil injection; and third, the main mineral composition, including clay, quartz, feldspar, calcite, dolomite, pyrite, etc., with higher clay content indicating greater oil production, and higher content of brittle minerals such as quartz indicating greater fracturing potential, making them excellent mining sections. Specifically, high organic carbon content is preferred, followed by a large ratio of pyrolysis parameter S1 to organic carbon content, and third, the content of different lithological minerals such as clay, siltstone, and dolomite is considered to achieve core sample screening. In this preferred embodiment, core samples of different lithologies are obtained for each typical lithofacies. Then, based on the organic carbon content and pyrolysis parameter S1 of each core sample, samples that can reflect the oil-bearing situation of that lithofacies are selected as typical lithological assemblage samples for that lithofacies.

[0122] The evaluation of the entire shale strata was completed by using different lithofacies of the shale strata in the study area as evaluation units.

[0123] Furthermore, by conducting lithofacies studies on the shale strata in the study area, typical lithofacies types were delineated, thereby determining the typical lithofacies of each shale strata in the study area. The determination of typical lithofacies can be carried out through conventional methods, which will not be elaborated here.

[0124] Further, in step A3, the evaluation of shale oil geological recoverable reserves based on the content of free oil and adsorbed oil in each core sample of the typical lithological assemblage samples of each typical lithofacies includes:

[0125] Step A31: Based on the content of free oil and adsorbed oil in each core sample of typical lithological combination samples of each typical facies, determine the sweet spot facies of shale oil.

[0126] Step A32: Based on the free oil content and adsorbed oil content of each core sample in the typical lithological assemblage samples of each shale oil sweet spot facies, determine the geologically recoverable reserves of shale oil.

[0127] Further, in step A32, based on the free oil content and adsorbed oil content of each core sample in the typical lithological assemblage samples of each shale oil sweet spot facies, the geologically recoverable reserves of shale oil are determined to include:

[0128] Step A311: Based on the contents of free oil and adsorbed oil in each core sample of typical lithological assemblage samples of each shale oil sweet spot facies, and combined with the source-reservoir relationship and oil-bearing characteristics, determine the range of free oil and adsorbed oil contents of each shale oil sweet spot facies.

[0129] Specifically, the content ranges of free oil and adsorbed oil in each core sample of each shale oil sweet spot facies are initially determined based on the content of free oil and adsorbed oil in typical lithological assemblage samples of each shale oil sweet spot facies. Then, the initially determined content ranges of free oil and adsorbed oil in each shale oil sweet spot facies are corrected according to the source-reservoir relationship and oil-bearing characteristics to make them conform to the conventional understanding in this field.

[0130] According to conventional understanding in this field: 1. Shale has the strongest adsorption capacity, with the largest proportion of adsorbed oil in the total oil volume, followed by dolomitic mudstone, silty mudstone, argillaceous dolomitic rock, argillaceous siltstone, and dolomitic siltstone; 2. The oil generation and drainage capacity decrease in the following order: shale, dolomitic mudstone, silty mudstone, argillaceous dolomitic rock, argillaceous siltstone, and dolomitic siltstone; 3. The oil storage capacity increases in the following order: shale, dolomitic mudstone, silty mudstone, argillaceous dolomitic rock, argillaceous siltstone, and dolomitic siltstone.

[0131] Step A312: Determine the geologically recoverable reserves of shale oil based on the range of free and adsorbed oil content in each sweet spot facies of shale oil.

[0132] Furthermore, in step A312, the geologically recoverable reserves of shale oil are determined using the free oil method for different lithofacies, specifically through the following formula:

[0133]

[0134] In the formula, Q R Geologically recoverable resources, unit 10 4 t; Q i The geologically recoverable resource quantity of the i-th lithofacies is expressed in units of 10. 4 t; A i Let be the oil-bearing area of ​​the i-th rock facies, in km². 2 H i ρ represents the effective thickness of the i-th lithofacies, in meters. i The density of the i-th lithofacies is t / m³. 3 S i denoted as the free oil content of the i-th facies, in mg / g rock; n is the total number of shale oil sweet spot facies in each shale interval of the study area; K is the free oil compensation coefficient, usually taken as 1.1-1.3;

[0135] Among them, the compensation coefficient K of the free oil can be determined based on the C6-C content in the free oil from the core samples obtained from the shale formations in the study area. 14 The proportion of lighter oils is used to determine this, typically C6-C. 14 The higher the proportion of lighter oil, the greater the compensation coefficient K of the free oil.

[0136] Further, in step A31, determining the sweet spot facies of shale oil based on the free oil content and adsorbed oil content of each core sample in the typical lithological assemblage samples of each typical facies can be done using conventional methods in the art; for example, determining the sweet spot facies of shale oil based on the free oil content and adsorbed oil content of each core sample in the typical lithological assemblage samples of each typical facies includes:

[0137] Based on the free oil content and adsorbed oil content of each core sample in the typical lithological assemblage samples of each typical lithofacies, and combined with the oil-bearing characteristic analysis, different oil-bearing levels and different sweet spot types are identified; thus, the sweet spot lithofacies of shale oil are determined.

[0138] Determining the sweet spot typically considers two factors: the content of free oil and the fracturing capability of the reservoir. Low organic matter abundance siltstones (including argillaceous siltstones and dolomitic siltstones) generally have a relatively high free oil content, with oil saturation depending on the degree of crude oil charging. High organic matter abundance shales have higher contents of free heavy oil and adsorbed hydrocarbons, which is related to the strong adsorption of organic matter and clay minerals. The amount of free oil in each rock facies is controlled by its oil generation, oil discharge, and the degree of crude oil charging. The comprehensive evaluation shows that the oil-bearing grade of the argillaceous siltstone facies, the dolomitic siltstone facies, and the argillaceous dolomitic facies is Grade 1, which is a Class 1 sweet spot area; the oil-bearing grade of the silty mudstone facies, the dolomitic mudstone facies, and the dolomitic facies is Grade 2, which is a Class 2 sweet spot area; and the oil-bearing grade of the mudstone shale facies is Grade 3, which is a Class 3 sweet spot area. The specific values ​​of oil saturation and free oil in different lithofacies depend on the oil and gas geological conditions of the study area. At the same time, the development of regional fractures and microfractures is a key factor in the selection of sweet spot areas.

[0139] Further, in step A2, the determination of the free oil content and adsorbed oil content of each core sample in the typical lithological combination sample of each typical lithofacies using the shale oil evaluation method provided in the above specific embodiments of the present invention includes: step A21: obtaining powder samples of each core sample; and performing steps A22-A23 for each powder sample of the core sample.

[0140] Step A22: Extract the powder sample with chloroform (i.e., chloroform) at 20℃-30℃ to obtain free light oil;

[0141] Step A23: Extract the residue obtained by chloroform extraction at 20℃-30℃ using a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy oil.

[0142] Step A24: The residue obtained by Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ is subjected to Soxhlet extraction with chloroform at 70℃-80℃ to obtain adsorbed oil.

[0143] Step A25: Based on the obtained free light oil, free heavy oil, and adsorbed oil, determine the content of free oil and the content of adsorbed oil (including rock mineral adsorption and kerogen adsorption);

[0144] Furthermore, in step A21, the particle size of the powder sample is 80-120 mesh;

[0145] Furthermore, in step A22, the extraction of the powder sample with chloroform (i.e., chloroform) at 20℃-30℃ to obtain free light oil includes: Step A221: Immersing the powder sample in chloroform and extracting it at 20℃-30℃ to perform solid-liquid separation; Step A222: Observing whether the separated liquid phase is colorless; if the separated liquid phase is colored, proceed to step A223; if the separated liquid phase is colorless (usually, step A223 needs to be repeated at least twice before the separated liquid phase becomes colorless), proceed to step A224; Step A223: Immersing the separated solid phase in chloroform and extracting it at 20℃-30℃ to perform solid-liquid separation; and repeating... Proceed to step A222; Step A224: Dry the liquid phase obtained from each solid-liquid separation, and the dried product is free light oil; Further, the solid-liquid separation is achieved by allowing the liquid phase to stand and then pouring it out; Further, in step A224, drying the liquid phase obtained from each solid-liquid separation includes: mixing the liquid phases obtained from each solid-liquid separation and then drying them; Mixing the liquid phases obtained from each solid-liquid separation and then drying them helps to reduce quantitative errors; Further, stirring is performed during the extraction process; Further, the drying is carried out by air drying; Further, in step S3, the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7;

[0146] Furthermore, in step A23, the step of extracting the residue with chloroform at 20℃-30℃ and then performing Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy oil includes: performing Soxhlet extraction on the residue obtained after extraction with chloroform at 20℃-30℃ with a mixture of dichloromethane and methanol at 60℃-70℃ until colorless, drying the liquid phase product, and obtaining the dried product as free heavy oil; further still, the drying is performed by air drying.

[0147] Furthermore, in step A24, the step of obtaining adsorbed oil by Soxhlet extraction of the residue obtained after Soxhlet extraction of the mixture of dichloromethane and methanol at 60℃-70℃ and chloroform at 70℃-80℃ includes: Soxhlet extraction of the residue obtained after Soxhlet extraction of the mixture of dichloromethane and methanol at 60℃-70℃ with chloroform at 70℃-80℃ until colorless, drying the liquid phase product, and the dried product is the adsorbed oil; further, the drying is carried out by air drying.

[0148] Furthermore, in step A25, determining the content of free oil and adsorbed oil includes:

[0149] The mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil were determined separately.

[0150] The content of free oil and the content of adsorbed oil are determined using the following formula based on the mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil:

[0151] S f =(m fl +m fh )÷m c

[0152] S a =m a ÷m c

[0153] In the formula, S f The free oil content is expressed in mg / g rock; m fl The mass of free light oil is expressed in mg; m fh The mass of free heavy oil is expressed in mg; m c The mass of the powdered sample from the shale core is expressed in grams (g); S a The content of adsorbed oil is expressed in mg / g rock; m a The mass of the adsorbed oil is expressed in mg.

[0154] Example 1

[0155] This embodiment uses the shale formation in region A as an example to evaluate the geologically recoverable reserves of shale oil.

[0156] Region A is primarily a fan delta-laminar fan-lacustrine sedimentary system within a saline-alkaline lacustrine context, belonging to the Fengcheng Formation depositional period. It comprises three shale layers: the first, second, and third. The lacustrine fan margin-deep lacustrine subfacies formed a large area of ​​silty, dolomitic, organic-rich shale, covering an area of ​​600 km². 2The burial depth is mostly greater than 4,000 meters, the geothermal gradient is about 3.2℃ / 100m, the geothermal temperature is greater than 120℃, the source rocks are mature, and there is sufficient oil generation and a large quantity. It is a favorable zone for shale oil development. Currently, many shale oil exploration wells such as A1, A2, and A3 have obtained industrial oil flow.

[0157] The specific methods for evaluating the geologically recoverable reserves of shale oil in shale formations in region A include:

[0158] Step 1: Obtain typical lithological assemblage samples of typical lithofacies in each shale stratum of the study area;

[0159] Specifically, lithofacies studies were conducted on the shale strata in the study area to delineate typical lithofacies types and determine the typical lithofacies of each shale strata. Core samples of different lithologies corresponding to the typical lithofacies types of each shale strata were collected. Organic carbon and pyrolysis analyses were performed on the collected core samples to determine the content of soluble and insoluble organic matter and the basic geochemical characteristics of each core sample. The analytical results are shown below. Figure 3 , Figure 4 , Figure 5 As shown; based on the organic carbon content and pyrolysis parameter S1 (i.e., free hydrocarbon content) of each core sample, typical lithological combination samples are screened out.

[0160] The overall characteristics of the shale strata in the study area are that the oil content of the core samples is positively correlated with the abundance of organic matter. Among them, the second shale strata at 4632.7m and 4667.6m have the highest oil content, accounting for 1.26%-1.34% by weight and 3%-4% by volume. The second and third shale strata have higher oil content than the first shale strata, and the proportion of high oil content in the third shale strata is greater than that in the second shale strata. The first shale strata have low organic matter abundance, but the soluble hydrocarbon content per unit organic matter is relatively high, reflecting the relative accumulation of crude oil. The oil content statistics of the second and third shale strata by lithology show that the soluble organic matter content of the total organic matter in the argillaceous siltstone and silty mudstone is higher than that in the dolomitic / gray / siliceous shale, reflecting the hydrocarbon expulsion and primary migration of crude oil.

[0161] Step 2: For each core sample in the typical lithological assemblage samples of each typical lithofacies, conduct shale oil content evaluation to determine the content of free oil and adsorbed oil in each core sample; the shale oil content evaluation includes:

[0162] Obtain powder samples from the rock core; the particle size of the powder samples is 80-120 mesh.

[0163] The powder sample was extracted with chloroform at room temperature to obtain free light oil. Specifically, step A: the powder sample was immersed in chloroform and stirred for extraction at room temperature. After standing, the liquid phase was poured out. Step B: the liquid phase was observed to see if it was colorless. If the poured liquid phase was colored, step C was performed. If the poured liquid phase was colorless, step D was performed. Step C: the poured solid phase was immersed in chloroform and stirred for extraction at room temperature. After standing, the liquid phase was poured out, and step B was repeated. Step D: the liquid phases poured out each time were mixed and dried to obtain free light oil.

[0164] The residue obtained by chloroform extraction at room temperature was subjected to Soxhlet extraction at 60°C with a mixture of dichloromethane and methanol (volume ratio of dichloromethane to methanol of 93:7) until colorless. The liquid product was dried to obtain free heavy oil.

[0165] The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60°C was subjected to Soxhlet extraction with chloroform at 70°C until colorless. The liquid product was dried, and the dried product was the adsorbed oil.

[0166] The masses of free light oil, free heavy oil, and adsorbed oil are determined separately. Based on these masses, the content of free oil and the content of adsorbed oil are determined using the following formulas:

[0167] S f =(m fl +m fh )÷m c

[0168] S a =m a ÷m c

[0169] In the formula, S f The free oil content is expressed in mg / g rock; m fl The mass of free light oil is expressed in mg; m fh The mass of free heavy oil is expressed in mg; m c The mass of the powdered sample from the shale core is expressed in grams (g); S a The content of adsorbed oil is expressed in mg / g rock; m a The mass of the adsorbed oil is expressed in mg.

[0170] The free light oil, free heavy oil, and adsorbed oil were analyzed by saturated hydrocarbon chromatography to determine the composition of the free oil and the adsorbed oil.

[0171] At this point, the separation and quantification of free oil and adsorbed oil in each sample have been completed. Figure 6This image shows a comparison of free and adsorbed oil in typical lithological assemblages of shale formations. The overall oil-bearing characteristics of different lithological reservoirs in the study area's shale formations are as follows: free heavy oil content is highest in high-organic-matter-rich shale, which is related to the adsorption of organic matter; adsorbed oil is characterized by relatively low overall content, with a low ratio (S0.05) to organic carbon. 重轻 The range of / TOC varies greatly, which is most closely related to the clay content in the rock. Shales with high organic matter abundance also have high free light oil content, which is related to their extensive oil generation processes; siltstones with low organic matter abundance do not necessarily have particularly low free light oil content, and their S... 游离轻 / TOC ratio and S in shale with high organic matter abundance 游离轻 The TOC / O ratio is relatively high, reflecting a strong hydrocarbon migration effect from crude oil. The thermal evolution degree of the Fengcheng Formation source foci (Ro) is 1.0%-1.4%, which is in the mature to over-mature stage, indicating a large amount of crude oil. The relatively low content of adsorbed hydrocarbons is closely related to the high content of brittle minerals, the development of microcracks, and the relatively low content of clay minerals and organic matter, which is the result of multiple factors. In addition, during the experiment, the sample was finely crushed, and the particle size decreased, which opened up the closed space of the oil storage, improved connectivity, and converted some part of the adsorbed oil in the particle and throat-like adsorbed state into free oil; at the same time, the smaller particle size increased the specific surface area, and some free oil was converted into adsorbed state.

[0172] Step 3: Based on the content of free oil and adsorbed oil in each core sample of typical lithological combination samples of each typical lithofacies, evaluate the geological recoverable reserves of shale oil.

[0173] Specifically: Based on the content of free oil and adsorbed oil in each core sample of typical lithological combination samples of each typical lithofacies, combined with oil-bearing characteristic analysis, different oil-bearing levels and different sweet spot types are delineated, and sweet spot segments are determined to identify shale oil sweet spot lithofacies.

[0174] Based on the free oil and adsorbed oil contents of each core sample in the typical lithological assemblage samples of each shale oil sweet spot facies, and combined with the oil-bearing characteristics of the source-reservoir relationship, the range of free oil and adsorbed oil contents of each shale oil sweet spot facies is determined; based on the range of free oil and adsorbed oil contents of each shale oil sweet spot facies, the geologically recoverable reserves of shale oil are determined by the following formula.

[0175]

[0176] In the formula, Q R Geologically recoverable resources, unit 10 4 t; Q i The geologically recoverable resource quantity of the i-th lithofacies is expressed in units of 10. 4 t; A i Let be the oil-bearing area of ​​the i-th rock facies, in km². 2 Hi ρ represents the effective thickness of the i-th lithofacies, in meters. i The density of the i-th lithofacies is t / m³. 3 S i denoted as the free oil content of the i-th facies, in mg / g rock; n is the total number of shale oil sweet spot facies in each shale stratum of the study area; K is the free oil compensation coefficient.

[0177] In this embodiment, shale strata are widely developed in the main slope-depression area of ​​the study area, with diverse lithological types, including mudstone shale, silty mudstone, dolomitic mudstone, argillaceous siltstone, dolomitic siltstone, argillaceous dolomitic dolomite, dolomite, alkaline mineral rocks, and volcanic rocks. Specifically, six typical lithofacies types can be identified, and their mineral assemblages, oil generation and storage properties, and oil-bearing characteristics are shown in Table 1.

[0178] Table 1. Six typical lithofacies types and oil-bearing grades of shale strata in the study area.

[0179]

[0180]

[0181] This indicates that the lithology is highly heterogeneous, with significant differences in reservoir properties, varying oil-bearing capacities across different lithofacies, well-developed fractures, and diverse reservoir types. The evaluation of sweet spots considers two factors: the amount of free oil and the degree of fracturing capability. The comprehensive evaluation results show that five lithofacies types in the study area are closely related to hydrocarbons (e.g., ...). Figure 7 As shown), the oil saturation of the argillaceous / lime-dolomite sandstone facies and the argillaceous-lime-dolomite facies is 40%-50%. f Rocks with oil content ranging from 6.40 to 18.28 mg / g are classified as Grade 1 oil-bearing rocks, belonging to the first-class sweet spot region; the silty / dolitic mudstone facies has an oil saturation of 40%-60%, and S... f 4.85-6.40 mg / g rock, dolomitic facies, oil saturation 20%-30%, S f Rocks with 4.85-6.40 mg / g oil content; combined with other factors, the oil-bearing grade is 2, belonging to the second-class sweet spot; the mudstone and shale facies have an oil saturation of 50%-70%, S... f Rocks with a concentration of 4.85-5.35 mg / g are classified as oil-bearing grade 3, belonging to the third-class sweet spot region.

[0182] There are six typical lithofacies types in the shale strata of the study area, of which five are shale oil sweet spot lithofacies (i.e., lithofacies closely related to oil and gas). The free oil compensation coefficient K in this area is taken as 1.3. Detailed data on the geologically recoverable reserves of shale oil in the study area are shown in Table 2. The calculated geologically recoverable reserves of shale oil are 2.26 × 10⁻⁶. 8 t-2.64×10 8 t.

[0183] Table 2 Evaluation parameters for geologically recoverable reserves of shale oil in the main lithofacies of the study area

[0184]

[0185]

[0186]

[0187] The above embodiments illustrate that, by applying this invention, the quantity of free and adsorbed oil in shale can be accurately evaluated. Compared with traditional methods, it provides a deeper understanding of the formation and evolution of shale oil and the flow properties of crude oil. Furthermore, by applying this invention, the optimal selection of sweet spots in shale oil and the evaluation of geologically recoverable reserves can be accurately completed.

Claims

1. A method for evaluating shale-bearing oil reserves, wherein, The method includes: Obtain powder samples from the target shale core; The powder sample was extracted with chloroform at 20℃-30℃ to obtain free light oil; The residue obtained after extraction with chloroform at 20℃-30℃ was subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ to obtain free heavy oil. The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ was subjected to Soxhlet extraction with chloroform at 70℃-80℃ to obtain adsorbed oil. Based on the obtained free light oil, free heavy oil, and adsorbed oil, determine the content of free oil and the content of adsorbed oil, and / or determine the composition of free oil and the composition of adsorbed oil.

2. The evaluation method according to claim 1, wherein, The particle size of the powder sample is 80-120 mesh.

3. The evaluation method according to claim 1, wherein, The extraction of free light oil from the powder sample using chloroform at 20℃-30℃ includes: Step 1: Immerse the powder sample in chloroform and extract it at 20℃-30℃ to achieve solid-liquid separation; Step 2: Observe whether the separated liquid phase is colorless; if the separated liquid phase is colored, proceed to Step 3; if the separated liquid phase is colorless, proceed to Step 4. Step 3: Immerse the separated solid phase in chloroform at 20℃-30℃ for extraction, thereby performing solid-liquid separation; and repeat Step 2: Step 4: Dry the liquid phase obtained from each solid-liquid separation. The product obtained from the drying is free light oil.

4. The evaluation method according to claim 1, wherein, The volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:

7.

5. The evaluation method according to claim 1, wherein, The process of extracting the residue with chloroform at 20°C-30°C and then performing Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil includes: The residue obtained after extraction with chloroform at 20℃-30℃ was subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60℃-70℃ until colorless. The liquid product was dried, and the dried product was the free heavy oil.

6. The evaluation method according to claim 1, wherein, The adsorbed oil obtained by Soxhlet extraction of the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C is further obtained by Soxhlet extraction with chloroform at 70°C-80°C includes: The residue obtained by Soxhlet extraction of a mixture of dichloromethane and methanol at 60℃-70℃ is subjected to Soxhlet extraction with chloroform at 70℃-80℃ until colorless. The liquid product is dried, and the dried product is the adsorbed oil.

7. The evaluation method according to claim 1, wherein, The determination of the free oil content and the adsorbed oil content includes: The mass of free light oil, free heavy oil, and adsorbed oil were determined separately. The content of free oil and the content of adsorbed oil are determined using the following formula based on the mass of free light oil, the mass of free heavy oil, and the mass of adsorbed oil: S f =(m fl +m fh )÷m c S a =m a ÷m c In the formula, S f The free oil content is expressed in mg / g rock; m fl The mass of free light oil is expressed in mg; m fh The mass of free heavy oil is expressed in mg; m c The mass of the powdered sample from the shale core is expressed in grams (g); S a The content of adsorbed oil is expressed in mg / g rock; m a The mass of the adsorbed oil is expressed in mg.

8. A method for evaluating the geologically recoverable reserves of shale oil, wherein, The method includes: Obtain typical lithological assemblages of each typical lithofacies in the shale strata of the study area; For each core sample in the typical lithological combination samples of each typical lithofacies, the content of free oil and adsorbed oil in each core sample is determined by the shale oil occurrence evaluation method described in any one of claims 1-7. Based on the content of free oil and adsorbed oil in each core sample of typical lithological assemblage samples of each typical lithofacies, the geological recoverable reserves of shale oil are evaluated.

9. The evaluation method according to claim 8, wherein, The typical lithological assemblage samples obtained from each typical lithofacies of the shale strata in the study area include: Core samples of different lithologies corresponding to typical rocks in each shale stratum of the study area were obtained; Organic carbon and pyrolysis analyses were performed on each core sample to determine the content of soluble and insoluble organic matter and geochemical characteristics in each core sample. Based on the organic carbon content and pyrolysis parameter S1 of each core sample, typical lithological combinations were selected.

10. The evaluation method according to claim 8, wherein, The evaluation of shale oil geological recoverable reserves includes the content of free hydrocarbons, the content of adsorbed hydrocarbons, the composition of free hydrocarbons, and the composition of adsorbed hydrocarbons in each core sample from typical lithological assemblage samples based on typical lithofacies. Based on the content of free oil and adsorbed oil in each core sample of typical lithological combination samples of each typical lithofacies, the sweet spot lithofacies of shale oil are determined. Based on the content of free oil and adsorbed oil in each core sample from typical lithological assemblage samples of various shale oil sweet spot facies, the geologically recoverable reserves of shale oil are determined.

11. The evaluation method according to claim 10, wherein, Based on the free oil content and adsorbed oil content of each core sample in typical lithological assemblage samples of various shale oil sweet spot facies, the geologically recoverable reserves of shale oil are determined to include: Based on the contents of free oil and adsorbed oil in each core sample of typical lithological assemblage samples of each shale oil sweet spot facies, and combined with the oil-bearing characteristics of the source-reservoir relationship, the range of free oil and adsorbed oil contents of each shale oil sweet spot facies is determined. Based on the range of free and adsorbed oil content in the sweet spot facies of each shale oil, the geologically recoverable reserves of shale oil are determined.

12. The evaluation method according to claim 11, wherein, The geologically recoverable reserves of shale oil are determined by the following formula: In the formula, Q R Geologically recoverable resources, unit 10 4 t; Q i The geologically recoverable resource quantity of the i-th lithofacies is expressed in units of 10. 4 t; A i Let be the oil-bearing area of ​​the i-th rock facies, in km². 2 ; H i ρ represents the effective thickness of the i-th lithofacies, in meters. i The density of the i-th lithofacies is t / m³. 3 ; S i denoted as the free oil content of the i-th facies, in mg / g rock; n is the total number of shale oil sweet spot facies in each shale stratum of the study area; K is the free oil compensation coefficient.

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