WO2024082410A1 - 一种页岩赋存油评价方法及页岩油地质可采储量评价方法 - Google Patents

一种页岩赋存油评价方法及页岩油地质可采储量评价方法 Download PDF

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WO2024082410A1
WO2024082410A1 PCT/CN2022/138947 CN2022138947W WO2024082410A1 WO 2024082410 A1 WO2024082410 A1 WO 2024082410A1 CN 2022138947 W CN2022138947 W CN 2022138947W WO 2024082410 A1 WO2024082410 A1 WO 2024082410A1
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oil
free
shale
adsorbed
content
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PCT/CN2022/138947
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English (en)
French (fr)
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杨智
王兆云
张天舒
张洪
冯有良
李嘉蕊
王小妮
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中国石油天然气股份有限公司
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Publication of WO2024082410A1 publication Critical patent/WO2024082410A1/zh

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • E21B49/08—Obtaining fluid samples or testing fluids, in boreholes or wells
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/06—Preparation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/24—Earth materials

Definitions

  • the invention relates to a method for evaluating shale oil deposits and a method for evaluating geologically recoverable reserves of shale oil.
  • the most important thing is that there is no good one-to-one correspondence between the extracts in each step and the crude oil in different occurrence states in the actual geological body, that is, the extraction products have no clear geological significance.
  • the second is the heating release method, which is based on the fact that shale oils in different states of occurrence have different molecular thermal volatility. Shale oil in fractures and macropores is easier to release thermally than oil in micropores, small molecular compounds are easier to release thermally than macromolecular compounds, and free compounds are easier to release thermally than adsorbed compounds. Therefore, the oils in different states of occurrence in the shale system can be quantitatively characterized by setting reasonable heating experimental conditions.
  • the problem with this method is that the heating effect increases the activity of the molecules and cannot objectively reflect the size of the molecular activity; in addition, the heating effect causes the insoluble organic matter kerogen to generate some soluble hydrocarbons.
  • the object of the present invention is to provide a method applicable to evaluating the quantity and characteristics of oil stored in different types of reservoirs in shale layers.
  • Another object of the present invention is to provide a method for accurately evaluating the geologically recoverable reserves of shale oil.
  • the present invention provides a method for evaluating shale oil, wherein the method comprises:
  • the powder sample is extracted with chloroform (i.e., chloroform) at 20°C-30°C to obtain free light oil;
  • chloroform i.e., chloroform
  • the free oil content and the adsorbed oil including rock mineral adsorption and kerogen adsorption) content are determined, and/or the free oil composition and the adsorbed oil composition are determined.
  • the particle size of the powder sample is 80 mesh-120 mesh.
  • extracting the powder sample with chloroform i.e., chloroform
  • chloroform i.e., chloroform
  • Step 1 Soak the powder sample in chloroform and extract it at 20°C-30°C, and then perform 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 (usually, step 3 needs to be repeated at least twice before the separated liquid phase is colorless), proceed to step 4;
  • Step 3 Soak the separated solid phase in chloroform at 20°C-30°C for extraction, and then perform solid-liquid separation; and repeat step 2:
  • Step 4 Dry the liquid phase obtained from each solid-liquid separation, and the product obtained by drying is free light oil.
  • the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7.
  • the step of extracting the residue obtained by extraction with chloroform at 20°C-30°C with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil by Soxhlet extraction comprises:
  • the residue obtained after extraction with chloroform at 20°C-30°C is subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C until it becomes colorless, and the liquid product is dried.
  • the dried product is the free heavy oil.
  • the step of extracting the residue obtained by Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C with chloroform at 70°C-80°C to obtain the adsorbed oil comprises:
  • the determining the free oil content and the adsorbed oil content comprises:
  • Sf is the content of free oil, in mg/g rock
  • mfl is the mass of free light oil, in mg
  • mfh is the mass of free heavy oil, in mg
  • mc is the mass of powder sample of shale core, in g
  • Sa is the content of adsorbed oil, in mg/g rock
  • ma is the mass of adsorbed oil, in mg.
  • the determining the composition of free oil and adsorbed oil comprises:
  • the obtained free light oil, free heavy oil and adsorbed oil were subjected to saturated hydrocarbon chromatography analysis respectively, so as to determine the composition of the free oil and the composition of the adsorbed oil.
  • the present invention also provides a method for evaluating geologically recoverable reserves of shale oil, wherein the method comprises:
  • the shale oil storage evaluation method For each core sample in the typical lithology combination sample of each typical lithofacies, the shale oil storage evaluation method provided by the above specific embodiment of the present invention is used to determine the free oil content and the adsorbed oil content corresponding to each core sample;
  • geologically recoverable reserves of shale oil are evaluated based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each typical lithofacies.
  • the obtaining of typical lithology combination samples of each typical lithofacies of the shale layer section in the study area includes:
  • organic carbon content and pyrolysis parameter S 1 ie, free hydrocarbon content
  • the shale oil geologically recoverable reserves evaluation based on the free oil content and the adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each typical lithofacies includes:
  • geologically recoverable reserves of shale oil are determined based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each shale oil sweet spot lithofacies.
  • determining the shale oil geologically recoverable reserves includes:
  • the free oil and adsorbed oil content range of each shale oil sweet spot lithofacies is determined;
  • geologically recoverable reserves of shale oil are determined by the following formula:
  • Q R is the geologically recoverable resources, unit is 10 4 t;
  • Qi is the geologically recoverable resources of the i-th lithofacies, unit is 10 4 t;
  • Ai is the oil-bearing area of the i-th lithofacies, unit is km 2 ;
  • Hi is the effective thickness of the i-th lithofacies, unit is m;
  • ⁇ i is the rock density of the i-th lithofacies, t/m 3 ;
  • Si is the free oil content of the i-th lithofacies, unit is mg/g rock;
  • n is the total number of shale oil sweet spot lithofacies in the shale layer of the study area;
  • K is the compensation coefficient of free oil.
  • the above-mentioned shale oil geological recoverable reserves evaluation method preferably, for each core sample in the typical lithology combination sample of each typical lithofacies, the above-mentioned shale oil evaluation method of the present invention is used to determine the free oil content and the adsorbed oil content corresponding to each core sample, including:
  • the powder sample is extracted with chloroform (i.e., chloroform) at 20°C-30°C to obtain free light oil;
  • chloroform i.e., chloroform
  • the content of free oil and the content of adsorbed oil (including rock mineral adsorption and kerogen adsorption) are determined.
  • the particle size of the powder sample is 80 mesh-120 mesh.
  • the extracting the powder sample with chloroform i.e., chloroform
  • the extracting the powder sample with chloroform i.e., chloroform
  • Step 1 Soak the powder sample in chloroform and extract it at 20°C-30°C, and then perform 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 (usually, step 3 needs to be repeated at least twice before the separated liquid phase is colorless), proceed to step 4;
  • Step 3 Soak the separated solid phase in chloroform at 20°C-30°C for extraction, and then perform solid-liquid separation; and repeat step 2:
  • Step 4 Dry the liquid phase obtained from each solid-liquid separation, and the product obtained by drying is free light oil.
  • the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7.
  • the step of subjecting the residue obtained after extraction with chloroform at 20°C-30°C to Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil comprises: subjecting the residue obtained after extraction with chloroform at 20°C-30°C to Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C until it becomes colorless, and drying the liquid product, wherein the product obtained by drying is the free heavy oil.
  • the step of subjecting the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to Soxhlet extraction with chloroform at 70°C-80°C to obtain adsorbed oil comprises: subjecting the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to Soxhlet extraction with chloroform at 70°C-80°C until colorless, drying the liquid product, and the product obtained by drying is the adsorbed oil.
  • the determining of the free oil content and the adsorbed oil content comprises:
  • Sf is the content of free oil, in mg/g rock
  • mfl is the mass of free light oil, in mg
  • mfh is the mass of free heavy oil, in mg
  • mc is the mass of powder sample of shale core, in g
  • Sa is the content of adsorbed oil, in mg/g rock
  • ma is the mass of adsorbed oil, in mg.
  • the evaluation of oil deposits in shale intervals is the core of shale reservoir evaluation.
  • the technical solution provided by the present invention can accurately evaluate the quantity and characteristics of free oil and adsorbed oil in shale, and provide support for decision-making for selecting sweet spots and accurately evaluating geological recoverable reserves. Compared with traditional methods, it can more deeply understand the generation and evolution process of crude oil in shale intervals, the adsorption force between crude oil and organic and inorganic substances in rocks, and the activity performance of crude oil.
  • FIG1 is a flow chart of a method for evaluating shale oil accumulation provided in a specific embodiment of the present invention.
  • FIG2 is a flow chart of a method for evaluating geologically recoverable reserves of shale oil provided in a specific embodiment of the present invention.
  • FIG3 is a comprehensive cross-section diagram of organic matter in the first, second and third segments of the Fengcheng Formation in the study area in Example 1 of the present invention.
  • FIG4 is a correlation diagram of soluble and insoluble organic matter in the first, second and third segments of the Fengcheng Formation in the study area in Example 1 of the present invention.
  • FIG. 5 is a correlation diagram of organic carbon and S 1 /TOC in the first, second and third segments of the Fengcheng Formation in the study area in Example 1 of the present invention.
  • FIG6 is a comparison diagram of free oil and adsorbed oil of typical lithology combination samples of shale layers in the study area in Example 1 of the present invention.
  • FIG. 7 is a distribution diagram of different lithofacies in the shale layer sections of the key wells in the study area in Example 1 of the present invention.
  • the current classification scheme does not correspond well to the occurrence form of oil in geological bodies, that is, it fails to objectively describe the occurrence characteristics of oil in geological bodies, thus affecting the evaluation of crude oil fluidity.
  • the occurrence state of crude oil in shale reservoirs is divided into two end members, namely adsorbed oil and free oil, and the "mutually soluble" end member is no longer divided.
  • the main reason is to consider the generation process of crude oil and its parent source, that is, crude oil is the product of thermal degradation of kerogen, which has been broken out of the structure of the parent body, so there is no mutual solubility of the two substances.
  • the basis for the existence of adsorbed crude oil is based on the principle of similar compatibility, and the adsorption capacity of organic matter is much greater than that of inorganic minerals.
  • the basis for the existence of free crude oil is that after a large amount of crude oil is generated to meet the adsorption of kerogen, it will diffuse to the space with low concentration; after further meeting the adsorption of surrounding inorganic minerals, a large amount of crude oil and kerogen form an "organic network", and continuous migration occurs. It can be seen that there is a clear boundary between adsorbed and free crude oil, which can be determined.
  • 1 Storage space, including size and connectivity free oil has a relatively large storage space, so its contact area with the solvent is larger and it is easy to be extracted, while crude oil contained in micropores and enveloped by kerogen macromolecules is difficult to be extracted due to its limited contact ability with the solvent; 2 Molecular polarity: free oil has generally smaller molecular polarity after migration and fractionation, and is easy to be extracted, while adsorbed oil generally has larger molecular polarity and is relatively difficult to be extracted; 3 Molecular thermal volatility: free oil has smaller molecules after migration and fractionation, and is generally easy to volatilize; 4 Molecular activity: free oil has less adsorption than adsorbed oil and is easier to extract.
  • a specific embodiment of the present invention provides a method for evaluating shale oil, wherein the method comprises:
  • Step S1 obtaining a powder sample of a target shale core
  • Step S2 extracting the powder sample with chloroform (i.e., chloroform) at 20°C-30°C to obtain free light oil;
  • chloroform i.e., chloroform
  • Step S3 extracting the residue obtained by chloroform at 20°C-30°C with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy and light oil;
  • Step S4 extracting the residue obtained by Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C with chloroform at 70°C-80°C to obtain adsorbed oil;
  • Step S5 Based on the obtained free light oil, free heavy oil and adsorbed oil, determine the free oil content and the adsorbed oil (including rock mineral adsorption and kerogen adsorption) content, and/or determine the free oil composition and the adsorbed oil composition.
  • the free oil content and the adsorbed oil including rock mineral adsorption and kerogen adsorption
  • the shale oil evaluation method provided by the present invention is proposed by the inventor based on the research and understanding of "dualism" (i.e., crude oil in the shale reservoir is divided into only two end members, adsorbed oil and free oil, without dividing the "mutually soluble” end member), and on the basis of re-understanding the oil content and the flow mechanism of crude oil and influencing factors.
  • chloroform is first used to extract the free light oil under the condition of 20°C-30°C. At this time, the free oil of components such as non-hydrocarbons and asphaltene with heavier molecular weight has not been completely extracted.
  • a mixture of dichloromethane and methanol with stronger polarity and better similarity is selected as a solvent to perform Soxhlet extraction under the condition of 60°C-70°C to further complete the extraction work, extract the free heavy and light, and finally use chloroform to perform Soxhlet extraction under the condition of 70°C-80°C to extract the adsorbed oil.
  • step S1 the particle size of the powder sample is 80 mesh-120 mesh.
  • step S2 extracting the powder sample with chloroform (i.e., chloroform) at 20° C.-30° C. to obtain free light oil comprises:
  • Step S21 soaking the powder sample in chloroform at 20°C-30°C for extraction, and then performing solid-liquid separation;
  • 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;
  • Step S23 soaking the separated solid phase in chloroform at 20°C-30°C for extraction, and then performing solid-liquid separation; and re-performing step S22:
  • Step S24 drying the liquid phase obtained from each solid-liquid separation, and the product obtained by drying is free light oil
  • the solid-liquid separation is achieved by pouring out the liquid phase after standing;
  • drying the liquid phase obtained from each solid-liquid separation includes: drying the liquid phase obtained from each solid-liquid separation after mixing; drying the liquid phase obtained from each solid-liquid separation after mixing helps to reduce quantitative errors;
  • drying is performed by air-drying.
  • step S3 the volume ratio of dichloromethane to methanol in the mixture of dichloromethane and methanol is 93:7.
  • step S3 the residue obtained after extraction with chloroform at 20°C-30°C is subjected to Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil, which comprises:
  • drying is performed by air-drying.
  • step S4 the step of extracting the residue obtained by Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C with chloroform at 70°C-80°C to obtain the adsorbed oil comprises:
  • drying is performed by air-drying.
  • step S5 determining the content of free oil and the content of adsorbed oil includes:
  • Sf is the content of free oil, in mg/g rock
  • mfl is the mass of free light oil, in mg
  • mfh is the mass of free heavy oil, in mg
  • mc is the mass of powder sample of shale core, in g
  • Sa is the content of adsorbed oil, in mg/g rock
  • ma is the mass of adsorbed oil, in mg.
  • determining the composition of free oil and the composition of adsorbed oil includes:
  • the obtained free light oil, free heavy oil and adsorbed oil were subjected to saturated hydrocarbon chromatography analysis respectively, so as to determine the composition of the free oil and the composition of the adsorbed oil.
  • a specific embodiment of the present invention provides a method for evaluating geologically recoverable reserves of shale oil, wherein the method comprises:
  • Step A1 Obtain typical lithology combination samples of each typical lithofacies in the shale layer section of the study area;
  • Step A2 for each core sample in the typical lithology combination sample of each typical lithofacies, the shale oil storage evaluation method provided by the above specific embodiment of the present invention is used to determine the free oil content and the adsorbed oil content corresponding to each core sample;
  • Step A3 Based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each typical lithofacies, the geologically recoverable reserves of shale oil are evaluated.
  • step A1 obtaining typical lithology combination samples of each typical lithofacies of the shale layer section in the study area includes:
  • Step A11 Obtain core samples of different lithologies corresponding to typical rocks in the shale layer section of the study area;
  • Step A12 Conducting organic carbon and pyrolysis analysis on each core sample to determine the soluble and insoluble organic matter content and geochemical characteristics of each core sample;
  • Step A13 based on the organic carbon content and the pyrolysis parameter S 1 (ie, the free hydrocarbon content) of each core sample, typical lithology combination samples are screened out;
  • one is the organic carbon content. The higher the content, the more oil it produces; the second is the ratio of the pyrolysis parameter S1 to the organic carbon content, which reflects the oil storage capacity and the amount of crude oil charged; the third is the main mineral composition, including clay, quartz, feldspar, calcite, dolomite, pyrite, etc.
  • the first choice is a high organic carbon content, followed by a large ratio of the pyrolysis parameter S1 to the organic carbon content, and thirdly, the content of different lithological minerals such as clay, siltstone, and lime dolomite is combined to achieve core sample screening; in this preferred embodiment, for each typical lithofacies, the corresponding core samples of different lithologies are obtained respectively, and then based on the organic carbon content of each core sample and the size of the pyrolysis parameter S1 , the samples that can reflect the oil content of the lithofacies are screened out as the typical lithological combination samples of the lithofacies.
  • the different lithofacies of the shale layer in the study area are used as evaluation units to complete the evaluation of the entire layer.
  • typical lithofacies types are delineated, thereby determining the typical lithofacies of the shale layers in the study area; the typical lithofacies can be determined by conventional methods, which will not be elaborated here.
  • step A3 the evaluation of geologically recoverable reserves of shale oil based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each typical lithofacies includes:
  • Step A31 determining the shale oil sweet spot lithofacies based on the free oil content and the adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each typical lithofacies;
  • Step A32 Determine the geologically recoverable reserves of shale oil based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each shale oil sweet spot lithofacies.
  • step A32 based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination sample of each shale oil sweet spot lithofacies, determining the geologically recoverable reserves of shale oil includes:
  • Step A311 Based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination sample of each shale oil sweet spot lithofacies, combined with the generation-reservoir relationship and oil-bearing characteristics, determine the free oil and adsorbed oil content range of each shale oil sweet spot lithofacies;
  • the content range of free oil and adsorbed oil of each shale oil sweet spot lithofacies is preliminarily determined based on the content of free oil and adsorbed oil corresponding to each core sample in the typical lithology combination samples of each shale oil sweet spot lithofacies; then, the content range of free oil and adsorbed oil of each shale oil sweet spot lithofacies preliminarily determined is corrected according to the generation-reservoir relationship and oil-bearing characteristics to make it consistent with the conventional knowledge in the field;
  • Mud shale has the strongest adsorption capacity, and the proportion of adsorbed oil to total oil is the largest, followed by lime-dolomie mudstone, silty mudstone, argillaceous lime-dolomie, argillaceous siltstone, and lime-dolomie siltstone; 2.
  • the oil generation capacity and oil discharge capacity decrease in the order of mud shale, lime-dolomie mudstone, silty mudstone, argillaceous lime-dolomie, argillaceous siltstone, and lime-dolomie siltstone; 3.
  • the oil storage capacity increases in the order of mud shale, lime-dolomie mudstone, silty mudstone, argillaceous lime-dolomie, argillaceous siltstone, and lime-dolomie siltstone.
  • Step A312 Determine the geologically recoverable reserves of shale oil based on the content range of free oil and adsorbed oil in each shale oil sweet spot lithofacies;
  • step A312 the geologically recoverable reserves of shale oil are determined using the free oil method of different lithofacies, specifically by the following formula:
  • Q R is the geological recoverable resources, unit 10 4 t
  • Qi is the geological recoverable resources of the ith lithofacies, unit 10 4 t
  • Ai is the oil-bearing area of the ith lithofacies, unit km 2
  • Hi is the effective thickness of the ith lithofacies, unit m
  • ⁇ i is the rock density of the ith lithofacies, t/m 3
  • Si is the free oil content of the ith lithofacies, unit mg/g rock
  • n is the total number of shale oil sweet spot lithofacies in the shale layer section of the study area
  • K is the compensation coefficient of free oil, usually 1.1-1.3;
  • the compensation coefficient K of free oil can be determined according to the proportion of C6 - C14 lighter oil in the free oil of the core taken out from the shale layer section of the study area. Generally, the greater the proportion of C6 - C14 lighter oil, the greater the compensation coefficient K of free oil.
  • determining the shale oil sweet spot lithofacies can be performed in a conventional manner in the art; for example, based on the free oil content and the adsorbed oil content corresponding to each core sample in the typical lithologic combination samples of each typical facies, determining the shale oil sweet spot lithofacies includes:
  • the determination of sweet spots usually considers two factors: the content of free oil and the degree of reservoir fracturing.
  • the free oil content in low organic matter abundance siltstone (including mud siltstone and lime dolomite siltstone) is relatively high, and the oil saturation depends on the degree of crude oil filling.
  • the free heavy oil and adsorbed hydrocarbon content in high organic matter abundance shale is high, which is related to the strong adsorption of organic matter and clay minerals.
  • the amount of free oil in each type of lithofacies is controlled by its oil generation amount, oil discharge amount, and crude oil filling degree.
  • the oil-bearing level of muddy siltstone facies, gray-dolomie siltstone facies, and muddy gray-dolomie facies is level 1, which is a type 1 sweet spot area;
  • the oil-bearing level of silty mudstone facies, gray-dolomie mudstone facies, and gray-dolomie facies is level 2, which is a type 2 sweet spot area;
  • the oil-bearing level of shale facies is level 3, which is a type 3 sweet spot area;
  • the specific values of oil saturation and free oil of different facies depend on the oil and gas geological conditions of the study area.
  • focusing on the development of regional fractures and microfractures is one of the important factors for the optimization of sweet spot sections.
  • step A2 for each core sample in the typical lithology combination sample of each typical lithofacies, the shale oil evaluation method provided in the above specific embodiment of the present invention is used to determine the free oil content and the adsorbed oil content corresponding to each core sample, which includes: step A21: obtaining a powder sample of each core sample; for each powder sample of each core sample, performing steps A22 to A23 respectively;
  • Step A22 extracting the powder sample with chloroform (i.e., chloroform) at 20°C-30°C to obtain free light oil;
  • chloroform i.e., chloroform
  • Step A23 extracting the residue obtained by chloroform at 20°C-30°C with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil;
  • Step A24 extracting the residue obtained by Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C with chloroform at 70°C-80°C to obtain adsorbed oil;
  • Step A25 determining the content of free oil and the content of adsorbed oil (including rock mineral adsorption and kerogen adsorption) based on the obtained free light oil, free heavy oil and adsorbed oil;
  • the particle size of the powder sample is 80 mesh-120 mesh
  • step A22 the extraction of the powder sample with chloroform (i.e., chloroform) at 20°C-30°C to obtain free light oil includes: step A221: immersing the powder sample in chloroform for extraction at 20°C-30°C, and then performing solid-liquid separation; step A222: observing whether the separated liquid phase is colorless; if the separated liquid phase is colored, performing step A223; if the separated liquid phase is colorless (usually, step A223 needs to be repeated at least twice before the separated liquid phase is colorless), performing step A224; step A223: immersing the separated solid phase in chloroform for extraction at 20°C-30°C, and then performing solid-liquid separation; and re- Step A222 is performed; Step A224: the liquid phase obtained from each solid-liquid separation is dried, and the product obtained by drying is free light oil; further, the solid-liquid separation is achieved by pouring out the liquid phase after standing; further, in step A224, the liquid phase obtained from each solid-liquid separation is dried after mixing; the
  • step A23 the step of extracting the residue obtained by chloroform extraction at 20°C-30°C with a mixture of dichloromethane and methanol at 60°C-70°C to obtain free heavy oil comprises: extracting the residue obtained by chloroform extraction at 20°C-30°C with a mixture of dichloromethane and methanol at 60°C-70°C until it is colorless, drying the liquid product, and the product obtained by drying is the free heavy oil; further, the drying is performed by air-drying;
  • step A24 the step of subjecting the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to Soxhlet extraction with chloroform at 70°C-80°C to obtain the adsorbed oil comprises: subjecting the residue obtained after Soxhlet extraction with a mixture of dichloromethane and methanol at 60°C-70°C to Soxhlet extraction with chloroform at 70°C-80°C until colorless, drying the liquid product, and the product obtained by drying is the adsorbed oil; further, the drying is performed by air-drying.
  • determining the content of free oil and the content of adsorbed oil includes:
  • Sf is the content of free oil, in mg/g rock
  • mfl is the mass of free light oil, in mg
  • mfh is the mass of free heavy oil, in mg
  • mc is the mass of powder sample of shale core, in g
  • Sa is the content of adsorbed oil, in mg/g rock
  • ma is the mass of adsorbed oil, in mg.
  • This example uses the shale layer section in area A as an example to evaluate the geologically recoverable reserves of shale oil.
  • the main body of area A is a fan delta-sublacustrine fan-lake sedimentary system under the background of saltwater-alkaline lake, which belongs to the sedimentary period of Fengcheng Formation, including the first, second and third shale intervals.
  • the sublacustrine fan margin-deep lake subfacies forms a large range of silty and dolomitic organic-rich shales with an area of 600km2 and a burial depth of more than 4000 meters.
  • the geothermal gradient is about 3.2°C/100m and the ground temperature is greater than 120°C.
  • the source rock has reached the mature stage, with sufficient oil generation and large quantity. It is a favorable zone for the development of shale oil.
  • many shale oil exploration wells such as A1, A2 and A3 have obtained industrial oil flow.
  • the specific evaluation methods for geologically recoverable reserves of shale oil in the shale layer section of area A include:
  • Step 1 Obtain typical lithology combination samples of each typical lithofacies in the shale layer section of the study area;
  • the overall characteristics of the shale sections in the study area are that the oil content of the core samples is positively correlated with the abundance of organic matter.
  • the second shale section 4632.7m and 4667.6m has the highest oil content, accounting for 1.26%-1.34% by weight and 3%-4% by volume;
  • the second and third shale sections have higher oil contents than the first shale section, and the proportion of high oil content in the third shale section is greater than that in the second shale section;
  • the first shale section has low organic matter abundance, but a high content of soluble hydrocarbons per unit of organic matter, reflecting the relative accumulation of crude oil;
  • the oil content statistics of the second and third shale sections by lithology show that the proportion of soluble organic matter in muddy siltstone and silty mudstone to total organic matter is higher than that in dolomitic/gray/siliceous shale, reflecting the hydrocarbon expulsion and primary migration of crude oil.
  • Step 2 For each core sample in the typical lithology combination sample of each typical lithofacies, shale oil storage evaluation is performed to determine the free oil content and adsorbed oil content corresponding to each core sample; wherein, shale oil storage evaluation includes:
  • step A immersing the powder sample in chloroform and stirring and extracting at room temperature, and pouring out the liquid phase after standing
  • step B observing whether the liquid phase is colorless, if the poured liquid phase is colored, proceeding to step C, and if the poured liquid phase is colorless, proceeding to step D
  • step C immersing the poured solid phase in chloroform and stirring and extracting at room temperature, and pouring out the liquid phase after standing, and repeating step B
  • step D mixing the poured liquid phases each time and drying them to obtain free light oil;
  • the mass of free light oil, the mass of free heavy oil and the mass of adsorbed oil are determined respectively; based on the mass of free light oil, the mass of free heavy oil and the mass of adsorbed oil, the free oil content and the adsorbed oil content are determined by the following formula:
  • Sf is the content of free oil, in mg/g rock
  • mfl is the mass of free light oil, in mg
  • mfh is the mass of free heavy oil, in mg
  • mc is the mass of powder sample of shale core, in g
  • Sa is the content of adsorbed oil, in mg/g rock
  • ma is the mass of adsorbed oil, in mg
  • the obtained free light oil, free heavy oil and adsorbed oil were subjected to saturated hydrocarbon chromatography analysis respectively, so as to determine the composition of the free oil and the composition of the adsorbed oil.
  • Figure 6 is a comparison of free oil and adsorbed oil in typical lithologic combination samples of shale intervals.
  • the overall oil-bearing characteristics of different lithologic reservoirs in the shale formations in the study area are that the free heavy oil content in high organic matter abundance shales is the highest, which is related to the adsorption of organic matter; the characteristics of adsorbed oil are that the overall content is relatively low, and its ratio of S heavy light to organic carbon/TOC varies widely, which is most closely related to the clay content in the rock.
  • the free light oil content in high organic matter abundance shales is also high, which is related to its large amount of oil generation; the free light oil content in low organic matter abundance siltstone is not particularly low, and its S free light /TOC ratio is comparable to that in high organic matter abundance shales , reflecting the strong hydrocarbon expulsion and migration of crude oil.
  • the thermal evolution degree of the Fengcheng Formation source kitchen Ro1.0%-1.4% which is in the mature to highly over-mature stage, has produced 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. It is the result of the combined effect of multiple factors.
  • the sample was finely crushed, the particle size became smaller, the closed space of the oil storage was opened, the connectivity became better, and some of the particle adsorbed and throat-shaped adsorbed oils were converted into free oils; at the same time, the particle size became smaller, the specific surface area increased, and some of the free oils were converted into adsorbed oils.
  • Step 3 Based on the free oil content and adsorbed oil content corresponding to each core sample in the typical lithology combination samples of each typical lithofacies, the geologically recoverable reserves of shale oil are evaluated;
  • the free oil and adsorbed oil content range of each shale oil sweet spot lithofacies is determined; based on the free oil and adsorbed oil content range of each shale oil sweet spot lithofacies, the geologically recoverable reserves of shale oil are determined by the following formula;
  • Q R is the geologically recoverable resources, unit is 10 4 t;
  • Qi is the geologically recoverable resources of the i-th lithofacies, unit is 10 4 t;
  • Ai is the oil-bearing area of the i-th lithofacies, unit is km 2 ;
  • Hi is the effective thickness of the i-th lithofacies, unit is m;
  • ⁇ i is the rock density of the i-th lithofacies, t/m 3 ;
  • Si is the free oil content of the i-th lithofacies, unit is mg/g rock;
  • n is the total number of shale oil sweet spot lithofacies in the shale layer of the study area;
  • K is the compensation coefficient of free oil.
  • the shale layer in the study area is widely developed in the main area of the slope-sag, with various lithology types, including mud shale, silty mudstone, lime-dolomitic mudstone, argillaceous siltstone, lime-dolomitic siltstone, argillaceous lime-dolomitic, lime-dolomitic, alkaline mineral rock, and volcanic rock.
  • lithology types including mud shale, silty mudstone, lime-dolomitic mudstone, argillaceous siltstone, lime-dolomitic siltstone, argillaceous lime-dolomitic, lime-dolomitic, alkaline mineral rock, and volcanic rock.
  • six typical lithofacies types can be divided, and their mineral combinations, oil generation and storage properties, and oil content characteristics are shown in Table 1.
  • the lithology is highly heterogeneous, the reservoir physical properties vary greatly, the oil content of different lithofacies varies greatly, fractures are well developed, and the reservoir types are diverse.
  • the evaluation of the sweet spot section takes two factors into consideration: the amount of free oil and the degree of fracturing.
  • the comprehensive evaluation results show that there are five lithofacies types in the study area that are closely related to oil and gas (as shown in Figure 7).
  • the argillaceous/lime-dolomite sandstone phase and the argillaceous lime-dolomite phase have an oil saturation of 40%-50%, S f 6.40-18.28 mg/g rock, and the comprehensive evaluation oil grade is 1, which is a type 1 sweet spot area;
  • the silty/lime-dolomite mudstone phase has an oil saturation of 40%-60%, S f 4.85-6.40 mg/g rock, and the lime-dolomite phase has an oil saturation of 20%-30%, S f 4.85-6.40 mg/g rock.
  • the comprehensive evaluation oil grade of the two is 2, which is a type 2 sweet spot area; the shale phase has an oil saturation of 50%-70%, S f 4.85-5.35 mg/g rock, and the comprehensive evaluation oil grade is 3, which is a type 3 sweet spot area.
  • lithofacies types there are six typical lithofacies types in the shale layer of the study area, among which there are five 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.
  • the relevant data of geologically recoverable reserves evaluation of shale oil in the study area are shown in Table 2.
  • the calculated geologically recoverable reserves of shale oil are 2.26 ⁇ 10 8 t-2.64 ⁇ 10 8 t.
  • the present invention can accurately evaluate the amount of free oil and adsorbed oil in shale, and can provide a deeper understanding of the generation and evolution of shale oil and the flow properties of crude oil compared to traditional methods.
  • the present invention can accurately complete the optimization of shale oil sweet spots and the evaluation of geologically recoverable reserves.

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Abstract

一种页岩赋存油评价方法及页岩油地质可采储量评价方法。页岩赋存油评价方法包括：获取目标页岩岩芯的粉末样；将粉末样用氯仿进行20℃-30℃条件下萃取得到游离的轻油；将用氯仿萃取后的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油；将用二氯甲烷和甲醇的混合物进行索氏抽提后的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油；基于游离的轻油、游离的重油和吸附油，确定游离油的含量和吸附油的含量，和/或，游离油的组成和吸附油组成。提供的技术方案能够准确评价页岩层段不同类型储层中游离油和吸附油的数量和特征，为研究区优选甜点段和评价页岩油开采效益提供支撑决策依据。

Description

一种页岩赋存油评价方法及页岩油地质可采储量评价方法 技术领域
本发明涉及一种页岩赋存油评价方法及页岩油地质可采储量评价方法。
背景技术
近年来，前人对页岩储层中油的赋存状态划分了3个端元，即吸附态油、互溶态油和游离态油，并以此为依据提出了不同的分离萃取定量技术和对应的页岩油资源量、地质可采储量的计算方法。分离萃取定量技术可归纳总结为两大类：一是溶剂分步萃取法，原理是基于页岩储层的不同赋存空间大小及分子极性的差异性，采用不同溶剂进行块样和粉末样品分别萃取获得。鉴于未梳理清原油的来源、生成过程以及原油与岩石中有机物、无机矿物间的相互关系、原油的活动性能等要素，所以萃取过程复杂，最重要的是每一步萃取物与实际地质体中不同赋存状态的原油未能有很好的一一对应关系，即萃取产物没有明确的地质意义。第二种是加热释放法，原理是基于不同赋存状态的页岩油具有不同的分子热挥发能力，赋存在裂缝及大孔隙中的页岩油相对微孔中的油容易热释放出来，小分子的化合物相对大分子的化合物容易热释放出来，而游离态的化合物相对吸附态的化合物容易热释放出来。因此，可以通过设置合理的加热实验条件对页岩体系中不同赋存状态的油进行定量表征。该方法的问题是加热作用增加了分子的活动性能，不能客观反映分子活动性能的大小；另外，加热作用使不溶有机质干酪根生成了部分可溶烃。
基于此，目前仍旧需要研究新的技术方案以更好的评价页岩赋存油为更好的评价页岩油地质可采储量、更好的优选页岩油甜点段奠定基础。
发明内容
本发明的目的在于提供一种能够适用于页岩层段不同类型储层中赋存油数量和特征评价的方法。
本发明的另一目的在于提供一种能够准确评价页岩油地质可采储量的方法。
为了实现上述目的，本发明提供了一种页岩赋存油评价方法，其中，该方法包括：
获取目标页岩岩心的粉末样；
将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油；
将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重轻油；
将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油；
基于得到的游离的轻油、游离的重油和吸附油，确定游离油的含量和吸附油(包括岩石矿物吸附和干酪根吸附)的含量，和/或，确定游离油的组成和吸附油组成。
在上述页岩赋存油评价方法中，优选地，所述粉末样的粒径为80目-120目。
在上述页岩赋存油评价方法中，优选地，所述将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油包括：
步骤1：将粉末样浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；
步骤2：观察分离后的液相是否为无色；如果分离后的液相有色，则进行步骤3；如果分离后的液相无色(通常情况下，在分离后的液相为无色前需要重复进行至少两次步骤3)，则进行步骤4；
步骤3：将分离后的固相浸泡浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；并重新进行步骤2：
步骤4：将每次固液分离得到的液相进行干燥，干燥得到的产物即为游离的轻油。
在上述页岩赋存油评价方法中，优选地，所述二氯甲烷和甲醇的混合物中二氯甲烷和甲醇的体积比为93:7。
在上述页岩赋存油评价方法中，优选地，所述将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油包括：
将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物在60℃-70℃条件下进行索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为游离的重油。
在上述页岩赋存油评价方法中，优选地，所述将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油包括：
将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣用氯仿进行70℃-80℃条件下索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为吸附油。
在上述页岩赋存油评价方法中，优选地，所述确定游离油的含量和吸附油的含量包括：
分别确定游离的轻油的质量、游离的重油的质量和吸附油的质量；
基于游离的轻油的质量、游离的重油的质量和吸附油的质量通过下述公式确定游离油的含量、吸附油的含量：
S f＝(m fl+m fh)÷m c
S a＝m a÷m c
式中，S f为游离油的含量，单位mg/g岩石；m fl为游离的轻油的质量，单位mg；m fh为游离的重油的质量，单位mg；m c为页岩岩心的粉末样的质量，单位g；S a为吸附油的含量，单位mg/g岩石；m a为吸附油的质量，单位mg。
在上述页岩赋存油评价方法中，优选地，所述确定游离油的组成和吸附油组成包括：
分别对得到的游离的轻油、游离的重油和吸附油进行饱和烃色谱分析，从而确定游离油的组成和吸附油组成。
本发明还提供了一种页岩油地质可采储量评价方法，其中，该方法包括：
获取研究区页岩层段各典型岩相的典型岩性组合样品；
针对各典型岩相的典型岩性组合样品中的各个岩芯样品，分别利用本发明上述具体实施方式提供的页岩赋存油评价方法，确定各个岩芯样品对应的游离油的含量和吸附油的含量；
基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，进行页岩油地质可采储量评价。
在上述页岩油地质可采储量评价方法中，优选地，所述获取研究区页岩层段各典型岩相的典型岩性组合样品包括：
获取研究区页岩层段各典型岩相对应的不同岩性的岩芯样品；
分别对各岩芯样品进行有机碳、热解分析，确定各岩芯样品中可溶和不溶有机质含量及地球化学特征；
基于各岩芯样品的有机碳含量和热解参数S 1(即游离烃含量)的大小(有机碳含量和热解参数S1)，筛选出典型岩性组合样品。
在上述页岩油地质可采储量评价方法中，优选地，所述基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，进行页岩油地质可采储量评价包括：
基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油甜点岩相；
基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油地质可采储量。
在上述页岩油地质可采储量评价方法中，优选地，基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油地质可采储量包括：
基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，结合生储关系合含油特征，确定各页岩油甜点岩相的游离油和吸附油的含量范围；
基于各页岩油甜点岩相的游离油和吸附油的含量范围，确定页岩油地质可采储量；
更优选地，页岩油地质可采储量通过如下公式确定：
Figure PCTCN2022138947-appb-000001
式中，Q R为地质可采资源量，单位10 4t；Q i为第i种岩相的地质可采资源量，单位10 4t；A i为第i种岩相的含油面积，单位km 2；H i为第i种岩相的有效厚度，单位m；ρ i为第i种岩相的岩石密度；t/m 3；S i为第i种岩相的游离油含量，单位mg/g岩石；n为研究区页岩层段的各页岩油甜点岩相的总数量；K为游离油的补偿系数。
在上述页岩油地质可采储量评价方法中，优选地，所述针对各典型岩相的典型岩性组合样品中的各个岩芯样品，分别利用本发明上述页岩赋存油评价方法，确定各个岩芯样品对应的游离油的含量和吸附油的含量包括：
获取各个岩芯样品的粉末样；针对各个岩芯样品的粉末样，分别进行下述步骤；
将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油；
将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油；
将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油；
基于得到的游离的轻油、游离的重油和吸附油，确定游离油的含量和吸附油(包括岩石矿物吸附和干酪根吸附)的含量。
在上述页岩油地质可采储量评价方法中，优选地，所述粉末样的粒径为80目-120目。
在上述页岩油地质可采储量评价方法中，优选地，所述将粉末样用氯仿(即三氯甲 烷)进行20℃-30℃条件下萃取得到游离的轻油包括：
步骤1：将粉末样浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；
步骤2：观察分离后的液相是否为无色；如果分离后的液相有色，则进行步骤3；如果分离后的液相无色(通常情况下，在分离后的液相为无色前需要重复进行至少两次步骤3)，则进行步骤4；
步骤3：将分离后的固相浸泡浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；并重新进行步骤2：
步骤4：将每次固液分离得到的液相进行干燥，干燥得到的产物即为游离的轻油。
在上述页岩油地质可采储量评价方法中，优选地，所述二氯甲烷和甲醇的混合物中二氯甲烷和甲醇的体积比为93:7。
在上述页岩油地质可采储量评价方法中，优选地，所述将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油包括：将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物在60℃-70℃条件下进行索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为游离的重油。
在上述页岩油地质可采储量评价方法中，优选地，所述将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油包括：将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣用氯仿进行70℃-80℃条件下索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为吸附油。
在上述页岩油地质可采储量评价方法中，优选地，所述确定游离油的含量和吸附油的含量包括：
分别确定游离的轻油的质量、游离的重油的质量和吸附油的质量；
基于游离的轻油的质量、游离的重油的质量和吸附油的质量通过下述公式确定游离油的含量、吸附油的含量：
S f＝(m fl+m fh)÷m c
S a＝m a÷m c
式中，S f为游离油的含量，单位mg/g岩石；m fl为游离的轻油的质量，单位mg；m fh为游离的重油的质量，单位mg；m c为页岩岩心的粉末样的质量，单位g；S a为吸附油的含量，单位mg/g岩石；m a为吸附油的质量，单位mg。
页岩层段赋存油评价是页岩储层评价的核心，本发明提供的技术方案能够准确评价页岩游离油和吸附油的数量、特征，为优选甜点段和准确评价地质可采储量提供支撑决策依据。与传统方法相比较，更能深层地认识页岩层段中原油的生成演化过程以及原油与岩石中有机物、无机物间的吸附力、原油的活动性能等。
附图说明
图1为本发明一具体实施方式提供的页岩赋存油评价方法的流程图。
图2为本发明一具体实施方式提供的页岩油地质可采储量评价方法的流程图。
图3为本发明实施例1中研究区风城组一、二、三段有机质综合剖面图。
图4为本发明实施例1中研究区风城组一、二、三段可溶和不溶有机质相关图。
图5为本发明实施例1中研究区风城组一、二、三段有机碳和S 1/TOC相关图。
图6为本发明实施例1中研究区页岩层段典型岩性组合样品的游离油和吸附油对比图。
图7为本发明实施例1中研究区重点井页岩层段不同岩相分布图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚完整的描述。显然，所描述的实施例是本发明的一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其它实施例，都属于本发明的保护范围。
目前的划分方案与地质体中油的赋存形式不能很好的一一对应，即未能客观表述地质体中油的赋存特征，从而影响了原油流动性的评价。由此出发，在本发明技术方案中将页岩储层中原油的赋存状态划分为2个端元，即吸附态油和游离态油，不再划分出“互溶态”端元，主要原因是考虑原油的生成过程及其母源，即原油是干酪根热降解的产物，已从母体的结构中断裂出来，所以不存在2种物质的互溶作用。吸附态原油存在的基础是基于相似相容原理，且有机质的吸附能力远大于无机矿物的。游离态原油存在的基础是，生成的大量原油满足干酪根的吸附后，就会向浓度低的空间扩散；进一步满足周边无机矿物的吸附后，大量原油与干酪根形成“有机网络”，就发生连续运移作用。由此可见，吸附态与游离态原油有明确的界限，可以厘定。
游离态油和吸附态油存在4个方面的差异，①赋存空间，包括大小及连通性：游离态油赋存空间大的相对较多，因而其与溶剂的接触面积较大，容易被萃取出，而赋存在 微孔中的、以及干酪根大分子包络的原油，由于与溶剂接触能力受限，难于被萃取出；②分子极性：游离态油经过运移分馏作用，一般分子极性较小，容易被萃取出，而吸附态油一般分子极性较大，相对不易被萃取；③分子热挥发能力：游离态油经过运移分馏，分子较小，一般容易挥发；④分子活动能力：游离态油较吸附态油少了吸附作用，更易被萃取。
基于强调分子活动能力(包括物理吸附、化学吸附、原油流动性)是游离态油的特殊因素的需求，结合对页岩储层中原油赋存状态“二端元”的研究，以及对萃取溶剂和实验条件进行的系统分析，选用不同溶剂不同温阶分步萃取定量技术，提出了本发明技术方案。
参见图1，本发明一具体实施方式提供了一种页岩赋存油评价方法，其中，该方法包括：
步骤S1：获取目标页岩岩心的粉末样；
步骤S2：将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油；
步骤S3：将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重轻油；
步骤S4：将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油；
步骤S5：基于得到的游离的轻油、游离的重油和吸附油，确定游离油的含量和吸附油(包括岩石矿物吸附和干酪根吸附)的含量，和/或，确定游离油的组成和吸附油组成。
本发明提供的页岩赋存油评价方法是发明人基于“二元论”的研究认识(即将页岩储层中的原油只划分了2个端元，吸附态油和游离态油，没有划出“互溶态”端元)，在重新认识含油性和原油的流动机理以及影响因素等基础上提出的。在该页岩赋存油评价方法中，先利用氯仿进行20℃-30℃条件下萃取将游离的轻油萃取出来，此时分子量较重的非烃、沥青质等组分的游离油尚未完全萃取出，选用极性更强、与其相似度更好的二氯甲烷和甲醇的混合物作为溶剂在60℃-70℃条件下进行索氏抽提进一步完成萃取工作，将游离的重轻萃取出来，最终再利用氯仿在70℃-80℃条件下行索氏抽提将吸附态油萃取出来。
进一步地，步骤S1中，所述粉末样的粒径为80目-120目。
进一步地，步骤S2中，所述将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油包括：
步骤S21：将粉末样浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；
步骤S22：观察分离后的液相是否为无色；如果分离后的液相有色，则进行步骤S23；如果分离后的液相无色(通常情况下，在分离后的液相为无色前需要重复进行至少两次步骤S23)，则进行步骤S24；
步骤S23：将分离后的固相浸泡浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；并重新进行步骤S22：
步骤S24：将每次固液分离得到的液相进行干燥，干燥得到的产物即为游离的轻油；
更进一步地，所述固液分离采用静置后倒出液相的方式实现；
更进一步地，步骤S24中，所述将每次固液分离得到的液相进行干燥包括：将每次固液分离得到的液相混合后进行干燥；将每次固液分离得到的液相混合后进行干燥，有助于减少定量的误差；
更进一步地，在所述萃取过程中，进行搅拌；
更进一步地，所述干燥采用晾干的方式进行。
进一步地，步骤S3中，所述二氯甲烷和甲醇的混合物中二氯甲烷和甲醇的体积比为93:7。
进一步地，步骤S3中，所述将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油包括：
将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物在60℃-70℃条件下进行索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为游离的重油；
更进一步地，所述干燥采用晾干的方式进行。
进一步地，步骤S4中，所述将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油包括：
将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣用氯仿进行70℃-80℃条件下索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为吸附油；
更进一步地，所述干燥采用晾干的方式进行。
进一步地，步骤S5中，所述确定游离油的含量和吸附油的含量包括：
分别确定游离的轻油的质量、游离的重油的质量和吸附油的质量；
基于游离的轻油的质量、游离的重油的质量和吸附油的质量通过下述公式确定游离油的含量、吸附油的含量：
S f＝(m fl+m fh)÷m c
S a＝m a÷m c
式中，S f为游离油的含量，单位mg/g岩石；m fl为游离的轻油的质量，单位mg；m fh为游离的重油的质量，单位mg；m c为页岩岩心的粉末样的质量，单位g；S a为吸附油的含量，单位mg/g岩石；m a为吸附油的质量，单位mg。
进一步地，步骤S5中，所述确定游离油的组成和吸附油组成包括：
分别对得到的游离的轻油、游离的重油和吸附油进行饱和烃色谱分析，从而确定游离油的组成和吸附油组成。
参见图2，本发明一具体实施方式提供了一种页岩油地质可采储量评价方法，其中，该方法包括：
步骤A1：获取研究区页岩层段各典型岩相的典型岩性组合样品；
步骤A2：针对各典型岩相的典型岩性组合样品中的各个岩芯样品，分别利用本发明上述具体实施方式提供的页岩赋存油评价方法，确定各个岩芯样品对应的游离油的含量和吸附油的含量；
步骤A3：基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，进行页岩油地质可采储量评价。
进一步地，步骤A1中，所述获取研究区页岩层段各典型岩相的典型岩性组合样品包括：
步骤A11：获取研究区页岩层段各典型岩相对应的不同岩性的岩芯样品；
步骤A12：分别对各岩芯样品进行有机碳、热解分析，确定各岩芯样品中可溶和不溶有机质含量及地球化学特征；
步骤A13：基于各岩芯样品的有机碳含量和热解参数S 1(即游离烃含量)的大小，筛选出典型岩性组合样品；
其中，筛选样品时，主要考虑3方面因素，一是有机碳含量，越高者生油越多，二是热解参数S 1与有机碳含量的比值的大小，反映储油能力和原油充注多少，三是主要矿物组成，包括黏土、石英、长石、方解石、白云石、黄铁矿等，黏土含量高者生油多， 石英等脆性矿物含量高者可压裂程度高，是很好的开采层段；具体而言，首选有机碳含量高，其次热解参数S 1与有机碳含量的比值大，第三结合黏土、粉砂岩、灰云岩矿物等不同岩性矿物的含量，从而实现岩芯样品筛选，；在该优选实施方式中，针对各典型岩相，分别获取其对应的不同岩性的岩芯样品，然后基于各岩芯样品的有机碳含量和热解参数S 1的大小，筛选出能够反应该岩相的含油情况的样品作为该岩相的典型岩性组合样品。
以研究区页岩层段不同岩相作为评价单元，完成整个层段的评价工作。
进一步地，通过开展研究区页岩层段岩相研究，划出典型的岩相类型，从而确定研究区页岩层段各典型岩相；典型岩相的确定通过常规方式进行确定即可，在此不在赘述。
进一步地，步骤A3中，所述基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，进行页岩油地质可采储量评价包括：
步骤A31：基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油甜点岩相；
步骤A32：基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量＝，确定页岩油地质可采储量。
进一步地，步骤A32中，基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油地质可采储量包括：
步骤A311：基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，结合生储关系和含油特征，确定各页岩油甜点岩相的游离油和吸附油的含量范围；
其中，基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量、吸附油的含量初步确定各页岩油甜点岩相的游离油和吸附油的含量范围；然后在根据生储关系和含油特征对初步确定的各页岩油甜点岩相的游离油和吸附油的含量范围进行校正，使其符合本领域的常规认知；
按照本领域的常规认知：一、，泥页岩吸附能力最强，吸附油占总油的比例最大，其次依次是灰云质泥岩、粉砂质泥岩、泥质灰云岩、泥质粉砂岩、灰云质粉砂岩；二、生油能力和排油能力按照泥页岩、灰云质泥岩、粉砂质泥岩、泥质灰云岩、泥质粉砂岩、灰云质粉砂岩依次减弱；三、储油能力按照泥页岩、灰云质泥岩、粉砂质泥岩、泥质灰云岩、泥质粉砂岩、灰云质粉砂岩依次增强。
步骤A312：基于各页岩油甜点岩相的游离油和吸附油的含量范围，确定页岩油地 质可采储量；
进一步地，步骤A312中，页岩油地质可采储量采用不同岩相游离油法进行确定，具体通过如下公式确定：
Figure PCTCN2022138947-appb-000002
式中，Q R为地质可采资源量，单位10 4t；Q i为第i种岩相的地质可采资源量，单位10 4t；A i为第i种岩相的含油面积，单位km 2；H i为第i种岩相的有效厚度，单位m；ρ i为第i种岩相的岩石密度；t/m 3；S i为第i种岩相的游离油含量，单位mg/g岩石；n为研究区页岩层段的各页岩油甜点岩相的总数量；K为游离油的补偿系数，通常取1.1-1.3；
其中，游离油的游离油的补偿系数K可以根据研究区页岩层段钻井取出的岩芯游离油中C 6-C 14较轻油的占比来确定，通常C 6-C 14较轻油的占比越大游离油的游离油的补偿系数K越大。
进一步地，步骤A31中，基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油甜点岩相可以采用本领域常规方式进行；举例而言，基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油甜点岩相包括：
基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，结合含油特征分析，划出不同的含油级别、不同的甜点类型；从而确定页岩油甜点岩相；
甜点段的确定通常考虑两方面的因素，游离油的含量以及储层可压裂程度；低有机质丰度的粉砂岩(包括泥质粉砂岩、灰云质粉砂岩)中游离油相对含量较高，含油饱和度视原油充注程度而定；高有机质丰度页岩中游离重油和吸附烃含量较高，与有机质和黏土矿物的强吸附作用有关；每一类岩相的游离油数量受控于其生油数量、排油数量、原油充注程度；综合评价泥质粉砂岩相、灰云质粉砂岩相、泥质灰云岩相含油级别为1级，为1类甜点区；粉砂质泥岩相、灰云质泥岩相、灰云岩相含油级别为2级，为2类甜点区；泥页岩相含油级别为3级，为3类甜点区；不同岩相的含油饱和度和游离油具体数值视研究区油气地质条件而定，同时重点关注区域裂缝和微裂缝的发育，是甜点段优选的重要因素之一。
进一步地，步骤A2中，所述针对各典型岩相的典型岩性组合样品中的各个岩芯样 品，分别利用本发明上述具体实施方式提供的页岩赋存油评价方法，确定各个岩芯样品对应的游离油的含量和吸附油的含量包括：步骤A21：获取各个岩心样品的粉末样；针对各个岩心样品的粉末样，分别进行步骤A22-步骤A23；
步骤A22：将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油；
步骤A23：将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油；
步骤A24：将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油；
步骤A25：基于得到的游离的轻油、游离的重油和吸附油，确定游离油的含量和吸附油(包括岩石矿物吸附和干酪根吸附)的含量；
更进一步地，步骤A21中，所述粉末样的粒径为80目-120目；
更进一步地，步骤A22中，所述将粉末样用氯仿(即三氯甲烷)进行20℃-30℃条件下萃取得到游离的轻油包括：步骤A221：将粉末样浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；步骤A222：观察分离后的液相是否为无色；如果分离后的液相有色，则进行步骤A223；如果分离后的液相无色(通常情况下，在分离后的液相为无色前需要重复进行至少两次步骤A223)，则进行步骤A224；步骤A223：将分离后的固相浸泡浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；并重新进行步骤A222；步骤A224：将每次固液分离得到的液相进行干燥，干燥得到的产物即为游离的轻油；再进一步地，所述固液分离采用静置后倒出液相的方式实现；再进一步地，步骤A224中，所述将每次固液分离得到的液相进行干燥包括：将每次固液分离得到的液相混合后进行干燥；将每次固液分离得到的液相混合后进行干燥，有助于减少定量的误差；再进一步地，在所述萃取过程中，进行搅拌；再进一步地，所述干燥采用晾干的方式进行；进一步地，步骤S3中，所述二氯甲烷和甲醇的混合物中二氯甲烷和甲醇的体积比为93:7；
更进一步地，步骤A23中，所述将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油包括：将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物在60℃-70℃条件下进行索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为游离的重油；再进一步地，所述干燥采用晾干的方式进行；
更进一步地，步骤A24中，所述将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油包括：将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣用氯仿进行70℃-80℃条件下索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为吸附油；再进一步地，所述干燥采用晾干的方式进行。
更进一步地，步骤A25中，所述确定游离油的含量和吸附油的含量包括：
分别确定游离的轻油的质量、游离的重油的质量和吸附油的质量；
基于游离的轻油的质量、游离的重油的质量和吸附油的质量通过下述公式确定游离油的含量、吸附油的含量：
S f＝(m fl+m fh)÷m c
S a＝m a÷m c
式中，S f为游离油的含量，单位mg/g岩石；m fl为游离的轻油的质量，单位mg；m fh为游离的重油的质量，单位mg；m c为页岩岩心的粉末样的质量，单位g；S a为吸附油的含量，单位mg/g岩石；m a为吸附油的质量，单位mg。
实施例1
本实施例以A地区的页岩层段为例进行页岩油地质可采储量评价。
A地区主体为咸水-碱湖背景下的扇三角洲—湖底扇—湖泊沉积体系，属于风城组沉积期，包括第一、第二、第三共计三个页岩层段，湖底扇缘-深湖亚相形成大范围粉砂质、白云质富有机质页岩，面积600km 2，埋深多大于4000米，地温梯度3.2℃/100m左右，地温大于120℃，烃源岩达成熟阶段，生油充分，数量多，是页岩油发育的有利区带，目前已实施的A1、A2、A3等多口页岩油探井均获得工业油流。
A地区的页岩层段的页岩油地质可采储量评价方法具体包括：
步骤1：获取研究区页岩层段各典型岩相的典型岩性组合样品；
具体而言，开展研究区页岩层段岩相研究，划出典型的岩相类型，确定研究区页岩层段各典型岩相；根据研究区页岩层段典型的岩相类型采集各典型岩相对应的不同岩性的岩心样品；对采集的岩芯样品进行有机碳、热解分析，确定各岩芯样品中可溶和不溶有机质含量及基础地球化学特征，分析结果示如图3、图4、图5所示；基于各岩芯样品的有机碳含量和热解参数S 1(即游离烃含量)的大小(有机碳含量和热解参数S 1)，筛选出典型岩性组合样品；
研究区页岩层段整体特征为岩芯样品含油数量与有机质丰度成正相关，其中，第二 页岩层段4632.7m、4667.6m含油量最多，重量占比1.26％-1.34％，体积占比3％-4％；第二、第三页岩层段较第一页岩层段含油量高，第三页岩层段含油量高的比例较第二岩层段大；第一页岩层段有机质丰度低，但单位有机质的可溶烃含量较高，反映原油的相对聚集；第二、第三页岩层段分岩性的含油量统计表明，泥质粉砂岩和粉砂质泥岩中可溶有机质占总有机质的比较云质/灰质/硅质页岩高，反映原油的排烃及初次运移作用。
步骤2：针对各典型岩相的典型岩性组合样品中的各个岩芯样品，分别进行页岩赋存油评价，确定各个岩心样品对应的游离油的含量和吸附油的含量；其中，页岩赋存油评价包括：
获取岩芯样品的粉末样；其中，粉末样的粒径为80目-120目；
将粉末样用氯仿进行室温萃取得到游离的轻油；具体而言，步骤A、将粉末样浸泡进氯仿中在室温下进行搅拌萃取，静置后倒出液相；步骤B、观察液相是否为无色，如果倒出的液相有色则进行步骤C，如果倒出的液相无色则进行步骤D；步骤C、将倒出后的固相浸泡浸泡进氯仿中在室温下进行搅拌萃取，静置后倒出液相，并重新进行步骤B；步骤D、将每次倒出的液相混合后晾干得到游离的轻油；
将用氯仿进行室温萃取后得到的残渣用二氯甲烷和甲醇的混合物(二氯甲烷和甲醇的体积比为93:7)在60℃下进行索氏抽提直至无色，将液相产物晾干得到游离的重油；
将用二氯甲烷和甲醇的混合物在60℃下进行索氏抽提后得到的残渣用氯仿进行70℃下索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为吸附油；
分别确定游离的轻油的质量、游离的重油的质量和吸附油的质量；基于游离的轻油的质量、游离的重油的质量和吸附油的质量通过下述公式确定游离油的含量、吸附油的含量：
S f＝(m fl+m fh)÷m c
S a＝m a÷m c
式中，S f为游离油的含量，单位mg/g岩石；m fl为游离的轻油的质量，单位mg；m fh为游离的重油的质量，单位mg；m c为页岩岩心的粉末样的质量，单位g；S a为吸附油的含量，单位mg/g岩石；m a为吸附油的质量，单位mg；
分别对得到的游离的轻油、游离的重油和吸附油进行饱和烃色谱分析，从而确定游离油的组成和吸附油组成。
至此，各样品中游离油和吸附油的分离、定量工作已完成。图6为页岩层段典型岩性组合样品的游离油和吸附油对比图。研究区页岩层系不同岩性储层的整体含油特征是 高有机质丰度页岩中游离重油含量最高，与有机质的吸附作用有关；吸附油的特征是整体含量都比较低，其与有机碳的比值S 重轻/TOC变化范围大，这与岩石中黏土含量关系最为密切。高有机质丰度页岩中游离轻油含量亦高，与其大量生油作用有关；低有机质丰度的粉砂岩中游离轻油含量并非特别低，其S 游离轻/TOC比值与高有机质丰度页岩中S 游离 轻/TOC比值相当，反映原油较强的排烃运移作用。风城组烃源灶热演化程度Ro1.0％-1.4％，处于成熟至高过成熟阶段，已大量原油。吸附烃含量相对较低，与脆性矿物含量高、微裂缝发育、黏土矿物含量和有机质含量相对较低关系密切，是多种因素共同作用的结果。另外，实验中，样品粉碎细，粒级变小，储油的封闭空间被打开，连通性变好，部分颗粒吸附态以及喉状吸附态油转化为游离态油；同时，粒级变小，比表面积增大，部分游离态油转化为吸附态。
步骤3：基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，进行页岩油地质可采储量评价；
具体而言：基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，结合含油特征分析，划出不同的含油级别、不同的甜点类型，确定甜点段确定页岩油甜点岩相；
基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，结合生储关系合含油特征，确定各页岩油甜点岩相的游离油和吸附油的含量范围；基于各页岩油甜点岩相的游离油和吸附油的含量范围，通过如下公式确定页岩油地质可采储量；
Figure PCTCN2022138947-appb-000003
式中，Q R为地质可采资源量，单位10 4t；Q i为第i种岩相的地质可采资源量，单位10 4t；A i为第i种岩相的含油面积，单位km 2；H i为第i种岩相的有效厚度，单位m；ρ i为第i种岩相的岩石密度；t/m 3；S i为第i种岩相的游离油含量，单位mg/g岩石；n为研究区页岩层段的各页岩油甜点岩相的总数量；K为游离油的补偿系数。
在本实施例中，研究区页岩层段在斜坡-凹陷主体区广泛发育，岩性类型多样，泥页岩、粉砂质泥岩、灰云质泥岩、泥质粉砂岩、灰云质粉砂岩、泥质灰云岩、灰云岩、碱性矿物岩、火山岩均有发育。具体可以划分出典型的6种岩相类型，其矿物组合及其生储油性能、含油性特征见表1。
表1研究区页岩层段6种典型岩相类型及含油级别
Figure PCTCN2022138947-appb-000004
由此可见，其岩性非均质性强，储层物性差异大，不同岩相含油性差异大，裂缝发育，油藏类型多样。甜点段的评价考虑两方面的因素，游离油的数量以及可压裂程度，综合评价结果研究区有5种岩相类型与油气关系密切(如图7所示)，其中泥质/灰云质砂岩相、泥质灰云岩相含油饱和度40％-50％，S f 6.40-18.28mg/g岩石，综合评价含油级别为1级，为1类甜点区；粉砂质/灰云质泥岩相含油饱和度40％-60％，S f 4.85-6.40mg/g岩石，灰云岩相含油饱和度20％-30％，S f 4.85-6.40mg/g岩石，二者综合评价含油级别为2级，为2类甜点区；泥页岩相含油饱和度50％-70％，S f 4.85-5.35mg/g岩石，综合评价含油级别为3级，为3类甜点区。
研究区页岩层段典型的岩相类型有6种，其中，页岩油甜点岩相(即与油气密切相关的岩相)有5种，该区游离油补偿系数K取1.3，研究区页岩油地质可采储量评价相关数据详见表2，计算的页岩油地质可采储量为2.26×10 8t-2.64×10 8t。
表2研究区主要岩相页岩油地质可采储量的评价参数
Figure PCTCN2022138947-appb-000005
Figure PCTCN2022138947-appb-000006
Figure PCTCN2022138947-appb-000007
以上实施例说明，应用本发明，可准确评价页岩中游离油和吸附油的数量，与传统方法相比较，更能从深层地认识页岩油的生成演化以及原油的流动性能等。另外，应用本发明，可准确完成页岩油甜点段优选和地质可采储量评价。

Claims (12)

  1. 一种页岩赋存油评价方法，其中，该方法包括：
    获取目标页岩岩芯的粉末样；
    将粉末样用氯仿进行20℃-30℃条件下萃取得到游离的轻油；
    将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油；
    将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油；
    基于得到的游离的轻油、游离的重油和吸附油，确定游离油的含量和吸附油的含量，和/或，确定游离油的组成和吸附油组成。
  2. 根据权利要求1所述的评价方法，其中，所述粉末样的粒径为80-120目。
  3. 根据权利要求1所述的评价方法，其中，所述将粉末样用氯仿进行20℃-30℃条件下萃取得到游离的轻油包括：
    步骤1：将粉末样浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；
    步骤2：观察分离后的液相是否为无色；如果分离后的液相有色，则进行步骤3；如果分离后的液相无色，则进行步骤4；
    步骤3：将分离后的固相浸泡进氯仿中在20℃-30℃条件下进行萃取，进而进行固液分离；并重新进行步骤2：
    步骤4：将每次固液分离得到的液相进行干燥，干燥得到的产物即为游离的轻油。
  4. 根据权利要求1所述的评价方法，其中，所述二氯甲烷和甲醇的混合物中二氯甲烷和甲醇的体积比为93:7。
  5. 根据权利要求1所述的评价方法，其中，所述将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提得到游离的重油包括：
    将用氯仿进行20℃-30℃条件下萃取后得到的残渣用二氯甲烷和甲醇的混合物在60℃-70℃条件下进行索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为游离的重油。
  6. 根据权利要求1所述的评价方法，其中，所述将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣进行70℃-80℃条件下氯仿索氏抽提得到吸附油包括：
    将用二氯甲烷和甲醇的混合物进行60℃-70℃条件下索氏抽提后得到的残渣用氯仿进行70℃-80℃条件下索氏抽提直至无色，将液相产物进行干燥，干燥得到的产物即为吸附油。
  7. 根据权利要求1所述的评价方法，其中，所述确定游离油的含量和吸附油的含量包括：
    分别确定游离的轻油的质量、游离的重油的质量和吸附油的质量；
    基于游离的轻油的质量、游离的重油的质量和吸附油的质量通过下述公式确定游离油的含量、吸附油的含量：
    S f＝(m fl+m fh)÷m c
    S a＝m a÷m c
    式中，S f为游离油的含量，单位mg/g岩石；m fl为游离的轻油的质量，单位mg；m fh为游离的重油的质量，单位mg；m c为页岩岩心的粉末样的质量，单位g；S a为吸附油的含量，单位mg/g岩石；m a为吸附油的质量，单位mg。
  8. 一种页岩油地质可采储量评价方法，其中，该方法包括：
    获取研究区页岩层段各典型岩相的典型岩性组合样品；
    针对各典型岩相的典型岩性组合样品中的各个岩芯样品，分别利用权利要求1-7任一项所述的页岩赋存油评价方法，确定各个岩芯样品对应的游离油的含量和吸附油的含量；
    基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，进行页岩油地质可采储量评价。
  9. 根据权利要求8所述的评价方法，其中，所述获取研究区页岩层段各典型岩相的典型岩性组合样品包括：
    获取研究区页岩层段各典型岩相对应的不同岩性的岩芯样品；
    分别对各岩芯样品进行有机碳、热解分析，确定各岩芯样品中可溶和不溶有机质含量及地球化学特征；
    基于各岩芯样品的有机碳含量和热解参数S 1的大小，筛选出典型岩性组合样品。
  10. 根据权利要求8所述的评价方法，其中，所述基于各典型岩相的典型岩性组合样品中的各个岩心样品对应的游离烃的含量、吸附烃的含量、游离烃的组成和吸附烃组成，进行页岩油地质可采储量评价包括：
    基于各典型岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸 附油的含量，确定页岩油甜点岩相；
    基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油地质可采储量。
  11. 根据权利要求10所述的评价方法，其中，基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，确定页岩油地质可采储量包括：
    基于各页岩油甜点岩相的典型岩性组合样品中的各个岩芯样品对应的游离油的含量和吸附油的含量，结合生储关系合含油特征，确定各页岩油甜点岩相的游离油和吸附油的含量范围；
    基于各页岩油甜点岩相的游离油和吸附油的含量范围，确定页岩油地质可采储量。
  12. 根据权利要求11所述的评价方法，其中，页岩油地质可采储量通过如下公式确定：
    Figure PCTCN2022138947-appb-100001
    式中，Q R为地质可采资源量，单位10 4t；Q i为第i种岩相的地质可采资源量，单位10 4t；A i为第i种岩相的含油面积，单位km 2；H i为第i种岩相的有效厚度，单位m；ρ i为第i种岩相的岩石密度；t/m 3；S i为第i种岩相的游离油含量，单位mg/g岩石；n为研究区页岩层段的各页岩油甜点岩相的总数量；K为游离油的补偿系数。
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