Method for measuring oil content in shale or tight rock and applications

Abstract

The present application relates to shale oil and gas and tight oil and gas exploration and development technical field, disclose a kind of shale or dense rock oil content measurement method and application.The method is by carrying out exuding oil, organic solvent extraction treatment to core sample, the specific index parameter of different types of oil in core is obtained by determination, and the oil content of core sample is calculated using the specific index parameter.The method can realize the accurate measurement of recoverable oil content, free oil content, residual oil content and oil content in fresh core sample and non-fresh core sample, significantly improve the evaluation precision of shale oil and gas or dense oil and gas resources and oil and gas reserves.

Description

Technical Field

[0001] This invention relates to the field of shale oil and gas and tight oil and gas exploration and development technology, specifically to a method and application for measuring the oil content of mudstone or tight rock. Background Technology

[0002] Shale oil and tight oil have become important areas of oil and gas exploration and development, and in recent years, they have become the main drivers of global oil reserve and production growth. However, shale oil and tight oil have unique characteristics compared to conventional oil and gas. They are mainly found in shale or tight reservoirs, and are self-generated and self-storing petroleum resources. Due to the tightness of shale and tight reservoirs and the adsorption of organic matter, crude oil in shale and tight rocks exists in both free and adsorbed states. From the perspective of crude oil mobility, some free crude oil can flow and be produced under changing formation pressure conditions; this portion is called recoverable oil. Some free and adsorbed crude oil can be extracted using organic solvents; these two portions are called free oil. Some crude oil needs to be crushed before extraction; this portion is called residual oil. Accurately measuring the recoverable oil, free oil, and residual oil in shale and tight rocks is crucial for shale oil and tight oil exploration and development, as well as resource and reserve calculations.

[0003] There are three main types of existing techniques for measuring the oil content and free oil content in shale and tight rocks, and all three have technical limitations. The first type is the pyrolysis method, which involves crushing shale or tight rocks and heating them to 300°C. The ratio of the pyrolysis oil mass to the rock mass is taken as the free oil content. The drawback of this technique is that a significant portion of light hydrocarbons volatilizes during sample collection and crushing, and some crude oil cracks during heating to 300°C, resulting in a large error in the measurement results. Furthermore, this technique cannot measure the recoverable oil content and residual oil content in shale and tight rocks, thus failing to accurately determine the oil content. The second type is the organic solvent extraction method. This involves crushing shale or dense rock core samples at low temperatures and extracting them with dichloromethane or chloroform to obtain the oil mass in the extract. The ratio of oil mass to core sample mass is the oil content. The drawback of this technique is that a large amount of light hydrocarbons are lost during sample collection, preparation, and organic solvent evaporation. Furthermore, dichloromethane or chloroform has a low boiling point, making it prone to overboiling and failing to reach the formation temperature where the sample is located. Therefore, the extraction temperature is much lower than the formation temperature where the core sample is located. Since the mobility of oil in shale or dense rocks is highly correlated with temperature, this method cannot reflect the oil mobility under formation temperature conditions, resulting in large measurement errors. Additionally, it cannot measure the free oil content and recoverable oil content in shale or dense rocks. The third type is nuclear magnetic resonance (NMR), which uses two-dimensional NMR technology to measure the free oil content and residual oil content in shale or dense rocks. This technique requires measurement at room temperature and the core sample to be prepared into small pieces. During the sample collection and preparation process, light hydrocarbons in the shale or dense rocks will be lost, making it impossible to accurately measure the free oil content and oil content in the shale or dense rocks. In addition, crude oil from the sample location needs to be collected for NMR signal calibration. There are large errors in the crude oil sampling and calibration measurement process.

[0004] Therefore, it is urgent to solve the problem of accurately measuring the recoverable oil content, free oil content, residual oil content, and oil content in mudstone, shale, and dense rocks. Summary of the Invention

[0005] This invention addresses the problem that existing methods for testing the oil content of shale or dense rocks cannot accurately measure recoverable oil content, free oil content, residual oil content, and total oil content. It provides a method and application for measuring the oil content of shale or dense rocks.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for measuring the oil content of shale or tight rock, comprising:

[0007] (S1) Place the collected fresh core sample in a sealed container, heat it to the sampling formation temperature, obtain the oil mass that seeps out from the fresh core sample, obtain the core after the oil seeps out, and calculate the recoverable oil content in the fresh core sample.

[0008] The mass percentage of carbon fractions in the oil seeping from the fresh core sample was determined by chromatography.

[0009] (S2) The core after the oil seepage is divided into two parts. The first part is immersed in a sealed container containing a first solvent for a first extraction, and the second part is immersed in a sealed container containing a second solvent for a second extraction. The oil mass obtained from the first extraction and the second extraction is obtained, and a fresh core sample after extraction is obtained. The content of free oil in the fresh core sample is calculated.

[0010] (S3) The extracted fresh core sample is immersed in a sealed container containing a third solvent, and the core is crushed and extracted in sequence to obtain the oil mass obtained by the third extraction and calculate the residual oil content in the fresh core sample.

[0011] The oil content of the fresh core sample is calculated based on the content of free oil and residual oil in the fresh core sample.

[0012] (S4) Collect non-fresh core samples from the same region and stratum as the fresh core samples, and divide the non-fresh core samples into two parts. The first part is immersed in a sealed container containing a first solvent for a fourth extraction, and the second part is immersed in a sealed container containing a second solvent for a fifth extraction. Obtain the oil mass of the fourth and fifth extractions, and obtain the extracted non-fresh core samples. Use chromatography to determine the mass percentage of carbon fractions in the oil obtained from the fourth and fifth extractions.

[0013] The content of free oil in the non-fresh core sample is calculated using the mass of oil obtained from the fourth and fifth extractions, the mass percentage of carbon fraction of oil seeping from the fresh core sample, and the mass percentage of carbon fraction of oil obtained from the fourth and fifth extractions.

[0014] The recoverable oil content in the non-fresh core sample is calculated using the free oil content in the non-fresh core sample, the recoverable oil content in the fresh core sample, and the free oil content in the fresh core sample.

[0015] (S5) The extracted non-fresh core sample is immersed in a sealed container containing a third solvent, and the core is crushed and extracted in sequence to obtain the oil mass obtained by the sixth extraction and calculate the residual oil content in the non-fresh core sample.

[0016] The oil content of the non-fresh core sample was calculated based on the content of free oil and residual oil in the non-fresh core sample.

[0017] The second aspect of this invention provides the application of the method for measuring the oil content of shale or tight rock described in the first aspect above in the exploration and development of shale oil and gas or tight oil and gas.

[0018] The method for measuring the oil content of shale or tight rocks provided by this invention can accurately measure the recoverable oil content, free oil content, residual oil content, and oil content in both fresh and non-fresh core samples. This provides accurate data for the precise measurement of recoverable oil content, free oil content, residual oil content, and oil content in shale or tight rocks, as well as for resource evaluation. It significantly improves the accuracy of evaluating shale oil and gas resources and reserves. Applying this method in shale oil and gas exploration and development can lay a better foundation for the selection of favorable areas and sweet spots. Attached Figure Description

[0019] Figure 1 The carbon number (C5) of the oil seeping from a fresh core sample in the example is given. + Mass percentage distribution of different carbon groups.

[0020] Figure 2 For the example and Figure 1 The carbon number C5 in the extract of the same fresh core sample + Mass percentage distribution of different carbon groups.

[0021] Figure 3 This is a comparison chart of the recoverable oil content in 20 fresh core samples and the corresponding non-fresh core samples in the example.

[0022] Figure 4 This is a comparison chart of the free oil content in 20 fresh core samples and the corresponding non-fresh core samples in the example.

[0023] Figure 5 This is a comparison chart showing the residual oil content in 20 fresh core samples and the residual oil content in corresponding non-fresh core samples in the example.

[0024] Figure 6 This is a comparison chart of the oil content of 20 fresh core samples and the corresponding non-fresh core samples in the example. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0027] The first aspect of this invention provides a method for measuring the oil content of shale or tight rock, comprising:

[0028] (S1) Place the collected fresh core sample in a sealed container, heat it to the sampling formation temperature, obtain the oil mass that seeps out from the fresh core sample, obtain the core after the oil seeps out, and calculate the recoverable oil content in the fresh core sample.

[0029] The mass percentage of carbon fractions in the oil seeping from the fresh core sample was determined by chromatography.

[0030] (S2) The core after the oil seepage is divided into two parts. The first part is immersed in a sealed container containing a first solvent for a first extraction, and the second part is immersed in a sealed container containing a second solvent for a second extraction. The oil mass obtained from the first extraction and the second extraction is obtained, and a fresh core sample after extraction is obtained. The content of free oil in the fresh core sample is calculated.

[0031] (S3) The extracted fresh core sample is immersed in a sealed container containing a third solvent, and the core is crushed and extracted in sequence to obtain the oil mass obtained by the third extraction and calculate the residual oil content in the fresh core sample.

[0032] The oil content of the fresh core sample is calculated based on the content of free oil and residual oil in the fresh core sample.

[0033] (S4) Collect non-fresh core samples from the same region and stratum as the fresh core samples, and divide the non-fresh core samples into two parts. The first part is immersed in a sealed container containing a first solvent for a fourth extraction, and the second part is immersed in a sealed container containing a second solvent for a fifth extraction. Obtain the oil mass of the fourth and fifth extractions, and obtain the extracted non-fresh core samples. Use chromatography to determine the mass percentage of carbon fractions in the oil obtained from the fourth and fifth extractions.

[0034] The content of free oil in the non-fresh core sample is calculated using the mass of oil obtained from the fourth and fifth extractions, the mass percentage of carbon fraction of oil seeping from the fresh core sample, and the mass percentage of carbon fraction of oil obtained from the fourth and fifth extractions.

[0035] The recoverable oil content in the non-fresh core sample is calculated using the free oil content in the non-fresh core sample, the recoverable oil content in the fresh core sample, and the free oil content in the fresh core sample.

[0036] (S5) The extracted non-fresh core sample is immersed in a sealed container containing a third solvent, and the core is crushed and extracted in sequence to obtain the oil mass obtained by the sixth extraction and calculate the residual oil content in the non-fresh core sample.

[0037] The oil content of the non-fresh core sample was calculated based on the content of free oil and residual oil in the non-fresh core sample.

[0038] In this invention, the fresh core sample refers to the core sample (shale core sample or dense rock core sample) taken within 10 minutes after exiting the sealed core well or pressure-maintaining core well. The fresh core sample is immediately placed in a liquid nitrogen tank or a freezer below -40°C for storage after being taken out.

[0039] In this invention, the non-fresh core sample refers to a core sample (shale or dense rock core sample) that has been left in a natural state for more than 10 minutes after being extracted from a conventional core well, a closed core well, or a pressure-maintaining core well. The non-fresh core sample and the fresh core sample are taken from adjacent locations in the same region and at the same stratigraphic level.

[0040] In this invention, the recoverable oil content (mg / g) refers to the percentage of oil mass that can naturally seep out from a unit mass of core under standard atmospheric pressure (1 atm) and the temperature of the formation where the core sample is located.

[0041] In this invention, the content of free oil (mg / g) refers to the sum of the percentage of oil that can naturally seep out of a unit mass of core under standard atmospheric pressure (1 atm) and the temperature of the formation where the core sample is located, and the percentage of oil obtained by organic solvent extraction.

[0042] In this invention, the residual oil content (mg / g) refers to the percentage of oil extracted from a unit mass of core after organic solvent extraction (first extraction), followed by crushing and further organic solvent extraction (second extraction).

[0043] In this invention, the oil content (mg / g) refers to the oil mass per unit mass of core, that is, the sum of the content of free oil and the content of residual oil.

[0044] According to the present invention, in the method for measuring the oil content of shale, the first solvent, the second solvent, and the third solvent are each independently selected from organic solvents that are insoluble in water. Preferably, the organic solvent has a boiling point ≥25°C at 1 atm, which is beneficial to improving the oil extraction efficiency from the rock, and does not boil at room temperature, which facilitates the extraction operation.

[0045] According to a preferred embodiment of the present invention, the first solvent, the second solvent, and the third solvent are each independently selected from toluene (C7H8) or p-xylene (C8H1N2). 10 Furthermore, the first solvent and the second solvent are not the same. For example, the first solvent is p-xylene, the second solvent is toluene, and the third solvent is p-xylene, which is more conducive to eliminating the influence of the first solvent and the second solvent on the chromatographic measurement value of oil in the extract.

[0046] According to the present invention, in the method for measuring the oil content of mudstone and shale, in step (S1), the fresh core sample is placed in a sealed container to prevent the loss of oil and water that seep from the fresh core sample.

[0047] According to the present invention, in step (S1), heating to the sampling formation temperature means heating the fresh core sample to the temperature of the formation from which it was taken.

[0048] According to the present invention, in step (S1), the conditions for obtaining the quality of oil seeping from the fresh core sample include: a pressure of 1 atm inside the sealed container, a temperature equal to the sampling formation temperature of the fresh core sample, and a placement time ≥ 48 hours. The placement time refers to the time the fresh core sample is placed in the sealed container under the aforementioned pressure and temperature conditions.

[0049] According to the present invention, in step (S1), after the placement time is reached, the mass of oil and water that seep from the fresh core sample are obtained, and the surface of the core after the oil seeps out is washed with an organic solvent (e.g., toluene or p-xylene). After drying, the mass of oil that seeps from the fresh core sample (i.e., the mass of recoverable oil) is calculated using the following formula (1).

[0050] m o1 =(m a1 Formula (1) = (-m2)×1000-m1;

[0051] Where, m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m a1 m1 is the mass of the fresh core sample, in g; m2 is the mass of the water that seeps from the fresh core sample, in mg; m3 is the mass of the core obtained after rinsing the surface of the core with an organic solvent and drying it, in mg.

[0052] According to the present invention, in the above formula (1), the mass of oil seeping from the fresh core sample (m) o1 The mass of oil and water (m1) refers to the mass of oil and water obtained after cooling the exudate collected from the fresh core sample to -5°C and separating it.

[0053] According to the present invention, in step (S1), the recoverable oil content in the fresh core sample is calculated using formula (2);

[0054]

[0055] Among them, W ro The recoverable oil content is expressed in mg / g; m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m a1 The mass of a fresh core sample is expressed in grams (g).

[0056] According to the present invention, in step (S1), when the amount of oil seeping from the fresh core sample is insufficient to carry out chromatographic testing, oil produced by a production well in the same region and at the same stratigraphic level as the fresh core sample and near the sampling location of the fresh core sample can be used as a substitute for chromatographic testing.

[0057] According to the present invention, in step (S1), the mass percentage of carbon fraction of the oil seeping from the fresh core sample includes: a carbon number of C 15 - The cumulative mass percentage and carbon number of the oil components are C. 15 + Cumulative mass percentage of oil components.

[0058] According to the present invention, in the method for measuring the oil content of shale or dense rock, in step (S2), the core sample after oil seepage is divided into two parts, which can be done in a conventional way, such as by splitting it open, to obtain a first core sample and a second core sample. The first core sample and the second core sample can have the same or different mass.

[0059] According to the present invention, in step (S2), preferably, in the sealed container, the liquid levels of the first solvent and the second solvent are respectively higher than the upper surfaces of the first part of the core and the second part of the core (i.e., the plane where the highest point of the core is located). More preferably, the liquid levels of the first solvent and the second solvent are respectively 3 cm or more higher than the upper surfaces of the first part of the core and the second part of the core.

[0060] According to the present invention, in step (S2), preferably, the ratio of the volume of the first solvent to the mass of the first portion of the core and the ratio of the volume of the second solvent to the mass of the second portion of the core are the same, so as to ensure that the oil concentration extracted from the core in the first solvent and the second solvent is substantially the same.

[0061] According to the present invention, in step (S2), preferably, the conditions for the first extraction and the second extraction each independently include: a pressure of 1 atm in the sealed container; an extraction temperature not lower than the boiling point temperature of the first solvent and the second solvent, and not higher than the boiling point temperature of the first solvent and the second solvent by 2°C; and an extraction time ≥ 24 hours. Wherein, the extraction temperature not lower than the boiling point temperature of the first solvent and the second solvent by 2°C means that during the first extraction in the sealed container containing the first solvent, the extraction temperature in the sealed container is not lower than the boiling point temperature of the first solvent and not higher than the boiling point temperature of the first solvent by 2°C, and during the second extraction in the sealed container containing the second solvent, the extraction temperature in the sealed container is not lower than the boiling point temperature of the second solvent and not higher than the boiling point temperature of the second solvent by 2°C, which can prevent over-boiling of the solvent while ensuring the extraction effect.

[0062] According to the present invention, in step (S2), the content of free oil in the fresh core sample is calculated using formula (3);

[0063]

[0064] Among them, W mo This refers to the content of free oil, in mg / g; m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m o2 The mass of the oil obtained from the first and second extractions is expressed in mg; m a1 The mass of a fresh core sample is expressed in grams (g).

[0065] According to the present invention, in the above formula (3), the mass of oil obtained by the first extraction and the second extraction can be obtained by subtracting the mass of the core sample after extraction and drying from the mass of the core sample after extraction and drying; wherein, the mass of the core sample after extraction and drying refers to the mass of the core sample after extraction and drying is the mass of the core sample after heating the core sample before extraction to the sampling formation temperature and holding it at a constant temperature for not less than 8 hours; the mass of the core sample after extraction and drying is the mass of the core sample after extraction and drying is the mass of the core sample after heating the core sample after extraction to the boiling point temperature of the solvent (extraction solvent) and holding it at a constant temperature for not less than 8 hours.

[0066] According to the present invention, in the method for measuring the oil content of mudstone and shale, in step (S3), the average particle size of the crushed core is not greater than 1000 μm, preferably 100-1000 μm, which is conducive to fully extracting oil from the rock and making the measurement results of residual oil more accurate.

[0067] In this invention, the average particle size is determined by a sieving method.

[0068] According to the present invention, in step (S3), preferably, in the sealed container, the liquid level of the third solvent is higher than the upper surface of the extracted fresh core sample (i.e., the plane where the highest point of the core is located). More preferably, the liquid level of the third solvent is 3 cm or more higher than the upper surface of the extracted fresh core sample, and then the extracted fresh core is sequentially crushed and subjected to a third extraction.

[0069] According to the present invention, in step (S3), the conditions for the third extraction include: the pressure inside the sealed container is 1 atm; the extraction temperature is not lower than the boiling point temperature of the third solvent and not higher than the boiling point temperature of the third solvent by 2°C; and the extraction time is ≥24h. By controlling the extraction temperature to be not lower than the boiling point temperature of the third solvent and not higher than the boiling point temperature of the third solvent by 2°C, it is possible to prevent the solvent from over-boiling while ensuring the extraction effect.

[0070] According to the present invention, in step (S3), the content of residual oil in the fresh core sample is calculated using formula (4);

[0071]

[0072] Among them, W rro The residual oil content is expressed in mg / g; m o3 The mass of the oil obtained from the third extraction (i.e., the residual oil mass), in mg; m a1 The mass of a fresh core sample is expressed in grams (g).

[0073] According to the present invention, in the above formula (4), the mass of oil obtained by the third extraction can be obtained by subtracting the mass of the core sample after pulverization and extraction from the mass of the core sample after drying before pulverization; wherein, the mass of the core sample after drying before pulverization refers to the mass of the core sample after extraction (first extraction, second extraction) is heated to the boiling point temperature of the solvent (extraction solvent used in the first extraction, second extraction) and kept at the temperature for not less than 8 hours; the mass of the core sample after pulverization and extraction and drying refers to the mass of the core sample after pulverization and extraction (third extraction) is heated to the boiling point temperature of the solvent (extraction solvent used in the third extraction) and kept at the temperature for not less than 8 hours.

[0074] According to the present invention, in step (S3), the oil content of the fresh core sample is calculated using formula (5);

[0075]

[0076] In the formula: W o Oil content, mg / g; m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m o2 The mass of the oil obtained from the first and second extractions is expressed in mg; m o3 The mass of the oil obtained from the third extraction is mg; m a1 The mass of a fresh core sample is expressed in grams (g).

[0077] According to the present invention, in step (S3), the oil content of the fresh core sample can also be determined by formula W. o =W mo +W rro Calculated; where W o Oil content, mg / g; W mo Free oil content, mg / g; W rro The residual oil content is expressed in mg / g.

[0078] According to the present invention, in the method for measuring the oil content of mudstone and shale, in step (S4), the non-fresh core sample is divided into two parts, which can be done in a conventional way, such as splitting it open, to obtain a first core and a second core. The first core and the second core may have the same or different mass.

[0079] According to the present invention, in step (S4), preferably, in the sealed container, the liquid levels of the first solvent and the second solvent are respectively higher than the upper surfaces of the first part of the core (referring to the first part of the non-fresh core) and the second part of the core (referring to the second part of the non-fresh core) (i.e., the plane where the highest point of the core is located). More preferably, the liquid levels of the first solvent and the second solvent are respectively 3 cm or more higher than the upper surfaces of the first part of the core and the second part of the core.

[0080] According to the present invention, in step (S4), preferably, the ratio of the volume of the first solvent to the mass of the first portion of the core and the ratio of the volume of the second solvent to the mass of the second portion of the core are the same, so as to ensure that the oil concentration extracted from the core in the first solvent and the second solvent is substantially the same.

[0081] According to the present invention, in step (S4), preferably, the conditions for the fourth and fifth extractions each independently include: a pressure of 1 atm in the sealed container; an extraction temperature not lower than the boiling point temperatures of the first and second solvents and not higher than the boiling point temperatures of the first and second solvents by 2°C; and an extraction time ≥ 24 hours. Wherein, the extraction temperature not lower than the boiling point temperatures of the first and second solvents and not higher than the boiling point temperatures of the first and second solvents by 2°C means that during the fourth extraction in the sealed container containing the first solvent, the extraction temperature in the sealed container is not lower than the boiling point temperature of the first solvent and not higher than the boiling point temperature of the first solvent by 2°C, and during the fifth extraction in the sealed container containing the second solvent, the extraction temperature in the sealed container is not lower than the boiling point temperature of the second solvent and not higher than the boiling point temperature of the second solvent by 2°C, thus preventing over-boiling of the solvent while ensuring the extraction effect.

[0082] According to the present invention, in step (S4), the mass percentage of carbon fraction of the oil obtained from the fourth and fifth extractions includes: [the percentage of carbon atoms is C]. 15 - The cumulative mass percentage and carbon number of the oil components are C. 15 + Cumulative mass percentage of oil components.

[0083] According to the present invention, in step (S4), preferably, when the first solvent and the second solvent are each independently selected from toluene or p-xylene, and the first solvent and the second solvent are not the same, the C7 oil measurement value in the chromatogram of the toluene extract is replaced with the C7 oil measurement value in the chromatogram of the p-xylene extract, and / or, the C8 oil measurement value in the chromatogram of the p-xylene extract is replaced with the C8 oil measurement value in the chromatogram of the toluene extract. This can effectively eliminate the influence of toluene and p-xylene on the chromatographic test results of their respective extracted oils, thereby accurately obtaining the mass percentage of carbon fractions in the oils obtained from the fourth and fifth extractions.

[0084] According to the present invention, in step (S4), the content of free oil in the non-fresh core sample is calculated using formula (6);

[0085]

[0086] W mo1 This refers to the content of free oil, in mg / g; m o4 The mass of the oil obtained from the fourth and fifth extractions is expressed in mg; C 15+_1 The carbon number C that seeped from the fresh core sample is... 15 + Cumulative mass percentage of oil components, %; C 15+_2The carbon number obtained from the fourth and fifth extractions is C. 15 + Cumulative mass percentage of oil components, %; m a2 The mass of the non-fresh core sample is expressed in grams.

[0087] According to the present invention, in step (S4), the recoverable oil content in the non-fresh core sample is calculated using formula (7);

[0088] W ro1 =W mo1 ×(W ro / W mo ) formula (7);

[0089] Among them, W ro1 The recoverable oil content is expressed in mg / g; W mo1 The content of free oil in non-fresh core samples, in mg / g; W ro W represents the recoverable oil content in a fresh core sample, in mg / g. mo The value represents the free oil content in a fresh core sample, expressed in mg / g.

[0090] According to the present invention, in the above formula (6), the oil mass obtained by the fourth extraction and the fifth extraction can be obtained by subtracting the mass of the core sample (not fresh) after extraction and drying from the mass of the core sample (not fresh) after extraction and drying; wherein, the mass of the core sample after extraction and drying refers to the mass of the core sample after extraction and heating it to the sampling formation temperature and holding it at a constant temperature for not less than 8 hours; the mass of the core sample after extraction and drying refers to the mass of the core sample after extraction and heating it to the boiling point temperature of the solvent (extraction solvent) and holding it at a constant temperature for not less than 8 hours.

[0091] According to the present invention, in step (S5), in the sealed container, the liquid level of the third solvent is higher than the upper surface of the extracted non-fresh core sample (i.e., the plane where the highest point of the core is located). More preferably, the liquid level of the third solvent is 3 cm or more higher than the upper surface of the extracted non-fresh core sample, and then the extracted non-fresh core sample is sequentially crushed and subjected to a sixth extraction.

[0092] According to the present invention, in step (S5), the average particle size of the crushed core (non-fresh) is not greater than 1000 μm, preferably 1000-1000 μm, which is conducive to fully extracting oil from the rock and making the measurement results of residual oil more accurate.

[0093] According to the present invention, in step (S5), the conditions for the sixth extraction include: the pressure inside the sealed container is 1 atm; the extraction temperature is not lower than the boiling point temperature of the third solvent and not higher than the boiling point temperature of the third solvent by 2°C; and the extraction time is ≥24h. By controlling the extraction temperature to be not lower than the boiling point temperature of the third solvent and not higher than the boiling point temperature of the third solvent by 2°C, it is possible to prevent the solvent from over-boiling while ensuring the extraction effect.

[0094] According to the present invention, in step (S5), the content of residual oil in the non-fresh core sample is calculated using formula (8);

[0095]

[0096] Among them, W rro1 The residual oil content is expressed in mg / g; m o5 The mass of the oil obtained from the sixth extraction (i.e., the residual oil mass), in mg; m a2 The mass of the non-fresh core sample is expressed in grams.

[0097] According to the present invention, in the above formula (8), the mass of oil obtained by the sixth extraction can be obtained by subtracting the mass of the core sample after pulverization and extraction from the mass of the core sample after drying before pulverization; wherein, the mass of the core sample after drying before pulverization refers to the mass of the core sample after extraction (fourth extraction, fifth extraction) is heated to the boiling point temperature of the solvent (extraction solvent used in the fourth extraction, fifth extraction) and kept at the temperature for not less than 8 hours; the mass of the core sample after pulverization and extraction and extraction refers to the mass of the core sample after pulverization and extraction (sixth extraction) is heated to the boiling point temperature of the solvent (extraction solvent used in the sixth extraction) and kept at the temperature for not less than 8 hours.

[0098] According to the present invention, in step (S5), the oil content of the non-fresh core sample is calculated using formula (9);

[0099] W o1 =W mo1 +W rro1 Formula (9);

[0100] Among them, W o1 Oil content, mg / g; W mo1 The content of free oil; W rro1 This refers to the content of residual oil.

[0101] Compared to existing technologies, the method for measuring oil content in shale or tight rocks provided by this invention overcomes the problem of unmeasurable and unrecoverable light hydrocarbon loss during core sample collection, preparation, and measurement processes. It also solves the problem of inaccurate measurement of recoverable oil content, free oil content, and oil content in non-fresh core samples. Furthermore, the method effectively addresses the problem of residual organic solvents in extracts affecting chromatographic carbon number peak measurements, enabling accurate measurement of recoverable oil content, free oil content, residual oil content, and oil content in both fresh and non-fresh core samples. This provides reliable data support for the evaluation of shale oil or tight oil resources and reserves.

[0102] The second aspect of this invention provides the application of the method for measuring the oil content of shale or tight rock described in the first aspect above in the exploration and development of shale oil and gas or tight oil and gas.

[0103] According to the present invention, the method for measuring the oil content of shale or tight rock described in the first aspect above can provide accurate data for the accurate measurement of recoverable oil content, free oil content, residual oil content and oil content in shale or tight rock, as well as for resource evaluation. The accuracy of the evaluation of shale oil and gas or tight oil and gas resources and reserves is higher. The application of this method in the exploration and development of shale oil and gas or tight oil and gas can lay a better foundation for the selection of favorable areas and sweet spots.

[0104] The present invention will be described in detail below through examples. Unless otherwise specified, all materials used in the following examples and comparative examples are commercially available products.

[0105] Example 1

[0106] The oil content of core samples (shale and mudstone) from a closed-loop core well in the Triassic Yanchang Formation, Member 7, of the Ordos Basin was tested. This closed-loop core well is located in the south-central part of the Ordos Basin. The core sample is from the Triassic Yanchang Formation, Member 7, at a burial depth of 2101m to 2121m, with a formation temperature of 81℃. The core diameter is approximately 10.15cm. One fresh core sample (approximately 10cm in length) was collected per meter (a total of 20 samples). Within 3-5 minutes of core extraction, surface drilling fluid and core extraction fluid were removed. The core was then split in two. One sample was used as a fresh core sample (mass of each sample is shown in Table 1) for recoverable oil content, free oil content, residual oil content, and oil content measurements. The other sample was stored for 72 hours as a non-fresh core sample (mass of each sample is shown in Table 2) for further recoverable oil content, free oil content, residual oil content, and oil content measurements.

[0107] (S1) Place the above 20 fresh core samples in a sealed container to prevent the loss of oil and water seeping from the samples; heat the above cores to the sampling formation temperature of 81°C, and place the above core samples in a sealed container for 72 hours under the conditions of 1 atm and 81°C to obtain the mass of oil and water seeping from the above fresh core samples (the mass of oil and water obtained after cooling the exudate collected from the fresh core samples to -5°C and separating it), and use p-xylene to wash the surface of the core after oil seepage, and after drying, use formula (1) to calculate the mass of oil seeping from the above 20 fresh core samples (i.e., the mass of recoverable oil, the results are shown in Table 1), and obtain the core after oil seepage.

[0108] m o1 =(m a1 Formula (1) = (-m2)×1000-m1;

[0109] Where, m o1 The mass of oil leached from a fresh core sample, in mg; m a1 m1 is the mass of the fresh core sample, in g; m2 is the mass of the water that seeps from the fresh core sample, in mg; m3 is the mass of the core obtained after rinsing the surface of the core with an organic solvent (p-xylene) and drying it, in mg.

[0110] The recoverable oil content in the above 20 fresh core samples was calculated using formula (2), and the results are shown in Table 1.

[0111]

[0112] Among them, W ro The recoverable oil content is expressed in mg / g; m o1 The mass of oil leached from a fresh core sample, in mg; m a1 The mass of a fresh core sample is expressed in grams.

[0113] The mass percentage of carbon fractions (C6N) of the oil seeping from the above 20 fresh core samples was determined by chromatography. 15 - The cumulative mass percentage and carbon number of the oil components are C. 15 + (Cumulative mass percentage of oil components); Figure 1 C5 of the oil that seeped from one of the fresh core samples +Mass percentage distribution of different carbon fractions. The burial depth and thermal evolution of organic matter in the 20 mudstone and shale samples are basically consistent, and the carbon fraction distribution of oil in the mudstone and shale is basically consistent. Alternatively, the carbon fraction mass distribution of oil from the permeated oil in one of the 20 fresh core samples can be used to replace the carbon fraction mass distribution of oil from the permeated oil in that core distribution section. The carbon fraction mass distribution of oil from the permeated oil in each fresh core sample can also be measured.

[0114] (S2) Each core sample obtained in step (S1) after oil seepage is split into two parts. The first part of the core is immersed in a sealed container containing para-xylene for a first extraction (the para-xylene level is 3.35 cm above the upper surface of the first part of the core; the volume ratio of para-xylene to the mass of the first part of the core is 8.5:1; the conditions for the first extraction are: pressure of 1 atm in the sealed container, extraction temperature of 139℃, and extraction time of 36 h). The second part is immersed in a sealed container containing toluene for a second extraction (the para-xylene level is higher than the second part of the core). The upper surface of the core sample is 3.35 cm; the volume ratio of p-toluene to the mass of the second core sample is 8.5:1; the conditions for the second extraction are: the pressure in the sealed container is 1 atm, the extraction temperature is 111℃, and the extraction time is 36h). The oil mass obtained from the first and second extractions is obtained (the mass of the core sample dried at 81℃ for 8h before extraction is reduced by the mass of the core sample dried at 139℃ for 8h after extraction). Fresh core samples after extraction are obtained, and the content of free oil in the above 20 fresh core samples is calculated using formula (3) (the results are shown in Table 1).

[0115]

[0116] Among them, W mo This refers to the content of free oil, in mg / g; m o1 The mass of oil leached from a fresh core sample, in mg; m o2 The mass of oil obtained from the first and second extractions is expressed in mg; m a1 The mass of a fresh core sample is expressed in grams.

[0117] The mass percentage of carbon components in the oils obtained from the first and second extractions was determined by chromatography. The C7 oil measurement value in the toluene extract was replaced by the C7 oil measurement value in the p-xylene extract, and the C8 oil measurement value in the p-xylene extract was replaced by the C8 oil measurement value in the toluene extract. This accurately yielded the mass percentage of carbon components in the oils obtained from the first and second extractions. Specifically, the carbon number C... 15 - The cumulative mass percentage (82.0104%) and carbon number of the oil component are C. 15+ Cumulative mass percentage of oil components (17.9896%); Figure 2 To and Figure 1 The carbon number C5 in the extract of the same fresh core sample + Mass percentage distribution of different carbon groups;

[0118] (S3) The fresh core sample obtained in step (S2) is immersed in a sealed container containing paraxylene (the paraxylene liquid level is 3.6 cm higher than the upper surface of the fresh core sample after extraction). Then, the fresh core sample is crushed (crushed to an average particle size of 400 μm) and then subjected to a third extraction (the conditions for the third extraction are: pressure in the sealed container is 1 atm, extraction temperature is 139℃, and extraction time is 36 h). The oil mass obtained from the third extraction is obtained (the mass of the core sample after the first extraction and the second extraction before crushing and drying at 139℃ for 8 h is subtracted from the mass of the core sample after crushing and the third extraction and drying at 139℃ for 8 h). The residual oil content in the above 20 fresh core samples is calculated using formula (4) (the results are shown in Table 1).

[0119]

[0120] Among them, W rro The residual oil content is expressed in mg / g; m o3 The mass of the oil obtained from the third extraction is in mg; m a1 The mass of a fresh core sample is expressed in grams.

[0121] The oil content of the above 20 fresh core samples was calculated using formula (5) (the results are shown in Table 1);

[0122]

[0123] In the formula: W o Oil content, mg / g; m o1 The mass of oil leached from a fresh core sample, in mg; m o2 The mass of oil obtained from the first and second extractions is expressed in mg; m o3 The mass of the oil obtained from the third extraction is in mg; m a1 The mass of a fresh core sample is expressed in grams.

[0124] (S4) Each of the aforementioned non-fresh core samples was split into two parts. The first part of the core was immersed in a sealed container containing toluene for a fourth extraction (the toluene level was 3.36 cm above the upper surface of the first part of the core; the volume ratio of toluene to the mass of the first part of the core was 8.55:1; the conditions for the fourth extraction were: pressure of 1 atm in the sealed container, extraction temperature of 111℃, and extraction time of 36 h). The second part of the core was immersed in a sealed container containing para-xylene for a fifth extraction (para-xylene...). The xylene level was 3.36 cm above the upper surface of the second core sample; the volume ratio of para-xylene to the mass of the second core sample was 8.55:1; the conditions for the fifth extraction were: pressure of 1 atm in the sealed container, extraction temperature of 139℃, and extraction time of 36 h. The oil mass obtained from the fourth and fifth extractions was obtained by subtracting the mass of the core sample dried at 81℃ for 8 h after extraction from the mass of the core sample dried at 139℃ for 8 h after extraction. The non-fresh core sample after extraction was obtained.

[0125] The carbon fraction mass percentage of the oils obtained from the fourth and fifth extractions was determined by chromatography. The C7 oil measurement values ​​in the toluene extract were replaced with the C7 oil measurement values ​​in the p-xylene extract, and the C8 oil measurement values ​​in the p-xylene extract were replaced with the C8 oil measurement values ​​in the toluene extract. This accurately obtained the carbon number composition of the oils obtained from the fourth and fifth extractions. Specifically, the carbon number was C... 15 - The cumulative mass percentage (81.5018%) and carbon number of the oil component are C. 15 + Cumulative mass percentage of oil components (18.4204%);

[0126] The carbon number (C5) of each sample was obtained by chromatography. + The sum of the mass percentages of the components is approximately 100%.

[0127] The free oil content in the above 20 non-fresh core samples was calculated using formula (6) (the results are shown in Table 2);

[0128]

[0129] Among them, W mo1 This refers to the content of free oil, in mg / g; m o4 The mass of the oil obtained from the fourth and fifth extractions is in mg; C 15+_1 The carbon number C that seeps from the fresh core sample is... 15 + Cumulative mass percentage of oil components, %; C 15+_2 The carbon number obtained from the fourth and fifth extractions is C.15 + Cumulative mass percentage of oil components, %; m a2 The mass of the non-fresh core sample is expressed in grams.

[0130] The recoverable oil content in the above 20 non-fresh core samples was calculated using formula (7) (the results are shown in Table 2);

[0131] W ro1 =W mo1 ×(W ro / W mo ) formula (7);

[0132] Among them, W ro1 The recoverable oil content is expressed in mg / g; W mo1 The content of free oil in non-fresh core samples, in mg / g; W ro W represents the recoverable oil content in a fresh core sample, in mg / g. mo The free oil content in a fresh core sample, in mg / g;

[0133] (S5) The non-fresh core sample obtained in step (S5) is immersed in a sealed container containing paraxylene (the paraxylene liquid level is 4 cm higher than the upper surface of the fresh core after extraction). Then the core is crushed (crushed to an average particle size of 400 μm) and then subjected to a sixth extraction (the conditions for the sixth extraction are: pressure in the sealed container is 1 atm, extraction temperature is 139℃, and extraction time is 36 h). The oil mass obtained from the sixth extraction is obtained (the mass of the core sample after the fourth and fifth extractions before crushing and drying at 139℃ for 8 h is subtracted from the mass of the core sample after crushing and the sixth extraction and drying at 139℃ for 8 h). The residual oil content in the above 20 non-fresh core samples is calculated using formula (8) (the results are shown in Table 2).

[0134]

[0135] Among them, W rro1 The residual oil content is expressed in mg / g; m o5 The mass of the oil obtained from the sixth extraction is mg; m a2 The mass of the non-fresh core sample is expressed in grams.

[0136] The oil content of the above 20 non-fresh core samples was calculated using formula (9) (the results are shown in Table 2);

[0137] W o1 =W mo1 +W rro1 Formula (9);

[0138] Among them, Wo1 Oil content, mg / g; W mo1 The content of free oil; W rro1 This refers to the content of residual oil.

[0139] Figure 3 This is a comparison chart of the recoverable oil content in the 20 fresh core samples and the corresponding non-fresh core samples.

[0140] Figure 4 This is a comparison chart of the free oil content in the above 20 fresh core samples and the free oil content in the corresponding non-fresh core samples.

[0141] Figure 5 This is a comparison chart of the residual oil content in the above 20 fresh core samples and the residual oil content in the corresponding non-fresh core samples.

[0142] Figure 6 This is a comparison chart of the oil content of the above 20 fresh core samples and the corresponding non-fresh core samples.

[0143] The relative errors in the measurement results of recoverable oil content, free oil content, residual oil content and oil content in the above 20 fresh core samples and the corresponding non-fresh core samples are shown in Table 3.

[0144] Table 1

[0145]

[0146]

[0147] Table 2

[0148]

[0149]

[0150] Table 3

[0151]

[0152]

[0153] Note: In Table 3, the relative error of recoverable oil content = (recoverable oil content of fresh core sample - recoverable oil content of non-fresh core sample) / recoverable oil content of fresh core sample × 100%;

[0154] Relative error of free oil content = (free oil content of fresh core sample - free oil content of non-fresh core sample) / free oil content of fresh core sample × 100%;

[0155] Relative oil content relative error = (residual oil content of fresh core sample - residual oil content of non-fresh core sample) / residual oil content of fresh core sample × 100%;

[0156] Relative error in oil content = (Oil content of fresh core sample - Oil content of non-fresh core sample) / Oil content of fresh core sample × 100%

[0157] As can be seen from the data in Tables 1, 2, and 3, the method for measuring the oil content of shale or tight rocks provided by this invention, using fresh core samples, yields recoverable oil content, free oil content, residual oil content, and oil content that can be considered as the true recoverable oil content, free oil content, residual oil content, and oil content in the formation. The measurement method provided by this invention exhibits low relative errors in the measurement results of recoverable oil content, free oil content, residual oil content, and oil content between fresh core samples and corresponding non-fresh core samples. Given the high cost of pressure-maintaining or sealed core sampling wells and the complexity of core preservation and measurement processes in actual construction, few wells use pressure-maintaining or sealed core sampling in the field. Obtaining recoverable oil content, free oil content, residual oil content, and oil content from fresh core samples obtained through pressure-maintaining or sealed core sampling wells can be used to calibrate the recoverable oil content, free oil content, residual oil content, and oil content of non-fresh core samples. In the examples, the absolute values ​​of the relative errors of recoverable oil content, free oil content, residual oil content, and oil content between fresh and non-fresh core samples of 20 mudstone and shale were all less than 7%. Compared with the absolute values ​​of the relative errors of oil content obtained by existing technologies, which are all greater than 30%, the measurement method of the present invention can significantly improve the measurement accuracy of oil content in mudstone or shale or dense rocks. At the same time, it can also accurately measure the recoverable oil content, free oil content, and residual oil content, with the absolute values ​​of the relative errors between fresh and non-fresh core samples all less than 7%.

[0158] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for measuring the oil content of mudstone, shale, or dense rock, characterized in that, include: (S1) Place the collected fresh core sample in a sealed container, heat it to the sampling formation temperature, obtain the oil mass that seeps out from the fresh core sample, obtain the core after the oil seeps out, and calculate the recoverable oil content in the fresh core sample. The mass percentage of carbon fractions in the oil seeping from the fresh core sample was determined by chromatography. (S2) The core after the oil seepage is divided into two parts. The first part is immersed in a sealed container containing a first solvent for a first extraction, and the second part is immersed in a sealed container containing a second solvent for a second extraction. The oil mass obtained from the first extraction and the second extraction is obtained, and a fresh core sample after extraction is obtained. The content of free oil in the fresh core sample is calculated. (S3) The extracted fresh core sample is immersed in a sealed container containing a third solvent, and the core is crushed and extracted in sequence to obtain the oil mass obtained by the third extraction and calculate the residual oil content in the fresh core sample. The oil content of the fresh core sample is calculated based on the content of free oil and residual oil in the fresh core sample. (S4) Collect non-fresh core samples from the same region and stratum as the fresh core samples, and divide the non-fresh core samples into two parts. The first part is immersed in a sealed container containing a first solvent for a fourth extraction, and the second part is immersed in a sealed container containing a second solvent for a fifth extraction. Obtain the oil mass of the fourth and fifth extractions, and obtain the extracted non-fresh core samples. Use chromatography to determine the mass percentage of carbon fractions in the oil obtained from the fourth and fifth extractions. The content of free oil in the non-fresh core sample is calculated using the mass of oil obtained from the fourth and fifth extractions, the mass percentage of carbon fraction of oil seeping from the fresh core sample, and the mass percentage of carbon fraction of oil obtained from the fourth and fifth extractions. The recoverable oil content in the non-fresh core sample is calculated using the free oil content in the non-fresh core sample, the recoverable oil content in the fresh core sample, and the free oil content in the fresh core sample. (S5) The extracted non-fresh core sample is immersed in a sealed container containing a third solvent, and the core is crushed and extracted in sequence to obtain the oil mass obtained by the sixth extraction and calculate the residual oil content in the non-fresh core sample. The oil content of the non-fresh core sample was calculated based on the content of free oil and residual oil in the non-fresh core sample.

2. The method according to claim 1, wherein, The first solvent, the second solvent, and the third solvent are each independently selected from organic solvents that are insoluble in water; Preferably, the organic solvent has a boiling point ≥25°C at 1 atm.

3. The method according to claim 2, wherein, The first solvent, the second solvent, and the third solvent are each independently selected from toluene or p-xylene, and the first solvent and the second solvent are not the same.

4. The method according to claim 3, wherein, In step (S1), the conditions for obtaining the quality of oil seeping from the fresh core sample include: the pressure inside the sealed container is 1 atm, the temperature is the sampling formation temperature of the fresh core sample, and the placement time is ≥48h. And / or, the mass of oil seeping from the fresh core sample is calculated using formula (1); m o1 =(m a1 Formula (1) = (-m2)×1000-m1; Where, m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m a1 m1 is the mass of the fresh core sample, in g; m2 is the mass of the water that seeps from the fresh core sample, in mg; m3 is the mass of the core obtained after rinsing the surface of the core with an organic solvent and drying it, in mg.

5. The method according to claim 4, wherein, In step (S1), the recoverable oil content in the fresh core sample is calculated using formula (2); Among them, W ro The recoverable oil content is expressed in mg / g; m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m a1 The mass of a fresh core sample is expressed in grams. And / or, in step (S1), the mass percentage of carbon fraction of the oil seeping from the fresh core sample includes: [the percentage of carbon atoms is missing from the original text]. 15 - The cumulative mass percentage and carbon number of the oil components are C. 15 + Cumulative mass percentage of oil components.

6. The method according to claim 4 or 5, wherein, In step (S2), the conditions for the first extraction and the second extraction each independently include: the pressure inside the sealed container is 1 atm; the extraction temperature is not lower than the boiling point temperature of the first solvent and the second solvent, and not higher than the boiling point temperature of the first solvent and the second solvent by 2°C; and the extraction time is ≥24h. And / or, in step (S2), the ratio of the volume of the first solvent to the mass of the first portion of the core is the same as the ratio of the volume of the second solvent to the mass of the second portion of the core. And / or, the content of free oil in the fresh core sample is calculated using formula (3); Among them, W mo This refers to the content of free oil, in mg / g; m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m o2 The mass of the oil obtained from the first and second extractions is expressed in mg; m a1 The mass of a fresh core sample is expressed in grams (g).

7. The method according to any one of claims 4-6, wherein, In step (S3), the average particle size of the crushed core is no greater than 1000 μm, preferably 100-1000 μm; And / or, the conditions for the third extraction include: the pressure inside the sealed container is 1 atm; the extraction temperature is not lower than the boiling point of the third solvent and not higher than the boiling point of the third solvent by 2°C; and the extraction time is ≥24h. And / or, the content of residual oil in the fresh core sample is calculated using formula (4); Among them, W rro The residual oil content is expressed in mg / g; m o3 The mass of the oil obtained from the third extraction is mg; m a1 The mass of a fresh core sample is expressed in grams. And / or, the oil content of the fresh core sample is calculated using formula (5); In the formula: W o Oil content, mg / g; m o1 The mass of oil that seeped from the fresh core sample is expressed in mg; m o2 The mass of the oil obtained from the first and second extractions is expressed in mg; m o3 The mass of the oil obtained from the third extraction is mg; m a1 The mass of a fresh core sample is expressed in grams (g).

8. The method according to any one of claims 4-7, wherein, In step (S4), the conditions for the fourth and fifth extractions each independently include: the pressure inside the sealed container is 1 atm; the extraction temperature is not lower than the boiling point temperature of the first solvent and the second solvent, and not higher than the boiling point temperature of the first solvent and the second solvent by 2°C; and the extraction time is ≥24h. And / or, in step (S4), the ratio of the volume of the first solvent to the mass of the first portion of the core is the same as the ratio of the volume of the second solvent to the mass of the second portion of the core. And / or, in step (S4), the mass percentage of carbon fraction in the oil obtained from the fourth and fifth extractions includes: [the percentage of carbon atoms is missing from the original text]. 15 - The cumulative mass percentage and carbon number of the oil components are C. 15 + Cumulative mass percentage of oil components; Preferably, in step (S4), when the first solvent and the second solvent are each independently selected from toluene or p-xylene, and the first solvent and the second solvent are not the same, the C7 oil measurement value in the chromatogram of the toluene extract is replaced with the C7 oil measurement value in the chromatogram of the p-xylene extract, and / or, the C8 oil measurement value in the chromatogram of the p-xylene extract is replaced with the C8 oil measurement value in the chromatogram of the toluene extract.

9. The method according to claim 8, wherein, In step (S4), the content of free oil in the non-fresh core sample is calculated using formula (6); Among them, W mo1 This refers to the content of free oil, in mg / g; m o4 The mass of the oil obtained from the fourth and fifth extractions is expressed in mg; C 15+_1 The carbon number C that seeped from the fresh core sample is... 15 + Cumulative mass percentage of oil components, %; C 15+_2 The carbon number obtained from the fourth and fifth extractions is C. 15 + Cumulative mass percentage of oil components, %; m a2 The mass of the non-fresh core sample is expressed in grams.

10. The method according to claim 9, wherein, In step (S4), the recoverable oil content in the non-fresh core sample is calculated using formula (7); W ro1 = W mo1 × (W ro / W mo ) Official (7); Among them, W ro1 The recoverable oil content is expressed in mg / g; W mo1 The content of free oil in non-fresh core samples, in mg / g; W ro W represents the recoverable oil content in a fresh core sample, in mg / g. mo The value represents the free oil content in a fresh core sample, expressed in mg / g.

11. The method according to any one of claims 9-10, wherein, In step (S5), the average particle size of the crushed core is not greater than 1000 μm, preferably 100-1000 μm; And / or, the conditions for the sixth extraction include: the pressure inside the sealed container is 1 atm; the extraction temperature is not lower than the boiling point of the third solvent and not higher than the boiling point of the third solvent by 2°C; and the extraction time is ≥24h. And / or, the content of residual oil in the non-fresh core sample is calculated using formula (8); Among them, W rro1 The residual oil content is expressed in mg / g; m o5 The mass of the oil obtained from the sixth extraction is mg; m a2 The mass of the non-fresh core sample is expressed in grams.

12. The method according to claim 11, wherein, In step (S5), the oil content of the non-fresh core sample is calculated using formula (9); W o1 = W mo1 +W rro1 Official (9); Among them, W o1 Oil content, mg / g; W mo1 The content of free oil; W rro1 This refers to the content of residual oil.

13. The application of the method for measuring the oil content of shale or tight rock as described in any one of claims 1-12 in the exploration and development of shale oil and gas or tight oil and gas.

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