A method, apparatus, storage medium, and electronic device for identifying shale oil migration.

Abstract

This invention relates to the field of oil and gas exploration and development technology, and particularly to a method, apparatus, storage medium, and electronic device for identifying shale oil migration. The method includes: performing rock pyrolysis analysis on each core sample to obtain the oil-generating window threshold and the proportion of cracked hydrocarbons in each core sample, wherein the oil-generating window threshold is used to determine whether the core is mature; performing whole-rock vitrinite reflectance testing on the core sample to obtain the maturity of the core sample, wherein the maturity is used to determine whether the core is mature; if the maturity judgment result based on the oil-generating window threshold does not match the maturity judgment result based on the maturity, and / or the evolution trend of the proportion of cracked hydrocarbons in the core sample does not match the normal thermal evolution trend, then the oil corresponding to the core is migrated oil; thereby enabling rapid identification of shale oil migration based on the core.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a method, apparatus, storage medium and electronic equipment for identifying shale oil migration. Background Technology

[0002] Oil and gas migration is a crucial link in the effective accumulation of conventional oil and gas. The distance of secondary migration of conventional oil and gas can range from a few millimeters to hundreds of kilometers (England, 1987). The direction, channels and modes of oil and gas migration are the research hotspots and key points of conventional oil and gas accumulation studies.

[0003] However, in unconventional shale oil systems, crude oil is retained in the source rock strata. In-situ retained shale oil resources are usually relatively large in scale, but the crude oil mobility is poor. In contrast, migrating and accumulating shale oil is relatively locally enriched, but the crude oil mobility is relatively good. Therefore, whether shale oil has migrated (i.e., the identification of shale oil migration) is an important basis for influencing the scale of shale oil enrichment, mobility assessment, and prediction of subsequent exploration and development deployment.

[0004] There is an urgent need in this field for a solution to the technical problem of the difficulty in quickly identifying the migration of shale oil. Summary of the Invention

[0005] This invention provides a method, apparatus, storage medium, and electronic device for identifying shale oil migration, which solves the technical problem that shale oil migration is difficult to identify quickly in some technical solutions.

[0006] In a first aspect, the present invention provides a method for identifying shale oil migration, the method comprising:

[0007] Each core sample was subjected to rock pyrolysis analysis to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold was used to determine whether the core was mature.

[0008] Whole-rock vitrinite reflectance tests were performed on the core samples to obtain the maturity of the core samples, whereby the maturity was used to determine whether the core was mature.

[0009] If the maturity judgment result based on the oil generation window threshold does not match the maturity judgment result based on maturity level and / or the evolution trend of the cracked hydrocarbon ratio in the core sample does not match the normal thermal evolution trend, then the oil corresponding to the core is migrated oil.

[0010] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample includes:

[0011] Each core sample was subjected to rock pyrolysis analysis to obtain the free hydrocarbons and cracked hydrocarbons of each core sample;

[0012] The proportion of cracked hydrocarbons in each core sample is obtained based on the ratio of cracked hydrocarbons in free hydrocarbons to cracked hydrocarbons.

[0013] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample further includes:

[0014] Each core sample was subjected to rock pyrolysis analysis to obtain the organic matter abundance and the highest pyrolysis temperature of each core sample.

[0015] The hydrogen index of each core sample was obtained based on the ratio of cracked hydrocarbons to organic matter abundance.

[0016] Based on the cross plot of hydrogen index versus highest pyrolysis temperature for all core samples, the oil generation window threshold of the cores was determined.

[0017] In some embodiments, the step of determining the oil generation window threshold of a core sample based on a cross-plot of the hydrogen index versus the highest pyrolysis temperature for all core samples includes:

[0018] Based on the cross plot of hydrogen index and highest pyrolysis temperature of all core samples, the organic matter type of the core was determined.

[0019] By combining the organic matter type with a preset mapping table, the oil-generating window threshold of the organic matter type is obtained.

[0020] In some embodiments, the step of performing whole-rock vitrinite reflectance testing on a core sample to obtain the maturity of the core sample includes:

[0021] At preset intervals at each depth, a core sample is selected for whole-rock vitrinite reflectance testing to obtain the maturity of the core sample.

[0022] In some embodiments, prior to the step of performing rock pyrolysis analysis on each core sample, the method further includes:

[0023] After the cores are extracted from the casing, core samples of different layers and different oil abundances are selected in the longitudinal direction;

[0024] All core samples were frozen;

[0025] Each core sample was sealed and crushed.

[0026] In some embodiments, the maturity determination result based on the oil-producing window threshold includes:

[0027] The proportion of core samples that fall within the oil-generating window threshold is taken out out of the total number of core samples. If the proportion is less than the threshold, the core is considered to have low maturity.

[0028] The proportion of core samples that fall within the oil generation window threshold to the total number of core samples includes: comparing the highest pyrolysis temperature of each core sample with the oil generation window threshold to determine whether the core sample falls within the oil generation window threshold.

[0029] Secondly, the present invention provides a shale oil migration identification device, the device comprising:

[0030] The first analysis module is used to perform rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold is used to determine whether the core is mature.

[0031] The second analysis module is used to perform whole-rock vitrinite reflectance testing on the core sample to obtain the maturity of the core sample, whereby the maturity is used to determine whether the core is mature.

[0032] The migration identification module is used to identify the oil in the core as migrated oil if the maturity judgment result based on the oil generation window threshold does not match the maturity judgment result based on maturity level and / or the evolution trend of the cracked hydrocarbon ratio in the core sample does not match the normal thermal evolution trend.

[0033] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method of the first aspect.

[0034] Fourthly, the present invention provides an electronic device including a processor and a memory, wherein a computer program is stored in the memory, and the processor executes the computer program to implement the method of the first aspect.

[0035] This invention provides a method, apparatus, storage medium, and electronic device for identifying shale oil migration. It involves performing rock pyrolysis analysis on each core sample to obtain the oil-generating window threshold and the proportion of cracked hydrocarbons in each core sample. The oil-generating window threshold is used to determine the maturity of the core. Whole-rock vitrinite reflectance testing is then performed on the core samples to obtain their maturity level, which is used to determine core maturity. If the maturity assessment results based on the oil-generating window threshold differ from those based on the maturity level, and / or the evolution trend of the cracked hydrocarbon proportion in the core sample does not conform to the normal thermal evolution trend, then the oil corresponding to the core is considered migrating oil. This enables rapid identification of shale oil migration based on the core sample. Attached Figure Description

[0036] The invention will now be described in more detail with reference to embodiments and the accompanying drawings:

[0037] Figure 1 This is a schematic diagram of a shale oil migration identification method provided in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of a shale oil migration identification device provided in an embodiment of the present invention;

[0039] Figure 3 A schematic diagram of Hi-Tmax intersection of test samples from a section of the Fengcheng Formation in Well A of the Mahu Depression in the Junggar Basin, provided in an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the cross-plotting of cracked hydrocarbon ratio and Tmax of a test sample from the Fengcheng Formation section of a well in the Mahu Depression of the Junggar Basin, provided as an embodiment of the present invention.

[0041] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present invention and to fully understand and implement the process of how the present invention uses technical means to solve technical problems and achieve corresponding technical effects, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The embodiments of the present invention and the various features therein can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0044] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0045] Oil and gas migration is a crucial link in the effective accumulation of conventional oil and gas. The distance of secondary migration of conventional oil and gas can range from a few millimeters to hundreds of kilometers (England, 1987). The direction, channels and modes of oil and gas migration are the research hotspots and key points of conventional oil and gas accumulation studies.

[0046] However, in unconventional shale oil systems, crude oil is retained in the source rock strata. In-situ retained shale oil resources are usually relatively large in scale, but the crude oil mobility is poor. In contrast, migrating and accumulating shale oil is relatively locally enriched, but the crude oil mobility is relatively good. Therefore, whether shale oil has migrated (i.e., the identification of shale oil migration) is an important basis for influencing the scale of shale oil enrichment, mobility assessment, and prediction of subsequent exploration and development deployment.

[0047] There are two main methods for identifying hydrocarbon migration in conventional sandstone reservoirs:

[0048] The first category is based on the "chromatic layer" effect during hydrocarbon migration. During the process of hydrocarbons moving from the "source" to the "reservoir," the geochemical composition of hydrocarbon molecules undergoes fractionation due to adsorption by the strata. Based on the characteristic changes in the geochemical composition of hydrocarbon molecules during migration, it is possible to determine whether hydrocarbon migration has occurred and the migration path. For example, in a device and method for identifying secondary hydrocarbon migration using isotopic fractionation effects, Li Maowen (2000) used absolute quantitative analysis of hydrocarbon biomarkers and neutral nitrogen compounds to determine the distance and direction of secondary migration through chemical tracing. Huang Haiping (2001) used the content of high molecular weight compounds during hydrocarbon migration to identify secondary migration. Huo Qiuli et al. (2006) combined the characteristic comparison of crude oil biomarkers in the Hailar Depression with oil-rock correlation to identify hydrocarbon migration. These methods are mainly used for conventional sandstone reservoirs and for identifying conventional oil and gas migration in source-reservoir separation. However, shale systems are different from conventional systems. Oil and gas usually migrate along the bedding planes within the system, and there is no clear boundary between source and reservoir. The differentiation of the geochemical characteristics of oil and gas molecules is not obvious. Therefore, it is difficult to determine whether oil and gas have migrated within the system.

[0049] The second category is based on traditional buoyancy pressure difference and fluid potential to determine oil and gas migration. Examples include methods that use buoyancy potential energy combined with source rock distribution to predict the dominant migration paths of oil and gas blocks; a device and experimental method simulating the migration process of hydrocarbons due to pressure difference under geological conditions; and Liu et al. (2018) used the amplitude changes in crude oil viscosity, density, light / heavy n-alkanes, nitrogen-containing compounds, and biomarker compounds corresponding to overpressure-driven, buoyancy-driven, and mixed-driven processes to study the modes and driving forces of oil and gas migration. However, in unconventional shale systems, the reservoir density is high, and there is usually no obvious oil-gas-water interface, making buoyancy potential energy less indicative, and thus making it difficult to identify oil and gas migration using buoyancy and pressure difference.

[0050] There is an urgent need in this field for a solution to identify shale oil migration.

[0051] To address the shortcomings of existing methods, this invention provides a method for rapidly identifying shale oil migration in shale formations by combining the results of frozen rock pyrolysis and whole-rock reflectance analysis of shale samples. This provides important evidence for evaluating shale oil enrichment scale, mobility assessment, and predicting subsequent exploration and development deployments. The technical solution and beneficial effects of this invention will be described below with reference to embodiments.

[0052] Example 1

[0053] Figure 1 This is a flowchart of a shale oil migration identification method according to an embodiment of the present invention. Figure 1 As shown, this embodiment provides a shale oil migration identification method, including:

[0054] Each core sample was subjected to rock pyrolysis analysis to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold was used to determine whether the core was mature.

[0055] Whole-rock vitrinite reflectance tests were performed on the core samples to obtain the maturity of the core samples, whereby the maturity was used to determine whether the core was mature.

[0056] If the maturity judgment result based on the oil generation window threshold does not match the maturity judgment result based on maturity level and / or the evolution trend of the cracked hydrocarbon ratio in the core sample does not match the normal thermal evolution trend, then the oil corresponding to the core is migrated oil.

[0057] In this embodiment, the core sample is a sample taken from the rock core. The object of rock pyrolysis analysis is the core sample. The cracked hydrocarbons and their proportions are parameters obtained from the rock pyrolysis analysis. The normal thermal evolution trend is the normal thermal evolution trend of oil generation, such as... Figure 4 As shown.

[0058] This embodiment provides a shale oil migration identification method. By performing rock pyrolysis analysis on each core sample to obtain the oil-generating window threshold and the proportion of cracked hydrocarbons in each core sample, the oil-generating window threshold is used to determine the maturity of the core. Whole-rock vitrinite reflectance testing is then performed on the core samples to obtain their maturity level, which is used to determine core maturity. If the maturity assessment results based on the oil-generating window threshold differ from those based on the maturity level, and / or the evolution trend of the cracked hydrocarbon proportion in the core sample does not conform to the normal thermal evolution trend, then the oil corresponding to the core is considered migrated oil. This allows for rapid identification of shale oil migration based on the core sample.

[0059] Example 2

[0060] Based on the above embodiments, the shale oil migration identification method of this embodiment includes the following steps: performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample.

[0061] Each core sample was subjected to rock pyrolysis analysis to obtain the free hydrocarbons and cracked hydrocarbons of each core sample;

[0062] The proportion of cracked hydrocarbons in each core sample is obtained based on the ratio of cracked hydrocarbons in free hydrocarbons to cracked hydrocarbons.

[0063] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample further includes:

[0064] Each core sample was subjected to rock pyrolysis analysis to obtain the organic matter abundance and the highest pyrolysis temperature of each core sample.

[0065] The hydrogen index of each core sample was obtained based on the ratio of cracked hydrocarbons to organic matter abundance.

[0066] Based on the cross plot of hydrogen index versus highest pyrolysis temperature for all core samples, the oil generation window threshold of the cores was determined.

[0067] In some implementations, the step of determining the oil generation window threshold of the core based on a cross-plot of the hydrogen index versus the highest pyrolysis temperature for all core samples includes:

[0068] Based on the cross plot of hydrogen index and highest pyrolysis temperature of all core samples, the organic matter type of the core was determined.

[0069] By combining the organic matter type with a preset mapping table, the oil-generating window threshold of the organic matter type is obtained.

[0070] In the technical solution of this embodiment, the preset mapping table is, for example, Table 2. In the technical solution of this embodiment, parameters such as the proportion of cracked hydrocarbons in the total hydrocarbons and the content of cracked hydrocarbons per unit of organic matter are calculated; and a graph is plotted as shown in Table 2. Figure 3 The cross plot of hydrogen index (S2 / TOC) versus maximum cracking peak temperature (Tmax) shown below, and as follows: Figure 4 The cross plot shown is a graph of the percentage of cracked hydrocarbons versus the highest cracking peak temperature (Tmax); based on... Figure 3 The cross plot of hydrogen index (S2 / TOC) and maximum cracking peak temperature (Tmax) shown indicates the type of organic matter; the Tmax threshold value for hydrocarbon generation of the sample is determined based on the type of organic matter.

[0071] In this embodiment, a 440-meter oil-bearing mudstone and shale core from Well A in the Fengcheng Formation of the Mahu Depression in the Junggar Basin is selected as an example. Typical mudstone and shale samples are selected at uniform intervals in the vertical layers. Based on the observation of the core samples, 109 samples are selected as test samples to analyze the data source. Sealed frozen fragmentation and rock pyrolysis tests are carried out. The free hydrocarbon S1, cracked hydrocarbon S2, organic matter abundance (TOC), calculated content, and maximum cracking temperature (Tmax) are obtained. Some test and calculation results are shown in Table 1. Table 1 shows the test values ​​of key parameters of some samples from the Fengcheng Formation section of Well A in the Fengcheng Formation of the Mahu Depression in the Junggar Basin. In this table, HI represents the measured hydrogen index (S2 / TOC), Ro represents the vitrinite reflectance, and □ indicates that there is no data at this position.

[0072] Table 1

[0073]

[0074]

[0075] Based on the cross plot of the measured sample hydrogen index Hi (S2 / TOC) and the highest cracking peak temperature (Tmax) ( Figure 1 It can be determined that the main type of organic matter is type II kerogen. Combined with Table 2, the oil window threshold Tmax temperature is 435℃. Table 2 shows the Tmax limit values ​​for different types of organic matter (Bordenave (1993)).

[0076] Table 2

[0077]

[0078] Plot the cross plot of Tmax and S2 / (S1+S2) for the sample, and label Tmax = 435℃. The interpretation chart shows:

[0079] More than 50% of the test data (60 test points) were below 435℃, and most of the measured Tmax values ​​were below the hydrocarbon generation threshold. Combined with the measured Ro values ​​(all greater than 0.7%), it can be judged that the organic matter in the test samples has reached the oil generation window threshold and is a mature sample. However, most of the measured Tmax values ​​are below 435℃, which is inconsistent with the maturity of the organic matter.

[0080] Furthermore, the evolution trend of the proportion of cracked hydrocarbons with Tmax value does not conform to the normal thermal evolution trend.

[0081] Based on comprehensive assessment, the shale oil in this stratum is considered to be migrating oil.

[0082] The technical solution of this embodiment obtains the oil generation window threshold and the proportion of cracked hydrocarbons in each core sample by performing rock pyrolysis analysis, and can determine the maturity of the core from the oil generation window threshold.

[0083] Example 3

[0084] Based on the above embodiments, the shale oil migration identification method of this embodiment includes the step of performing whole-rock vitrinite reflectance testing on core samples to obtain the maturity of the core samples, comprising:

[0085] At preset intervals at each depth, a core sample is selected for whole-rock vitrinite reflectance testing to obtain the maturity of the core sample.

[0086] In this embodiment, vitrinite reflectance is the most important indicator of organic matter maturity and is used to characterize the thermal evolution of organic matter from early diagenesis to deep metamorphic stages. Vitrinite is a coal-like substance, but without visible plant tissue; it is mainly composed of aromatic fused-ring compounds. As the degree of coalification increases, the degree of condensation of aromatic structures also increases, resulting in increased vitrinite reflectance. The thermal cracking process of the source rock is closely related to the evolution of vitrinite; therefore, vitrinite reflectance is a good indicator of organic matter maturity. The deeper the thermal metamorphism of organic matter, the greater the vitrinite reflectance. Generally, a vitrinite reflectance Ro between 0.5% and 1.2% is considered a sign of petroleum maturity.

[0087] Based on on-site core observations, 109 samples were selected as test samples for data analysis. Sealed frozen fragmentation and rock pyrolysis tests were conducted. The free hydrocarbon S1, cracked hydrocarbon S2, and calculated total organic matter (TOC) content, as well as the maximum cracking temperature (Tmax), were obtained. Some test and calculation results are shown in Table 1. In Table 1, HI represents the measured hydrogen index (S2 / TOC), Ro represents the vitrinite reflectance, and □ indicates that no data is available at that location. As shown in Table 1, the measured vitrinite reflectance (Ro) values ​​are all greater than 0.7%, indicating that the test samples are mature samples.

[0088] The technical solution of this embodiment obtains the maturity of the core sample by conducting a whole-rock vitrinite reflectance test.

[0089] Example 4

[0090] Based on the above embodiments, the shale oil migration identification method of this embodiment further includes, before the step of performing rock pyrolysis analysis on each core sample:

[0091] After the cores are extracted from the casing, core samples of different layers and different oil abundances are selected in the longitudinal direction;

[0092] All core samples were frozen;

[0093] Each core sample was sealed and crushed.

[0094] In this embodiment, after the core sample from a newly drilled well is extracted, multiple samples are selected for testing. These samples are from different vertical layers with varying oil abundance. The samples are protected by liquid nitrogen cryopreservation and promptly sent to the laboratory for analysis. 5-10 grams of the sample are selected and pulverized in a sealed environment under liquid nitrogen cryopreservation. The pulverized sample is then subjected to rock pyrolysis analysis to obtain parameters such as free hydrocarbons (S1), cracked hydrocarbons (S2), calculated total organic matter (TOC) content, and the maximum cracking temperature (Tmax). One sample is selected at 100-meter intervals at each depth for whole-rock vitrinite reflectance testing to obtain the maturity value of the sample.

[0095] Vitrinite reflectance is the most important indicator of organic matter maturity and is used to characterize the thermal evolution of organic matter from early diagenesis to deep metamorphic stages. Vitrinite is a coal-like substance, but without visible plant tissue; it is mainly composed of aromatic fused-ring compounds. As the degree of coalification increases, the degree of condensation of aromatic structures also increases, leading to increased vitrinite reflectance. The thermal cracking process of the source rock is closely related to the evolution of vitrinite, therefore, vitrinite reflectance is a good indicator of organic matter maturity; the deeper the thermal metamorphism of organic matter, the greater the vitrinite reflectance. Generally, a vitrinite reflectance Ro between 0.5% and 1.2% is considered a sign of petroleum maturity.

[0096] The technical solution of this embodiment, by selecting core samples from different vertical layers and with different oil abundances after the core is extracted from the core tube; freezing all core samples; and sealing and crushing each core sample, can ensure the accuracy of subsequent analysis.

[0097] Example 5

[0098] Based on the above embodiments, the shale oil migration identification method of this embodiment, based on the maturity judgment result of the oil generation window threshold, includes:

[0099] The proportion of core samples that fall within the oil-generating window threshold is taken out out of the total number of core samples. If the proportion is less than the threshold, the core is considered to have low maturity.

[0100] The proportion of core samples that fall within the oil generation window threshold to the total number of core samples includes: comparing the highest pyrolysis temperature of each core sample with the oil generation window threshold to determine whether the core sample falls within the oil generation window threshold.

[0101] In the technical solution of this embodiment, a cross-plot of Tmax and S2 / (S1+S2) of the sample is drawn, and Tmax = 435℃ is marked. As can be seen from the identification chart:

[0102] More than 50% of the test data (60 test points) were below 435℃, and most of the measured Tmax values ​​were below the hydrocarbon generation threshold. Combined with the measured Ro values ​​(all greater than 0.7%), it can be judged that the organic matter in the test samples has reached the oil generation window threshold and is a mature sample. However, most of the measured Tmax values ​​are below 435℃, which is inconsistent with the maturity of the organic matter.

[0103] Furthermore, the evolution trend of the proportion of cracked hydrocarbons with Tmax value does not conform to the normal thermal evolution trend.

[0104] Based on comprehensive assessment, the shale oil in this stratum is considered to be migrating oil.

[0105] The technical solution of this embodiment obtains the proportion of the number of core samples falling into the oil-generating window threshold to the total number of core samples. If the proportion is less than the threshold, the maturity of the core is judged to be low; conversely, if the proportion is greater than or equal to the threshold, the maturity of the core is judged to be high.

[0106] Example 6

[0107] Based on the above embodiments, Figure 2 This is a schematic diagram of a shale oil migration identification device according to an embodiment of the present invention. Figure 2 As shown, this embodiment provides a shale oil migration identification device, the device comprising:

[0108] The first analysis module is used to perform rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold is used to determine whether the core is mature.

[0109] The second analysis module is used to perform whole-rock vitrinite reflectance testing on the core sample to obtain the maturity of the core sample, whereby the maturity is used to determine whether the core is mature.

[0110] The migration identification module is used to identify the oil in the core as migrated oil if the maturity judgment result based on the oil generation window threshold does not match the maturity judgment result based on maturity level and / or the evolution trend of the cracked hydrocarbon ratio in the core sample does not match the normal thermal evolution trend.

[0111] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample includes:

[0112] Each core sample was subjected to rock pyrolysis analysis to obtain the free hydrocarbons and cracked hydrocarbons of each core sample;

[0113] The proportion of cracked hydrocarbons in each core sample is obtained based on the ratio of cracked hydrocarbons in free hydrocarbons to cracked hydrocarbons.

[0114] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample further includes:

[0115] Each core sample was subjected to rock pyrolysis analysis to obtain the organic matter abundance and the highest pyrolysis temperature of each core sample.

[0116] The hydrogen index of each core sample was obtained based on the ratio of cracked hydrocarbons to organic matter abundance.

[0117] Based on the cross plot of hydrogen index versus highest pyrolysis temperature for all core samples, the oil generation window threshold of the cores was determined.

[0118] In some implementations, the step of determining the oil generation window threshold of the core based on a cross-plot of the hydrogen index versus the highest pyrolysis temperature for all core samples includes:

[0119] Based on the cross plot of hydrogen index and highest pyrolysis temperature of all core samples, the organic matter type of the core was determined.

[0120] By combining the organic matter type with a preset mapping table, the oil-generating window threshold of the organic matter type is obtained.

[0121] In some embodiments, the step of performing whole-rock vitrinite reflectance testing on the core sample to obtain the maturity of the core sample includes:

[0122] At preset intervals at each depth, a core sample is selected for whole-rock vitrinite reflectance testing to obtain the maturity of the core sample.

[0123] In some implementations, prior to the step of performing rock pyrolysis analysis on each core sample, the following steps are also included:

[0124] After the cores are extracted from the casing, core samples of different layers and different oil abundances are selected in the longitudinal direction;

[0125] All core samples were frozen;

[0126] Each core sample was sealed and crushed.

[0127] In some implementations, the maturity assessment result based on the oil-producing window threshold includes:

[0128] The proportion of core samples that fall within the oil-generating window threshold is taken out out of the total number of core samples. If the proportion is less than the threshold, the core is considered to have low maturity.

[0129] The proportion of core samples that fall within the oil generation window threshold to the total number of core samples includes: comparing the highest pyrolysis temperature of each core sample with the oil generation window threshold to determine whether the core sample falls within the oil generation window threshold.

[0130] It should be understood that the apparatus of this embodiment has all the beneficial effects of the method embodiment.

[0131] Example 7

[0132] Based on the above embodiments, this embodiment provides an application example of the technical solution of the present invention.

[0133] The present invention adopts the following technical solution:

[0134] Step 1) Select multiple test samples after the new well core is extracted. Each test sample is a sample from a different layer and with different oil abundance in the vertical direction. The test samples are frozen and protected with liquid nitrogen and sent to the laboratory for testing in a timely manner.

[0135] Step 2) Select 5-10 grams of the sample to be tested and crush it in a sealed environment under liquid nitrogen freezing. The crushed sample is then subjected to rock pyrolysis analysis to obtain parameters such as free hydrocarbons (S1), cracked hydrocarbons (S2), calculated organic matter abundance (TOC), and the maximum cracking temperature (Tmax). One sample is selected at 100-meter intervals for whole-rock vitrinite reflectance testing to obtain the maturity value of the sample. Vitrinite reflectance is the most important indicator of organic matter maturity and is used to calibrate the thermal evolution of organic matter from early diagenesis to deep metamorphic stages. Vitrinite is a coal-like substance, but without visible plant tissue. It is mainly composed of aromatic fused-ring compounds. As the degree of coalification increases, the degree of condensation of aromatic structures also increases, resulting in increased vitrinite reflectance. The thermal cracking process of the source rock is closely related to the evolution of vitrinite; therefore, vitrinite reflectance is a good indicator of organic matter maturity. The deeper the thermal metamorphism of organic matter, the greater the vitrinite reflectance. It is generally believed that a vitrinite reflectance Ro between 0.5% and 1.2% indicates a mature petroleum zone.

[0136] Step 3) Calculate parameters such as the proportion of cracked hydrocarbons in total hydrocarbons and the content of cracked hydrocarbons per unit of organic matter;

[0137] Step 4) Plot the cross plot of hydrogen index (S2 / TOC) with the highest cracking peak temperature (Tmax) and the cross plot of cracked hydrocarbon ratio with the highest cracking peak temperature (Tmax).

[0138] Step 5) Determine the type of organic matter based on the cross plot of hydrogen index (S2 / TOC) and maximum cracking peak temperature (Tmax);

[0139] Step 6) Determine the Tmax threshold for hydrocarbon generation of the sample based on the type of organic matter;

[0140] Step 7) Migrating oil identification:

[0141] Step 7.1) Compare whether the measured highest pyrolysis temperature Tmax of the sample reaches the Tmax threshold value. This result serves as the basis for determining whether the organic matter of the mudstone and shale is mature and whether it is affected by migrating hydrocarbons.

[0142] Step 7.2) Based on the measured Tmax value after the Tmax threshold and the trend of the change in the proportion of cracked hydrocarbons, determine whether the sample is affected by the migrating hydrocarbons.

[0143] This invention provides an analytical method for rapidly identifying shale oil migration in shale formations by combining the results of frozen rock pyrolysis and whole-rock reflectance analysis of shale samples. This method serves as an important basis for evaluating the enrichment scale and mobility of shale oil, as well as for predicting subsequent exploration and development deployments.

[0144] The following explanation uses the Junggar Basin as an example.

[0145] Regarding the samples, a 440-meter oil-bearing mudstone and shale core from Well A in the Fengcheng Formation of the Mahu Depression in the Junggar Basin was selected as an example. Typical mudstone and shale samples were selected at uniform intervals in the vertical strata.

[0146] Regarding typical mudstone and shale samples and test results, based on on-site core observations, 109 samples were selected as test samples to analyze data sources. Sealed frozen fragmentation and rock pyrolysis tests were conducted to obtain the free hydrocarbon S1, cracked hydrocarbon S2, organic matter abundance TOC calculated content, and the highest cracking temperature Tmax. Some test and calculation results are shown in Table 1, where HI represents the measured hydrogen index (S2 / TOC) of the sample, Ro represents the vitrinite reflectance, and □ indicates that there is no data at that position.

[0147] Table 1

[0148]

[0149]

[0150] Regarding the identification of oil and gas migration, the cross plot of the measured hydrogen index Hi (S2 / TOC) and the highest cracking peak temperature (Tmax) of the sample is used. Figure 1 It can be determined that the main type of organic matter is type II kerogen, and based on Table 2, the oil window threshold Tmax temperature is 435℃.

[0151] Table 2

[0152]

[0153] Plot the cross plot of Tmax and S2 / (S1+S2) for the sample, and label Tmax = 435℃. The interpretation chart shows:

[0154] More than 50% of the test data (60 test points) were below 435℃, and most of the measured Tmax values ​​were below the hydrocarbon generation threshold. Combined with the measured Ro values ​​(all greater than 0.7%), it can be judged that the organic matter in the test samples has reached the oil generation window threshold and is a mature sample. However, most of the measured Tmax values ​​are below 435℃, which is inconsistent with the maturity of the organic matter.

[0155] Furthermore, the evolution trend of the proportion of cracked hydrocarbons with Tmax value does not conform to the normal thermal evolution trend.

[0156] Based on comprehensive assessment, the shale oil in this stratum is considered to be migrating oil.

[0157] Thus, this invention provides an analytical method for rapidly identifying shale oil migration in shale formations by combining the results of frozen rock pyrolysis and whole-rock reflectance analysis of shale samples. This provides an important basis for evaluating the scale of shale oil enrichment, its mobility, and predicting subsequent exploration and development deployments.

[0158] Example 8

[0159] This embodiment provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method of the above embodiment.

[0160] The aforementioned storage media can be flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, server, app store, etc.

[0161] The method implemented in this embodiment includes:

[0162] Each core sample was subjected to rock pyrolysis analysis to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold was used to determine whether the core was mature.

[0163] Whole-rock vitrinite reflectance tests were performed on the core samples to obtain the maturity of the core samples, whereby the maturity was used to determine whether the core was mature.

[0164] If the maturity judgment result based on the oil generation window threshold does not match the maturity judgment result based on maturity level and / or the evolution trend of the cracked hydrocarbon ratio in the core sample does not match the normal thermal evolution trend, then the oil corresponding to the core is migrated oil.

[0165] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample includes:

[0166] Each core sample was subjected to rock pyrolysis analysis to obtain the free hydrocarbons and cracked hydrocarbons of each core sample;

[0167] The proportion of cracked hydrocarbons in each core sample is obtained based on the ratio of cracked hydrocarbons in free hydrocarbons to cracked hydrocarbons.

[0168] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample further includes:

[0169] Each core sample was subjected to rock pyrolysis analysis to obtain the organic matter abundance and the highest pyrolysis temperature of each core sample.

[0170] The hydrogen index of each core sample was obtained based on the ratio of cracked hydrocarbons to organic matter abundance.

[0171] Based on the cross plot of hydrogen index versus highest pyrolysis temperature for all core samples, the oil generation window threshold of the cores was determined.

[0172] In some embodiments, the step of determining the oil generation window threshold of a core sample based on a cross-plot of the hydrogen index versus the highest pyrolysis temperature for all core samples includes:

[0173] Based on the cross plot of hydrogen index and highest pyrolysis temperature of all core samples, the organic matter type of the core was determined.

[0174] By combining the organic matter type with a preset mapping table, the oil-generating window threshold of the organic matter type is obtained.

[0175] In some embodiments, the step of performing whole-rock vitrinite reflectance testing on a core sample to obtain the maturity of the core sample includes:

[0176] At preset intervals at each depth, a core sample is selected for whole-rock vitrinite reflectance testing to obtain the maturity of the core sample.

[0177] In some embodiments, prior to the step of performing rock pyrolysis analysis on each core sample, the method further includes:

[0178] After the cores are extracted from the casing, core samples of different layers and different oil abundances are selected in the longitudinal direction;

[0179] All core samples were frozen;

[0180] Each core sample was sealed and crushed.

[0181] In some embodiments, the maturity determination result based on the oil-producing window threshold includes:

[0182] The proportion of core samples that fall within the oil-generating window threshold is taken out out of the total number of core samples. If the proportion is less than the threshold, the core is considered to have low maturity.

[0183] The proportion of core samples that fall within the oil generation window threshold to the total number of core samples includes: comparing the highest pyrolysis temperature of each core sample with the oil generation window threshold to determine whether the core sample falls within the oil generation window threshold.

[0184] Example 9

[0185] This embodiment provides an electronic device, including a processor and a memory, wherein a computer program is stored in the memory, and the processor executes the computer program to implement the method of the above embodiment.

[0186] The processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic components, and is used to execute the methods in the above embodiments.

[0187] Memory can be implemented from any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0188] The method implemented in this embodiment includes:

[0189] Each core sample was subjected to rock pyrolysis analysis to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold was used to determine whether the core was mature.

[0190] Whole-rock vitrinite reflectance tests were performed on the core samples to obtain the maturity of the core samples, whereby the maturity was used to determine whether the core was mature.

[0191] If the maturity judgment result based on the oil generation window threshold does not match the maturity judgment result based on maturity level and / or the evolution trend of the cracked hydrocarbon ratio in the core sample does not match the normal thermal evolution trend, then the oil corresponding to the core is migrated oil.

[0192] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample includes:

[0193] Each core sample was subjected to rock pyrolysis analysis to obtain the free hydrocarbons and cracked hydrocarbons of each core sample;

[0194] The proportion of cracked hydrocarbons in each core sample is obtained based on the ratio of cracked hydrocarbons in free hydrocarbons to cracked hydrocarbons.

[0195] In some embodiments, the step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample further includes:

[0196] Each core sample was subjected to rock pyrolysis analysis to obtain the organic matter abundance and the highest pyrolysis temperature of each core sample.

[0197] The hydrogen index of each core sample was obtained based on the ratio of cracked hydrocarbons to organic matter abundance.

[0198] Based on the cross plot of hydrogen index versus highest pyrolysis temperature for all core samples, the oil generation window threshold of the cores was determined.

[0199] In some embodiments, the step of determining the oil generation window threshold of a core sample based on a cross-plot of the hydrogen index versus the highest pyrolysis temperature for all core samples includes:

[0200] Based on the cross plot of hydrogen index and highest pyrolysis temperature of all core samples, the organic matter type of the core was determined.

[0201] By combining the organic matter type with a preset mapping table, the oil-generating window threshold of the organic matter type is obtained.

[0202] In some embodiments, the step of performing whole-rock vitrinite reflectance testing on a core sample to obtain the maturity of the core sample includes:

[0203] At preset intervals at each depth, a core sample is selected for whole-rock vitrinite reflectance testing to obtain the maturity of the core sample.

[0204] In some embodiments, prior to the step of performing rock pyrolysis analysis on each core sample, the method further includes:

[0205] After the cores are extracted from the casing, core samples of different layers and different oil abundances are selected in the longitudinal direction;

[0206] All core samples were frozen;

[0207] Each core sample was sealed and crushed.

[0208] In some embodiments, the maturity determination result based on the oil-producing window threshold includes:

[0209] The proportion of core samples that fall within the oil-generating window threshold is taken out out of the total number of core samples. If the proportion is less than the threshold, the core is considered to have low maturity.

[0210] The proportion of core samples that fall within the oil generation window threshold to the total number of core samples includes: comparing the highest pyrolysis temperature of each core sample with the oil generation window threshold to determine whether the core sample falls within the oil generation window threshold.

[0211] In the embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0212] It should be noted that, in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0213] While the embodiments disclosed in this invention are as described above, the above content is merely for the purpose of facilitating understanding of this invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed in this invention; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for identifying shale oil migration, characterized in that, The method includes: Each core sample was subjected to rock pyrolysis analysis to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample, wherein the oil generation window threshold is used to determine whether the core is mature. Whole-rock vitrinite reflectance test was performed on the core sample to obtain the maturity of the core sample, wherein the maturity was used to determine whether the core was mature; If the maturity judgment result based on the oil generation window threshold is inconsistent with the maturity judgment result based on the maturity level and / or the evolution trend of the cracked hydrocarbon ratio of the core sample is inconsistent with the normal thermal evolution trend, then the oil corresponding to the core is migrating oil.

2. The shale oil migration identification method according to claim 1, characterized in that, The step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample includes: Each core sample was subjected to rock pyrolysis analysis to obtain the free hydrocarbons and cracked hydrocarbons of each core sample; The proportion of cracked hydrocarbons in each core sample is obtained based on the ratio of cracked hydrocarbons in free hydrocarbons to cracked hydrocarbons.

3. The shale oil migration identification method according to claim 2, characterized in that, The step of performing rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample further includes: Each core sample was subjected to rock pyrolysis analysis to obtain the organic matter abundance and the highest pyrolysis temperature of each core sample. The hydrogen index of each core sample was obtained based on the ratio of cracked hydrocarbons to organic matter abundance. Based on the cross-plot of the hydrogen index and the highest pyrolysis temperature for all core samples, the oil generation window threshold of the core was determined.

4. The shale oil migration identification method according to claim 3, characterized in that, The step of determining the oil generation window threshold of the core based on the cross-plot of the hydrogen index and the highest pyrolysis temperature of all core samples includes: Based on the cross plot of the hydrogen index and the highest pyrolysis temperature of all core samples, the organic matter type of the core was determined; By combining the organic matter type with a preset mapping table, the oil-generating window threshold of the organic matter type is obtained.

5. The shale oil migration identification method according to claim 1, characterized in that, The step of performing whole-rock vitrinite reflectance testing on the core sample to obtain the maturity of the core sample includes: At preset intervals at each depth, a core sample is selected for whole-rock vitrinite reflectance testing to obtain the maturity of the core sample.

6. The shale oil migration identification method according to claim 1, characterized in that, Before the step of performing rock pyrolysis analysis on each core sample, the method further includes: After the cores are extracted from the casing, core samples of different layers and different oil abundances are selected in the longitudinal direction; All of the core samples were frozen; Each of the core samples was sealed and crushed.

7. The shale oil migration identification method according to claim 1, characterized in that, The maturity judgment result based on the oil-producing window threshold includes: The proportion of core samples falling within the oil-generating window threshold to the total number of core samples is obtained. If the proportion is less than the threshold, the maturity of the core is judged to be low. The step of obtaining the proportion of core samples falling within the oil-generating window threshold to the total number of core samples includes: comparing the highest pyrolysis temperature of each core sample with the oil-generating window threshold to determine whether the core sample falls within the oil-generating window threshold.

8. A shale oil migration identification device, characterized in that, The device includes: The first analysis module is used to perform rock pyrolysis analysis on each core sample to obtain the oil generation window threshold of the core and the proportion of cracked hydrocarbons in each core sample. The oil generation window threshold is used to determine whether the core is mature. The second analysis module is used to perform whole-rock vitrinite reflectance testing on the core sample to obtain the maturity of the core sample, wherein the maturity is used to determine whether the core is mature. The migration identification module is used to determine if the maturity judgment result based on the oil generation window threshold is inconsistent with the maturity judgment result based on the maturity level and / or the evolution trend of the cracked hydrocarbon ratio of the core sample is inconsistent with the normal thermal evolution trend, then the oil corresponding to the core is the migrating oil.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 7.

10. An electronic device comprising a processor and a memory, characterized in that, The memory stores a computer program, and the processor executes the computer program to implement the method of any one of claims 1 to 7.

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