A method for determining whether a shale reservoir is a deepwater sandy muddy debris flow deposit

Abstract

The application provides a method for determining whether a shale reservoir is a deep-water sandy muddy debris flow deposit. The method determines whether the target shale reservoir is a deep-water sandy muddy debris flow deposit by determining whether the target shale reservoir has characteristics 1, 2 and 3; wherein characteristic 1 is that coarse-grained material is suspended in fine-grained material; characteristic 2 is that there are partially long strip-shaped shallow-water interstitial materials arranged in a bedding manner in some areas, and there are partially long strip-shaped shallow-water interstitial materials not arranged in a bedding manner in some areas; wherein the bedding manner refers to an angle of not more than 10° with the stratum; and characteristic 3 is that there are a terrestrial subsystem, a shallow-water subsystem and a deep-water subsystem; wherein if there is coarse-grained terrestrial quartz, the terrestrial subsystem exists; if there is coarse-grained interstitial material, the shallow-water subsystem exists; and if there is muddy biological silica and an organic clay complex with a honeycomb-shaped organic pore, the deep-water subsystem exists.

Description

Technical Field

[0001] This invention relates to a method for determining whether a shale reservoir is a deep-water sandy-muddy debris flow deposit. Background Technology

[0002] Shale reservoirs are currently one of the main targets for shale gas exploration and development. However, the analysis of the sedimentary environment of shale reservoirs is still incomplete. The formation environment of shale reservoirs remains unresolved, with some reservoirs even exhibiting two diametrically opposed theories: shallow-water origin and deep-water origin.

[0003] Existing sedimentary environment analysis techniques for shale reservoirs are mostly based on outcrops, cores, and thin sections, with a few relying on whole-rock analysis data. When these two techniques are used to analyze the sedimentary environment of shale reservoirs containing a mixture of coarse and fine-grained materials and organic matter contaminating fine-grained minerals, the results generally suffer from high uncertainty. When analyzing the sedimentary environment of shale reservoirs with a mixture of coarse and fine-grained materials and organic matter contaminating fine-grained minerals based on outcrops, cores, and thin sections, the contamination of organic matter means that outcrops and cores only show coarse-grained particles, and while thin sections may show some fine-grained particles, it is difficult to observe fine silt and mud particles, let alone identify their mineral types. This leads to the common assumption that the sedimentary environment is determined based on coarse-grained particles, and that the mineral types of fine silt and mud particles satisfy the coarse-grained sedimentary environment criteria. Therefore, the determined sedimentary environment results are highly uncertain. When analyzing the sedimentary environment of shale reservoirs with a mixture of coarse and fine-grained materials and organic matter impregnating fine-grained minerals based on whole-rock analysis data, the whole-rock analysis data is obtained through X-ray diffraction testing of rock powder, which cannot reflect the occurrence state of minerals and their relationship with organic matter. This makes it difficult to identify the sedimentary facies type, and therefore it is difficult to determine the sedimentary environment or the determined sedimentary environment results are highly uncertain.

[0004] In summary, new techniques for analyzing the sedimentary environment of shale reservoirs are still needed to better determine the sedimentary environment of shale reservoirs that contain a mixture of coarse and fine-grained materials and organic matter that infiltrates fine-grained minerals. Summary of the Invention

[0005] The purpose of this invention is to provide a technical solution for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit. This technical solution can be used to determine whether the depositional environment of a shale reservoir with a mixture of coarse and fine-grained materials and organic matter impregnating fine-grained minerals is a deep-water sandy-muddy clastic flow deposit.

[0006] To achieve the above objectives, the present invention provides a method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, the method comprising:

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

[0008] Based on core samples from the target shale reservoir, determine whether the target shale reservoir possesses characteristics 1, 2, and 3; if the target shale reservoir possesses characteristics 1, 2, and 3, then the target shale reservoir is a deep-water sandy-muddy clastic flow deposit; among which,

[0009] Feature 1: Coarse-grained materials are suspended in fine-grained materials;

[0010] Feature 2: Some areas have elongated shallow water debris arranged parallel to the bedding plane, while other areas have elongated shallow water debris arranged non-parallel to the bedding plane; among them, parallel arrangement refers to horizontal arrangement, specifically meaning that the angle between the debris and the strata does not exceed 10°.

[0011] Feature 3: It has a terrestrial subsystem, a shallow water subsystem, and a deep water subsystem; among them, if coarse-grained terrestrial quartz is present, it has a terrestrial subsystem; if coarse-grained microcrystals are present, it has a shallow water subsystem; if mud-grade biomass silica and an organic clay particle complex with honeycomb-like organic pores are present, it has a deep water subsystem.

[0012] The inventors of this invention, through analysis and characterization of the petrological features of deep-water sandy-muddy clastic flow deposits, discovered that if a shale reservoir possesses feature 1 (coarse-grained material suspended in fine-grained material), feature 2 (some of the elongated shallow-water debris is arranged in a bedding plane and some is arranged out of bedding plane), and feature 3 (possessing terrigenous subsystems, shallow-water subsystems, and deep-water subsystems), then this shale reservoir is a deep-water sandy-muddy clastic flow deposit. Thus, features 1, 2, and 3 can effectively characterize shale reservoirs as deep-water sandy-muddy clastic flow deposits.

[0013] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, the target shale reservoir sample is a shale sample in which coarse-grained mineral particles and fine-grained mineral particles are mixed and organic matter is impregnated in the fine-grained minerals.

[0014] According to a specific implementation method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, the terrigenous subsystem also includes fine-grained terrigenous quartz and / or clay minerals.

[0015] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, the shallow-water subsystem also includes fine-grained media.

[0016] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, the deep-water subsystem also includes fine silt-mud grade calcite, and / or fine silt-mud grade dolomite with a rhomboid profile, and / or fine silt-mud grade berry-like pyrite.

[0017] According to a specific implementation of the method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, the deep-water subsystem also includes clay minerals, and / or pure organic matter with honeycomb-like organic pores, and / or pure organic matter without pores.

[0018] According to a specific implementation method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, based on a target shale reservoir sample, determining whether the target shale reservoir possesses characteristic 1, characteristic 2, and characteristic 3 includes:

[0019] Core observation was performed on core samples from the target shale reservoir.

[0020] Prepare thin sections of core samples from the target shale reservoir;

[0021] Observe thin sections of core from the target shale reservoir under an optical microscope;

[0022] Electron probe microscopy was used to observe thin sections of cores from the target shale reservoir.

[0023] Preparation of argon-ion polished discs of target shale reservoirs based on core thin sections of target shale reservoirs;

[0024] MAPS rock image data volume analysis was performed on argon-ion polished slides of the target shale reservoir;

[0025] Based on core observations, optical microscopy observations, electron probe microscopy observations, and MAPS rock image data volume analysis, the mineral types and occurrence states of coarse-grained, coarse-silt, fine-silt, and mudstone-grade materials in the target shale reservoir were determined, thereby determining whether the target shale reservoir possesses characteristics 1, 2, and 3.

[0026] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, core observation of the target shale reservoir core sample includes observing the cylindrical surface of the target shale reservoir core sample and observing the longitudinal section of the target shale reservoir core sample.

[0027] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy muddy clastic flow deposition, preferably, during the core observation of the core sample of the target shale reservoir, the mineral type and occurrence state of the coarse-grained material are observed.

[0028] More preferably, during the core observation of the target shale reservoir core sample, the observation of the mineral type and occurrence state of the coarse-grained material includes: observing the occurrence state of coarse-grained shallow-water debris and coarse-grained terrigenous quartz.

[0029] More preferably, during the core observation of the target shale reservoir core sample, the observation of the mineral type and occurrence state of the coarse-grained material includes: observing the presence of coarse-grained shallow-water cuttings, observing the presence of coarse-grained terrigenous quartz (i.e., non-porous quartz), observing the presence of elongated shallow-water cuttings that are partly arranged parallel to the bedding plane and partly arranged non-parallel to the bedding plane, and observing whether the coarse-grained material is suspended in the fine-grained material.

[0030] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, the core section of the target shale reservoir has a length of 2.5-7cm, a width of 2.5-5cm, and a thickness of 30-40μm.

[0031] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, the top and bottom surfaces of the target shale reservoir core section are parallel to the top and bottom surfaces of the target shale reservoir core sample in its underground state, so as to better reveal the underground state information of the rock.

[0032] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, during the observation of the core thin section of the target shale reservoir under an optical microscope, the top and bottom surfaces of the core thin section of the target shale reservoir are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0033] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy muddy clastic flow deposit, preferably, during the observation of the core thin section of the target shale reservoir under an optical microscope, the mineral types and occurrence states of coarse-grained and coarse silt-sized materials are observed.

[0034] More preferably, during the observation of the core thin section of the target shale reservoir under an optical microscope, the observation of the mineral types and occurrence states of the coarse-grained and coarse-silt-grade materials includes: observing the occurrence states of the coarse-grained and coarse-silt-grade shallow-water sediments and the coarse-grained and coarse-silt-grade terrigenous quartz.

[0035] More preferably, during the observation of the core thin section of the target shale reservoir under an optical microscope, the observation of the mineral types and occurrence states of the coarse-grained and coarse-silt-grade materials includes: observing the presence of coarse-grained and coarse-silt-grade shallow-water media, observing the presence of coarse-grained and coarse-silt-grade terrigenous quartz (i.e., non-porous quartz), and observing whether the coarse-grained and coarse-silt-grade materials are suspended in the fine-silt-grade and mud-grade materials.

[0036] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, during the observation of the target shale reservoir core thin section under an electron probe microscope, the top and bottom surfaces of the target shale reservoir core thin section are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0037] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, the observation of the target shale reservoir core thin section under an electron probe microscope includes observing the spectral image of the target shale reservoir core thin section and observing the C, Si, Ca, Mg, Al, Fe, and S elemental surface scans within the spectral image range of the target shale reservoir core thin section.

[0038] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy muddy clastic flow deposit, preferably, during the observation of the core thin section of the target shale reservoir under an electron probe microscope, the mineral types and occurrence states of fine silt and muddy materials are determined.

[0039] More preferably, during the observation of the core thin section of the target shale reservoir under an electron probe microscope, the determination of the mineral types and occurrence states of the fine silt-mud grade materials includes: determining whether fine silt-mud grade quartz exists, determining whether fine silt-mud grade organic matter exists, determining whether fine silt-mud grade clay exists, and determining the relationship between fine silt-mud grade minerals and organic matter.

[0040] More preferably, during the observation of the core thin section of the target shale reservoir under an electron probe microscope, the determination of the mineral types and occurrence states of the fine silt and mudstone also includes: determining the mineral composition of the fine silt and mudstone.

[0041] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, the length of the argon ion polishing sheet of the target shale reservoir is 0.8-2cm, the width is 0.8-2cm, and the thickness is 0.3-0.8cm.

[0042] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposition, preferably, the top and bottom surfaces of the argon ion polished sheet of the target shale reservoir are parallel to the top and bottom surfaces of the core sample of the target shale reservoir in its underground state, so as to better reveal the underground state information of the rock.

[0043] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, preferably, MAPS rock image data volume analysis of the target shale reservoir argon-ion polished slides includes:

[0044] Acquire MAPS rock image data from argon-ion polished slides of the target shale reservoir;

[0045] The MAPS rock image data of the target shale reservoir argon-ion polished slides were analyzed.

[0046] More preferably, the acquisition of MAPS rock image data volume of the argon ion polished sheet of the target shale reservoir includes: selecting an area with a length and width not exceeding 400 μm on the polished surface of the argon ion polished sheet of the target shale reservoir, and acquiring the MAPS rock image data volume;

[0047] More preferably, during the acquisition of MAPS rock image data from argon-ion polished discs of the target shale reservoir, the top and bottom surfaces of the argon-ion polished discs of the target shale reservoir are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0048] More preferably, during the analysis of the MAPS rock image data volume of the acquired argon-ion polished slides of the target shale reservoir, an image editor (such as the offline image editor ATLAS) is used. TM (BROWSER-BASEDVIEWER) allows viewing of MAPS rock image data volumes on a computer;

[0049] More preferably, the resolution of the MAPS rock image data volume of the argon-ion polished slide of the target shale gas sweet spot rock is 1-10 nm.

[0050] According to the specific implementation method of determining whether a shale reservoir is a deep-water sandy muddy clastic flow deposit, preferably, during the MAPS rock image data volume analysis of the argon ion polished slide of the target shale reservoir, the mineral types, pore development and occurrence state of fine sand and mud particles are clarified.

[0051] More preferably, during the MAPS rock image data volume analysis of the argon ion polished slides of the target shale reservoir, the determination of the mineral type, pore development and occurrence state of the fine sand and mud particles includes: determining whether the mud-grade biomass silica, i.e., porous quartz, exists, and determining whether the fine sand-mud-grade organic clay particle complex with honeycomb organic pores exists.

[0052] More preferably, during the MAPS rock image data volume analysis of the argon-ion polished slides of the target shale reservoir, the determination of the mineral type, pore development, and occurrence state of the fine silt and mud particles further includes: determining whether fine silt-mud calcite exists, and / or determining whether fine silt-mud dolomite with a rhomboid outline exists, and / or determining whether fine silt-mud berry-like pyrite exists, and / or determining whether fine silt-mud pure organic matter with honeycomb-like organic pores exists, and / or determining whether fine silt-mud pure organic matter without pores exists.

[0053] The technical solution provided by this invention enables the determination of whether a shale reservoir containing a mixture of coarse and fine-grained materials and organic matter impregnating fine-grained minerals is a deep-water sandy-muddy clastic flow deposit by characterizing the petrological features of shale. This will contribute to the development of deep-water sedimentology and guide the exploration deployment and site selection of shale gas. Attached Figure Description

[0054] Figure 1a This is a core cylinder diagram from Example 1.

[0055] Figure 1b This is a longitudinal section of the core sample from Example 1.

[0056] Figure 1c This is a single-polarized light image of a core thin section from Example 1.

[0057] Figure 1d This is an orthogonal light pattern of a core thin section from Example 1.

[0058] Figure 1e The image shows the spectrum of the core thin section in Example 1.

[0059] Figure 1f This is a surface scan of Si element in the core thin section of Example 1.

[0060] Figure 1g This is a surface scan of Ca content in a core thin section from Example 1.

[0061] Figure 1h This is a surface scan of Mg element in a core thin section from Example 1.

[0062] Figure 1i This is a surface scan of Al content in a core thin section from Example 1.

[0063] Figure 1j This is a surface scan of Fe element in a core thin section from Example 1.

[0064] Figure 1k This is a surface scan of the S element in the core thin section of Example 1.

[0065] Figure 11 This is a surface scan of C element in a core thin section from Example 1.

[0066] Figure 1m The images show the quartz diagrams of the silt and mud grades in Example 1.

[0067] Figure 1n This is a diagram of the mud-grade quartz in Example 1.

[0068] Figure 1o This is a diagram of mud-grade calcite in Example 1.

[0069] Figure 1p This is a diagram of the fine sand-grade dolomite in Example 1.

[0070] Figure 1q This is a diagram of the mud-grade organic clay particle composite in Example 1.

[0071] Figure 1r The image shows the silt-grade pyrite in Example 1.

[0072] Figure 1s This is a diagram of mud-grade pyrite in Example 1.

[0073] Figure 1t The diagram shows the organic matter of the silt and mud grades in Example 1.

[0074] Figure 2a This is a core cylinder diagram from Example 2.

[0075] Figure 2b This is a longitudinal section of the core sample from Example 2.

[0076] Figure 2c This is a single-polarized light image of a core thin section from Example 2.

[0077] Figure 2d This is an orthogonal light pattern of a core thin section from Example 2.

[0078] Figure 2e The image shows the spectrum of the core thin section in Example 2.

[0079] Figure 2f This is a surface scan of Si element in the core thin section from Example 2.

[0080] Figure 2g This is a surface scan of the Ca element in the core thin section from Example 2.

[0081] Figure 2h This is a surface scan of Mg element in a core thin section from Example 2.

[0082] Figure 2i This is a surface scan of Al elements in a core thin section from Example 2.

[0083] Figure 2j This is a surface scan of Fe element in a core thin section from Example 2.

[0084] Figure 2k This is a surface scan of the S element in the core thin section from Example 2.

[0085] Figure 2l This is a surface scan of C element in a core thin section from Example 2.

[0086] Figure 2m The images show the quartz diagrams of the silt and mud grades in Example 2.

[0087] Figure 2n This is a diagram of the mud-grade quartz in Example 2.

[0088] Figure 2o This is a diagram of mud-grade calcite in Example 2.

[0089] Figure 2p This is a diagram of the fine sand-grade dolomite in Example 2.

[0090] Figure 2q This is a diagram of the silt-grade organic clay particle composite in Example 2.

[0091] Figure 2r This is a diagram of mud-grade pyrite in Example 2.

[0092] Figure 2s The image shows the silt-grade pyrite in Example 2.

[0093] Figure 2t This is a diagram of pure organic matter with honeycomb-like organic pores in the mud grade of Example 2.

[0094] Figure 2u This is a diagram of the pure organic matter in the mud grade, which is free of pores, in Example 2. Detailed Implementation

[0095] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0096] Coarse-grained particles have a diameter ≥60μm;

[0097] Fine-grained particles with a diameter <60μm;

[0098] The particle size of silt grade is 4-60μm;

[0099] The particle size of coarse silt is 30-60μm;

[0100] The particle size of fine sand is greater than or equal to 4μm and less than 30μm;

[0101] The particle size of the mud grade is <4μm;

[0102] The particle size of fine sand-mud grade is <30μm.

[0103] Existing sedimentary environment analysis techniques for shale reservoirs mostly rely on outcrops, cores, and thin sections, with a few based on whole-rock analysis data. The mixture of coarse and fine-grained minerals, and the disseminated organic matter, makes it difficult to effectively observe the occurrence of fine-grained materials and organic matter using outcrops, cores, and ordinary thin sections. Whole-rock analysis data cannot reflect the occurrence state of minerals and their interaction with organic matter. Therefore, existing sedimentary environment analysis techniques for shale reservoirs with a mixture of coarse and fine-grained materials and organic matter disseminated in fine-grained minerals yield highly uncertain results. Based on this, the inventors are dedicated to researching a method for analyzing the sedimentary environment of shale reservoirs with a mixture of coarse and fine-grained materials and organic matter disseminated in fine-grained minerals.

[0104] The inventors of this invention have pioneered the characterization and analysis of shale petrological features. By systematically integrating core observation, thin-section optical microscopy, thin-section electron probe microscopy analysis, and MAPS rock image data volume analysis, they have achieved petrological characterization of shale reservoirs with a mixture of coarse and fine-grained materials and organic matter impregnation of fine-grained minerals, which are deposited in deep-water sandy-muddy clastic flow environments. Based on this, they have proposed a method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit. This method can determine whether a shale reservoir with a mixture of coarse and fine-grained materials and organic matter impregnation of fine-grained minerals is a deep-water sandy-muddy clastic flow deposit.

[0105] In one specific embodiment, the present invention provides a method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, the method comprising:

[0106] Obtain core samples from the target shale reservoir;

[0107] Based on core samples from the target shale reservoir, determine whether the target shale reservoir possesses characteristics 1, 2, and 3; if the target shale reservoir possesses characteristics 1, 2, and 3, then the target shale reservoir is a deep-water sandy-muddy clastic flow deposit; among which,

[0108] Feature 1: Coarse-grained materials are suspended in fine-grained materials;

[0109] Feature 2: Some areas contain elongated shallow water debris arranged parallel to the bedding plane, while other areas contain elongated shallow water debris arranged non-parallel to the bedding plane; where parallel arrangement refers to horizontal arrangement, specifically an angle with the strata not exceeding 10°; non-parallel arrangement refers to non-horizontal arrangement, specifically an angle with the strata greater than 10°.

[0110] Feature 3: It has a terrestrial subsystem, a shallow water subsystem, and a deep water subsystem; among them, if coarse-grained terrestrial quartz is present, it has a terrestrial subsystem; if coarse-grained microcrystals are present, it has a shallow water subsystem; if mud-grade biomass silica and an organic clay particle complex with honeycomb-like organic pores are present, it has a deep water subsystem.

[0111] The inventors of this invention, through analysis and characterization of the petrological features of deep-water sandy-muddy clastic flow deposits, discovered that if a shale reservoir possesses feature 1 (coarse-grained material suspended in fine-grained material), feature 2 (some of the elongated shallow-water debris is arranged in a bedding plane and some is arranged out of bedding plane), and feature 3 (possessing terrigenous subsystems, shallow-water subsystems, and deep-water subsystems), then this shale reservoir is a deep-water sandy-muddy clastic flow deposit. Thus, features 1, 2, and 3 can effectively characterize shale reservoirs as deep-water sandy-muddy clastic flow deposits.

[0112] Furthermore, the terrigenous subsystem also includes fine-grained terrigenous quartz.

[0113] Furthermore, the terrestrial subsystem also includes clay minerals.

[0114] Furthermore, the shallow water subsystem also includes fine-grained debris.

[0115] Furthermore, the deep-water subsystem also includes fine silt-mud grade calcite.

[0116] Furthermore, the deep-water subsystem also includes fine silt-mud grade dolomite with a rhomboid profile.

[0117] Furthermore, the deepwater subsystem also includes fine silt-mud grade berry-like pyrite.

[0118] Furthermore, the deep-water subsystem also includes silt-mud clay minerals.

[0119] Furthermore, the deep-water subsystem also includes pure organic matter with honeycomb-like organic pores in the fine silt-mud grade.

[0120] Furthermore, the deep-water subsystem also includes fine silt-mud grade non-porous pure organic matter.

[0121] Furthermore, the target shale reservoir sample is a shale sample containing a mixture of coarse and fine-grained mineral particles and organic matter impregnating the fine-grained minerals.

[0122] Furthermore, based on the target shale reservoir samples, determining whether the target shale reservoir possesses characteristic 1, characteristic 2, and characteristic 3 includes:

[0123] Core observation was performed on core samples from the target shale reservoir.

[0124] Prepare thin sections of core samples from the target shale reservoir;

[0125] Observe thin sections of core from the target shale reservoir under an optical microscope;

[0126] Electron probe microscopy was used to observe thin sections of cores from the target shale reservoir.

[0127] Preparation of argon-ion polished discs of target shale reservoirs based on core thin sections of target shale reservoirs;

[0128] MAPS rock image data volume analysis was performed on argon-ion polished slides of the target shale reservoir;

[0129] Based on core observation results, optical microscopy observation results, electron probe microscopy observation results, and MAPS rock image data volume analysis results, the mineral types and occurrence states of coarse-grained, coarse silt, fine silt, and mudstone materials in the target shale reservoir are determined, thereby determining whether the target shale reservoir has characteristics 1, 2, and 3.

[0130] Core observation can only reveal the occurrence state of coarse-grained materials; thin-section observation under an optical microscope can reveal the occurrence state of coarse-grained and coarse-silt-sized mineral particles, but it is difficult to reveal the occurrence state of fine-grained sand and mud-sized materials; thin-section observation under an electron probe microscope is more suitable for confirming mineral types; MAPS rock image data is more suitable for analyzing the mineral types and occurrence states of fine-grained sand and mud-sized particles. Based on this, and based on the results of core observation, optical microscope observation, electron probe microscope observation, and MAPS rock image data analysis, it is possible to better determine whether the target shale reservoir has characteristics 1, 2, and 3.

[0131] Furthermore, core observation of the target shale reservoir core samples includes observing the cylindrical surface of the target shale reservoir core samples and observing the longitudinal section of the target shale reservoir core samples.

[0132] Furthermore, during the core observation of the target shale reservoir core samples, the mineral types and occurrence states of coarse-grained materials are observed. Even further, during the core observation of the target shale reservoir core samples, the observation of the mineral types and occurrence states of coarse-grained materials includes: observing the occurrence states of coarse-grained shallow-water cuttings and coarse-grained terrigenous quartz. Still further, during the core observation of the target shale reservoir core samples, the observation of the mineral types and occurrence states of coarse-grained materials includes: observing the presence of coarse-grained shallow-water cuttings; observing the presence of coarse-grained terrigenous quartz (i.e., non-porous quartz); observing the presence of elongated shallow-water cuttings, some arranged parallel to the bedding plane and some arranged disparallel to the bedding plane; and observing whether coarse-grained materials are suspended within fine-grained materials.

[0133] During the core observation of the target shale reservoir core samples, the white or grayish-white elongated calcite observed were coarse-grained shallow-water debris, and the small white spots without pores observed were terrigenous quartz.

[0134] Furthermore, the core sections of the target shale reservoir are 2.5-7 cm long, 2.5-5 cm wide, and 30-40 μm thick.

[0135] Furthermore, the top and bottom surfaces of the target shale reservoir core sections are parallel to the top and bottom surfaces of the target shale reservoir core samples in their subsurface state, in order to better reveal information about the subsurface state of the rocks.

[0136] Furthermore, during the observation of the target shale reservoir core thin section under an optical microscope, the top and bottom surfaces of the target shale reservoir core thin section are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0137] Furthermore, during the observation of the target shale reservoir core thin sections under an optical microscope, the mineral types and occurrence states of coarse-grained and coarse-silt-grade materials are observed. Even further, during the observation of the target shale reservoir core thin sections under an optical microscope, the observation of the mineral types and occurrence states of coarse-grained and coarse-silt-grade materials includes: observing the occurrence states of coarse-grained and coarse-silt-grade shallow-water cuttings and coarse-grained and coarse-silt-grade terrigenous quartz. Still further, during the observation of the target shale reservoir core thin sections under an optical microscope, the observation of the mineral types and occurrence states of coarse-grained and coarse-silt-grade materials includes: observing the presence of coarse-grained and coarse-silt-grade shallow-water cuttings, observing the presence of coarse-grained and coarse-silt-grade terrigenous quartz (i.e., non-porous quartz), and observing whether coarse-grained and coarse-silt-grade materials are suspended in fine-silt-grade and mud-grade materials.

[0138] During the observation of core thin sections of the target shale reservoir under an optical microscope, the presence of shallow water debris and terrigenous quartz (non-porous quartz) can be well confirmed by observing with single polarized light and cross-polarized light.

[0139] Furthermore, during the observation of the target shale reservoir core thin section under an electron probe microscope, the top and bottom surfaces of the target shale reservoir core thin section are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0140] Furthermore, electron probe microscopy observations were performed on the core thin sections of the target shale reservoir, including observations of the spectral images of the core thin sections and observations of the C, Si, Ca, Mg, Al, Fe, and S elemental surface scans within the spectral image range of the core thin sections.

[0141] Furthermore, during the observation of thin sections of the target shale reservoir core under an electron probe microscope, the mineral types and occurrence states of fine silt and mudstone are determined. Even further, during the observation of thin sections of the target shale reservoir core under an electron probe microscope, determining the mineral types and occurrence states of fine silt and mudstone includes: determining the presence of fine silt-mudstone quartz, the presence of fine silt-mudstone organic matter, the presence of fine silt-mudstone clay, and the relationship between fine silt-mudstone minerals and organic matter. Still further, during the observation of thin sections of the target shale reservoir core under an electron probe microscope, determining the mineral types and occurrence states of fine silt and mudstone also includes: determining the mineral composition of fine silt and mudstone.

[0142] During observation under an electron probe microscope, the presence of coarse-grained and silty calcite (grayish-white), quartz (gray), and pyrite (bright white) can be clearly observed through spectral images, but information on clay-grade materials is difficult to observe. By scanning the surface of seven elements (C, Si, Ca, Mg, Al, Fe, and S) within the spectral image range, the presence of fine-grained silty-clay-grade quartz, calcite, dolomite, clay, pyrite, and organic matter can be determined, but the morphology of these fine-grained silty-clay-grade minerals is difficult to observe. Quartz has the highest Si content, calcite has the highest Ca content, and pyrite has the highest S content. Coarse-grained detrital quartz and calcite are easily distinguishable based on the Si and Ca surface scan results. The areas where Al overlaps with Mg, Fe, and / or Ca are clay minerals. The red and pink micro-areas in the C surface scan are organic matter. Fine-grained materials cause a color degradation in the elemental surface scan due to mutual shielding.

[0143] Furthermore, the argon ion polishing sheet for the target shale reservoir has a length of 0.8-2 cm, a width of 0.8-2 cm, and a thickness of 0.3-0.8 cm.

[0144] Furthermore, the top and bottom surfaces of the argon-ion polished section of the target shale reservoir are parallel to the top and bottom surfaces of the target shale reservoir core sample in its subsurface state, in order to better reveal information about the subsurface state of the rock.

[0145] Furthermore, the MAPS rock image data volume analysis of the argon-ion polished slides of the target shale reservoir includes:

[0146] Acquire MAPS rock image data from argon-ion polished slides of the target shale reservoir;

[0147] The MAPS rock image data of the target shale reservoir argon-ion polished slides were analyzed.

[0148] Furthermore, the acquisition of MAPS rock image data from the argon-ion polished sheet of the target shale reservoir includes: selecting an area with a length and width not exceeding 400 μm on the polished surface of the argon-ion polished sheet of the target shale reservoir, and acquiring the MAPS rock image data.

[0149] Furthermore, during the acquisition of MAPS rock image data from argon-ion polished slides of the target shale reservoir, the top and bottom surfaces of the argon-ion polished slides of the target shale reservoir are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0150] Furthermore, during the analysis of the MAPS rock image data volume of the acquired argon-ion polished sections of the target shale reservoir, an image editor (such as the offline image editor ATLAS) was used. TM (BROWSER-BASEDVIEWER) allows viewing of MAPS rock image data volumes on a computer;

[0151] Furthermore, the resolution of the MAPS rock image data volume of the argon-ion polished slides of the target shale gas sweet spot rock was 1-10 nm.

[0152] Furthermore, during the MAPS rock image data volume analysis of the argon-ion polished sections of the target shale reservoir, the mineral types, pore development, and occurrence states of the fine silt and mud particles were clarified. Even further, during the MAPS rock image data volume analysis of the argon-ion polished sections of the target shale reservoir, clarifying the mineral types, pore development, and occurrence states of the fine silt and mud particles includes: determining the presence of mud-grade biomass silica (i.e., porous quartz) and determining the presence of fine silt-mud-grade organic clay particle complexes with honeycomb-like organic pores; and even further... In the process of performing MAPS rock image data volume analysis on argon-ion polished sections of the target shale reservoir, the determination of the mineral type, pore development and occurrence state of fine silt and mud particles also includes: determining whether fine silt-mud particles contain calcite, and / or whether fine silt-mud particles contain dolomite with rhomboid outlines, and / or whether fine silt-mud particles contain berry-like pyrite, and / or whether fine silt-mud particles contain pure organic matter with honeycomb-like organic pores, and / or whether fine silt-mud particles contain pure organic matter without pores.

[0153] The mixed coarse and fine mineral grains, along with the disseminated mixture of fine grains and organic matter, make it difficult to effectively observe the occurrence of fine-grained materials and organic matter in outcrops, cores, and ordinary rock thin sections. This is one of the main reasons why the study of sedimentary processes in Shale A reservoirs has been weak for a long time. The sedimentary type of Shale A reservoirs is clarified below through Examples 1 and 2.

[0154] Example 1:

[0155] This embodiment provides a method for determining whether Shale A reservoir is a deep-water sandy-muddy debris flow deposit.

[0156] The method specifically includes:

[0157] 1. Obtain core samples from the target shale reservoir.

[0158] In this embodiment, Shale A is selected as the target shale reservoir, and core samples collected from the sandy shale section of Shale A are used as core samples of the target shale reservoir.

[0159] 2. Core observation of core samples from the target shale reservoir;

[0160] ① Core specimen observation revealed that the target shale reservoir is characterized by black shale with unevenly distributed coarse-grained material. The coarse-grained material consists of shallow-water clastic material and terrigenous quartz (non-porous quartz). The shallow-water clastic material comprises elongated calcite strips arranged both parallel and non-parallel to the bedding plane (e.g., Figure 1a (As indicated by the red arrow in the middle), terrigenous quartz appears as small white dots (such as...). Figure 1a (as indicated by the green arrow in the middle);

[0161] ② Through the longitudinal section of the core, it can be clearly observed that the coarse-grained material includes terrigenous quartz (non-porous quartz) and shallow-water debris. This coarse-grained material, including terrigenous quartz (non-porous quartz) and shallow-water debris, is suspended within the fine-grained material. The lower part has a high content of terrigenous quartz, while the upper part has a high content of shallow-water debris. The micro-regions of the coarse-grained material exhibit a natural transition between dense and sparse distribution (e.g., Figure 1b (as indicated by the red arrow in the middle) or mutation contact (such as...) Figure 1b (As indicated by the green arrow in the middle), some of the long, shallow-water debris are arranged horizontally (such as...). Figure 1b (As indicated by the blue arrow) that is arranged in layers, with the remaining parts piled up randomly (such as...) Figure 1b The area indicated by the purple arrow (in the middle) exhibits discontinuous stratification, with micro-regions containing high levels of terrigenous quartz forming discontinuous banded sandy shale (such as...). Figure 1b (The part within the solid yellow box).

[0162] 3. Prepare thin sections of core samples from the target shale reservoir.

[0163] In this embodiment, a thin section of the target shale reservoir core sample with a length of 7 cm, a width of 5 cm, and a thickness of 35 μm is prepared using the target shale reservoir core sample. The top and bottom surfaces of the thin section are parallel to the top and bottom surfaces of the target shale reservoir core sample in its underground state, so as to better reveal the underground state information of the rock.

[0164] 4. Observe the core thin sections of the target shale reservoir under an optical microscope.

[0165] In this embodiment, when observing under an optical microscope, the top and bottom of the rock section are kept at the top and bottom of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0166] Under an optical microscope, the occurrence of coarse-grained and coarse-silt minerals can be observed, but the occurrence of fine-silt and clay minerals and organic matter is difficult to observe. In this embodiment, observation under an optical microscope shows that the target shale reservoir generally consists of coarse-grained and coarse-silt materials floating in black fine-silt and clay materials (e.g., Figure 1c , Figure 1d As shown); through single-polarized light (such as...) Figure 1c ) and orthogonal lights (such as Figure 1d Repeated observations revealed that the coarse-grained and coarse-silt minerals in the target shale reservoir are shallow-water clastic materials (such as...). Figure 1c , Figure 1d (as indicated by the red arrow in the middle) and terrigenous quartz, i.e., non-porous quartz (such as...) Figure 1c , Figure 1d (As indicated by the green arrow in the middle), coarse-grained and coarse silt-grade terrigenous quartz and shallow-water debris account for 41% and 33% of the rock volume percentage, respectively, while black fine silt-grade and mud-grade materials account for 26% of the rock volume percentage.

[0167] 5. Observe the core thin sections of the target shale reservoir under an electron probe microscope.

[0168] In this embodiment, when observing under an electron probe microscope, the top and bottom of the rock section are kept at the top and bottom of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0169] In this embodiment, electron probe microscopy observation of the target shale reservoir core thin sections includes observing the spectral images of the target shale reservoir core thin sections and observing the elemental surface scans of C, Si, Ca, Mg, Al, Fe, and S within the spectral image range of the target shale reservoir core thin sections. The acquired spectral images clearly show coarse-grained and silty shallow-water cuttings (such as... Figure 1e (as indicated by the red arrow in the middle), quartz (such as...) Figure 1e (as indicated by the green arrow) and pyrite (such as Figure 1e(As indicated by the blue arrow in the middle), but information about the mud-grade materials is difficult to observe. Surface scanning of seven elements (C, Si, Ca, Mg, Al, Fe, and S) across the spectral image range revealed that the fine silt and mud-grade materials are a mixture of quartz, calcite, dolomite, clay, pyrite, and organic matter, but mineral morphology is difficult to observe. Quartz has the highest Si content, calcite has the highest Ca content, and pyrite has the highest S content. Coarse-grained detrital quartz and calcite are easily distinguishable based on the Si and Ca surface scanning results. The areas where Al overlaps with Mg, Fe, and / or Ca are clay minerals. The red and pink micro-areas in the C surface scan are organic matter. The fine-grained materials exhibit color degradation due to mutual shielding (e.g., ...). Figure 1f , Figure 1g , Figure 1h , Figure 1i , Figure 1j , Figure 1k , Figure 11 (As shown).

[0170] 6. Preparation of argon-ion polished discs of target shale reservoir based on core thin sections of the target shale reservoir.

[0171] In this embodiment, an argon-ion polishing sheet is prepared within a sandy shale region containing the rock thin section, measuring 1cm x 1cm x 0.5cm in length x width x thickness. The top and bottom surfaces of the argon-ion polishing sheet are parallel to the top and bottom surfaces of the target shale reservoir core sample in its underground state, in order to better reveal the underground state information of the rock.

[0172] 7. Perform MAPS rock image volume analysis on argon-ion polished slides of the target shale reservoir.

[0173] In this embodiment, a region with a length and width not exceeding 400 μm is selected on the polished surface of the argon-ion polished disc of the target shale reservoir, and a MAPS rock image data volume with a resolution of 4 nm is acquired. The acquired MAPS rock image data volume of the target shale reservoir argon-ion polished disc is then analyzed. During the acquisition of the MAPS rock image data volume of the target shale reservoir argon-ion polished disc, the top and bottom surfaces of the target shale reservoir argon-ion polished disc are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely magnified representations of the underground state of the rock. During the analysis of the acquired MAPS rock image data volume of the target shale reservoir argon-ion polished disc, an image editor (the offline version of the image editor ATLAS) is used. TM The BROWSER-BASEDVIEWER allows for the viewing of MAPS rock image data volumes on a computer.

[0174] In this embodiment, analysis of the 4nm MAPS rock image data revealed that the silt and mud-grade materials were composed of quartz, calcite, dolomite, clay, pyrite, organic matter, and other substances. Among these, the non-porous quartz consisted of terrigenous particles (such as...). Figure 1m (As indicated by the red arrow in the middle), porous quartz is biomass silicon (such as...) Figure 1n As shown), irregular calcite (such as...) Figure 1o The red arrow in the middle indicates that the dolomite may be a source of retransportation from both shallow-water clastic and deep-water sedimentary debris. The rhomboid-shaped dolomite is a retransportation mineral of cementitious materials in deep-water sediments (such as...). Figure 1p (As indicated by the red arrow in the middle), clay and organic matter combine to form an organic clay-particle complex (such as...). Figure 1q (As indicated by the red arrow in the middle), pyrite mainly manifests as berry-like pyrite subjected to intense pressure solution (such as...). Figure 1r (as shown) and extruded quartz particles (such as Figure 1s (as indicated by the red arrow in the middle) berry-like pyrite (such as Figure 1s As shown), organic matter can be divided into organic clay particle complexes with honeycomb-like organic pores (such as...). Figure 1q Pure organic matter with honeycomb-like organic pores (as indicated by the red arrow in the middle) Figure 1t (as indicated by the red arrow in the middle) and pure organic matter without pores (such as...) Figure 1t (As indicated by the green arrow).

[0175] 8. Based on core observations, optical microscopy, electron probe microscopy, and MAPS rock image data volume analysis, determine the mineral types and occurrence states of coarse-grained, coarse-silt, fine-silt, and mudstone-grade materials in the target shale reservoir, thereby determining whether the target shale reservoir possesses characteristics 1, 2, and 3. Characteristic 1: Coarse-grained material is suspended within fine-grained material; Characteristic 2: Some areas contain elongated shallow-water cuttings arranged parallel to the bedding plane, while others contain elongated shallow-water cuttings arranged horizontally; Specific characteristic 3: The reservoir possesses terrigenous, shallow-water, and deep-water subsystems; The presence of coarse-grained terrigenous quartz indicates a terrigenous subsystem; the presence of coarse-grained cuttings indicates a shallow-water subsystem; and the presence of mudstone-grade biomass silica and organic clay particles with honeycomb-like organic pores indicates a deep-water subsystem.

[0176] In this embodiment, based on comprehensive petrological characteristics derived from core observations, optical microscopy, electron probe microscopy, and MAPS rock image data analysis, the coarse-grained and coarse-silty sand particles were identified as calcite and quartz, while the fine-silty and mud-like particles were identified as quartz, calcite, dolomite, clay, pyrite, and organic matter. Quartz can be classified as non-porous or porous based on porosity; non-porous quartz is terrigenous quartz, while porous quartz is biomass silica. Both coarse-grained and coarse-silty sand particles are non-porous terrigenous quartz, while fine-silty and mud-like sand particles contain both terrigenous quartz and biomass silica. The coarse-grained and coarse-silty sand particles are shallow-water clastic materials, while the fine-silty and mud-like sand particles may be shallow-water clastic materials. Debris may also be a source of re-transportation of clastic particles from deep-water sediments; dolomite is a diagenetic mineral in deep-water sediments that has been remodeled by deep-water gravity flows into clastic particles; pyrite is a product of bromelain pyrite in deep-water sediments that has been remodeled by deep-water gravity flows and strongly burial and diagenetic altered; organic matter can be divided into organic clay-particle complexes with honeycomb-like organic pores, pure organic matter with honeycomb-like organic pores, and pure organic matter without pores. Among them, organic clay-particle complexes with honeycomb-like organic pores are formed by the thermal degradation of settled organic clay-particle complexes into tar pitch; pure organic matter with honeycomb-like organic pores is formed by the thermal degradation of pre-migrating bitumen into tar pitch; and pure organic matter without pores is formed by the thermal evolution of migrating petroleum into tar pitch. Using a comprehensive phase surface method based on optical microscopic images of cores and thin sections, spectral images and elemental surface scan images of thin sections, and MAPS rock image data, coarse-grained and coarse-silty shallow-water sedimentary debris and terrigenous quartz accounted for 33% and 41% of the rock volume percentage, respectively. Fine-silty and muddy terrigenous quartz, biomass silica, calcite, and organic clay aggregates accounted for 6%, 11%, 4%, and 3% of the rock volume percentage, respectively. Fine-silty and muddy dolomite, pyrite, pure organic matter with honeycomb-like organic pores, and pure organic matter without pores each accounted for less than 1% of the rock volume percentage. Guided by systems theory, the target shale reservoir comprises three subsystems: a terrigenous subsystem, a shallow-water subsystem, and a deep-water subsystem. The terrigenous subsystem consists of coarse-grained and fine-grained terrigenous quartz and clay minerals. The shallow-water subsystem consists of coarse-grained and fine-grained clastic materials. The deep-water subsystem consists of fine-grained and mud-grade biomass silica, calcite, dolomite, pyrite, clay minerals, organic-clay composites with honeycomb-like organic pores, pure organic matter with honeycomb-like organic pores, and non-porous pure organic matter. Among these minerals and organic matter, the fine-grained and mud-grade calcite have sources from both the shallow-water and deep-water subsystems, making them difficult to distinguish. Similarly, the clay minerals have sources from both the terrigenous and deep-water subsystems, making them difficult to distinguish.

[0177] In summary, the target shale reservoir has characteristics 1, 2, and 3.

[0178] 9. Given that the target shale reservoir has characteristics 1, 2 and 3, the target shale reservoir is a deep-water sandy muddy clastic flow deposit.

[0179] Therefore, it can be concluded that Shale A is a deep-water sandy-muddy clastic flow deposit.

[0180] Example 2

[0181] This embodiment provides a method for determining whether Shale A reservoir is a deep-water sandy-muddy debris flow deposit.

[0182] The method specifically includes:

[0183] 1. Obtain core samples from the target shale reservoir.

[0184] In this embodiment, Shale A was selected as the target shale reservoir, and core samples were obtained from the black shale section rich in shallow water cuttings in Shale A as the core samples of the target shale reservoir.

[0185] 2. Core observation of core samples from the target shale reservoir;

[0186] ① Core specimen observation revealed that the target shale reservoir is characterized by black shale with unevenly distributed coarse-grained material. The coarse-grained material consists of shallow-water clastic material and terrigenous quartz (non-porous quartz). The shallow-water clastic material comprises elongated calcite strips arranged both parallel and non-parallel to the bedding plane (e.g., Figure 2a (As indicated by the red arrow in the middle), terrigenous quartz appears as small white dots (such as...). Figure 2a (as indicated by the green arrow in the middle);

[0187] ② Through the longitudinal section of the core, it can be clearly observed that the coarse-grained material includes terrigenous quartz (non-porous quartz) and shallow-water debris. This coarse-grained material, including terrigenous quartz (non-porous quartz) and shallow-water debris, is suspended within the fine-grained material. The lower part has a high content of terrigenous quartz, while the upper part has a high content of shallow-water debris. The micro-regions of the coarse-grained material exhibit a natural transition between dense and sparse distribution (e.g., Figure 2b (as indicated by the red arrow in the middle) or mutation contact (such as...) Figure 2b (As indicated by the green arrow in the middle), some of the long, shallow-water debris are arranged horizontally (such as...). Figure 2b (As indicated by the blue arrow) that is arranged in layers, with the remaining parts piled up randomly (such as...) Figure 2b (As indicated by the purple arrow) exhibits dissociated bedding, with micro-regions of low terrigenous quartz content forming black shale rich in clastic material (such as...). Figure 2b (The part within the solid yellow box).

[0188] 3. Prepare thin sections of core samples from the target shale reservoir.

[0189] In this embodiment, a thin section of the target shale reservoir core sample with a length of 7 cm, a width of 5 cm, and a thickness of 35 μm is prepared using the target shale reservoir core sample. The top and bottom surfaces of the thin section are parallel to the top and bottom surfaces of the target shale reservoir core sample in its underground state, so as to better reveal the underground state information of the rock.

[0190] 4. Observe the core thin sections of the target shale reservoir under an optical microscope.

[0191] In this embodiment, when observing under an optical microscope, the top and bottom of the rock section are kept at the top and bottom of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0192] Under an optical microscope, the occurrence of coarse-grained and coarse-silt minerals can be observed, but the occurrence of fine-silt and clay minerals and organic matter is difficult to observe. In this embodiment, observation under an optical microscope shows that the target shale reservoir generally consists of coarse-grained and coarse-silt materials floating in black fine-silt and clay materials (e.g., Figure 2c , Figure 2d As shown); through single-polarized light (such as...) Figure 2c ) and orthogonal lights (such as Figure 2d Repeated observations revealed that the coarse-grained and coarse-silt minerals in the target shale reservoir are shallow-water clastic materials (such as...). Figure 2c , Figure 2d (as indicated by the red arrow in the middle) and terrigenous quartz, i.e., non-porous quartz (such as...) Figure 2c , Figure 2d (As indicated by the green arrow in the middle), coarse-grained and coarse silt-grade terrigenous quartz and shallow-water debris account for 11% and 18% of the rock volume percentage, respectively, while black fine silt-grade and mud-grade materials account for 71% of the rock volume percentage.

[0193] 5. Observe the core thin sections of the target shale reservoir under an electron probe microscope.

[0194] In this embodiment, when observing under an electron probe microscope, the top and bottom of the rock section are kept at the top and bottom of the field of view, respectively, to ensure that the observed microscopic phenomena are merely an amplification of the underground state of the rock.

[0195] In this embodiment, electron probe microscopy observation of the target shale reservoir core thin sections includes observing the spectral images of the target shale reservoir core thin sections and observing the elemental surface scans of C, Si, Ca, Mg, Al, Fe, and S within the spectral image range of the target shale reservoir core thin sections. The acquired spectral images clearly show coarse-grained and silty shallow-water cuttings (such as... Figure 2e (as indicated by the red arrow in the middle), quartz (such as...) Figure 2e (as indicated by the green arrow) and pyrite (such as Figure 2e(As indicated by the blue arrow in the middle), but information about the mud-grade materials is difficult to observe. Surface scanning of seven elements (C, Si, Ca, Mg, Al, Fe, and S) across the spectral image range revealed that the fine silt and mud-grade materials are a mixture of quartz, calcite, dolomite, clay, pyrite, and organic matter, but mineral morphology is difficult to observe. Quartz has the highest Si content, calcite has the highest Ca content, and pyrite has the highest S content. Coarse-grained detrital quartz and calcite are easily distinguishable based on the Si and Ca surface scanning results. The areas where Al overlaps with Mg, Fe, and / or Ca are clay minerals. The red and pink micro-areas in the C surface scan are organic matter. The fine-grained materials exhibit color degradation due to mutual shielding (e.g., ...). Figure 2f , Figure 2g , Figure 2h , Figure 2i , Figure 2j , Figure 2k , Figure 2l (As shown).

[0196] 6. Preparation of argon-ion polished discs of target shale reservoir based on core thin sections of the target shale reservoir.

[0197] In this embodiment, an area with a length × width × thickness of 1cm × 1cm × 0.5cm is selected within the black shale where the rock thin section is located to prepare an argon-ion polishing sheet; wherein, the top and bottom surfaces of the argon-ion polishing sheet are parallel to the top and bottom surfaces of the target shale reservoir core sample in its underground state, so as to better reveal the underground state information of the rock.

[0198] 7. Perform MAPS rock image volume analysis on argon-ion polished slides of the target shale reservoir.

[0199] In this embodiment, a region with a length and width not exceeding 400 μm is selected on the polished surface of the argon-ion polished disc of the target shale reservoir, and a MAPS rock image data volume with a resolution of 4 nm is acquired. The acquired MAPS rock image data volume of the target shale reservoir argon-ion polished disc is then analyzed. During the acquisition of the MAPS rock image data volume of the target shale reservoir argon-ion polished disc, the top and bottom surfaces of the target shale reservoir argon-ion polished disc are kept at the top and bottom surfaces of the field of view, respectively, to ensure that the observed microscopic phenomena are merely magnified representations of the underground state of the rock. During the analysis of the acquired MAPS rock image data volume of the target shale reservoir argon-ion polished disc, an image editor (the offline version of the image editor ATLAS) is used. TM The BROWSER-BASEDVIEWER allows for the viewing of MAPS rock image data volumes on a computer.

[0200] In this embodiment, analysis of the 4nm MAPS rock image data revealed that the silt and mud-grade materials were composed of quartz, calcite, dolomite, clay, pyrite, organic matter, and other substances. Among these, the non-porous quartz consisted of terrigenous particles (such as...). Figure 2m (As indicated by the red arrow in the middle), porous quartz is biomass silicon (such as...) Figure 2m The green arrow points to and as shown Figure 2n As shown), irregular calcite (such as...) Figure 2o The red arrow in the middle indicates that the dolomite may be a source of retransportation from both shallow-water clastic and deep-water sedimentary debris. The rhomboid-shaped dolomite is a retransportation mineral of cementitious materials in deep-water sediments (such as...). Figure 2p (As indicated by the red arrow in the middle), clay and organic matter combine to form an organic clay-particle complex (such as...). Figure 2q (As indicated by the red arrow in the middle), pyrite mainly manifests as berry-like pyrite subjected to intense pressure solution (such as...). Figure 2r (as shown) and extruded quartz particles (such as Figure 2s (as indicated by the red arrow in the middle) berry-like pyrite (such as Figure 2s As shown), organic matter can be divided into organic clay particle complexes with honeycomb-like organic pores (such as...). Figure 2q Pure organic matter with honeycomb-like organic pores (as indicated by the red arrow in the middle) Figure 2t (as shown) and non-porous pure organic matter (such as Figure 2u (As shown).

[0201] 8. Based on core observations, optical microscopy, electron probe microscopy, and MAPS rock image data volume analysis, determine the mineral types and occurrence states of coarse-grained, coarse-silt, fine-silt, and mudstone-grade materials in the target shale reservoir, thereby determining whether the target shale reservoir possesses characteristics 1, 2, and 3. Characteristic 1: Coarse-grained material is suspended within fine-grained material; Characteristic 2: Some areas contain elongated shallow-water cuttings arranged parallel to the bedding plane, while others contain elongated shallow-water cuttings arranged horizontally; Specific characteristic 3: The reservoir possesses terrigenous, shallow-water, and deep-water subsystems; The presence of coarse-grained terrigenous quartz indicates a terrigenous subsystem; the presence of coarse-grained cuttings indicates a shallow-water subsystem; and the presence of mudstone-grade biomass silica and organic clay particles with honeycomb-like organic pores indicates a deep-water subsystem.

[0202] In this embodiment, based on the comprehensive petrological characteristics determined by core observation, optical microscopy, electron probe microscopy, and MAPS rock image data volume analysis, the coarse-grained and coarse-silty sand particles are calcite and quartz, while the fine-silty and mud-like particles are quartz, calcite, dolomite, clay, pyrite, organic matter, etc. According to the presence or absence of porosity, quartz can be divided into non-porous quartz and porous quartz. Non-porous quartz is terrigenous quartz, while porous quartz is biomass silica. The coarse-grained and coarse-silty sand particles are both non-porous terrigenous quartz, while the fine-silty and mud-like particles contain both terrigenous quartz and biomass silica. The coarse-grained and coarse-silty sand particles are shallow-water clastic materials, while the fine-silty and mud-like particles may be clastic materials. The debris may also be calcite residues secreted by surface microorganisms; dolomite is a diagenetic mineral in deep-water sediments that has been remodeled by deep-water gravity currents and become clastic particles; pyrite is a product of bromelain pyrite in deep-water sediments that has been remodeled by deep-water gravity currents and strongly burial and diagenetic altered; organic matter can be divided into organic clay-particle complexes with honeycomb-like organic pores, pure organic matter with honeycomb-like organic pores, and pure organic matter without pores. Among them, organic clay-particle complexes with honeycomb-like organic pores are formed by the thermal degradation of settled organic clay-particle complexes into tar pitch; pure organic matter with honeycomb-like organic pores is formed by the thermal degradation of pre-migrating asphalt into tar pitch; and pure organic matter without pores is formed by the thermal evolution of migrating petroleum into tar pitch. Using a comprehensive phase surface method based on optical microscopic images of cores and thin sections, spectral images and elemental surface scan images of thin sections, and MAPS rock image data, coarse-grained and coarse-silty shallow-water sedimentary debris and terrigenous quartz accounted for 18% and 11% of the rock volume percentage, respectively. Fine-silty and mud-grade terrigenous quartz, biomass silica, calcite, organosilicon particle complexes with honeycomb-like organic pores, pure organic matter with honeycomb-like organic pores, and non-porous pure organic matter accounted for 4%, 22%, 12%, 27%, 3%, and 2% of the rock volume percentage, respectively. Fine-silty and mud-grade dolomite and pyrite each accounted for less than 1% of the rock volume percentage. Guided by systems theory, the target shale reservoir comprises three subsystems: a terrigenous subsystem, a shallow-water subsystem, and a deep-water subsystem. The terrigenous subsystem consists of coarse-grained and fine-grained terrigenous quartz and clay minerals. The shallow-water subsystem consists of coarse-grained and fine-grained clastic materials. The deep-water subsystem consists of fine-grained and mud-grade biomass silica, calcite, dolomite, pyrite, clay minerals, organic-clay composites with honeycomb-like organic pores, pure organic matter with honeycomb-like organic pores, and pure organic matter without pores. Among these minerals and organic matter, the fine-grained and mud-grade calcite have sources from both the shallow-water and deep-water subsystems, making them difficult to distinguish. Similarly, the clay minerals have sources from both the terrigenous and deep-water subsystems, making them difficult to distinguish.

[0203] In summary, does the target shale reservoir possess characteristics 1, 2, and 3?

[0204] 9. Given that the target shale reservoir has characteristics 1, 2 and 3, the target shale reservoir is a deep-water sandy muddy clastic flow deposit.

[0205] Therefore, it can be concluded that Shale A is a deep-water sandy-muddy clastic flow deposit.

[0206] Examples 1 and 2 both conclude that Shale A reservoir is a deep-water sandy-muddy clastic flow deposit. Through comprehensive observation of core samples, thin sections, electron probe microanalysis, and MAPS rock image data, Examples 1 and 2 show that Shale A reservoir contains a certain amount of organic clay aggregates with honeycomb-like organic pores and pure organic matter. This indicates that Shale A is not a tight barrier for shale gas as previously thought, but rather a shale gas reservoir, thus guiding efficient shale gas exploration and development. Examples 1 and 2 pioneered the orderly characterization of sedimentary facies types through the sequential integration of core samples, thin sections, electron probe microanalysis, and MAPS rock image data, confirming that Shale A reservoir is a deep-water sandy-muddy clastic flow deposit, breaking through the bottleneck in the study of Shale A reservoir sedimentary facies, and contributing to the development of deep-water sedimentology. The confirmation of the sedimentary type of Shale A reservoir will help guide shale gas exploration deployment and site selection.

[0207] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining whether a shale reservoir is a deep-water sandy-muddy clastic flow deposit, wherein, The method includes: Obtain core samples from the target shale reservoir; wherein, the target shale reservoir sample is a shale sample in which coarse-grained mineral particles and fine-grained mineral particles are mixed and organic matter is impregnated in the fine-grained minerals; Based on core samples from the target shale reservoir, determine whether the target shale reservoir possesses characteristics 1, 2, and 3; among which... Feature 1: Coarse-grained materials are suspended in fine-grained materials; Feature 2: Some areas contain elongated shallow water debris arranged parallel to the bedding plane, while other areas contain elongated shallow water debris arranged non-parallel to the bedding plane; among them, parallel arrangement refers to the angle between the debris and the strata not exceeding 10°. Feature 3: It has terrestrial subsystems, shallow water subsystems, and deep water subsystems; among them, if coarse-grained terrestrial quartz is present, it has a terrestrial subsystem; if coarse-grained microclasts are present, it has a shallow water subsystem; if mud-grade biomass silica and organic clay particle composites with honeycomb organic pores are present, it has a deep water subsystem. If the target shale reservoir has characteristics 1, 2 and 3, then the target shale reservoir is a deep-water sandy-muddy clastic flow deposit.

2. The method according to claim 1, wherein, The terrigenous subsystem also includes fine-grained terrigenous quartz and / or clay minerals; and / or The shallow water subsystem also includes fine-grained debris; and / or The deep-water subsystem also includes fine-grained calcite, and / or fine-grained dolomite with a rhombic profile, and / or bromelain pyrite; and / or The deep-water subsystem also includes clay minerals, and / or pure organic matter with honeycomb-like organic pores, and / or pure organic matter without pores.

3. The method according to claim 1 or 2, wherein, Based on the target shale reservoir sample, determining whether the target shale reservoir possesses characteristic 1, characteristic 2, and characteristic 3 includes: Core observation was performed on core samples from the target shale reservoir. Prepare thin sections of core samples from the target shale reservoir; Observe thin sections of core from the target shale reservoir under an optical microscope; Electron probe microscopy was used to observe thin sections of cores from the target shale reservoir. Preparation of argon-ion polished discs of target shale reservoirs based on core thin sections of target shale reservoirs; MAPS rock image data volume analysis was performed on argon-ion polished slides of the target shale reservoir; Based on core observations, optical microscopy observations, electron probe microscopy observations, and MAPS rock image data volume analysis, the mineral types and occurrence states of coarse-grained, coarse-silt, fine-silt, and mudstone-grade materials in the target shale reservoir were determined, thereby determining whether the target shale reservoir possesses characteristics 1, 2, and 3.

4. The method according to claim 3, wherein, Core observation of the target shale reservoir core samples includes observing the cylindrical surface of the target shale reservoir core samples and observing the longitudinal section of the target shale reservoir core samples.

5. The method according to claim 3, wherein, The target shale reservoir core sections are 2.5-7 cm long, 2.5-5 cm wide, and 30-40 µm thick; and / or The top and bottom surfaces of the target shale reservoir core section are parallel to the top and bottom surfaces of the target shale reservoir core sample in its subsurface state; and / or During optical microscopy observation of thin sections of the target shale reservoir core, the top and bottom surfaces of the thin sections are kept at the top and bottom of the field of view, respectively; and / or During electron probe microscopy observation of thin sections of cores from the target shale reservoir, the top and bottom surfaces of the core sections are kept at the top and bottom of the field of view, respectively; and / or Electron probe microscopy observation of thin sections of the target shale reservoir core includes observation of the spectral images of the target shale reservoir core thin sections and observation of elemental surface scans of C, Si, Ca, Mg, Al, Fe, and S within the spectral image range of the target shale reservoir core thin sections; and / or The target shale reservoir argon ion polishing sheet has a length of 0.8-2 cm, a width of 0.8-2 cm, and a thickness of 0.3-0.8 cm; and / or The top and bottom surfaces of the argon-ion polished section of the target shale reservoir are parallel to the top and bottom surfaces of the core sample of the target shale reservoir in its subsurface state; and / or The MAPS rock image data volume analysis of the argon-ion polished slides of the target shale reservoir includes: acquiring the MAPS rock image data volume of the argon-ion polished slides of the target shale reservoir; and analyzing the acquired MAPS rock image data volume of the argon-ion polished slides of the target shale reservoir.

6. The method according to claim 5, wherein, The acquisition of MAPS rock image data from argon-ion polished wafers of the target shale reservoir includes: selecting an area with a length and width not exceeding 400 μm on the polished surface of the argon-ion polished wafer of the target shale reservoir, and acquiring the MAPS rock image data.

7. The method according to claim 5, wherein, During the acquisition of MAPS rock image data from argon-ion polished slides of the target shale reservoir, the top and bottom surfaces of the argon-ion polished slides of the target shale reservoir are kept at the top and bottom surfaces of the field of view, respectively.

8. The method according to claim 5, wherein, The resolution of the MAPS rock image data volume of the argon-ion polished slides of the target shale gas sweet spot rock is 1-10 nm.

9. The method according to claim 3, wherein, During the core observation of core samples from the target shale reservoir, the mineral types and occurrence states of coarse-grained materials are observed.

10. The method according to claim 9, wherein, During the core observation of the target shale reservoir core samples, the observation of the mineral types and occurrence states of coarse-grained materials includes: observing the occurrence states of coarse-grained shallow-water sediments and coarse-grained terrigenous quartz.

11. The method according to claim 10, wherein, During the core observation of the target shale reservoir core sample, the observation of the mineral type and occurrence state of the coarse-grained material includes: observing the presence of coarse-grained shallow-water cuttings, observing the presence of coarse-grained terrigenous quartz (i.e., non-porous quartz), observing the presence of elongated shallow-water cuttings, some of which are arranged parallel to the bedding plane and some of which are arranged disparallel to the bedding plane, and observing whether the coarse-grained material is suspended in the fine-grained material.

12. The method according to claim 3, wherein, During the observation of thin sections of core from the target shale reservoir under an optical microscope, the mineral types and occurrence states of coarse-grained and coarse-silt-sized materials were observed.

13. The method according to claim 12, wherein, During the observation of the core thin section of the target shale reservoir under an optical microscope, the mineral types and occurrence states of the coarse-grained and coarse-silt-grade materials observed include: observing the occurrence states of coarse-grained and coarse-silt-grade shallow-water sediments and coarse-grained and coarse-silt-grade terrigenous quartz.

14. The method according to claim 13, wherein, During the observation of the core thin section of the target shale reservoir under an optical microscope, the mineral types and occurrence states of the coarse-grained and coarse silt-grade materials include: observing the presence of shallow-water cuttings in the coarse-grained and coarse silt-grade materials; observing the presence of terrigenous quartz (i.e., non-porous quartz) in the coarse-grained and coarse silt-grade materials; and observing whether the coarse-grained and coarse silt-grade materials are suspended in the fine silt-grade and mud-grade materials.

15. The method according to claim 3, wherein, During the observation of thin sections of cores from the target shale reservoir under an electron probe microscope, the mineral types and occurrence states of fine silt and mudstone were determined.

16. The method according to claim 15, wherein, During the observation of the core thin section of the target shale reservoir under an electron probe microscope, the determination of the mineral types and occurrence states of the fine silt and mud grades includes: determining whether fine silt-mud grade quartz exists, whether fine silt-mud grade organic matter exists, whether fine silt-mud grade clay exists, and determining the relationship between fine silt-mud grade minerals and organic matter.

17. The method according to claim 16, wherein, During the observation of thin sections of cores from the target shale reservoir under an electron probe microscope, determining the mineral types and occurrence states of fine silt and mudstone also includes determining the mineral composition of the fine silt and mudstone.

18. The method according to claim 3, wherein, During the MAPS rock image data volume analysis of the argon-ion polished slides of the target shale reservoir, the mineral types, pore development, and occurrence state of the fine silt and mud particles were identified.

19. The method according to claim 18, wherein, During the MAPS rock image data volume analysis of the argon ion polished slides of the target shale reservoir, the determination of the mineral type, pore development and occurrence state of the fine sand and mud particles includes: determining whether there is porous quartz in the mud particles and whether there is an organic clay particle complex with honeycomb organic pores in the fine sand-mud particles.

20. The method according to claim 19, wherein, During the MAPS rock image data volume analysis of the argon-ion polished slides of the target shale reservoir, the determination of the mineral type, pore development and occurrence state of fine silt and mud particles also includes: determining whether fine silt-mud calcite exists, and / or whether fine silt-mud dolomite with a rhomboid outline exists, and / or whether fine silt-mud berry-like pyrite exists, and / or whether fine silt-mud pure organic matter with honeycomb-like organic pores exists, and / or whether fine silt-mud pure organic matter without pores exists.

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