Method for determining whether siliceous shale is a hydrostatic physicochemical deposit

Abstract

The application provides a method for judging whether siliceous shale is hydrochemical deposition. The method comprises the following steps: determining whether the target siliceous shale has characteristics 1, 2, 3 and 4, and if yes, the target siliceous shale is hydrochemical deposition; characteristic 1: biogenic silica accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and terrigenous quartz and terrigenous feldspar account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock; characteristic 2: containing calcite and dolomite; characteristic 3: containing ordinary framboidal pyrite, and the ordinary framboidal pyrite refers to framboidal pyrite with intercrystalline pore organic matter; characteristic 4: containing organic clay complex with honeycomb nanopores. Judging whether siliceous shale is hydrochemical deposition helps to determine the shale gas sweet spot of siliceous shale, so as to realize efficient exploration and development of shale gas of siliceous shale.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for judging whether siliceous shale is hydrochemical deposition. BACKGROUND

[0002] The type of deposition of siliceous shale, as the main lithofacies of the sweet spot section of shale oil and gas and the target body of shale oil and gas horizontal wells, has been a hot issue of concern in the industry. According to the existing research results, the research methods of the type of deposition of deep-water organic-rich shale including siliceous shale mainly include geochemical method and petrologic feature description method. The research results of the geochemical method show that the siliceous shale is all oceanic deposition or relatively closed bay deposition, and the oceanic deposition and the relatively closed bay deposition are collectively referred to as hydrochemical deposition. Taking the observation of the stratification characteristics of shale by rock thin section as the main argument, the type of deposition of deep-water black shale including siliceous shale is divided into hydrochemical deposition, deep-water gravity flow deposition and deep-water traction flow deposition.

[0003] According to the geochemical test data as the argument to judge the oxidation-reduction property of deep-water body, it is considered that the deep-water organic-rich shale including siliceous shale is all hydrochemical deposition, and the siliceous shale system as the target body of shale oil and gas horizontal wells is the siliceous ooze formed by the sinking of surface marine biological remains to the deep-water seabed. The geochemical method cannot observe the occurrence state information of minerals and organic matter, and cannot characterize and analyze the petrologic features of siliceous shale, resulting in the flattening of the understanding of the type of deposition. It is also not consistent with the theory of marine sedimentology that the deep-water black shale including siliceous shale is all hydrochemical deposition, that is, the deep-water environment not only develops hydrochemical deposition, but also develops deep-water traction flow deposition and deep-water gravity flow deposition.

[0004] Thin section observation found that the shale developed four types of horizontal bedding, i.e., gradational type, sand-mud gradational type, sand-mud interbedded type and book type. It is considered that the gradational type and sand-mud gradational type are of deep-water turbidity current origin, the sand-mud interbedded type is of deep-water contour current origin, and the book type is of static water physicochemical sedimentation origin. The explanation of the sedimentary type of shale by thin section observation only considers the change of mineral grain size without considering the origin of minerals, which leads to the following defects: the main minerals of deep-water shale, such as quartz and calcite, mainly come from the dissolution and precipitation of siliceous biological skeletons and the metabolism of marine surface water excreted calcium carbonate microorganisms, which form static water physicochemical sedimentation by suspension and sedimentation to the sea floor. When the primary productivity of marine surface water organisms changes with the seasons, the content of quartz and calcite also changes accordingly, forming static water physicochemical sedimentation of the gradational type and sand-mud gradational type, which is mistakenly considered as deep-water gravity flow deposition by thin section observation. When the sand-sized siliceous shale formed by siliceous biological skeletons and the mud-sized siliceous shale formed by siliceous biological skeletons constitute the sand-mud interbedded type horizontal bedding, this static water physicochemical sedimentary combination may be explained as deep-water traction flow deposition according to the phenomenon of thin section observation. Therefore, the horizontal bedding of thin section observation cannot clearly determine the sedimentary type of deep-water black shale including siliceous shale.

[0005] Due to the small size of shale mineral particles and high content of organic matter, it is difficult to effectively observe the occurrence state of minerals and organic matter in shale at multiple macro and micro scales, which is one of the main reasons for the long-term weakness of shale sedimentation research. The shale revolution in North America at the beginning of this century made shale reservoir research a popular topic in the petroleum geology field, and the introduction of MAPS technology made it possible to obtain high-resolution and large-view shale petrographic images, providing first-hand data for shale sedimentation research. MAPS technology divides the argon ion polished sample into a series of regular grids, scans and images each grid to obtain a secondary electron scan image, and splices the images of all grids to obtain a two-dimensional large-view scan image data body. The research results of MAPS rock image data body at this stage mainly focus on the description of organic pores, and a small amount of research results realize the petrographic characterization and analysis of organic matter and organic pores. There is no systematic research on the petrographic characterization and analysis of deep-water black shale including siliceous shale.

[0006] Although the introduction of MAPS technology provides a technical possibility for the realization of shale petrographic characterization and analysis, the complexity of the occurrence state of shale minerals and organic matter caused by the large difference in compaction intensity has not yet seen systematic research results on shale petrographic characterization.

[0007] In summary, there is still a need to study the petrological characteristics of hydrostatically-physicochemically deposited siliceous shale to promote the determination of siliceous shale as a high-quality reservoir of shale gas sweet spot, so as to realize the efficient exploration and development of shale gas as a high-quality reservoir of siliceous shale. SUMMARY

[0008] The purpose of the present application is to provide a technical solution that can determine whether siliceous shale is hydrostatically-physicochemically deposited, thereby promoting the determination of siliceous shale as a high-quality reservoir of shale gas sweet spot, so as to realize the efficient exploration and development of shale gas as a high-quality reservoir of siliceous shale.

[0009] To achieve the above purpose, the present application provides a method for determining whether siliceous shale is hydrostatically-physicochemically deposited, comprising:

[0010] Obtaining target siliceous shale; wherein the quartz mass content of the target siliceous shale is higher than 50%, the clay mass content is not less than 5%, and the total organic carbon mass content is higher than 2%;

[0011] Determining whether the target siliceous shale has the following characteristics 1, characteristics 2, characteristics 3 and characteristics 4:

[0012] Characteristic 1: biogenic siliceous matter accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and terrigenous quartz and terrigenous feldspar together account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock;

[0013] Characteristic 2: containing calcite and dolomite;

[0014] Characteristic 3: containing raspberry pyrite; wherein the raspberry pyrite includes ordinary raspberry pyrite, which refers to raspberry pyrite with intercrystalline pore organic matter;

[0015] Characteristic 4: containing organic matter; wherein the organic matter includes organic clay complex with honeycomb-shaped nanopores;

[0016] If the target siliceous shale has characteristics 1, characteristics 2, characteristics 3 and characteristics 4, the target siliceous shale is hydrostatically-physicochemically deposited.

[0017] The inventors of the present application determine the distribution range of the physical-chemical deposition of the siliceous shale by analyzing and characterizing the petrological characteristics of the siliceous shale, which helps to guide the efficient exploration and development of shale gas. If the siliceous shale has characteristics 1 (biogenic silica accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and terrigenous quartz and terrigenous feldspar account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock), characteristics 2 (contains calcite and dolomite), characteristics 3 (contains ordinary berry-shaped pyrite), and characteristics 4 (contains organic clay complex with honeycomb nanopores), the siliceous shale is the lithified product of the physical-chemical deposition of the siliceous ooze, and thus characteristics 1, characteristics 2, characteristics 3, and characteristics 4 can effectively characterize the physical-chemical deposition.

[0018] According to the preferred embodiment of the method for judging whether the siliceous shale is physically-chemically deposited, the target siliceous shale is obtained, including:

[0019] The total rock analysis and total organic carbon test are performed on the siliceous shale to be detected to determine the mass content of quartz, the mass content of clay, and the mass content of total organic carbon in the siliceous shale to be detected.

[0020] If the mass content of quartz in the siliceous shale to be detected is higher than 50%, the mass content of clay is not less than 5%, and the mass content of total organic carbon is higher than 2%, the siliceous shale to be detected is taken as the target siliceous shale.

[0021] According to the preferred embodiment of the method for judging whether the siliceous shale is physically-chemically deposited, the determination of whether the target siliceous shale has characteristics 1, characteristics 2, characteristics 3, and characteristics 4 includes:

[0022] The argon ion polished slice of the target siliceous shale is made by using the core of the target siliceous shale.

[0023] The MAPS rock image data body of the argon ion polished slice of the target siliceous shale is collected.

[0024] Based on the collected MAPS rock image data body of the argon ion polished slice of the target siliceous shale, whether the target siliceous shale has characteristics 1, characteristics 2, characteristics 3, and characteristics 4 is observed.

[0025] More preferably, the resolution of the collected MAPS rock image data body of the argon ion polished slice of the target siliceous shale is 4-10 nm resolution.

[0026] More preferably, the length of the argon ion polished slice of the target siliceous shale is 0.8-2 cm.

[0027] More preferably, the width of the argon ion polished slice of the target siliceous shale is 0.8-2 cm.

[0028] More preferably, the thickness of the argon-ion-polished slice of the target siliceous shale is 0.3-0.8 cm;

[0029] More preferably, the polishing surface of the argon-ion-polished slice of the target siliceous shale is parallel to the cylinder surface of the target siliceous shale core;

[0030] More preferably, the process of collecting the MAPS rock image data volume of the argon-ion-polished slice of the target siliceous shale comprises: selecting an area with a length and a width not exceeding 400 μm in the polishing surface of the argon-ion-polished slice of the target siliceous shale, and collecting the MAPS rock image data volume;

[0031] More preferably, in the process of collecting the MAPS rock image data volume of the argon-ion-polished slice of the target siliceous shale, the top surface of the argon-ion-polished slice of the target siliceous shale is located above the field of view, and the bottom surface of the argon-ion-polished slice of the target siliceous shale is located below the field of view, so as to ensure that all phenomena observed in the collected MAPS rock image data volume are only magnifications of natural phenomena;

[0032] More preferably, in the process of observing whether the target siliceous shale has at least one of the four characteristics (characteristic 1, characteristic 2, characteristic 3, and characteristic 4) based on the collected MAPS rock image data volume of the argon-ion-polished slice of the target siliceous shale, an image editor (such as an offline image editor ATLAS TM BROWSER-BASED VIEWER) is used to observe the MAPS rock image data volume on a computer.

[0033] According to the preferred embodiment of the method for judging whether the siliceous shale is a physical and chemical deposition in still water, in characteristic 2, the calcite is irregular particles.

[0034] According to the preferred embodiment of the method for judging whether the siliceous shale is a physical and chemical deposition in still water, in characteristic 2, the dolomite is a rhombic iron-containing dolomite wrapped dolomite particles.

[0035] According to the preferred embodiment of the method for judging whether the siliceous shale is a physical and chemical deposition in still water, in characteristic 3, the raspberry pyrite further comprises overgrown raspberry pyrite, and the overgrown raspberry pyrite is raspberry pyrite with intercrystalline pores remaining in the interior without filling organic matter.

[0036] According to the preferred embodiment of the method for judging whether the siliceous shale is a physical and chemical deposition in still water, in characteristic 3, the ordinary raspberry pyrite comprises at least one of grain linear contact raspberry pyrite, grain point contact raspberry pyrite, and grain floating in organic matter raspberry pyrite.

[0037] According to the preferred embodiment of the method for judging whether the siliceous shale is a static water physical and chemical deposition, in the characteristic 4, the organic matter further comprises pure organic matter (the pure organic matter is opposite to the organic matter in the form of complex with other substances, which means the organic matter exists alone), and the pure organic matter comprises at least one of pure organic matter with honeycomb nanopores and pure organic matter without pores.

[0038] According to the preferred embodiment of the method for judging whether the siliceous shale is a static water physical and chemical deposition, the method for judging whether the siliceous shale is a static water physical and chemical deposition further comprises:

[0039] When the target siliceous shale is a static water physical and chemical deposition, it is determined which one of the multi-cavity biological siliceous shale, the single-cavity biological siliceous shale and the non-cavity biological siliceous shale the target siliceous shale is;

[0040] In the static water physical and chemical deposition siliceous shale, the multi-cavity biological siliceous shale as the target shale gas horizontal well has high yield, the single-cavity biological siliceous shale as the target shale gas horizontal well has medium yield, and the non-cavity biological siliceous shale as the target shale gas horizontal well has low yield. Distinguishing whether the static water physical and chemical deposition siliceous shale is the multi-cavity biological siliceous shale, the single-cavity biological siliceous shale or the non-cavity biological siliceous shale is more helpful to determine the development potential of the static water physical and chemical deposition siliceous shale, and is helpful to guide the efficient exploration and development of shale gas;

[0041] More preferably, in the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the total amount of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the cavity of the biological siliceous matter is filled with pure organic matter with honeycomb nanopores, then the target siliceous shale is a multi-cavity biological siliceous shale.

[0042] More preferably, in the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the total amount of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the cavity of the biological siliceous matter is filled with organic silicon particle complex and / or calcite, then the target siliceous shale is a single-cavity biological siliceous shale.

[0043] More preferably, in the target siliceous shale, if the biological siliceous matter accounts for less than 90% and more than or equal to 70% of the total volume of quartz and terrigenous feldspar in the rock, and the total amount of terrigenous quartz and terrigenous feldspar accounts for more than 10% and less than or equal to 30% of the total volume of quartz and terrigenous feldspar in the rock, then the target siliceous shale is a non-cavity biological siliceous shale.

[0044] The technical solution provided by this invention enables the determination of whether siliceous shale is a lithological product of still-water physicochemical sedimentation by characterizing its petrological features. This solution helps to optimize the distribution range of siliceous shale formed by still-water physicochemical sedimentation, promotes the identification of shale gas sweet spots, and thus guides the efficient exploration and development of shale gas. The proposed technical solution breaks through the bottleneck in the study of deep-water shale sedimentary environments and contributes to the development of deep-water sedimentology. Attached Figure Description

[0045] Figure 1 This is an observation diagram of the MAPS rock image data volume in the image editor in Embodiment 1 of the present invention.

[0046] Figure 2 This is an observation diagram of the MAPS rock image data volume in the image editor in Embodiment 2 of the present invention.

[0047] Figure 3 This is an observation diagram of the MAPS rock image data volume in the image editor in Embodiment 3 of the present invention. Detailed Implementation

[0048] 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.

[0049] To eliminate the interference of compaction, systematic petrological characterization of shale needs to be implemented in at least three stages. The first stage involves petrological characterization of shale with low clay mineral content, low compaction intensity, and high organic matter content, analyzing its petrological characteristics, and identifying the depositional environment and type of sedimentation. The second stage involves petrological characterization of shale with moderate clay mineral content and moderate compaction, analyzing its petrological characteristics, and identifying the depositional environment and type of sedimentation. The results of the first stage constrain the results of the second stage, and vice versa, only then can the interference of compaction be truly eliminated, achieving systematic characterization of shale petrological characteristics and analysis of the depositional environment.

[0050] The inventor of the present application initiates the precedent of characterizing and analyzing the petrologic characteristics of shale, and determines whether the siliceous shale is a hydrostatic physical and chemical deposition by characterizing and analyzing the petrologic characteristics of the siliceous shale. The method for characterizing and analyzing the petrologic characteristics of the siliceous shale provides an effective method for reference for systematically characterizing and analyzing the petrologic characteristics of shale. Compared with the need for different research methods to carry out the description of the petrologic characteristics of shale and the analysis of the sedimentary environment at the present stage, the method provided by the present application solves the characterization of the petrologic characteristics of shale and the analysis of the sedimentation, and achieves a research effect of more than twice the effort.

[0051] The inventors of the present application found through analysis and characterization of petrologic characteristics of siliceous shale that the siliceous shale formed by static water physicochemical deposition includes multi-cavity biological siliceous shale, single-cavity biological siliceous shale and cavity-free biological siliceous shale, biological siliceous matter (usually quartz with lamellar structure), terrigenous quartz (usually quartz without lamellar structure) and carbonates, raspberry-like pyrite and the like constitute the rock framework of the siliceous shale, and clay and organic matter are distributed among the framework. The common characteristics of the siliceous shale formed by static water physicochemical deposition are: ① the biological siliceous matter accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and the terrigenous quartz and terrigenous feldspar together account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock; ② contains calcite and dolomite, wherein the calcite is mostly irregular particles, and the dolomite is mostly rhombic iron-containing dolomite particles wrapped with dolomite particles; ③ contains raspberry-like pyrite, which includes overgrown raspberry-like pyrite and ordinary raspberry-like pyrite, the overgrown raspberry-like pyrite has intercrystalline pores with residual organic matter inside, and the ordinary raspberry-like pyrite includes raspberry-like pyrite with linear contact of crystal grains, raspberry-like pyrite with point contact of crystal grains and raspberry-like pyrite with crystal grains floating in organic matter, and the intercrystalline pores of the ordinary raspberry-like pyrite are filled with organic matter; ④ contains organic matter, which includes organic clay complex with honeycomb-shaped nanopores, pure organic matter with honeycomb-shaped nanopores and pure organic matter without pores. The differences between the siliceous shales are: ① the types of biological siliceous fossils are different, and the siliceous shale formed by biological siliceous fossils with not less than 2 cavities, the siliceous shale formed by biological siliceous fossils with only 1 cavity and the siliceous shale formed by biological siliceous fossils without cavities; ② the multi-cavity biological siliceous matter and the single-cavity biological siliceous matter have a 3-layer structure composed of inner and outer secondary quartz and pore quartz composed of transformation of the middle biological siliceous skeleton, and the cavity-free biological siliceous matter has a double-layer structure composed of pore quartz transformed from the biological siliceous skeleton as the inner core and secondary quartz as the outer shell; ③ the cavities of the multi-cavity biological siliceous matter are filled with pure organic matter with honeycomb-shaped nanopores, the cavities of the single-cavity biological siliceous matter are filled with organic silica particle complex and / or calcite, and the cavity-free biological siliceous matter does not have these phenomena; ④ the volume of the biological siliceous matter in the multi-cavity biological siliceous shale and the single-cavity biological siliceous shale is more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the volume of the terrigenous quartz and feldspar is less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the volume of the biological siliceous matter in the cavity-free biological siliceous shale is 70-90% of the volume of the rock, and the volume of the terrigenous quartz and feldspar is 10-30% of the total volume of quartz and terrigenous feldspar in the rock. On this basis, the inventors of the present application determined the petrologic characteristics capable of identifying whether the siliceous shale is formed by static water physicochemical deposition, and further proposed the method for judging whether the siliceous shale is formed by static water physicochemical deposition.

[0052] In a specific embodiment, the present application provides a method for judging whether siliceous shale is formed by static water physicochemical deposition, comprising:

[0053] The target siliceous shale is obtained; wherein the quartz mass content of the target siliceous shale is higher than 50%, the clay mass content is not less than 5%, and the total organic carbon mass content is higher than 2%;

[0054] It is determined whether the target siliceous shale has the following characteristics 1, characteristic 2, characteristic 3 and characteristic 4:

[0055] Characteristic 1: biogenic silica accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and terrigenous quartz and terrigenous feldspar account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock;

[0056] Characteristic 2: contains calcite and dolomite;

[0057] Characteristic 3: contains raspberry pyrite; wherein the raspberry pyrite includes ordinary raspberry pyrite, and the ordinary raspberry pyrite refers to raspberry pyrite with intercrystalline pore organic matter;

[0058] Characteristic 4: contains organic matter; wherein the organic matter includes organic clay complex with honeycomb nanopores;

[0059] If the target siliceous shale has characteristics 1, characteristic 2, characteristic 3 and characteristic 4, the target siliceous shale is a physical and chemical sediment of still water.

[0060] Further, the target siliceous shale is obtained, comprising:

[0061] The whole rock analysis and total organic carbon test are performed on the to-be-detected siliceous shale to determine the mass content of quartz, the mass content of clay and the mass content of total organic carbon in the to-be-detected siliceous shale;

[0062] If the mass content of quartz in the to-be-detected siliceous shale is higher than 50%, the mass content of clay is not less than 5%, and the mass content of total organic carbon is higher than 2%, the to-be-detected siliceous shale is taken as the target siliceous shale.

[0063] Further, it is determined whether the target siliceous shale has the following characteristics 1, characteristic 2, characteristic 3 and characteristic 4, comprising:

[0064] An argon ion polished slice of the target siliceous shale is made by using the target siliceous shale core;

[0065] A MAPS rock image data body of the argon ion polished slice of the target siliceous shale is collected;

[0066] Based on the collected MAPS rock image data body of the argon ion polished slice of the target siliceous shale, it is observed whether the target siliceous shale has characteristics 1, characteristic 2, characteristic 3 and characteristic 4;

[0067] Further, the resolution of the collected MAPS rock image data body of the argon ion polished slice of the target siliceous shale is 4-10 nm resolution.

[0068] Further, the argon ion polished slice of the target siliceous shale has a length of 0.8-2 cm.

[0069] Further, the argon ion polished slice of the target siliceous shale has a width of 0.8-2 cm.

[0070] Further, the argon ion polished slice of the target siliceous shale has a thickness of 0.3-0.8 cm.

[0071] Further, the polishing surface of the argon ion polished slice of the target siliceous shale is parallel to the cylinder surface of the target siliceous shale core.

[0072] Further, the process of collecting the MAPS rock image data volume of the argon ion polished slice of the target siliceous shale comprises: selecting an area with a length and a width of no more than 400 μm in the polishing surface of the argon ion polished slice of the target siliceous shale, and collecting the MAPS rock image data volume.

[0073] Further, in the process of collecting the MAPS rock image data volume of the argon ion polished slice of the target siliceous shale, the top surface of the argon ion polished slice of the target siliceous shale is located above the field of view, and the bottom surface of the argon ion polished slice of the target siliceous shale is located below the field of view, so as to ensure that all phenomena observed in the collected MAPS rock image data volume are only magnifications of natural phenomena.

[0074] Further, in the process of observing whether the target siliceous shale has the four characteristics of characteristic 1, characteristic 2, characteristic 3, and characteristic 4 based on the collected MAPS rock image data volume of the argon ion polished slice of the target siliceous shale, an image editor (such as an offline image editor ATLAS TM BROWSER-BASED VIEWER) is used to observe the MAPS rock image data volume on a computer.

[0075] Further, in characteristic 2, the calcite is irregular particles.

[0076] Further, in characteristic 2, the dolomite is rhombic iron-containing dolomite wrapped dolomite particles.

[0077] Further, in characteristic 3, the raspberry pyrite further comprises overgrown raspberry pyrite, and the overgrown raspberry pyrite is raspberry pyrite with intercrystalline pores left by residual organic matter.

[0078] Further, in characteristic 3, the ordinary raspberry pyrite comprises at least one of grain linear contact raspberry pyrite, grain point contact raspberry pyrite, and grain floating in organic matter raspberry pyrite.

[0079] Further, in feature 4, the organic matter further comprises pure organic matter (pure organic matter as the opposite of organic matter in the form of a complex with other substances, refers to organic matter that exists alone rather than in the form of a complex with other substances), and the pure organic matter comprises at least one of pure organic matter with honeycomb nanopores and pure organic matter without pores.

[0080] Further, the method for judging whether the siliceous shale is a hydrochemical sedimentation further comprises:

[0081] When the target siliceous shale is a hydrochemical sedimentation, it is determined which one of the multi-cavity biological siliceous shale, single-cavity biological siliceous shale and cavity-free biological siliceous shale the target siliceous shale is;

[0082] Among the hydrochemical sedimentary siliceous shale, the multi-cavity biological siliceous shale as a target body has high production of shale gas horizontal wells, the single-cavity biological siliceous shale as a target body has medium production of shale gas horizontal wells, and the cavity-free biological siliceous shale as a target body has low production of shale gas horizontal wells. Distinguishing whether the hydrochemical sedimentary siliceous shale is a cavity biological siliceous shale, a single-cavity biological siliceous shale or a cavity-free biological siliceous shale is more helpful to determine the development potential of the hydrochemical sedimentary siliceous shale and guide the efficient exploration and development of shale gas;

[0083] Further, in the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the total volume of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the cavities of the biological siliceous matter are filled with honeycomb nanoporous pure organic matter, then the target siliceous shale is a multi-cavity biological siliceous shale.

[0084] Further, in the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the total volume of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the cavities of the biological siliceous matter are filled with organic silicon particle complexes and / or calcite, then the target siliceous shale is a single-cavity biological siliceous shale.

[0085] Further, in the target siliceous shale, if the biological siliceous matter accounts for less than 90% and more than or equal to 70% of the total volume of quartz and terrigenous feldspar in the rock, and the total volume of terrigenous quartz and terrigenous feldspar accounts for more than 10% and less than or equal to 30% of the total volume of quartz and terrigenous feldspar in the rock, then the target siliceous shale is a cavity-free biological siliceous shale.

[0086] The rock skeleton of siliceous shale is composed of rigid particles such as biogenic silica, terrigenous quartz, calcite, dolomite and pyrite, and has strong anti-compaction ability, so that the overlying strata have limited compaction effect on organic matter. Therefore, the organic matter with honeycomb-like nanopores is converted from the pyrobituminous clay complex of the sedimentary organic clay complex, the pure organic matter with honeycomb-like nanopores is the pyrobituminized solid bitumen, and the pure organic matter without pores is the pyrobituminized petroleum. The skeleton of siliceous organisms is finally converted into porous quartz with ring structure through dissolution and precipitation reaction, so that the quartz with ring structure is biogenic silica, and the quartz without ring structure is terrigenous quartz. The irregular calcite with obvious dissolution phenomenon is the calcite residue formed in the surface water, and part of it fills the cavity of single-cavity biogenic silica; the rhombic dolomite is formed near the water-sediment interface and in the shallow burial diagenetic stage. The raspberry-shaped pyrite is formed in the BSR near the sulfurized water body and the water-sediment interface and in the AOM-SR of the shallow burial diagenetic stage. Through the analysis of the results of the analysis of minerals, organic matter, and organic clay complex and organic silica particle complex, it is considered that the siliceous shale system with these characteristics is the siliceous ooze formed by the physical and chemical sedimentation of still water.

[0087] The depositional and diagenetic processes of these siliceous shales are clarified, and the rationality and reliability of the siliceous ooze of these siliceous shales are consolidated. The depositional and diagenetic processes of these siliceous shales can be divided into 3 processes and 6 stages. The 3 processes are in turn the depositional process, the water-sediment interface diagenetic process and the burial diagenetic process. The depositional process is further divided into the upper water body depositional stage and the lower water body depositional stage. The burial diagenetic process is further divided into the shallow burial diagenetic stage, the medium burial early diagenetic stage, the medium burial late diagenetic stage and the deep burial diagenetic stage. In the upper water body depositional stage, which is located above the CSD, the siliceous biogenic skeletons, terrigenous quartz, calcite, clay and other detritus are suspended and settled. The siliceous biogenic skeletons are dissolved and precipitated after the death of the siliceous organisms. In the lower water body depositional stage, which is located below the CSD, the calcite is dissolved, especially below the CLD and below the CCD. The organic-silica particle complex occupies the calcite dissolved pores of the radiolarian shell cavity. The water is sulfidized, and the berry-like pyrite is precipitated. The clay adsorbs the dissolved organic matter to form the organic clay particle complex. In the deep water seabed, the siliceous biogenic skeletons (multi-cavity, single-cavity and non-cavity organisms), calcite (including the calcite of the radiolarian shell cavity), organic clay particle complex, organic-silica particle complex of the radiolarian shell cavity, berry-like pyrite and terrigenous detritus (such as quartz and clay) together constitute the siliceous ooze. In the water-sediment interface diagenetic process, the berry-like pyrite continues to precipitate and grow under the action of BSR, and the dolomite is precipitated. In the shallow burial diagenetic stage, the berry-like pyrite is precipitated and grown under the action of AOM-SR, and the ferruginous dolomite is precipitated and forms the rhombic ferruginous dolomite wrapping dolomite. The sedimentary organic matter is transformed into kerogen, and the organic clay particle complex is transformed into kerogen clay particle complex, and the organic-silica particle complex is transformed into kerogen silica particle complex. In the medium burial early diagenetic stage, the kerogen is transformed into oil precursor pitch, the kerogen clay particle complex is transformed into oil precursor pitch clay particle complex, and the kerogen silica particle complex is transformed into oil precursor pitch silica particle complex. In the process of generating oil precursor pitch, the volume expansion of kerogen produces abnormal high pressure, which drives the oil precursor pitch to migrate to the pores. When the abnormal high pressure is large enough, the hydrocarbon generation pressure fracture is generated, which serves as the initial migration channel of the oil precursor pitch. In the medium burial late diagenetic stage, the oil precursor pitch is transformed into solid pitch and oil, the oil precursor pitch clay particle complex is transformed into solid pitch clay particle complex, and the oil precursor pitch silica particle complex is transformed into solid pitch silica particle complex. In the process of generating oil, the volume expansion of organic matter produces abnormal high pressure, which drives the oil to migrate to the pores. When the abnormal high pressure is large enough, the hydrocarbon generation pressure fracture is generated, which serves as the initial migration channel of the oil. The siliceous biogenic skeletons are transformed into porous quartz with secondary quartz enlargement (biogenic silica with lamellar structure) under the action of dissolution and precipitation.In deep burial diagenetic stage, solid bitumen is converted into coking bitumen with honeycomb pores, oil is converted into coking bitumen without pores, solid bitumen clay complex is converted into coking bitumen (organic) clay complex with honeycomb pores, solid bitumen silica complex is converted into coking bitumen (organic) silica complex with honeycomb pores.

[0088] Embodiment 1:

[0089] The embodiment provides a method for judging whether or not the siliceous shale in an A target siliceous shale area is a hydrostatic physical and chemical deposit, comprising the following steps:

[0090] 1. Whole rock analysis and total organic carbon test are performed on a core of the siliceous shale to be detected from the A target siliceous shale area, so as to determine the mass content of quartz, the mass content of clay and the mass content of total organic carbon in the siliceous shale to be detected; if the mass content of quartz in the siliceous shale to be detected is higher than 50%, the mass content of clay is not lower than 5% and the mass content of total organic carbon is higher than 2%, the siliceous shale to be detected is regarded as the target siliceous shale.

[0091] In the embodiment, the whole rock test data of the siliceous shale to be detected show that the quartz, feldspar, calcite, dolomite, iron-containing dolomite, clay and pyrite respectively account for 75.3%, 1.1%, 4.5%, 7.9%, 1.6%, 8.2% and 1.4% of the rock volume; the total organic carbon test data show that the total organic carbon accounts for 4.2% of the rock mass fraction. Therefore, the mass content of quartz in the siliceous shale to be detected is higher than 50%, the mass content of clay is not lower than 5% and the mass content of total organic carbon is higher than 2%, so the siliceous shale to be detected is regarded as the target siliceous shale, and the core of the siliceous shale to be detected can be directly used as the core of the siliceous shale to be detected.

[0092] 2. An argon ion polished slice of the target siliceous shale is prepared by using the core of the target siliceous shale; the argon ion polished slice of the target siliceous shale has a length of 2 cm, a width of 2 cm and a thickness of 0.5 cm; the polishing surface of the argon ion polished slice of the target siliceous shale is parallel to the cylindrical surface of the core of the target siliceous shale, and the top surface and the bottom surface of the argon ion polished slice are marked.

[0093] 3. A region with a length and a width of no more than 400 μm is selected on the polishing surface of the argon ion polished slice of the target siliceous shale, and a MAPS rock image data body with a resolution of 4 nm is collected; during the collection of the MAPS rock image data body, the top surface of the argon ion polished slice of the target siliceous shale is located above the visual field, and the bottom surface of the argon ion polished slice of the target siliceous shale is located below the visual field, so that all the phenomena observed in the collected MAPS rock image data body are only magnifications of natural phenomena.

[0094] 4. An image editor (offline image editor ATLASTM The computer is used to observe the collected MAPS rock image data volume by a browser-based viewer; whether the target siliceous shale has the four features: feature 1, feature 2, feature 3 and feature 4;

[0095] Feature 1: biogenic silica accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and terrigenous quartz and terrigenous feldspar account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock;

[0096] Feature 2: contains calcite and dolomite; calcite is irregular particles, and dolomite is rhombic ankerite wrapped dolomite particles;

[0097] Feature 3: contains ordinary framboidal pyrite and overgrowth framboidal pyrite; ordinary framboidal pyrite refers to framboidal pyrite with intergranular pore organic matter, and overgrowth framboidal pyrite refers to framboidal pyrite with residual intergranular pores without filling organic matter; ordinary framboidal pyrite includes at least one of framboidal pyrite with grain linear contact, framboidal pyrite with grain point contact and framboidal pyrite with grain floating in organic matter;

[0098] Feature 4: contains organic clay complex with honeycomb nanopores and pure organic matter (pure organic matter as the opposite of organic matter complex with other substances, refers to organic matter existing alone without being in the form of complex with other substances); pure organic matter includes at least one of pure organic matter with honeycomb nanopores and pure organic matter without pores;

[0099] If the target siliceous shale has the four features: feature 1, feature 2, feature 3 and feature 4, the target siliceous shale is a physical and chemical sedimentary under still water.

[0100] In this embodiment, quartz, calcite, ankerite wrapped dolomite, and framboidal pyrite form the rock framework, and clay, organic matter and organic clay complex are distributed between the framework (as shown in Figure 1 Quartz is composed of biogenic silica (showing a zonal structure, see the red arrow in a and e-f of Figure 1 ) and terrigenous quartz (showing no zonal structure, see the yellow arrow in e of Figure 1 ). Biogenic silica accounts for 64.6% of the volume of the rock, and terrigenous quartz and terrigenous feldspar account for 3.3% of the volume of the rock. Irregular calcite (see the blue arrow in e of Figure 1 ) accounts for 4.6% of the volume of the rock, and rhombic ankerite wrapped dolomite (see the green arrow in e of Figure 1 ) accounts for 12.5% of the volume of the rock. Framboidal pyrite includes overgrowth framboidal pyrite (see Figure 1(l) and common berry pyrite, common berry pyrite including berry pyrite with linear grain contact (see l) Figure 1 m), berry-like pyrite with point-like grain contact (see m) Figure 1 (n) and berry-like pyrite with grains floating in organic matter (see n) Figure 1 (o in the text), berry-like pyrite accounts for 0.6% of the rock volume. Clay is in banded form (see...). Figure 1 (arrow in h) and clumps (see Figure 1 i) is the main component, accounting for 5.9% of the rock volume. Pure organic matter with honeycomb nanopores and organic clay particle composites with honeycomb nanopores (see...) Figure 1 The cd) in the rock is difficult to distinguish as it is distributed among the rock framework composed of quartz, carbonates, and pyrite, accounting for 6.9% of the rock volume; pure organic matter with honeycomb-like nanopores occupies the cavities of biogenic silica, accounting for 1.2% of the rock volume; pure organic matter without pores fills the cracks in a banded pattern (see...). Figure 1 (jk) accounts for 0.4% of the rock volume.

[0101] In summary, in this embodiment, the target siliceous shale satisfies the four characteristics of feature 1, feature 2, feature 3, and feature 4, indicating that it is a still water physicochemical deposit.

[0102] 5. Determine which type of target siliceous shale it is: multi-cavity biogenic siliceous shale, single-cavity biogenic siliceous shale, or non-cavity biogenic siliceous shale;

[0103] Among them, in the target siliceous shale, if biogenic silica accounts for more than 90% of the volume of quartz in the rock, and the total volume of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the volume of quartz in the rock, and the cavities of biogenic silica are filled with pure organic matter in honeycomb-shaped nanopores, then the target siliceous shale is a multi-cavity biogenic siliceous shale.

[0104] Among them, in the target siliceous shale, if biogenic silica accounts for more than 90% of the quartz volume in the rock, and the total volume of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the quartz volume in the rock, and the cavities of biogenic silica are filled with organosilicon particle complexes and / or calcite, then the target siliceous shale is a single-cavity biogenic siliceous shale.

[0105] Among them, in the target siliceous shale, if biogenic silica accounts for less than 90% and greater than or equal to 70% of the quartz volume in the rock, and terrigenous quartz and terrigenous feldspar together account for more than 10% and less than or equal to 30% of the quartz volume in the rock, then the target siliceous shale is a cavityless biogenic siliceous shale.

[0106] In the target siliceous shale, the biosilica accounts for more than 90% of the volume of quartz in the rock, the total of terrigenous quartz and terrigenous feldspar accounts for less than 10% of the volume of quartz in the rock, and the pure organic matter of the cavity of the biosilica fills the honeycomb-shaped nanopores, so the target siliceous shale is a multi-cavity biosiliceous shale.

[0107] The multi-cavity biosilica is formed in the surface water body deposition stage, and is converted into quartz with a zonal structure in the medium burial late diagenesis stage. The calcite is formed in the upper water body, and the terrigenous quartz, feldspar and clay fall into the lower water body. The calcite is dissolved, and the dissolved organic matter and clay form an organic clay complex. The sulfidic water body is conducive to the precipitation of framboidal pyrite. In the deep water seabed, the multi-cavity biosilica, calcite, terrigenous quartz, feldspar, framboidal pyrite, clay and organic clay complex form a siliceous ooze. In the water-sediment interface diagenesis process, the dolomite and framboidal pyrite are precipitated. In the shallow burial diagenesis stage, the environment of framboidal pyrite precipitation changes from the sulfidic water body to the BSR and AOM-SR, the rhombic iron-containing dolomite wraps the precipitated dolomite, and the deposited organic clay complex is converted into a kerogen clay complex. In the medium burial early diagenesis stage, the kerogen clay complex is converted into a pre-oil bitumen clay complex, and the volume of the kerogen expands when it is converted into pre-oil bitumen, and the expanded part migrates and occupies the pores. In the medium burial late diagenesis stage, the pre-oil bitumen clay complex is converted into a solid bitumen clay complex, and the volume of the pre-oil bitumen expands when it is converted into solid bitumen and oil, which causes abnormal high pressure to generate cracks and form channels for the primary migration of oil. In the deep burial diagenesis stage, the solid bitumen clay complex is converted into a fusain bitumen clay complex with honeycomb-shaped nanopores, the solid bitumen is converted into fusain bitumen with honeycomb-shaped nanopores, the oil is converted into fusain bitumen without pores, and the oil filled in the hydrocarbon-generating pressure cracks is converted into long strip-shaped fusain bitumen without pores.

[0108] The area where the target siliceous shale is located (i.e., the A target siliceous shale area) is a shale gas sweet spot area, and the shale gas horizontal well with the target siliceous shale area (i.e., the A target siliceous shale area) as the target body has high production and high exploration and development potential.

[0109] Embodiment 2

[0110] The embodiment provides a method for judging whether the siliceous shale in the B target siliceous shale area is a physical and chemical deposition in still water, which comprises the following steps:

[0111] 1. Whole rock analysis and total organic carbon test are performed on the core of the target siliceous shale area to determine the mass content of quartz, clay and total organic carbon in the target siliceous shale; if the mass content of quartz in the target siliceous shale is higher than 50%, the mass content of clay is not less than 5%, and the mass content of total organic carbon is higher than 2%, the target siliceous shale is taken as the target siliceous shale.

[0112] In this embodiment, the whole rock test data of the target siliceous shale shows that the quartz, feldspar, calcite, dolomite, iron-containing dolomite, clay and pyrite account for 69.8%, 2.8%, 13.1%, 3.2%, 3.8%, 5.4% and 1.9% of the rock volume respectively; the total organic carbon test data shows that the total organic carbon accounts for 5.3% of the rock mass fraction. Therefore, the mass content of quartz in the target siliceous shale is higher than 50%, the mass content of clay is not less than 5%, and the mass content of total organic carbon is higher than 2%, so the target siliceous shale is taken as the target siliceous shale, and the core of the target siliceous shale can be directly taken as the core of the target siliceous shale.

[0113] 2. An argon ion polished slice of the target siliceous shale is made by using the core of the target siliceous shale; the length of the argon ion polished slice of the target siliceous shale is 2 cm, the width is 2 cm, and the thickness is 0.5 cm; the polishing surface of the argon ion polished slice of the target siliceous shale is parallel to the cylindrical surface of the core of the target siliceous shale, and the top surface and the bottom surface of the argon ion polished slice are marked.

[0114] 3. A region with a length and a width not more than 400 μm is selected on the polishing surface of the argon ion polished slice of the target siliceous shale, and a MAPS rock image data body with a resolution of 4 nm is collected; during the collection of the MAPS rock image data body, the top surface of the argon ion polished slice of the target siliceous shale is located above the field of view, and the bottom surface of the argon ion polished slice of the target siliceous shale is located below the field of view, so as to ensure that all the phenomena observed in the collected MAPS rock image data body are only magnifications of natural phenomena.

[0115] 4. An image editor (offline image editor ATLAS TM BROWSER-BASED VIEWER) is used to observe the collected MAPS rock image data body on the computer; whether the target siliceous shale has the four characteristics of characteristic 1, characteristic 2, characteristic 3 and characteristic 4 is observed.

[0116] Characteristic 1: biogenic siliceous matter accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and the total amount of terrigenous quartz and terrigenous feldspar accounts for 5-30% of the total volume of quartz and terrigenous feldspar in the rock;

[0117] Feature 2: Contains calcite and dolomite; the calcite is in the form of irregular particles, and the dolomite consists of rhombic iron-bearing dolomite particles encasing dolomite.

[0118] Feature 3: Contains both common berry pyrite and overgrown berry pyrite; common berry pyrite refers to berry pyrite with intergranular pores filled with organic matter, while overgrown berry pyrite is berry pyrite with intergranular pores remaining unfilled with organic matter; common berry pyrite includes at least one of the following: berry pyrite with linear grain contact, berry pyrite with point grain contact, and berry pyrite with grains floating in organic matter;

[0119] Feature 4: Contains an organic clay particle complex with honeycomb-like nanopores and pure organic matter (pure organic matter, as the opposite of organic matter in the form of a complex with other substances, refers to organic matter that exists alone rather than in the form of a complex with other substances); pure organic matter includes at least one of pure organic matter with honeycomb-like nanopores and pure organic matter without pores.

[0120] If the target siliceous shale exhibits the four characteristics 1, 2, 3, and 4, then the target siliceous shale is a still water physicochemical sediment.

[0121] In this embodiment, quartz, calcite, and ferruginous dolomite encapsulate dolomite and bromelain to form a rock framework, while clay, organic matter, organic clay particle complexes, and organosilicon particle complexes are distributed within the framework (e.g., Figure 2 (As shown). Quartz is composed of biogenic silica (exhibiting a layered structure, see...) Figure 2 a and i in Figure 2 In the middle section d, the blue solid circle defines the inner layer of biogenic silica, while the area outside the blue solid circle represents the inner and outer layers of biogenic silica. Biogenic silica chips (which exhibit a layered structure, see [reference]) Figure 2 In the diagram, the blue solid circle in 'e' represents the core of biogenic silica, and the area between the blue and yellow solid circles represents the outer shell of the biogenic silica. Terrigenous quartz and terrigenous feldspar (which exhibit a non-layered structure, see [reference]) are also mentioned. Figure 2 Composition b) of the rock. Biogenic silica and biogenic silica fragments account for 57.9% of the rock volume (biogenic silica fragment content is extremely low), and terrigenous quartz and terrigenous feldspar account for 2.6% of the total rock volume. Irregular calcite (see [link to article]). Figure 2 (a, m) account for 4.6% of the rock volume, and rhombic iron-bearing dolomite encapsulates dolomite (see...). Figure 1 (n) accounts for 12.6% of the rock volume. Berry pyrite includes overgrown berry pyrite (see...). Figure 2 (o) and common berry pyrite, common berry pyrite including berry pyrite with linear grain contact (see o). Figure 2 p), berry-like pyrite with point-like grain contact (see p) Figure 2q) and berry pyrite floating in organic matter (see Figure 2 r) in FIG. 6, the berry pyrite accounts for 0.8% of the rock volume. The clay is mainly in the form of bands (see Figure 2 yellow bands in h) in FIG. 6), accounting for 4.6% of the rock volume. The organic clay complex with honeycomb nanopores coexists with the pure organic matter with honeycomb nanopores (see Figure 2 the green solid circle in j) in FIG. 6) or the pure organic matter with honeycomb nanopores and the pure organic matter without pores (see Figure 2 the green solid circle in f) in FIG. 6) accounts for 4.5% of the rock volume. Figure 2 s) and the pure organic matter without pores (see Figure 2 t) in FIG. 6) can fill a pore alone or coexist in a pore (see Figure 2 the white solid circle in u) in FIG. 6) accounts for 4.5% of the rock volume. Figure 2 v) in FIG. 6), wherein the organic clay complex with honeycomb nanopores accounts for 5.3% of the rock volume, the pure organic matter with honeycomb nanopores accounts for 3.9% of the rock volume, and the pure organic matter without pores accounts for 1.7% of the rock volume. The biological siliceous cavity calcite dissolved pore is filled with the organic siliceous particle complex with honeycomb nanopores (see Figure 2 a and c) in FIG. 6) and the biological siliceous cavity is completely filled with the organic siliceous particle complex with honeycomb nanopores (see Figure 3 i and k) in FIG. 6), the organic siliceous particle complex with honeycomb nanopores accounts for 4.5% of the rock volume.

[0122] In summary, in this embodiment, the target siliceous shale satisfies the four characteristics of characteristic 1, characteristic 2, characteristic 3, and characteristic 4, and is a physical-chemical sedimentation in still water.

[0123] 5. Determine which one of the multi-cavity biological siliceous shale, single-cavity biological siliceous shale, and cavity-free biological siliceous shale the target siliceous shale is;

[0124] Wherein, in the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the quartz volume in the rock, the total of the terrigenous quartz and the terrigenous feldspar accounts for less than 10% of the quartz volume in the rock, and the cavities of the biological siliceous matter are filled with honeycomb nanopores of pure organic matter, then the target siliceous shale is a multi-cavity biological siliceous shale.

[0125] wherein, in the target siliceous shale, if the biosilica accounts for 90% or more of the volume of quartz in the rock, and the total of the land-derived quartz and the land-derived feldspar accounts for 10% or less of the volume of quartz in the rock, and the cavities of the biosilica are filled with organic-silica particle composite and / or calcite, then the target siliceous shale is a single-cavity biosilica siliceous shale;

[0126] wherein, in the target siliceous shale, if the biosilica accounts for less than 90% and 70% or more of the volume of quartz in the rock, and the total of the land-derived quartz and the land-derived feldspar accounts for more than 10% and 30% or less of the volume of quartz in the rock, then the target siliceous shale is a non-cavity biosilica siliceous shale.

[0127] In this embodiment, in the target siliceous shale, the biosilica accounts for 90% or more of the volume of quartz in the rock, and the total of the land-derived quartz and the land-derived feldspar accounts for 10% or less of the volume of quartz in the rock, and the cavities of the biosilica are filled with organic-silica particle composite, so the target siliceous shale is a single-cavity biosilica siliceous shale.

[0128] The single-cavity biogenic siliceous is formed in the surface water body deposition stage and is transformed into quartz with zonal structure in the middle burial late diagenesis stage. The calcite is formed in the upper water body and fills the cavity of the biogenic siliceous, and the terrigenous quartz, feldspar and clay fall into the lower water body, the calcite is dissolved, the dissolved organic matter and clay combine to form the organic clay complex, the dissolved calcite in the cavity of the biogenic siliceous is filled with the organic siliceous complex, and the sulfidic water body is beneficial to the precipitation of framboidal pyrite. In the deep water seabed, the single-cavity biogenic siliceous and the siliceous ooze, the organic siliceous complex in the cavity, the terrigenous quartz, feldspar, calcite, framboidal pyrite, clay and organic clay complex form the siliceous ooze. In the water-sediment interface diagenesis process, the dolomite and framboidal pyrite are precipitated. In the shallow burial diagenesis stage, the environment of framboidal pyrite precipitation is from the sulfidic water body to the BSR and AOM-SR, the rhombic iron-dolomite encloses the dolomite, the deposited organic clay complex is transformed into the kerogen clay complex, and the deposited organic siliceous complex is transformed into the kerogen siliceous complex. In the middle burial early diagenesis stage, the kerogen clay complex is transformed into the oil-potential bitumen clay complex, the kerogen siliceous complex is transformed into the oil-potential bitumen siliceous complex, and the kerogen is transformed into the oil-potential bitumen, which expands in volume, and the expanded part migrates and occupies the pores. In the middle burial late diagenesis stage, the oil-potential bitumen clay complex is transformed into the solid bitumen clay complex, the oil-potential bitumen siliceous complex is transformed into the solid bitumen siliceous complex, and the oil-potential bitumen is transformed into the solid bitumen and oil, which expands in volume, resulting in abnormal high pressure, cracks and channels for the primary migration of oil. In the deep burial diagenesis stage, the solid bitumen clay complex is transformed into the pyrobitumen clay complex with honeycomb-like nanopores, the solid bitumen siliceous complex is transformed into the pyrobitumen siliceous complex with honeycomb-like nanopores, the solid bitumen is transformed into the pyrobitumen with honeycomb-like nanopores, the oil is transformed into the non-porous pyrobitumen, and the oil filled in the pressure fracture is transformed into the long strip-shaped non-porous pyrobitumen.

[0129] The shale gas horizontal well in the target siliceous shale area (i.e. B target siliceous shale area) has a medium exploration and development potential.

[0130] Embodiment 3

[0131] The embodiment provides a method for judging whether the siliceous shale in the C target siliceous shale area is hydrostatic physical and chemical deposition, which comprises the following steps:

[0132] 1. Whole rock analysis and total organic carbon test are performed on the core of the siliceous shale to be detected in the C target siliceous shale area, so as to determine the mass content of quartz, the mass content of clay and the mass content of total organic carbon in the siliceous shale to be detected; if the mass content of quartz in the siliceous shale to be detected is higher than 50%, the mass content of clay is not lower than 5%, and the mass content of total organic carbon is higher than 2%, the siliceous shale to be detected is taken as the target siliceous shale.

[0133] In this embodiment, the whole rock test data of the to-be-tested siliceous shale shows that the quartz, feldspar, calcite, dolomite, iron-containing dolomite, clay and pyrite account for 59.1%, 4.3%, 10.3%, 3.0%, 1.7%, 19.3% and 2.3% of the volume of the rock respectively; the total organic carbon test data shows that the total organic carbon accounts for 3.7% of the mass fraction of the rock. Therefore, the mass content of quartz in the to-be-tested siliceous shale is higher than 50%, the mass content of clay is not less than 5% and the mass content of total organic carbon is higher than 2%, so the to-be-tested siliceous shale is taken as the target siliceous shale, and the core of the to-be-tested siliceous shale is directly taken as the core of the to-be-tested siliceous shale.

[0134] 2. An argon ion polished slice of the target siliceous shale is made by using the core of the target siliceous shale; wherein the length of the argon ion polished slice of the target siliceous shale is 2 cm, the width is 2 cm and the thickness is 0.5 cm; the polishing surface of the argon ion polished slice of the target siliceous shale is parallel to the cylindrical surface of the core of the target siliceous shale, and the top surface and the bottom surface of the argon ion polished slice are marked.

[0135] 3. A region with a length and a width of no more than 400 μm is selected in the polishing surface of the argon ion polished slice of the target siliceous shale, and a MAPS rock image data body with a resolution of 4 nm is collected; wherein during the collection of the MAPS rock image data body, the top surface of the argon ion polished slice of the target siliceous shale is located above the field of view and the bottom surface of the argon ion polished slice of the target siliceous shale is located below the field of view, so as to ensure that all the phenomena observed in the collected MAPS rock image data body are only magnifications of natural phenomena.

[0136] 4. An image editor (offline image editor ATLAS TM BROWSER-BASED VIEWER) is used to observe the collected MAPS rock image data body on a computer; whether the target siliceous shale has the four features of feature 1, feature 2, feature 3 and feature 4 is observed.

[0137] Feature 1: biogenic silica accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and the total amount of terrigenous quartz and terrigenous feldspar accounts for 5-30% of the total volume of quartz and terrigenous feldspar in the rock;

[0138] Feature 2: containing calcite and dolomite; the calcite is irregular particles, and the dolomite is rhombic iron-containing dolomite wrapped dolomite particles;

[0139] Feature 3: containing common framboidal pyrite and overgrowth framboidal pyrite; the common framboidal pyrite refers to the framboidal pyrite with intercrystalline pore organic matter, and the overgrowth framboidal pyrite refers to the framboidal pyrite with intercrystalline pores inside remaining unfilled organic matter; the common framboidal pyrite includes at least one of the framboidal pyrite with grain linear contact, the framboidal pyrite with grain point contact and the framboidal pyrite with grain floating in organic matter;

[0140] Feature 4: containing organic clay complex with honeycomb nanopores and pure organic matter (the pure organic matter refers to the organic matter existing alone rather than in the form of complex with other substances, as the opposite of the organic matter complex with other substances); the pure organic matter includes at least one of the pure organic matter with honeycomb nanopores and the pure organic matter without pores;

[0141] If the target siliceous shale has the four features of Feature 1, Feature 2, Feature 3 and Feature 4, the target siliceous shale is a physical and chemical sediment of static water.

[0142] In the embodiment, quartz, calcite, iron-bearing dolomite enclosing dolomite (the arrow in a of Figure 3 ), and framboidal pyrite constitute the rock framework, and clay, organic matter and organic clay complex are distributed among the framework (for example, as shown in Figure 3 ). The quartz is composed of biogenic silica (which is shown to have a lamellar structure, see the arrow in a of Figure 3 , g of Figure 3 , which points to the inner lamellar of the non-cavity biogenic silica with pores, and the outer shell of the non-cavity biogenic silica without pores) and terrigenous quartz (which is shown to have no lamellar structure, see the arrow in a of Figure 3 ). The biogenic silica accounts for 47.4% of the rock volume, and the terrigenous quartz and terrigenous feldspar account for 7.1% of the rock volume. The irregular calcite (see a of Figure 3 ) accounts for 10.3% of the rock volume, and the rhombic iron-bearing dolomite enclosing dolomite (see the arrow in a of Figure 3 ) accounts for 4.2% of the rock volume. The framboidal pyrite includes overgrowth framboidal pyrite (see o of Figure 3 ) and common framboidal pyrite, and the common framboidal pyrite includes framboidal pyrite with grain linear contact (see p of Figure 3 ), framboidal pyrite with grain point contact (see q of Figure 3 ) and framboidal pyrite with grain floating in organic matter (see r of Figure 3 ), and the framboidal pyrite accounts for 1.5% of the rock volume. The clay is mainly in the form of a strip (see c-e of Figure 3 ) and accounts for 20.7% of the rock volume. The organic clay complex with honeycomb nanopores (see Figure 3b, g) in the figure are distributed among the rock framework composed of quartz, carbonate and pyrite, accounting for 4.7% of the rock volume; pure organic matter with honeycomb nanopores occupies secondary pores in the form of clumps (see ​ f, h) in the figure or occupies cracks in the form of strips (see ​ j, m-n) in the figure, accounting for 3.6% of the rock volume; pure organic matter without pores fills cracks in the form of strips (see ​ i, k-l) in the figure, accounting for 0.5% of the rock volume.

[0143] In summary, in this embodiment, the target siliceous shale satisfies the four characteristics of characteristic 1, characteristic 2, characteristic 3, and characteristic 4, and is a physical-chemical sedimentation in still water.

[0144] 5. Determine which one of the multi-cavity biological siliceous shale, single-cavity biological siliceous shale and cavity-free biological siliceous shale the target siliceous shale is;

[0145] In the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the quartz volume in the rock, the total of the terrigenous quartz and the terrigenous feldspar accounts for less than 10% of the quartz volume in the rock, and the cavities of the biological siliceous matter are filled with pure organic matter with honeycomb nanopores, then the target siliceous shale is a multi-cavity biological siliceous shale.

[0146] In the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the quartz volume in the rock, the total of the terrigenous quartz and the terrigenous feldspar accounts for less than 10% of the quartz volume in the rock, and the cavities of the biological siliceous matter are filled with organic silicon particle composite and / or calcite, then the target siliceous shale is a single-cavity biological siliceous shale.

[0147] In the target siliceous shale, if the biological siliceous matter accounts for less than 90% and greater than or equal to 70% of the quartz volume in the rock, and the total of the terrigenous quartz and the terrigenous feldspar accounts for more than 10% and less than or equal to 30% of the quartz volume in the rock, then the target siliceous shale is a cavity-free biological siliceous shale.

[0148] In the target siliceous shale in this embodiment, the biological siliceous matter accounts for less than 90% and greater than or equal to 70% of the quartz volume in the rock, and the total of the terrigenous quartz and the terrigenous feldspar accounts for more than 10% and less than or equal to 30% of the quartz volume in the rock, so the target siliceous shale is a cavity-free biological siliceous shale.

[0149] The non-cavity organism siliceous matter is formed in the surface water body deposition stage, and is transformed into quartz with the zonal structure in the middle burial late diagenesis stage. The calcite is formed in the upper water body, and the terrigenous quartz, feldspar and clay fall into the lower water body. The calcite is dissolved, and the dissolved organic matter and clay combine to form the organic clay complex. The sulfidic water body is conducive to the precipitation of framboidal pyrite. In the deep water seabed, the non-cavity organism siliceous matter, calcite, terrigenous quartz, feldspar, framboidal pyrite, clay and organic clay complex form the siliceous ooze. In the water-sediment interface diagenesis process, the dolomite and framboidal pyrite are precipitated. In the shallow burial diagenesis stage, the environment for the precipitation of framboidal pyrite changes from the sulfidic water body to the BSR and AOM-SR. The rhombic iron-containing dolomite wraps the dolomite, and the deposited organic clay complex is transformed into the kerogen clay complex. In the middle burial early diagenesis stage, the kerogen clay complex is transformed into the oil-potential bitumen clay complex. When the kerogen is transformed into the oil-potential bitumen, the volume expands, and the hydrocarbon generation pressure hole (secondary pore) and fracture are generated as the channel for the primary migration of the oil-potential bitumen. In the middle burial late diagenesis stage, the oil-potential bitumen clay complex is transformed into the solid bitumen clay complex. When the oil-potential bitumen is transformed into the solid bitumen and oil, the volume expands, and the fracture is generated due to the abnormal high pressure, forming the channel for the primary migration of the oil. In the deep burial diagenesis stage, the solid bitumen clay complex is transformed into the pyrobitumen clay complex with the honeycomb-shaped nanopores. The solid bitumen is transformed into the pyrobitumen with the honeycomb-shaped nanopores, and the oil is transformed into the pyrobitumen without pores.

[0150] The shale gas horizontal well with the target siliceous shale region (i.e., the C target siliceous shale region) as the target has low production and low exploration and development potential.

[0151] The above-described specific embodiments further specifically describe the purposes, technical solutions and advantages of the present application. It should be understood that the above-described specific embodiments are merely specific embodiments of the present application and are not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for determining whether a siliceous shale is a hydrochemical sedimentation, comprising: obtaining a target siliceous shale; wherein the quartz content of the target siliceous shale is higher than 50%, the clay content of the target siliceous shale is not less than 5%, and the total organic carbon content of the target siliceous shale is higher than 2%; determining whether the target siliceous shale has the following characteristics 1, 2, 3 and 4: Characteristic 1: biogenic silica accounts for 70-95% of the total volume of quartz and terrigenous feldspar in the rock, and terrigenous quartz and terrigenous feldspar account for 5-30% of the total volume of quartz and terrigenous feldspar in the rock; Characteristic 2: contains calcite and dolomite; Characteristic 3: contains raspberry pyrite; wherein the raspberry pyrite comprises ordinary raspberry pyrite, and the ordinary raspberry pyrite refers to raspberry pyrite with intercrystalline pore organic matter; Characteristic 4: contains organic matter; wherein the organic matter comprises organic clay complex with honeycomb nanopores; If the target siliceous shale has the characteristics 1, 2, 3 and 4, the target siliceous shale is a hydrochemical sedimentation.

2. The method of claim 1, wherein, Obtaining a target siliceous shale, comprising: performing whole rock analysis and total organic carbon test on the siliceous shale to be detected to determine the mass content of quartz, clay and total organic carbon in the siliceous shale to be detected; If the quartz content of the siliceous shale to be detected is higher than 50%, the clay content is not less than 5%, and the total organic carbon content is higher than 2%, the siliceous shale to be detected is taken as the target siliceous shale.

3. The method of claim 1, wherein, Determining whether the target siliceous shale has the following characteristics 1, 2, 3 and 4, comprising: using the target siliceous shale core to make an argon ion polished slice of the target siliceous shale; collecting a MAPS rock image data body of the argon ion polished slice of the target siliceous shale; based on the collected MAPS rock image data body of the argon ion polished slice of the target siliceous shale, observing whether the target siliceous shale has the characteristics 1, 2, 3 and 4.

4. The method of claim 3, wherein, The polishing surface of the argon ion polished slice of the target siliceous shale is parallel to the column surface of the target siliceous shale core.

5. The method of claim 3, wherein, The resolution of the collected MAPS rock image data body of the argon ion polished slice of the target siliceous shale is 4-10 nm resolution.

6. The method of claim 3, wherein, The length of the argon ion polished slice of the target siliceous shale is 0.8-2 cm, the width of the argon ion polished slice of the target siliceous shale is 0.8-2 cm, and the thickness of the argon ion polished slice of the target siliceous shale is 0.3-0.8 cm.

7. The method of claim 3, wherein, Collecting the MAPS rock image data body of the argon ion polished slice of the target siliceous shale comprises: selecting an area with a length and a width of not more than 400 μm in the polishing surface of the argon ion polished slice of the target siliceous shale, and collecting the MAPS rock image data body.

8. The method of claim 3, wherein, During the collection of the MAPS rock image data body of the argon ion polished slice of the target siliceous shale, the top surface of the argon ion polished slice of the target siliceous shale is located above the field of view, and the bottom surface of the argon ion polished slice of the target siliceous shale is located below the field of view.

9. The method of claim 1, wherein, In characteristic 2, the calcite is irregular particles.

10. The method of claim 1, wherein, In characteristic 2, the dolomite is rhombic iron-containing dolomite wrapped dolomite particles.

11. The method of claim 1, wherein, In feature 3, the framboidal pyrite further comprises overgrowth framboidal pyrite, which is framboidal pyrite with intercrystalline pores inside remaining unfilled by organic matter.

12. The method of claim 1, wherein, In feature 3, the common framboidal pyrite comprises at least one of grain linearly contacted framboidal pyrite, grain punctiformly contacted framboidal pyrite and grain floating in organic matter framboidal pyrite.

13. The method of claim 1, wherein, In feature 4, the organic matter further comprises pure organic matter, which comprises at least one of pure organic matter with honeycomb-like nanopores and pure organic matter without pores.

14. The method of claim 1, wherein, The method for judging whether the siliceous shale is hydrochemically deposited in still water further comprises: When the target siliceous shale is hydrochemically deposited in still water, determining which one of the multi-cavity biological siliceous shale, single-cavity biological siliceous shale and cavity-free biological siliceous shale the target siliceous shale is.

15. The method of claim 14, wherein, In the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the terrigenous quartz and terrigenous feldspar together account for less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the cavities of the biological siliceous matter are filled with pure organic matter with honeycomb-like nanopores, then the target siliceous shale is a multi-cavity biological siliceous shale; In the target siliceous shale, if the biological siliceous matter accounts for more than 90% of the total volume of quartz and terrigenous feldspar in the rock, and the terrigenous quartz and terrigenous feldspar together account for less than 10% of the total volume of quartz and terrigenous feldspar in the rock, and the cavities of the biological siliceous matter are filled with organic silicon particle composite and / or calcite, then the target siliceous shale is a single-cavity biological siliceous shale; In the target siliceous shale, if the biological siliceous matter accounts for less than 90% and more than or equal to 70% of the total volume of quartz and terrigenous feldspar in the rock, and the terrigenous quartz and terrigenous feldspar together account for more than 10% and less than or equal to 30% of the total volume of quartz and terrigenous feldspar in the rock, then the target siliceous shale is a cavity-free biological siliceous shale.

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