Component classification method and system for marine facies pulveryte

Abstract

The invention discloses a component classification method and system for marine facies pulveryte. The method comprises the following steps: obtaining an experimental rock sample related to the marine facies pulveryte; performing indoor experimental analysis on the experimental rock sample to obtain mineral content data and total organic carbon data; calculating a clay mineral content index, a carbonate rock content index and a quartz content index according to the mineral content data; according to the current three content indexes, determining a basic name of the current rock sample by using a pre-constructed three-end-member triangular projection drawing; based on the basic naming, determining a definitive name representing the abundance of the organic matter in combination with the total organic carbon data; and obtaining a complete classification name according to the basic name and the defined name. According to the method, the control of the sedimentary environment on the lithofacies and the difference of effective boundary lines of different lithologic source rocks are fully considered, the defect of marine facies fine-grained rock lithofacies classification is effectively overcome, and the method is simple and easy to operate and has very high scientificity and geological applicability.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploration and marine argillaceous carbonate rock sedimentology, and in particular to a composition classification method and system for marine fine-grained sedimentary rocks. Background Art

[0002] Fine-grained sediments refer to clay- and silt-grade sediments with a particle size of less than 62.5 μm, and their components mainly include clay minerals, terrigenous detrital minerals, chemically derived authigenic minerals, organic matter, etc. Sedimentary rocks composed of fine-grained sediments (content greater than 50%) are fine-grained sedimentary rocks. Fine-grained sedimentary rocks are very rich in rock types, including siltstone and claystone in the clastic rock system, lime marl (cloud) rock in the carbonate rock system, and a large number of transitional types.

[0003] Marine fine-grained sedimentary rocks are important targets for unconventional oil and gas exploration, and industrial oil and gas discoveries have been made in places such as the Fort Worth Basin in the United States and many places in China. Due to the diverse development environments of fine-grained sedimentary rocks, their lithological types are rich, so the previous classification and naming methods that were only applied to shale cannot be simply applied. How to scientifically, effectively and operationally formulate a classification and naming method for marine fine-grained sedimentary rocks from the perspective of source rocks is of great significance to deepening unconventional oil and gas exploration.

[0004] The existing classification and naming methods have their own characteristics, and there are still problems in the following aspects:

[0005] (1) The end-member selection is unreasonable when applying the terrestrial fine-grained rock classification scheme;

[0006] Existing fine-grained rock classification schemes mostly adopt the form of triangular diagrams, and the selection of end members is very important. The existing patent document (patent number is CN104007484A) discloses a classification method for mudstone, and the three end members selected by this scheme are gray (cloud) minerals, felsic minerals and clay minerals. Felsic generally refers to light-colored minerals such as feldspar, quartz, and muscovite. However, feldspar is generally considered to be terrestrial input, while quartz in marine fine-grained sediments is mostly authigenic quartz, which is of biological or hydrothermal origin. Therefore, in terms of sedimentary environment differentiation, in marine fine-grained sedimentary rocks, quartz and feldspar are not suitable to be placed in the same component end member. The same problem also appears in the existing patent document (patent number is CN114859009A), which adds quartz, feldspar, and mica as silicon-containing minerals as one of the three end members of the component type. There are significant differences in the sources of quartz between marine and terrestrial fine-grained sedimentary rocks. Therefore, based on the sedimentary environment, it is not feasible to simply apply the terrestrial fine-grained rock classification scheme to the marine one.

[0007] (2) The mixed lithology of the transition zone needs to be precisely divided;

[0008] For transitional rock types with the content of clay, ash (cloud) and silica components all less than 50%, some studies did not conduct separate classification or only made general divisions. This makes it difficult to obtain effective guidance for the lithology in the transitional zone in practical applications. Rock samples with only slight differences in mineral components are classified into different major lithology categories, which is not conducive to the restoration of the original sedimentary environment. The existing patent literature (patent number: CN111965727A) discloses a method for dividing and describing the heterogeneity of mixed sedimentary rocks. In this scheme, mixed fine-grained rocks with the content of dolomite + evaporite minerals accounting for more than 60% of the total mineral content are defined as evaporite-bearing mixed fine-grained rocks, and vice versa as saline mud-bearing mixed fine-grained rocks. Similar methods for dividing mixed sedimentary rocks are relatively single and have limited application ranges, and cannot be used in non-shallow water evaporation environments in marine facies.

[0009] (3) The classification criteria for organic matter abundance under different lithologies need to be distinguished;

[0010] Exploration practices and simulation experiments show that different lithology source rocks (such as carbonate rocks and shales) have different hydrocarbon generation capabilities under the condition of equal organic matter abundance. Therefore, in the classification scheme of marine fine-grained rocks, the criteria for "rich, high, medium, and low" organic matter abundance in different major categories of fine-grained rocks should also be further distinguished. The existing patent literature (patent number: CN112686994A) discloses a quantitative identification and three-dimensional characterization method for the lithofacies classification of marine shales. In this scheme, using 1%-2%, 2%-3%, 3%-4%, and greater than 4% as the unified criteria, all lithology marine fine-grained rocks are divided into four categories: low-carbon, medium-carbon, high-carbon, and rich-carbon. If emphasizing the source rock attribute of fine-grained rocks, this unified criterion cannot truly reflect the hydrocarbon generation capabilities of each lithology (especially carbonate rocks and some mixed sedimentary rocks), and there is room for optimization and improvement.

[0011] Therefore, the existing technology needs to provide a composition classification and naming scheme applicable to marine fine-grained sedimentary rocks. Summary of the Invention

[0012] The purpose of the present invention is to provide a composition classification and naming scheme applicable to marine fine-grained sedimentary rocks.

[0013] To solve the above technical problems, an embodiment of the present invention provides a composition classification method for marine fine-grained sedimentary rocks, including: obtaining experimental rock samples of marine fine-grained sedimentary rocks; conducting indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data; calculating the clay mineral content index, carbonate rock content index, and quartz content index according to the mineral content data; using a pre-constructed ternary triangular projection diagram based on the above three content indexes to determine the basic naming of the current rock sample; based on the basic naming, combining with the total organic carbon data, determining the qualified name representing the organic matter abundance; and obtaining the complete classification naming according to the basic naming and the qualified name.

[0014] Preferably, the original rock samples of marine fine-grained sedimentary rocks are obtained from outcrops or cored intervals in the field; the heterogeneity of the original rock samples is identified, and the original rock samples are preliminarily processed according to the identification results; the preliminarily processed original rock samples are crushed into two experimental rock samples.

[0015] Preferably, in the step of identifying the heterogeneity of the original rock samples and preliminarily processing the original rock samples according to the identification results, it includes: determining the rock samples with obvious nodules or interlayers as strongly heterogeneous rock samples, removing the weathered surface of the samples for the strongly heterogeneous rock samples, and avoiding the veins filled in the microfractures, and drilling corresponding experimental rock samples from different lithological parts respectively, otherwise determining them as weakly heterogeneous rock samples, removing the weathered surface of the samples for the weakly heterogeneous rock samples, and avoiding the veins filled in the microfractures, and drilling several experimental rock samples from the same part. Among them, the preliminarily processed original rock samples are crushed into two experimental rock samples meeting a preset mesh number, and the preset mesh number is 320 mesh.

[0016] Preferably, in the step of carrying out indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data, it includes: carrying out quantitative X-ray diffraction analysis of the whole rock on the first sample in the experimental rock samples to obtain the mineral content data; carrying out total hydrocarbon organic carbon content analysis on the second sample in the experimental rock samples to obtain the total organic carbon data.

[0017] Preferably, in the step of calculating the clay mineral content index, carbonate rock content index and quartz content index according to the mineral content data, it includes: adding the measured calcite content, measured dolomite content and measured aragonite content in the mineral content data to obtain the initial value of carbonate rock; normalizing the measured clay mineral content, measured quartz content and the initial value of carbonate rock in the mineral content data so that the sum of the three is 1, thereby calculating the clay mineral content index, the carbonate rock content index and the quartz content index.

[0018] Preferably, the ternary triangular projection diagram is established with the clay mineral content, carbonate rock content, and quartz content as the end members. Among them, in the step of determining the basic name of the current rock sample by using the pre-constructed ternary triangular projection diagram according to the current three content indicators, it includes: projecting the data points corresponding to the current three content indicators into the ternary triangular projection diagram, and determining the small class name of the area where the current projection point is located as the basic name of the current rock sample. Among them, the small class name of the basic name is determined according to the large class of the rock type of the target horizon in the area to be studied where the experimental rock sample is located. Among them, the large class of the basic name is selected from one or several of carbonate rocks, clay rocks, siliceous rocks, and mixed sedimentary rocks. The small class of the basic name is selected from the combinations of several of pure carbonate rock, silica-bearing carbonate rock, clay-bearing carbonate rock, silica carbonate rock, clayey carbonate rock, pure siliceous rock, carbonate-bearing siliceous rock, clay-bearing siliceous rock, carbonate-silica rock, clayey siliceous rock, pure clay rock, carbonate-bearing clay rock, silica-bearing clay rock, carbonate-clay rock, silica-clay rock, carbonate-clayey mixed sedimentary rock, silica-carbonate mixed sedimentary rock, and clayey-silica mixed sedimentary rock.

[0019] Preferably, if the basic name of the current rock sample contains a carbonate rock field, the measured calcite content and the measured dolomite content in the mineral content data are compared, and the current basic name is updated according to the comparison result, which includes: if the measured calcite content is much more than the measured dolomite content, the carbonate rock field in the current basic name is changed to a limestone field; if the measured dolomite content is much more than the measured calcite content, the carbonate rock field in the current basic name is changed to a dolomite field; if the measured calcite content is close to the measured dolomite content, the current basic name remains unchanged.

[0020] Preferably, in the step of determining the qualified name representing the organic matter abundance based on the basic name and combining the total organic carbon data, it includes: if the current basic name contains a carbonate rock or limestone or dolomite field, the qualified name is determined according to the total organic carbon data, which includes: when the total organic carbon data is less than the first threshold of the first type of organic carbon, the qualified name is determined as carbon-poor; when the total organic carbon data is greater than or equal to the first threshold of the first type of organic carbon and less than the second threshold of the first type of organic carbon, the qualified name is determined as carbon-medium; when the total organic carbon data is greater than or equal to the second threshold of the first type of organic carbon and less than the third threshold of the first type of organic carbon, the qualified name is determined as carbon-rich; when the total organic carbon data is greater than or equal to the third threshold of the first type of organic carbon, the qualified name is determined as carbon-abundant. Among them, the first threshold of the first type of organic carbon is 0.5%, the second threshold of the first type of organic carbon is 1.5%, and the third threshold of the first type of organic carbon is 3%.

[0021] Preferably, in the step of determining the qualified name characterizing the organic matter abundance based on the basic naming and combining the total organic carbon data, the following steps are further included: if the current basic naming contains fields of claystone or siliceous rock or mixed sedimentary rock, then determine the qualified name according to the total organic carbon data, including: when the total organic carbon data is less than the first threshold of the second type of organic carbon, determine the qualified name as carbon-poor; when the total organic carbon data is greater than or equal to the first threshold of the second type of organic carbon and less than the second threshold of the second type of organic carbon, determine the qualified name as carbon-medium; when the total organic carbon data is greater than or equal to the second threshold of the second type of organic carbon and less than the third threshold of the second type of organic carbon, determine the qualified name as carbon-high; when the total organic carbon data is greater than or equal to the third threshold of the second type of organic carbon, determine the qualified name as carbon-rich, wherein the first threshold of the second type of organic carbon is 0.5%, the second threshold of the second type of organic carbon is 2%, and the third threshold of the second type of organic carbon is 6%.

[0022] On the other hand, an embodiment of the present invention further provides a composition classification system for marine fine-grained sedimentary rocks, including: a rock sample collection module configured to obtain experimental rock samples of marine fine-grained sedimentary rocks; a feature generation module configured to conduct indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data; a content index generation module configured to calculate clay mineral content indexes, carbonate rock content indexes, and quartz content indexes according to the mineral content data; a basic naming generation module configured to determine the basic naming of the current rock sample by using a pre-constructed ternary triangular projection diagram according to the current three content indexes; a qualified name generation module configured to determine the qualified name characterizing the organic matter abundance based on the basic naming and combining the total organic carbon data; and a complete naming generation module configured to obtain a complete classification naming according to the basic naming and the qualified name.

[0023] Compared with the prior art, one or more embodiments in the above solution may have the following advantages or beneficial effects:

[0024] The present invention provides a composition classification method and system for marine fine-grained sedimentary rocks. The method and system obtain samples of marine fine-grained sedimentary rocks in the target horizon of the study area; conduct whole-rock X-ray diffraction quantitative analysis and rock total hydrocarbon organic carbon content analysis on the sample powder; calculate the normalized mineral content according to the obtained XRD data; perform "ternary" plotting to obtain the basic naming of the rock sample; and add qualified names such as "carbon-rich", "carbon-high", "carbon-medium", "carbon-poor" before the basic naming according to the obtained TOC data to obtain a complete classification naming. The method provided by the present invention fully considers the control of the sedimentary environment on the lithofacies and the differences in the effective boundaries of hydrocarbon source rocks with different lithologies, effectively makes up for the short board of the lithofacies classification of marine fine-grained rocks, is simple and easy to operate, and has strong scientificity and geological applicability.

[0025] In addition, the method for classifying the composition of marine fine-grained sedimentary rocks provided by the present invention can start from the sedimentary environment and effectiveness of hydrocarbon source rocks, be constrained by the primary environment of minerals, combine geological reality and industry usage habits, and is a scientific and easy-to-operate classification method based on component analysis. The present invention innovatively updates the previous "felsic" end member from the perspective of sedimentary environment; innovatively applies different classification criteria for organic matter abundance to fine-grained rocks of different lithologies. Moreover, the present invention accurately determines the favorable organic-rich lithofacies in each sedimentary environment of the target stratigraphic series and has been applied to various marine fine-grained sedimentary rock series.

[0026] Other features and advantages of the present invention will be described in the following specification, and in part, will become apparent from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Description of the Drawings

[0027] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0028] Figure 1 It is a schematic diagram of the steps of the method for classifying the composition of marine fine-grained sedimentary rocks according to the embodiment of the present application.

[0029] Figure 2 It is a schematic diagram of the specific process of the method for classifying the composition of marine fine-grained sedimentary rocks according to the embodiment of the present application.

[0030] Figure 3 It is a schematic diagram of the principle of the complete naming in the method for classifying the composition of marine fine-grained sedimentary rocks according to the embodiment of the present application.

[0031] Figure 4 It is an example diagram of the triangular projection result in the method for classifying the composition of marine fine-grained sedimentary rocks according to the embodiment of the present application.

[0032] Figure 5 It is a block diagram of the module of the system for classifying the composition of marine fine-grained sedimentary rocks according to the embodiment of the present application. Detailed Embodiments

[0033] The following will describe in detail the embodiments of the present invention in combination with the drawings and embodiments, so as to fully understand how the present invention uses technical means to solve technical problems and achieve the realization process of technical effects and implement accordingly. It should be noted that as long as there is no conflict, each embodiment in the present invention and each feature in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0034] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than herein.

[0035] The terms used herein are merely for describing specific embodiments and are not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a" and "an" used herein are also intended to include the plural. It should also be understood that the terms "comprises" and / or "comprising" specify the presence of the stated features, integers, steps, operations, units, and / or components, and do not preclude the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0036] In order to solve the technical problems in the above-mentioned background art, an embodiment of the present application proposes a method and system for classifying the composition of marine fine-grained sedimentary rocks. The method and system take the classical "three-endmember four-component" classification as the structural framework, are constrained by the primary environment of minerals, are compatible with existing classification methods for fine-grained rocks and mudstones, and combine the actual geological situation to formulate a method for classifying the composition of marine fine-grained sedimentary rocks. The present invention uses the data of quantitative analysis of whole-rock X-ray diffraction of rocks and the analysis data of total hydrocarbon organic carbon content of rocks to obtain the mineral composition and total organic carbon data of rock samples, so as to accurately name the rock samples.

[0037] Example 1

[0038] Figure 1 is a schematic diagram of the steps of the method for classifying the composition of marine fine-grained sedimentary rocks according to an embodiment of the present application. As Figure 1 shown, the composition classification method described in an embodiment of the present invention includes the following steps: Step S110, obtaining experimental rock samples of marine fine-grained sedimentary rocks; Step S120, conducting indoor experimental analysis on the experimental rock samples obtained in Step S110 to obtain mineral content data and total organic carbon data; Step S130, calculating the clay mineral content index, carbonate rock content index, and quartz content index according to the mineral content data obtained in Step S120; Step S140, using a pre-constructed three-endmember triangular projection diagram according to the current three content indexes obtained in Step S130 to determine the basic name of the current rock sample; Step S150, based on the basic name determined in Step S140, combining the total organic carbon data obtained in Step S120 to determine the defined name representing the abundance of organic matter; finally, Step S160, obtaining the complete classification name of the current rock sample according to the basic name determined in Step S140 and the defined name determined in Step S150.

[0039] In this way, the embodiments of the present invention use the above steps S110 to S150 to obtain a refined and complete naming result applicable to marine fine-grained sedimentary rocks, including the refined classification results of the rock sample transition zone and the organic carbon grade level, only using the mineral content data and the total organic carbon data.

[0040] Figure 2 FIG. is a schematic flow chart of the composition classification method for marine fine-grained sedimentary rocks according to the embodiments of the present application. The following will be combined with Figure 1 and Figure 2 to illustrate the specific step flow of the composition classification method described in the embodiments of the present invention.

[0041] In step S110, it is necessary to obtain experimental rock samples of marine fine-grained sedimentary rocks in the target layer of the area to be studied.

[0042] As Figure 2 shown, step S1 obtains the original rock samples of marine fine-grained sedimentary rocks from field geological outcrops or core sections. Specifically, at least one original rock sample of marine fine-grained sedimentary rocks in the target layer of the area to be studied is collected from field geological outcrops or core sections.

[0043] In S1, the selection method of argillaceous carbonate rock samples is preliminary observation in the field outcrop and analysis under a general microscopic thin section. Considering the similarity in appearance between argillaceous carbonate rocks and calcareous mudstones, the selection of rock samples in S1 does not require strict selection. In addition, marine mudstones are also applicable to this classification method.

[0044] Step S2 identifies the degree of heterogeneity of the original rock samples and performs preliminary processing on the original rock samples according to the identification results. Step S3 crushes the preliminarily processed original rock samples into two experimental rock samples (i.e., small pieces of samples).

[0045] The original rock samples are preliminarily observed, roughly classified according to the degree of heterogeneity, and sampled and preprocessed, so as to crush the preliminarily processed original rock samples into two experimental rock samples meeting the preset mesh number to make experimental rock samples according to the rough classification results.

[0046] In one embodiment, the rock samples with obvious nodules or interlayers are determined as strongly heterogeneous rock samples, and the surface treatment of the weathered samples is removed for the determined strongly heterogeneous rock samples, and the veins filled in the microcracks are avoided, and the experimental rock samples at the corresponding positions are drilled from different lithological parts.

[0047] In another embodiment, the rock samples without nodules or interlayers are determined as weakly heterogeneous rock samples, and the surface treatment of the weathered samples is removed for the determined weakly heterogeneous rock samples, and the veins filled in the microcracks are avoided, and several experimental rock samples are drilled from the same part.

[0048] In the embodiments of the present invention, the number of experimental rock samples drilled from the original rock sample is at least two.

[0049] In one embodiment, the preset mesh number is 320 mesh. That is to say, the size of each experimental rock sample is less than 40 μm.

[0050] After obtaining the corresponding at least two experimental rock samples for each original rock sample, it proceeds to step S120 to respectively conduct indoor experimental analysis on the two experimental rock samples belonging to the same original rock sample obtained in step S110, and obtain the mineral content data and total organic carbon data of the current experimental rock sample.

[0051] In step S120, step S4 conducts quantitative analysis of whole-rock X-ray diffraction on the first sample of the experimental rock sample obtained in step S3 to obtain the mineral content data of the current experimental rock sample.

[0052] For the first sample obtained in step S3, according to the pretreatment process in "SY / T 5163-CN 114199911 A2010 Analysis Method of X-ray Diffraction for Clay Minerals and Common Non-clay Minerals in Sedimentary Rocks", the processed sample is subjected to quantitative analysis of whole-rock X-ray diffraction to obtain the content data of various minerals in the sample, that is, the mineral content data (also known as "whole-rock mineral composition data").

[0053] Moreover, step S5 conducts analysis of the total hydrocarbon organic carbon content on the second sample of the experimental rock sample obtained in step S3 to obtain the total organic carbon data of the current experimental rock sample.

[0054] For the second sample obtained in step S3, according to the pretreatment process in "GB / T 19145-2003 Determination of Total Organic Carbon in Sedimentary Rocks", the processed sample is subjected to analysis of the total hydrocarbon organic carbon content of the rock to obtain the total organic carbon (TOC) data of the sample.

[0055] After obtaining the mineral content data and total organic carbon data of the current experimental rock sample, it proceeds to step S130, and in step S130, the clay mineral content index, carbonate rock content index, and quartz content index are calculated according to the current mineral content data.

[0056] In step S130, step S6 adds the measured calcite content, measured dolomite content, and measured aragonite content in the mineral content data obtained in step S4 to obtain the initial value C of carbonate rock.

[0057] According to the mineral content data obtained in step S4, the calcite content, dolomite content, and aragonite content in the current mineral content data are added to obtain the carbonate mineral content C.

[0058] After that, in step S7, the measured clay mineral content in the current mineral content data, the measured quartz content in the current mineral content data, and the above initial value of carbonate rock are normalized so that the sum of the three is 1, thereby calculating the clay mineral content index M', the carbonate rock content index C', and the quartz content index Q'.

[0059] According to the clay mineral content M and quartz content Q obtained in step S4, and the carbonate mineral content C obtained in S6, normalization is performed, and the sum of the three is made 100%. The normalized clay mineral content M', carbonate mineral content C', and quartz content Q' corresponding to the rock sample are obtained.

[0060] According to the clay mineral content M and quartz content Q in the current mineral content data obtained in step S4, and the carbonate mineral content C obtained in step S6, these three are normalized, and the sum of the three is made 100%, thereby obtaining the normalized clay mineral content index M', carbonate mineral content index C', and quartz content index Q' corresponding to the current experimental rock sample.

[0061] After obtaining the clay mineral content index, carbonate rock content index, and quartz content index corresponding to the current experimental rock sample, it enters step S140, and in step S140, the basic naming of the current experimental rock sample is determined according to the clay mineral content index, carbonate rock content index, and quartz content index corresponding to the current experimental rock sample.

[0062] Step S8 projects the data points corresponding to the current three content indexes onto a ternary triangular projection diagram, and determines the small class name of the area where the current projection point is located as the basic naming of the current rock sample.

[0063] According to (M', C', Q') obtained in S7, the obtained (M', C', Q') is subjected to ternary triangular projection on a pre-constructed ternary triangular projection diagram, and the small class lithology type to which the landing position of the current projection point belongs is determined as the basic naming of the current experimental rock sample.

[0064] In the embodiment of the present invention, for different types of target layers to be evaluated, the ternary triangular projection diagram may be different. In one embodiment, according to the major category of the rock type of the target layer in the area to be studied where the experimental rock sample is collected, the small class name of the basic naming is determined. Among them, the major category of the basic naming is selected from one or more of carbonate rock, clay rock, siliceous rock, and mixed sedimentary rock. In this way, the small class of the basic naming can be determined according to the major category rock type of the target layer to be evaluated.

[0065] In step S8, the basic naming of the rock sample is selected from a combination of several of the following 18 sub-categories: (1) pure carbonate rock; (2) carbonate rock containing silica; (3) carbonate rock containing clay; (4) silica carbonate rock; (5) clay carbonate rock; (6) pure silica rock; (7) silica rock containing carbonate; (8) silica rock containing clay; (9) carbonate silica rock; (10) clay silica rock; (11) pure clay rock; (12) clay rock containing carbonate; (13) clay rock containing silica; (14) carbonate clay rock; (15) silica clay rock; (16) carbonate clay mixed rock; (17) silica carbonate mixed rock; (18) clay silica mixed rock.

[0066] Due to the differences in the major lithology types of different types of target layers, the composition of the selected sub-categories of the basic naming is different. Therefore, the construction principles of the ternary triangular projection diagrams in the embodiments of the present invention are different.

[0067] In one embodiment, when the major lithology types of the target layer to be studied include the above four categories and the basic naming of the rock sample includes all the above 18 sub-categories, as Figure 3 shown, the triangular graph corresponding to the mineral composition part is the constructed ternary triangular projection diagram. This ternary triangular projection diagram takes the clay mineral content, carbonate rock content, and quartz content as three end-members and is established using a ternary four-group classification structure framework. In the embodiments of the present invention, the number of groups in the classification structure framework matches the number of major lithology types of the selected target layer to be studied. The "ternary" refers to the clay mineral end-member, carbonate mineral end-member, and quartz end-member. Thus, the basic naming of the rock sample can be obtained according to the area where the point is plotted.

[0068] In addition, in step S140, in the component classification method described in the embodiments of the present invention, in step S8, if the basic naming of the current rock sample contains a carbonate rock field, the measured calcite content and the measured dolomite content in the mineral content data obtained in step S4 are compared, so as to update the basic naming of the current one containing the carbonate rock field according to the comparison result.

[0069] In the first embodiment, if the measured calcite content is much more than the measured dolomite content, the carbonate rock field in the current basic naming is changed to (replaced by) a limestone field.

[0070] In the second embodiment, if the measured dolomite content is much more than the measured calcite content, the carbonate rock field in the current basic naming is changed to (replaced by) a dolomite field.

[0071] In the third embodiment, if the measured calcite content is close to the measured dolomite content, the current basic naming remains unchanged.

[0072] After completing the basic naming of the current experimental rock sample, proceed to step S150 to determine the qualified name of the current experimental rock sample based on the basic naming and total organic carbon data of the current experimental rock sample. Then, step S160 will combine the basic naming and the qualified name of the current experimental rock sample to obtain the overall classification naming result of the current experimental rock sample.

[0073] According to the TOC value of the rock sample obtained in step S5, step S9 adds a qualified name such as "carbon-rich", "high-carbon", "medium-carbon", or "carbon-poor" before the basic naming obtained in S8, so as to obtain a complete classification naming.

[0074] As Figure 3 shown, when determining the qualified name, the embodiment of the present invention will divide different organic matter abundance evaluation criteria according to different basic namings (i.e., types of lithologic subcategories).

[0075] In one embodiment, if the basic naming of the current experimental rock sample contains fields such as carbonate rock, limestone, or dolomite, the qualified name of the basic naming rock sample currently containing fields such as carbonate rock, limestone, or dolomite is determined according to the total organic carbon data obtained in step S5.

[0076] Specifically, when the total organic carbon data is less than the first threshold of the first type of organic carbon, the qualified name of the current experimental rock sample is determined as carbon-poor; when the total organic carbon data is greater than or equal to the first threshold of the first type of organic carbon and less than the second threshold of the first type of organic carbon, the qualified name of the current experimental rock sample is determined as medium-carbon; when the total organic carbon data is greater than or equal to the second threshold of the first type of organic carbon and less than the third threshold of the first type of organic carbon, the qualified name of the current experimental rock sample is determined as high-carbon; when the total organic carbon data is greater than or equal to the third threshold of the first type of organic carbon, the qualified name of the current experimental rock sample is determined as carbon-rich.

[0077] In the embodiment of the present invention, the first threshold of the first type of organic carbon is 0.5%, the second threshold of the first type of organic carbon is 1.5%, and the third threshold of the first type of organic carbon is 3%.

[0078] In another embodiment, if the basic naming of the current experimental rock sample contains fields such as claystone, siliceous rock, or mixed sedimentary rock, the qualified name of the basic naming rock sample currently containing fields such as claystone, siliceous rock, or mixed sedimentary rock is determined according to the total organic carbon data obtained in step S5.

[0079] Specifically, when the total organic carbon data is less than the first threshold of the second type of organic carbon, it is determined that the qualification name of the current experimental rock sample is carbon-poor; when the total organic carbon data is greater than or equal to the first threshold of the second type of organic carbon and less than the second threshold of the second type of organic carbon, it is determined that the qualification name of the current experimental rock sample is medium-carbon; when the total organic carbon data is greater than or equal to the second threshold of the second type of organic carbon and less than the third threshold of the second type of organic carbon, it is determined that the qualification name of the current experimental rock sample is high-carbon; when the total organic carbon data is greater than or equal to the third threshold of the second type of organic carbon, it is determined that the qualification name of the current experimental rock sample is carbon-rich.

[0080] In the embodiment of the present invention, the first threshold of the second type of organic carbon is 0.5%, the second threshold of the second type of organic carbon is 2%, and the third threshold of the second type of organic carbon is 6%.

[0081] In this way, after determining the qualification name of the current experimental rock sample, the determined qualification name is loaded before the basic naming determined in step S8, so as to obtain the complete classification naming of the current experimental rock sample.

[0082] Example 2

[0083] Taking the X section in a certain area as an example, the specific step process of the composition classification method for marine fine-grained sedimentary rocks described in the above Embodiment 1 will be described in detail. As Figure 2 shown, it specifically includes the following steps:

[0084] Step S1: Collect samples of marine fine-grained sedimentary rocks from the target horizon in the study area from outcrops in the field;

[0085] Specifically, the X section in a certain area is a typical marine fine-grained rock section, with the Sinian Doushantuo Formation and Dengying Formation completely exposed, and part of the Lower Cambrian Yanjiahe Formation exposed. The research degree is relatively high, and the stratigraphic boundary and sedimentary facies division are clear. In this embodiment, 15 original rock samples from the Doushantuo Formation, 6 from the Dengying Formation, and 4 from the Yanjiahe Formation at different horizons in the X section are collected respectively.

[0086] Step S2: Conduct a preliminary observation on the original rock samples, roughly divide the rock samples into two categories according to the strength of heterogeneity, and drill the corresponding experimental rock samples respectively.

[0087] According to the heterogeneity characteristics of the rock samples involved in the embodiment, in step two, the pretreatment of the two types of samples is carried out in the following ways respectively:

[0088] (1) For samples with weak heterogeneity, remove the weathered surface of the sample, avoid the veins filled in the microfractures, and drill small pieces of samples.

[0089] (2) For samples with strong heterogeneity, that is, rock samples with obvious nodules, interlayers, etc., after removing the weathered surface of the sample, avoid the veins filled in the microfractures, and drill small pieces of samples again for different lithologic parts.

[0090] Step S3: Crush the small piece of sample obtained in Step S2 into two parts with a size of 320 mesh.

[0091] Step S4: For the first sample obtained in Step S3, according to the pretreatment process in "SY / T 5163-CN 114199911 A2010 X-ray Diffraction Analysis Method for Clay Minerals and Common Non-Clay Minerals in Sedimentary Rocks", carry out quantitative X-ray diffraction analysis of the whole rock of the treated sample to obtain the content data of various minerals in the sample.

[0092] Step S5: For the second sample obtained in Step S3, according to the pretreatment process in "GB / T 19145-2003 Determination of Total Organic Carbon in Sedimentary Rocks", carry out analysis of the total hydrocarbon organic carbon content of the whole rock of the treated sample to obtain the total organic carbon (TOC) data of the sample.

[0093] Step S6: According to the whole rock mineral composition data obtained in Step S4, add the contents of calcite, dolomite and aragonite to obtain the carbonate mineral content C.

[0094] Step S7: According to the clay mineral content M, quartz content Q obtained in Step S4, and the carbonate mineral content C obtained in Step S6, perform normalization processing so that the sum of the three is 100%. Obtain the normalized clay mineral content M', carbonate mineral content C', and quartz content Q' corresponding to the rock sample, as shown in Table 1 below.

[0095] Table 1 Calculation Table of Clay Mineral Content, Carbonate Mineral Content and Quartz Content of Samples in X Profile

[0096]

[0097]

[0098] Step S8: According to (M', C', Q') obtained in Step S7, perform a "three-endmember" triangular plot (as Figure 4 shown). The "three endmembers" refer to the clay mineral endmember, carbonate mineral endmember and quartz endmember. According to the area where the projection point is located, obtain the basic naming of the rock sample.

[0099] In the second embodiment, the basic naming of the marine fine-grained rock samples in the X profile includes three major categories and 8 sub-categories. The three major categories are: carbonate rocks, siliceous rocks and mixed sedimentary rocks. The 8 sub-categories are: (1) pure carbonate rock; (2) carbonate rock containing silica; (3) carbonate rock containing clay; (4) silica carbonate rock; (5) pure siliceous rock; (6) siliceous rock containing clay; (7) carbonate-bearing siliceous rock; (8) siliceous carbonate-bearing mixed sedimentary rock.

[0100] During the process of step S8 in the second embodiment, for the rock samples whose basic names obtained contain "×× carbonate rock", according to the relative proportion of calcite and dolomite in their carbonate minerals, if calcite is much more than dolomite, the basic name can be determined as "×× limestone", otherwise it is determined as "×× dolomite", and if the proportion of calcite and dolomite is close, it is still determined as "×× carbonate rock".

[0101] Step S9: According to the TOC value of the rock samples obtained in step S5, add limiting names such as "carbon-rich", "high-carbon", "medium-carbon", "carbon-poor" before the basic names obtained in step S8 to obtain the complete classification names, as shown in Table 2 below.

[0102] Table 2 Complete naming results of samples in X section

[0103]

[0104]

[0105] During the process of step S9 in the second embodiment, for the rock samples whose basic names obtained in step S8 are "×× claystone" or "×× siliceous rock" or "×× mixed sedimentary rock", use "TOC≥6.0%", "2.0≤TOC<6.0%", "0.5≤TOC<2.0%", "TOC<0.5%" as the classification criteria for "carbon-rich", "high-carbon", "medium-carbon", "carbon-poor" respectively. For the rock samples whose basic names obtained in step S8 are "×× carbonate rock", "×× limestone" or "×× dolomite", use "TOC≥3.0%", "1.5≤TOC<3.0%", "0.5≤TOC<1.5%", "TOC<0.5%" as the classification criteria for "carbon-rich", "high-carbon", "medium-carbon", "carbon-poor" respectively.

[0106] The component classification and corresponding petrological naming of marine fine-grained rock samples in section X of a certain area that can be obtained by applying the present invention.

[0107] Example 3

[0108] Based on the above component classification method, the embodiment of the present invention also provides a component classification system for marine fine-grained sedimentary rocks. This component classification system is used to implement the above component classification method.

[0109] Figure 5 It is a module block diagram of the component classification system for marine fine-grained sedimentary rocks in an embodiment of this application. As Figure 5 shown, the component classification system described in the embodiment of the present invention includes: a rock sample collection module 51, a feature generation module 52, a content index generation module 53, a basic naming generation module 54, a limiting name generation module 55, and a complete naming generation module 56.

[0110] Specifically, the rock sample collection module 51 is implemented according to the method described in step S110 above, and is configured to obtain experimental rock samples of marine fine-grained sedimentary rocks; the feature generation module 52 is implemented according to the method described in step S120 above, and is configured to conduct indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data; the content index generation module 53 is implemented according to the method described in step S130 above, and is configured to calculate the clay mineral content index, carbonate rock content index, and quartz content index based on the mineral content data; the basic naming generation module 54 is implemented according to the method described in step S140 above, and is configured to determine the basic naming of the current rock sample by using a pre-constructed three-endmember triangular projection diagram based on the current three content indexes; the qualified name generation module 55 is implemented according to the method described in step S150 above, and is configured to determine the qualified name representing the organic matter abundance based on the basic naming and in combination with the total organic carbon data; the complete naming generation module 56 is implemented according to the method described in step S160 above, and is configured to obtain the complete classification naming based on the basic naming and the qualified name.

[0111] The present invention discloses a composition classification method and system for marine fine-grained sedimentary rocks. The method and system obtain samples of marine fine-grained sedimentary rocks in the target horizon of the study area; conduct whole-rock X-ray diffraction quantitative analysis and rock total hydrocarbon organic carbon content analysis on the sample powder; calculate the normalized mineral content based on the obtained XRD data; perform "three-endmember" plotting to obtain the basic naming of the rock sample; and add qualified names such as "carbon-rich", "high-carbon", "medium-carbon", "carbon-poor", etc. before the basic naming according to the obtained TOC data to obtain the complete classification naming. The method provided by the present invention fully considers the control of the sedimentary environment on the lithofacies and the differences in the effective boundaries of hydrocarbon source rocks of different lithologies, effectively makes up for the short board of the lithofacies classification of marine fine-grained rocks, is simple and easy to operate, and has strong scientificity and geological applicability.

[0112] In addition, the composition classification method of marine fine-grained sedimentary rocks provided by the present invention can start from the sedimentary environment and effectiveness of hydrocarbon source rocks, be restricted by the primary environment of minerals, combine geological reality and industry usage habits, and is a scientific and easy-to-operate classification method based on composition analysis. The present invention innovatively updates the previous "felsic" endmember from the perspective of the sedimentary environment; innovatively applies different organic matter abundance classification criteria to fine-grained rocks of different lithologies. Moreover, the present invention accurately determines the favorable organic-rich lithofacies in each sedimentary environment of the target stratigraphic series and has been applied to various marine fine-grained sedimentary rock series.

[0113] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

[0114] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, terms such as "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0115] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0116] It should be understood that the embodiments disclosed by the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not mean to limit.

[0117] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in connection with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0118] Although the disclosed embodiments of the present invention are as above, the content described is only the embodiment adopted for the convenience of understanding the present invention and is not used to limit the present invention. Any person skilled in the art within the technical field to which the present invention pertains can make any modifications and changes in the form of implementation and details without departing from the spirit and scope disclosed by the present invention. However, the patent protection scope of the present invention still shall be subject to the scope defined by the appended claims.

Claims

1. A method for the compositional classification of marine fine-grained sedimentary rocks, characterized in that, Comprising: Obtaining experimental rock samples of marine fine-grained sedimentary rocks; Conducting indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data; Calculating the clay mineral content index, carbonate rock content index, and quartz content index based on the mineral content data; Determining the basic name of the current rock sample using a pre-constructed ternary triangular projection diagram according to the current three content indexes; Based on the basic name, combining with the total organic carbon data, determining the defined name characterizing the organic matter abundance; Obtaining the complete classification name according to the basic name and the defined name.

2. The component classification method according to claim 1, wherein: Obtaining the original rock samples of marine fine-grained sedimentary rocks from field geological outcrops or cored intervals; Identifying the degree of heterogeneity of the original rock samples, and performing preliminary processing on the original rock samples according to the identification results; Crushing the preliminarily processed original rock samples into two experimental rock samples.

3. The component classification method according to claim 2, wherein In the step of identifying the degree of heterogeneity of the original rock samples and performing preliminary processing on the original rock samples according to the identification results, it includes: Determining the rock samples with obvious nodules or interlayers as strongly heterogeneous rock samples, removing the weathered surface of the samples for the strongly heterogeneous rock samples, and avoiding the veins filled in the microfractures, and drilling corresponding experimental rock samples from different lithological parts respectively, otherwise determining them as weakly heterogeneous rock samples, removing the weathered surface of the samples for the weakly heterogeneous rock samples, and avoiding the veins filled in the microfractures, and drilling several experimental rock samples from the same part. Among them, Crushing the preliminarily processed original rock samples into two experimental rock samples that meet a preset mesh number, and the preset mesh number is 320 mesh.

4. The method for classifying components according to claim 2 or 3, characterized in that, In the step of conducting indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data, it includes: Conducting quantitative X-ray diffraction analysis of the whole rock on the first sample of the experimental rock samples to obtain the mineral content data; Conducting total hydrocarbon organic carbon content analysis on the second sample of the experimental rock samples to obtain the total organic carbon data.

5. The component classification method according to any one of claims 1 to 4, characterized in that, In the step of calculating the clay mineral content index, carbonate rock content index, and quartz content index based on the mineral content data, it includes: Adding the measured calcite content, measured dolomite content, and measured aragonite content in the mineral content data to obtain the initial value of carbonate rocks; Normalizing the measured clay mineral content, measured quartz content, and the initial value of carbonate rocks in the mineral content data so that the sum of the three is 1, thereby calculating the clay mineral content index, the carbonate rock content index, and the quartz content index.

6. The component classification method according to any one of claims 1 to 5, characterized in that The ternary triangular projection diagram is established with clay mineral content, carbonate rock content, and quartz content as end members. Among them, in the step of determining the basic name of the current rock sample using the pre-constructed ternary triangular projection diagram according to the current three content indexes, it includes: Projecting the data points corresponding to the current three content indexes into the ternary triangular projection diagram, and determining the small class name of the current projection point area as the basic name of the current rock sample. Among them, Determine the small-class name of the basic naming according to the major category of the rock type of the target horizon in the area to be studied where the experimental rock sample is located. Among them, the major category of the basic naming is selected from one or more of carbonate rocks, clay rocks, siliceous rocks, and mixed sedimentary rocks. The small classes of the basic naming are selected from combinations of several of pure carbonate rock, silica-bearing carbonate rock, clay-bearing carbonate rock, silica carbonate rock, clayey carbonate rock, pure siliceous rock, carbonate-bearing siliceous rock, clay-bearing siliceous rock, carbonate-silica rock, clayey siliceous rock, pure clay rock, carbonate-bearing clay rock, silica-bearing clay rock, carbonate-clay rock, silica-clay rock, carbonate-clayey mixed sedimentary rock, silica-carbonate mixed sedimentary rock, and clayey-silica mixed sedimentary rock.

7. The composition classification method according to claim 6, wherein If the basic naming of the current rock sample contains the carbonate rock field, compare the measured calcite content with the measured dolomite content in the mineral content data, and update the current basic naming according to the comparison result, including: If the measured calcite content is much more than the measured dolomite content, change the carbonate rock field in the current basic naming to the limestone field; If the measured dolomite content is much more than the measured calcite content, change the carbonate rock field in the current basic naming to the dolomite field; If the measured calcite content is close to the measured dolomite content, keep the current basic naming unchanged.

8. The component classification method according to claim 7, characterized in that In the step of determining the defined name representing the organic matter abundance based on the basic naming and combining the total organic carbon data, it includes: If the current basic naming contains the carbonate rock or limestone or dolomite field, determine the defined name according to the total organic carbon data, including: When the total organic carbon data is less than the first threshold of the first type of organic carbon, determine the defined name as carbon-poor; When the total organic carbon data is greater than or equal to the first threshold of the first type of organic carbon and less than the second threshold of the first type of organic carbon, determine the defined name as carbon-medium; When the total organic carbon data is greater than or equal to the second threshold of the first type of organic carbon and less than the third threshold of the first type of organic carbon, determine the defined name as carbon-high; When the total organic carbon data is greater than or equal to the third threshold of the first type of organic carbon, determine the defined name as carbon-rich, where The first threshold of the first type of organic carbon is 0.5%, the second threshold of the first type of organic carbon is 1.5%, and the third threshold of the first type of organic carbon is 3%.

9. The component classification method according to any one of claims 1 to 8, characterized in that In the step of determining the defined name representing the organic matter abundance based on the basic naming and combining the total organic carbon data, it also includes: If the current basic naming contains the clay rock or siliceous rock or mixed sedimentary rock field, determine the defined name according to the total organic carbon data, including: When the total organic carbon data is less than the first threshold of the second type of organic carbon, determine the defined name as carbon-poor; When the total organic carbon data is greater than or equal to the first threshold of the second type of organic carbon and less than the second threshold of the second type of organic carbon, determine the defined name as carbon-medium; When the total organic carbon data is greater than or equal to the second threshold of the second type of organic carbon and less than the third threshold of the second type of organic carbon, determine that the defined name is high carbon; When the total organic carbon data is greater than or equal to the third threshold of the second type of organic carbon, determine that the defined name is carbon-rich, where the first threshold of the second type of organic carbon is 0.5%, the second threshold of the second type of organic carbon is 2%, and the third threshold of the second type of organic carbon is 6%.

10. A compositional classification system for marine fine-grained sedimentary rocks, characterized in that, Including: A rock sample collection module configured to obtain experimental rock samples of marine fine-grained sedimentary rocks; A characteristic generation module configured to conduct indoor experimental analysis on the experimental rock samples to obtain mineral content data and total organic carbon data; A content index generation module configured to calculate clay mineral content indexes, carbonate rock content indexes, and quartz content indexes according to the mineral content data; A basic naming generation module configured to determine the basic naming of the current rock sample by using a pre-constructed three-endmember triangular projection diagram based on the current three content indexes; A defined name generation module configured to determine the defined name representing the organic matter abundance in combination with the total organic carbon data based on the basic naming; A complete naming generation module configured to obtain the complete classification naming according to the basic naming and the defined name.

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