Method for classifying and naming mixed sedimentary rocks of foraminifera
The classification and naming method for foraminiferal mixed sedimentary rocks solves the problem that low-energy mud and biocavity filling are not considered in the existing rock classification system, and realizes accurate assessment and prediction of reservoir properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NAT OFFSHORE OIL CORP
- Filing Date
- 2026-03-10
- Publication Date
- 2026-07-03
AI Technical Summary
The existing rock classification system fails to accurately cover the mud components in low-energy environments and ignores the filling of biological calcium cavities, resulting in inaccurate reservoir evaluation.
A classification and naming method for foraminiferal mixed sedimentary rocks was adopted. The contents of terrigenous clastics, low-energy/chemical carbonates and biogenic calcium components were identified and calculated, and the classification and naming were performed using a triangulation diagram in combination with the foraminiferal infill rate.
It enables accurate assessment of low-energy sludge and biocavity filling, improving the accuracy of reservoir property evaluation and the reliability of reservoir quality prediction.
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Figure CN122333209A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of petrography in the petroleum exploration industry, and in particular to a method for classifying and naming foraminiferous mixed sedimentary rocks. Background Technology
[0002] In oil and gas reservoir evaluation and other related fields, mixed sedimentary rocks are of crucial significance as an important rock type resulting from the mixing of terrigenous clastic and carbonate rocks. Since Mount (1984) first systematically explored the concept of mixed sedimentary rocks, scholars have gradually focused on their classification, genesis, and reservoir characteristics (Yose and Heller, 1989; Sanders and Pons, 1999). Existing classification systems mainly rely on thin-section component identification and statistical results, emphasizing the relative content of end-member components. For example, a terrigenous clastic content of 50%–80% is defined as mixed sedimentary rocks dominated by terrigenous clastics, and when the carbonate content is greater than 50%, further distinctions are made between biogenic and chemically formed end-members (Ye et al., 2018). However, this existing system has two main problems that limit its effectiveness in accurate reservoir evaluation.
[0003] First, the existing system's definition of chemically formed carbonate end-members has shortcomings in its academic definition, failing to accurately cover the geological elements represented by low-energy environmental mud components. Ye Maosong et al. (2018) defined chemically precipitated carbonate end-members as "chemically precipitated carbonates," including micritic or microcrystalline structures. However, this definition only emphasizes in-situ chemical deposition processes and does not explicitly include the deposition process of suspended mud particles transported from other sites under low-energy conditions. In classic carbonate-clastic mixed sedimentary reservoir cases in the Bohai Sea and Baiyun Depression, low-energy sedimentary mud components account for a large proportion, easily leading to pore blockage and reduced permeability. Existing end-member classification systems do not explicitly include low-energy mud in the carbonate end-member component classification, resulting in omissions. This deficiency makes it impossible to effectively distinguish between different genetic mud components (in-situ chemically precipitated mud vs. low-energy sedimentary mud) and their different effects on reservoir permeability when evaluating reservoir properties.
[0004] Secondly, existing systems do not consider the internal filling of biogenic calcareous cavities. For mixed sedimentary rocks with abundant biogenic calcareous cavities but severe filling, this significantly interferes with the assessment of porosity and reservoir efficiency. Current systems use biogenic carbonate particles (such as bioclastics and oolitic grains) as one of the three end-members, but only focus on the overall particle content, failing to further distinguish whether the biogenic cavities are filled with cement, secondary minerals, mud, or clay matrix. It should be noted that in mixed sedimentary rocks with highly developed biogenic calcareous cavities (especially those of coccidia), the internal filling condition of the cavities significantly affects physical properties. Processes such as spar crystal cementation, mud / clay matrix filling, and secondary mineral growth lead to a high degree of filling, thus significantly reducing primary porosity; while unfilled or incompletely filled cavities can retain higher porosity. Current classifications lack the ability to distinguish these differences in microstructural filling, making it impossible to quantify the control of the filling process of biogenic cavities on porosity and permeability when assessing and predicting reservoir performance.
[0005] The aforementioned problems result in significant limitations of the existing naming system in the accurate evaluation of complex reservoirs in carbonate-clastic mixed sedimentary rocks. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a method for classifying and naming foraminiferal mixed sedimentary rocks.
[0007] The technical solution adopted by this invention to solve its technical problem is: a method for classifying and naming foraminiferal mixed sedimentary rocks, comprising the following steps: S1. The rock was identified and its components were classified to obtain the initial values of the contents of three types of components. The three types of components include terrigenous clastic components, low-energy / chemical carbonate components, and biogenic calcareous components. The low-energy / chemical carbonate components include mud, and the biogenic calcareous components include foraminifera. S2. Identify, classify and statistically analyze the filling components of foraminifera, obtain statistical data on the filling components, and calculate the foraminifera infill rate. S3. Based on the initial values of the contents of the three types of components, combined with the statistical data of the filling components and the foraminifera filling rate, calculate the final values of the contents of the three types of components. S4. Based on the final values of the contents of the three components, the final classification and naming of the rock is determined using a pre-established triangular diagram with the three components as end members.
[0008] Preferably, in step S1, the component identification includes grain size analysis and rock and mineral identification; the component classification divides the rocks and minerals into terrigenous clastic components, low-energy / chemical carbonate components and biological calcareous components according to their genesis. The terrigenous clastic components include quartz, feldspar, mica, rock fragments, and argillaceous material; the low-energy / chemical carbonate components include carbonate shards and carbonate mudstones, with carbonate shards including calcite shards and dolomite shards, and carbonate mudstones including mud and dolomite mudstones; the biogenic calcareous components include bioclastic material, which includes foraminifera, and foraminifera include coccidioides.
[0009] Preferably, in step S2, the filling components are classified into three categories according to their origin: the terrestrial detrital component is classified as the terrestrial detrital component, the low-energy / chemical carbonate component is classified as the low-energy / chemical carbonate component, and the biological calcium component is classified as the biological calcium component.
[0010] Preferably, in step S3, the initial values of the contents of the three types of components are corrected based on the statistical data of the filling components and the foraminifera filling rate, and the corrected values of the contents of the three types of components are obtained respectively. Then, normalization calculations are performed to obtain the final values of the contents of the terrigenous detrital components, low-energy / chemical carbonate components and biological calcium components respectively.
[0011] Preferably, in step S3, the content correction values of the three types of components are calculated using equations (1)-(3): Corrected value of terrigenous detrital component content = Initial value of terrigenous detrital component content + Initial value of biological calcium component content × Foraminifera infill rate × Statistical data of terrigenous detrital component (1) Corrected value of low-energy / chemical carbonate content = Initial value of low-energy / chemical carbonate content + Initial value of biological calcium content × Foraminifera infill rate × Statistical data of low-energy / chemical carbonate component (2) Corrected value of biological calcium content = Initial value of biological calcium content × (1 - foraminifera infill rate) (3).
[0012] Preferably, in steps S2 and S3, the filling components include glauconite, succinate, clay, calcite crystals, dolomite crystals, mortar, dolomite mud crystals, quartz, and unfilled cavities; wherein glauconite, succinate, clay, and 50% quartz are classified as terrigenous detrital components, calcite crystals, dolomite crystals, mortar, and dolomite mud crystals are classified as low-energy / chemical carbonate components, and cavities are classified as biological calcium components.
[0013] Preferably, in step S4, after projecting the final values of the contents of the three components onto the triangular diagram, the name of the area where the diagram is projected is determined as the basic name of the rock; then, based on the grain size and composition of the rock, the basic name is updated to the final classification name.
[0014] Preferably, in step S4, the basic naming includes a main name and at least one prefix name; The main name is determined by the component with a final content of more than 50% in the rock. If the final content of all three components does not exceed 50%, the main name is mixed sedimentary rock. The prefix name is determined by the component with a final content of 10-50% in the rock. If the basic name includes two prefix names, the prefix name determined by the component with the lower final content is written first.
[0015] Preferably, in step S4, the basic names are clastic rocks, low-energy / chemical carbonate clastic rocks, low-energy / chemical carbonate clastic rocks, biogenic calcareous low-energy / chemical clastic rocks, low-energy / chemical biogenic calcareous clastic rocks, biogenic calcareous clastic rocks, terrigenous low-energy / chemical carbonate rocks, terrigenous low-energy / chemical carbonate rocks, terrigenous biomass low-energy / chemical carbonate rocks, terrigenous-low-energy / chemical mixed rocks, terrigenous-biogenic mixed rocks, low-energy / chemical-biogenic mixed rocks, rocks with no more than 50% mixed sedimentary content, terrigenous biogenic limestone, terrigenous biogenic limestone, terrigenous low-energy / chemical biogenic limestone, microcrystalline / sparkling carbonate rocks, or biogenic grain limestone.
[0016] Preferably, in step S4, if the main name or prefix name is determined by terrigenous clastic components, then the main name or prefix name is updated according to the grain size of the rock; and / or, If the main name is determined by the low-energy / chemical carbonate component, the content of calcite and dolomite in the low-energy / chemical carbonate component is compared, and the main name is updated according to the comparison results.
[0017] The beneficial effects of this invention are: The method for classifying and naming foraminiferous mixed sedimentary rocks of this invention explicitly includes mud components in the low-energy / chemical carbonate components and performs quantitative calculations to help define the influence of geological factors related to the low-energy mud deposition process on the physical properties of rock reservoirs. It introduces the identification of foraminiferous infilling components and the calculation of infill rates, classifying the infilling components into three categories to quantify the influence of the internal structure of biocavities on rock reservoir properties, thereby more accurately assessing the key impact of the degree of biocavity filling on rock reservoir porosity. The content of the three categories of components is plotted and classified using a three-terminal triangulation diagram of "terrigenous clastic-low-energy / chemical carbonate-biological calcareous" structure. This closely integrates the mineralogical classification of rocks with the physical properties of rock reservoirs, thereby achieving a more accurate classification and naming of foraminiferous mixed sedimentary rocks. Attached Figure Description
[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of a method for classifying and naming foraminiferous mixed sedimentary rocks in some embodiments of the present invention; Figure 2This is a triangular diagram with three component categories as endmembers for the classification and naming method of foraminiferal mixed sedimentary rocks in some embodiments of the present invention. Figure 3 a, Figure 3 b、 Figure 3 c. Figure 3 d is a statistical example diagram of the filling composition of the foraminifera of the present invention; Figure 4 a, Figure 4 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 1 of the present invention; Figure 5 a, Figure 5 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 2 of the present invention; Figure 6 a, Figure 6 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 3 of the present invention; Figure 7 a, Figure 7 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 4 of the present invention; Figure 8 a, Figure 8 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 5 of the present invention; Figure 9 a, Figure 9 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 6 of the present invention; Figure 10 a, Figure 10 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 7 of the present invention; Figure 11 a, Figure 11 b is a microscopic observation of the foraminifera mixed sedimentary rock of Example 8 of the present invention; Figure 12 a, Figure 12 b is a microscopic observation of the foraminiferal mixed sedimentary rock of Example 9 of the present invention. Detailed Implementation
[0019] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0020] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.
[0021] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0022] like Figure 1 As shown, the method for classifying and naming foraminiferal mixed sedimentary rocks in some embodiments of the present invention includes the following steps: S1. The rock was identified and its components were classified to obtain the initial values of the contents of three types of components. The three types of components include terrigenous clastic components, low-energy / chemical carbonate components, and biological calcareous components. The low-energy / chemical carbonate components include mud, and the biological calcareous components include foraminifera.
[0023] In step S1, compositional identification includes grain size analysis and rock and mineral identification. Specifically, rock thin sections are analyzed under a microscope using a medium-power objective lens (e.g., 10×, 20×) or a high-power objective lens. Grain size analysis measures the size of clastic particles, classifying them according to the standard SY / T 5368-2016 Rock Thin Section Identification (National Energy Administration, 2016). Clastic particles smaller than 15.6 μm are classified as clay (mud), and particles between 15.6 and 62.5 μm are classified as silt, etc. In rock and mineral identification, staining is used to distinguish the specific components of low-energy / chemical carbonate components.
[0024] The compositional classification divides rocks and minerals into terrigenous clastic components, low-energy / chemical carbonate components, and biogenic calcareous components based on their origin. Authigenic minerals such as glauconite and pyrite are not included in the naming, compositional classification, or content statistics.
[0025] In some embodiments, the terrigenous clastic component includes quartz, feldspar, mica, rock fragments, and argillaceous material; the low-energy / chemical carbonate component includes carbonate spar and carbonate micritic, with the carbonate spar including calcite spar and dolomite spar, and the carbonate micritic including mud (calcite micritic) and dolomite micritic; the biogenic calcareous component includes bioclastic material, which includes biogenic calcareous particles such as foraminifera, and foraminifera including coccidial particles. Since biogenic calcareous particles are mainly coccidial particles in foraminiferal (coccidial) mixed sedimentary rocks, foraminifera can be considered as the biogenic calcareous component. If other biogenic calcareous particles exist besides foraminifera, the biogenic calcareous component includes the cavities of foraminifera and other biogenic calcareous particles.
[0026] S2. Identify, classify and statistically analyze the filling components of foraminifera to obtain statistical data on the filling components and calculate the foraminifera filling rate.
[0027] In step S2, the rock thin sections are observed and analyzed under a microscope. The filling components in the cavity of the foraminifera are identified and classified into three categories according to their origin. The area ratio of the filling components is calculated, and the filling rate of the foraminifera is calculated to quantify the filling status inside the cavity of the foraminifera.
[0028] The infill components classified as terrigenous clastic components are the terrigenous clastic portion; the infill components classified as low-energy / chemical carbonate components are the low-energy / chemical carbonate portion; and the infill components classified as biogenic calcareous components are the biogenic calcareous portion. Authigenic minerals in the infill components, such as pyrite, are not included in the naming or classification process.
[0029] S3. Based on the initial values of the contents of the three types of components, combined with the statistical data of the filling components and the foraminifera filling rate, calculate the final values of the contents of the three types of components.
[0030] In step S3, based on the statistical data of the infill components and the foraminifera infill rate, the initial values of the contents of the three types of components are corrected and calculated to obtain the corrected values of the contents of the three types of components. Then, normalization calculations are performed to obtain the final values of the contents of the terrigenous detrital component, the low-energy / chemical carbonate component, and the biogenic calcium component. The statistical data of the infill components refers to the area proportion of each infill component. The corrected values of the contents of the three types of components are normalized so that the sum of the three is 1, thus obtaining the final values of the contents of the three types of components.
[0031] Preferably, the content correction values of the three types of components are calculated using equations (1)-(3): Corrected value of terrigenous detrital component content = Initial value of terrigenous detrital component content + Initial value of biological calcium component content × Foraminifera infill rate × Statistical data of terrigenous detrital component (1) Corrected value of low-energy / chemical carbonate content = Initial value of low-energy / chemical carbonate content + Initial value of biological calcium content × Foraminifera infill rate × Statistical data of low-energy / chemical carbonate component (2) Corrected value of biological calcium content = Initial value of biological calcium content × (1 - foraminifera infill rate) (3).
[0032] In some embodiments, the filling components include glauconite, succinate, clay, calcite sprue, dolomite sprue, mortar (calcite mud crystals), dolomite mud crystals, quartz, and unfilled cavities. Glauconite, succinate, clay, and 50% quartz are classified as terrigenous detrital components; calcite sprue, dolomite sprue, mortar, and dolomite mud crystals are classified as low-energy / chemical carbonate components; and the cavities are classified as biological calcium components. Figure 3 This is a statistical example of the infill composition of foraminifera observed under a microscope, in which... Figure 3 a, Figure 3b is a microscopic image observed under single-polarization light. Figure 3 c. Figure 3 Figure d shows a cross-polarized light micrograph, where the filling components are exemplarily labeled, including clay, plaster, calcite (Cal), quartz (Qtz), pyrite (Py), and cavities. In actual observation, the various components in the micrograph must be labeled in detail.
[0033] In some embodiments, the mineral composition of the three types of components and the foraminifera filling composition are shown in Table 1.
[0034] Table 1. Mineral composition and foraminiferal infilling components of the three categories. Based on Table 1, it can be understood that in foraminiferal mixed sedimentary rocks, the terrigenous clastic components actually include the quartz, feldspar, mica and rock fragments, and argillaceous material identified in step S1, as well as the glauconite, succinate, clay, and 50% quartz in the foraminiferal filling components identified in step S2. The low-energy / chemical carbonate components actually include the carbonate sprues and carbonate micrites identified in step S1, as well as the dolomite sprues, calcite sprues, dolomite micrites, and mudstone in the foraminiferal filling components identified in step S2. The biogenic calcareous components are the unfilled cavities in the foraminifera.
[0035] S4. Based on the final values of the contents of the three types of components in step S3, the final classification and naming of the rock is determined using a pre-established triangular diagram with the three types of components as end members.
[0036] Among them, a three-endmember triangular diagram is pre-established with the content of terrigenous detrital components, low-energy / chemical carbonate components, and biological calcium components as endmembers, such as... Figure 2 As shown.
[0037] In step S4, after projecting the final values of the three component contents onto a three-terminal triangulation diagram, the name of the region where the diagram is located is determined as the basic name of the rock; then, based on the grain size and composition of the rock, the basic name is updated to the final classification name. The basic name includes a main name and at least one prefix name, with the prefix name preceding the main name.
[0038] The primary name is determined by the component with a final content exceeding 50% in the rock. Specifically, if the final content of terrigenous clastic components exceeds 50%, the primary name of the rock is clastic rock. If the final content of low-energy / chemical carbonate components exceeds 50%, the primary name of the rock is carbonate rock; if the final content of low-energy / chemical carbonate components exceeds 45% and the final content of terrigenous clastic components is less than 10%, the primary name of the rock is microcrystalline / spargeous carbonate rock. If the final content of biogenic calcareous components exceeds 50%, the primary name of the rock is biogenic limestone; if the final content of biogenic calcareous components exceeds 45% and the final content of terrigenous clastic components is less than 10%, the primary name of the rock is biogenic grain limestone.
[0039] The prefix name is determined by the component with a final content of 10-50% in the rock. Specifically, if the final content of a certain component is 10-25%, the prefix name is determined by the content of that component. For example, "contains terrestrial debris," "contains biological calcium," or "contains low-energy / chemical substances." If the final content of a certain component is 25-50%, the prefix name is... Substances, such as "terrestrial sediments," "low-energy / chemical sediments," and "biomass." If the basic nomenclature includes two prefixes, the prefix determined by the component with the lower final content value is written first.
[0040] If the final content of all three components does not exceed 50%, the rock is primarily named a mixed sedimentary rock. When the primary name is mixed sedimentary rock, if the final content of both the first and second components is 25-50%, the rock's prefix is determined by the first and second components, and the prefix can be "continental debris-low energy / chemical," "continental debris-biological," or "low energy / chemical-biological." If the final content of all three components is 25-50%, the rock is basically named a mixed sedimentary rock with no component exceeding 50%.
[0041] In step S4, the basic names are clastic rocks, low-energy / chemical carbonate clastic rocks, low-energy / chemical carbonate clastic rocks, biogenic calcareous low-energy / chemical clastic rocks, low-energy / chemical biogenic calcareous clastic rocks, biogenic calcareous clastic rocks, terrigenous low-energy / chemical carbonate rocks, terrigenous low-energy / chemical carbonate rocks, terrigenous biomass low-energy / chemical carbonate rocks, terrigenous-low-energy / chemical mixed rocks, terrigenous-biogenic mixed rocks, low-energy / chemical-biogenic mixed rocks, rocks with less than 50% mixed sedimentary content, terrigenous biogenic limestone, terrigenous biogenic limestone, terrigenous low-energy / chemical biogenic limestone, microcrystalline / sparkling carbonate rocks, or biogenic grain limestone.
[0042] like Figure 2As shown, the basic classification of rocks includes seven categories: clastic rocks with a terrigenous clastic component content of more than 75% (Category A), clastic rocks with a terrigenous clastic component content of 50-75% (Category B), low-energy / chemical carbonate rocks (Category C), mixed sedimentary rocks (Category D), biogenic limestone (Category E), microcrystalline / sparkling carbonate rocks (Category F), and biogenic grain limestone (Category G).
[0043] Category B includes five subcategories: low-energy / chemical carbonate clastic rocks (B1), low-energy / chemical carbonate clastic rocks (B2), low-energy / chemical clastic rocks with biogenic calcareous inclusions (B3), low-energy / chemical clastic rocks with biogenic calcareous inclusions (B4), and biogenic calcareous clastic rocks (B5). Category C includes three subcategories: terrigenous low-energy / chemical carbonate rocks (C1), terrigenous low-energy / chemical carbonate rocks (C2), and terrigenous biomass low-energy / chemical carbonate rocks (C3). Category D includes four subcategories: terrigenous-low-energy / chemical mixed sedimentary rocks (D1), terrigenous-biogenic mixed sedimentary rocks (D2), low-energy / chemical-biogenic mixed sedimentary rocks (D3), and rocks with less than 50% mixed sedimentary content (D4). Category E includes three subcategories: terrigenous biogenic limestone (Category E1), terrigenous biogenic limestone (Category E2), and terrigenous low-energy / chemical biogenic limestone (Category E3).
[0044] Specifically, the content ranges of the three categories of components with the above-mentioned 18 basic names are as follows: The composition and percentage of clastic rocks (Type A) are as follows: terrigenous clastic components >75%, low-energy / chemical carbonate components <25%, and biogenic calcareous components <25%.
[0045] The composition and percentage content of low-energy / chemical carbonate clastic rocks (Type B1) are as follows: terrigenous clastic component 50-75%, low-energy / chemical carbonate component 25-50%, and biogenic calcareous component <25%.
[0046] The composition and percentage of low-energy / chemical carbonate clastic rocks (Type B2) are as follows: terrigenous clastic component 60-75%, low-energy / chemical carbonate component 15-25%, and biogenic calcareous component <15%.
[0047] The components and percentages of biogenic calcareous low-energy / chemical clastic rocks (Type B3) are as follows: terrigenous clastic components 50-70%, low-energy / chemical carbonate components 15-25%, and biogenic calcareous components 15-25%, with the content of biogenic calcareous components being lower than that of low-energy / chemical carbonate components.
[0048] The composition and percentage of low-energy / chemical biogenic calcareous clastic rocks (Type B4) are as follows: terrigenous clastic component 60-75%, low-energy / chemical carbonate component <15%, and biogenic calcareous component 15-25%.
[0049] The composition and percentage content of biogenic calcareous clastic rocks (B5 type) are as follows: terrigenous clastic component 50-75%, low-energy / chemical carbonate component <25%, and biogenic calcareous component 25-50%.
[0050] The composition and percentage content of terrigenous low-energy / chemical carbonate rocks (C1 type) are as follows: terrigenous clastic component 25-50%, low-energy / chemical carbonate component 50-75%, and biogenic calcareous component <25%.
[0051] The composition and percentage of terrigenous low-energy / chemical carbonate rocks (C2 type) are as follows: terrigenous clastic component 10-25%, low-energy / chemical carbonate component 50-90%, and biogenic calcareous component <25%.
[0052] The composition and percentage of terrigenous biomass-bearing low-energy / chemical carbonate rocks (C3 type) are as follows: terrigenous clastic component 10-25%, low-energy / chemical carbonate component 50-65%, and biogenic calcareous component 25-40%.
[0053] The composition and percentage of terrigenous-low-energy / chemical mixed sedimentary rocks (D1 type) are as follows: terrigenous clastic component 25-50%, low-energy / chemical carbonate component 25-50%, and biogenic calcareous component < 25%.
[0054] The composition and percentage of terrigenous-biogenic mixed sedimentary rocks (D2 type) are as follows: terrigenous clastic component 25-50%, low-energy / chemical carbonate component < 25%, and biogenic calcareous component 25-50%.
[0055] The composition and percentage content of low-energy / chemical-biological mixed sedimentary rocks (D3 type) are as follows: terrigenous clastic component 10-25%, low-energy / chemical carbonate component 25-50%, and biological calcareous component 25-50%.
[0056] The components and their percentage contents of mixed sedimentary rocks (D4 type) that do not exceed 50% are as follows: terrigenous clastic components 25-50%, low-energy / chemical carbonate components 25-50%, and biogenic calcareous components 25-50%.
[0057] The composition and percentage of terrigenous biogenic limestone (E1 type) are as follows: terrigenous clastic components account for 25-50%, low-energy / chemical carbonate components account for <25%, and biogenic calcareous components account for 50-75%.
[0058] The composition and percentage of terrigenous biogenic limestone (E2 type) are as follows: terrigenous clastic component 10-25%, low-energy / chemical carbonate component <25%, and biogenic calcareous component 50-90%.
[0059] The composition and percentage of terrigenous low-energy / chemical biogenic limestone (E3 type) are as follows: terrigenous clastic component 10-25%, low-energy / chemical carbonate component 25-40%, and biogenic calcareous component 50-65%.
[0060] The composition and percentage content of microcrystalline / sparkling carbonate rocks (Type F) are as follows: terrigenous clastic components <10%, low-energy / chemical carbonate components >45%, and biogenic calcareous components <45%.
[0061] The composition and percentage content of biogenic granular limestone (Type G) are as follows: terrigenous clastic components <10%, low-energy / chemical carbonate components <50%, and biogenic calcareous components >45%.
[0062] Furthermore, if the main name or prefix is determined by terrigenous clastic components, the main name or prefix is updated accordingly based on the grain size of the rock. For example, if the main name is "clastic rock" and the rock grain size is classified as silt, the main name is updated to "siltstone"; if the prefix is "terrigenous material" and the rock grain size is classified as silt, the prefix is updated to "silty material".
[0063] If the main name is determined by the low-energy / chemical carbonate component, the content of calcite and dolomite in the low-energy / chemical carbonate component is compared, and the main name is updated according to the comparison results. Specifically, if the content of calcite is much higher than that of dolomite, the main name is updated to "limestone"; if the content of calcite is much lower than that of dolomite, the main name is updated to "dolomite"; if the content of calcite and dolomite is similar, the main name remains unchanged.
[0064] If the prefix name is determined by the low-energy / chemical carbonate component, the content of carbonate mud crystals and carbonate crystalline crystals in the low-energy / chemical carbonate component is compared, and the prefix name is updated according to the comparison result. Specifically, if the content of carbonate mud crystals is higher than the content of carbonate crystalline crystals, the "low-energy / chemical" field in the prefix name is updated to the "mud crystals" field; if the content of carbonate mud crystals is lower than the content of carbonate crystalline crystals, the "low-energy / chemical" field in the prefix name is updated to the "crystalline crystals" field.
[0065] When the final value of the content of terrigenous clastic components exceeds 75%, the area where the map is located is named clastic rock, that is, the basic name of the rock is clastic rock. If the final value of the content of biological calcareous components and / or low-energy / chemical carbonate components exceeds 10%, according to the naming rules of the aforementioned prefix name, biological calcareous components and / or low-energy / chemical carbonate components can participate in the naming.
[0066] The existing three-end-member (terrigenous clastic, biogenic carbonate, and chemically precipitated carbonate) classification and nomenclature system has two main limitations: First, the chemically precipitated carbonate end-member does not fully cover the mud components formed in low-energy environments, which makes it impossible to accurately reflect its negative impact on reservoir properties in study areas with a large proportion of mud (such as the Bohai Sea); Second, it does not consider the internal filling of biogenic calcareous cavities, making it difficult to quantify the control effect of biogenic particle cavity structure on porosity.
[0067] To address the aforementioned technical challenges, this invention employs the following measures: (1) It refines the academic definition of carbonate end-members, explicitly including low-energy mud components within the "low-energy / chemical carbonate" end-member, to assist in defining the impact of geological factors related to the low-energy mud deposition process on reservoir physical properties; (2) It expands the classification detail of biogenic end-members, introducing biocavity filling component characteristics as key microstructural parameters, specifically introducing the identification of foraminifera filling components and filling rate calculation, to quantify the impact of the internal structure of biocavities on reservoir physical properties, and to help establish a more accurate reservoir physical property prediction model. Through these improvements, this invention can provide more reliable technical support for the evaluation of complex carbonate-clastic mixed sedimentary reservoirs.
[0068] Compared with existing naming systems, this invention has the following significant advantages and positive effects: First, the end-member classification has been improved and is more consistent with actual geological conditions. Addressing the issue that existing nomenclature systems do not adequately cover low-energy mudstone components in the definition of chemically formed carbonate end-members, this invention explicitly includes low-energy mudstone components in the "low-energy / chemical carbonate" end-member and performs quantitative calculations. This solves the problem that low-energy mudstone components, which constitute a large proportion in the coccidioidomytic sedimentary rocks of the study area, cannot be accurately reflected in the classification, thus making the classification and nomenclature more accurately reflect the rock composition.
[0069] Secondly, it improves the accuracy of reservoir property evaluation. Addressing the issue that existing nomenclature systems neglect the impact of biological calcareous cavity filling on properties, this invention innovatively introduces the identification of foraminiferal filling components and the calculation of filling rates, assigning filling components to corresponding endmembers based on their origin. This allows the classification method to effectively distinguish the degree of filling of biological cavities, thereby more accurately assessing their key impact on reservoir porosity and providing a more reliable basis for predicting reservoir quality in coccidial mixed sedimentary rocks.
[0070] The classification and naming method for foraminifera mixed sedimentary rocks based on the content of three end-member components provided by this invention overcomes the shortcomings of existing classification systems in describing low-energy components and the internal structure of biological cavities by optimizing the definition of end-members and introducing microstructural parameters. This makes the correspondence between lithological naming and reservoir quality evaluation of coccidioidal mixed sedimentary rocks and other similar mixed sedimentary rocks more scientific, direct and reliable, providing more effective technical support for the exploration and development of such complex reservoirs.
[0071] The key to this invention lies in emphasizing the characteristics of the internal filling of biogenic calcareous deposits, classifying the filling components within the cavities of biogenic calcareous particles according to their origin, thus making the statistical analysis of mineral composition more accurate in terms of genetic origin. The final determined "terrigenous clastic-low-energy / chemical carbonate-biogenic calcareous" three-end-member naming system can directly represent the reservoir spatial relationship of "clastic-cementation-porosity" in production. This closely integrates the mineralogical classification of rocks with the physical properties of reservoirs, providing a more direct and reliable lithological basis for the accurate prediction of reservoir quality. The classification and naming method of this invention is a complete and quantifiable process, including the identification and statistical analysis of foraminiferal filling components, dynamic correction calculation of end-members based on foraminiferal filling rates, and a three-end-member triangular diagram mapping and naming method.
[0072] The following is an illustration through specific examples: Example 1 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2924.98 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 4 As shown, where Figure 4 a is a microscopic image observed under single-polarized light. Figure 4 b is a microscopic observation image under crossed polarized light. Statistical data on the three rock components and foraminiferal infilling components (steps S1 and S2) are shown in Table 2.
[0073] Table 2 Statistical data of rock composition in Example 1 according to Figure 4 It is evident that the rock contains abundant foraminiferal fossils, and no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily foraminiferal. Based on Table 2, the initial values for the terrigenous detrital component are 61%, the low-energy / chemical carbonate component is 11%, and the biogenic calcium component is 24%. After correction calculations in step S3, the initial values for the contents of the terrigenous detrital component, low-energy / chemical carbonate component, and biogenic calcium component are 69.56%, 11.88%, and 10.33%, respectively. After normalization calculations, the final values for the contents of the three components are 75.79%, 12.95%, and 11.26%, respectively.
[0074] The final values of the three components meet the following criteria: terrigenous clastic component content >75%, low-energy / chemical carbonate component content <25%, and biogenic calcareous component content <25%. The resulting triangulation of the three-terminal element is clastic rock. According to the naming rules in step S4, since the final values of both the low-energy / chemical carbonate and biogenic calcareous components are greater than 10%, and the final value of the biogenic calcareous component is lower, the basic name of the rock is biogenic calcareous low-energy / chemical carbonate clastic rock. Because the biogenic calcareous component in the rock is mainly composed of foraminifera, and the micritic content in the low-energy / chemical carbonate component is much higher than the spar content, and based on the rock clastic grain size, it is classified as silty mudstone. Therefore, the final classification of the depth rock in this embodiment is foraminifera-bearing micritic silty mudstone.
[0075] Example 2 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2925.04 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 5 As shown, where Figure 5 a is a microscopic image observed under single-polarized light. Figure 5 b is a microscopic observation image under crossed polarized light. Statistical data on the three components of the rock and the foraminiferal infilling components (steps S1 and S2) are shown in Table 3.
[0076] Table 3 Statistical data of rock composition in Example 2 according to Figure 5 The rock contains abundant foraminiferal fossils, but no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily foraminiferal. Based on Table 3, the initial values for the terrigenous detrital component are 53%, the low-energy / chemical carbonate component is 8%, and the biogenic calcium component is 34%. After correction calculations in step S3, the initial values for the contents of the terrigenous detrital component, low-energy / chemical carbonate component, and biogenic calcium component are 62.54%, 9.75%, and 17%, respectively. After normalization, the final values for the contents of the three components are 70.04%, 10.92%, and 19.04%, respectively.
[0077] The final values of the three components' contents conform to the following: terrigenous clastic components have a final content of 50-75%, low-energy / chemical carbonate components have a final content of <15%, and biogenic calcareous components have a final content of 15-25%. The projection result of the three-terminal triangulation diagram is low-energy / chemical carbonate-bearing biogenic calcareous clastic rock. According to the naming rules in step S4, since the final contents of both low-energy / chemical carbonate and biogenic calcareous components are greater than 10% and less than 25%, and the final content of low-energy / chemical carbonate is even lower, the basic name of the rock is low-energy / chemical carbonate-bearing biogenic calcareous clastic rock. Since the biogenic calcareous components in the rock are mainly foraminifera, and the micritic content in the low-energy / chemical carbonate components is much higher than the spar content, and based on the rock clastic grain size, it is classified as silty mudstone. Therefore, the final classification of the depth rock in this embodiment is micritic-bearing, foraminifera-bearing, silty mudstone.
[0078] Example 3 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2925.66 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 6 As shown, where Figure 6 a is a microscopic image observed under single-polarized light. Figure 6 b is a microscopic observation image under crossed polarized light. Statistical data on the three rock components and foraminiferal infilling components (steps S1 and S2) are shown in Table 4.
[0079] Table 4. Statistical data on rock composition in Example 3 according to Figure 6 It is evident that the rock contains abundant foraminiferal fossils, and no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily composed of foraminifera. Based on Table 4, the initial values for the terrigenous detrital component are 14%, the low-energy / chemical carbonate component is 41%, and the biogenic calcium component is 42%. After correction calculations in step S3, the initial values for the contents of the terrigenous detrital component, low-energy / chemical carbonate component, and biogenic calcium component are 17.06%, 77.15%, and 1.79%, respectively. After normalization calculations, the final values for the contents of the three components are 17.77%, 80.36%, and 1.86%, respectively.
[0080] The final values of the three components are consistent with the following: terrigenous clastic components have a final content of 10-25%, low-energy / chemical carbonate components have a final content of 50-90%, and biogenic calcareous components have a final content of <25%. The resulting triangulation of the three-terminal element indicates a terrigenous low-energy / chemical carbonate rock. According to the naming rules in step S4, since the biogenic calcareous component has a final content of less than 10%, it is not included in the naming. The terrigenous clastic components have a final content of 10-25%, so the basic name of the rock is terrigenous low-energy / chemical carbonate rock. Because the micritic content in the low-energy / chemical carbonate component is much lower than the spar crystal content, and the calcite content is much higher than the dolomite content, the final classification of the deep rock in this embodiment is terrigenous spar limestone.
[0081] Example 4 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2925.95m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 7 As shown, where Figure 7 a is a microscopic image observed under single-polarized light. Figure 7 b is a microscopic observation image under crossed polarized light. Statistical data on the three components of the rock and the foraminiferal infilling components (steps S1 and S2) are shown in Table 5.
[0082] Table 5. Statistical data on rock composition in Example 4 according to Figure 7 It is evident that the rock contains abundant foraminiferal fossils, and no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily foraminiferal. Based on Table 5, the initial values for the terrigenous clastic component are 46%, the low-energy / chemical carbonate component is 6%, and the biogenic calcium component is 43%. After correction calculations in step S3, the initial values for the contents of the terrigenous clastic component, low-energy / chemical carbonate component, and biogenic calcium component are 54.88%, 6.88%, and 29.79%, respectively. After normalization calculations, the final values for the contents of the three components are 59.95%, 7.51%, and 32.54%, respectively.
[0083] The final values of the three components meet the following criteria: terrigenous clastic components have a final content of 50-75%, low-energy / chemical carbonate components have a final content of <25%, and biogenic calcareous components have a final content of 25-50%. The resulting triangulation of the three-terminal element indicates biogenic calcareous clastic rock. According to the naming rules in step S4, since the final content of low-energy / chemical carbonate components is less than 10%, they are not included in the naming. The final content of biogenic calcareous components is 25-50%, therefore the basic name of the rock is biogenic calcareous clastic rock. Because the biogenic calcareous components in the rock are mainly foraminifera, and based on the rock fragment grain size, it is classified as silty mudstone. Therefore, the final classification of the depth rock in this embodiment is foraminiferous silty mudstone.
[0084] Example 5 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2929.26 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 8 As shown, where Figure 8 a is a microscopic image observed under single-polarized light. Figure 8 b is a microscopic observation image under crossed polarized light. Statistical data on the three components of the rock and the foraminiferal infilling components (steps S1 and S2) are shown in Table 6.
[0085] Table 6. Statistical data on rock composition of Example 5 according to Figure 8 It is evident that the rock contains abundant foraminiferal fossils, and no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily foraminiferal. Based on Table 6, the initial values for the terrigenous clastic component are 50%, the low-energy / chemical carbonate component is 17%, and the biogenic calcium component is 28%. After correction calculations in step S3, the initial values for the contents of the terrigenous clastic component, low-energy / chemical carbonate component, and biogenic calcium component are 53.58%, 19.79%, and 18.04%, respectively. After normalization calculations, the final values for the contents of the three components are 58.62%, 21.65%, and 19.73%, respectively.
[0086] The final values of the three components are consistent with the following: terrigenous clastic components have a final content of 50-75%, low-energy / chemical carbonate components have a final content of 15-25%, and biogenic calcareous components have a final content of 15-25%. Furthermore, the final content of biogenic calcareous components is lower than that of low-energy / chemical carbonate components. The resulting triangulation of the three-terminal element diagram indicates a biogenic calcareous low-energy / chemical clastic rock. According to the naming rules in step S4, since the final contents of both low-energy / chemical carbonate and biogenic calcareous components are greater than 10% and less than 25%, and the final content of biogenic calcareous components is lower, the basic name of the rock is biogenic calcareous low-energy / chemical clastic rock. Because the biogenic calcareous components in the rock are mainly foraminifera, and the content of micritic crystals in the low-energy / chemical carbonate components is much higher than that of spar crystals, and based on the rock fragment grain size, it is classified as silty mudstone. Therefore, the final classification of the deep rock in this embodiment is foraminifera-bearing micritic silty mudstone.
[0087] Example 6 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2926.43 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 9 As shown, where Figure 9 a is a microscopic image observed under single-polarized light. Figure 9 b is a microscopic observation image under crossed polarized light. Statistical data on the three rock components and foraminiferal infilling components (steps S1 and S2) are shown in Table 7.
[0088] Table 7 Statistical data of rock composition in Example 6 according to Figure 9 The rock contains abundant foraminiferal fossils, but no other biogenic calcium deposits were observed. Based on Table 6, the initial values for the terrigenous detrital component are 65%, the low-energy / chemical carbonate component is 21%, and the biogenic calcium component is 9%. After correction calculations in step S3, the initial values for the contents of the terrigenous detrital component, low-energy / chemical carbonate component, and biogenic calcium component are 67.52%, 24.78%, and 0.69%, respectively. After normalization, the final values for the contents of the three components are 72.62%, 26.65%, and 0.74%, respectively.
[0089] The final values of the three components conform to the following: terrigenous clastic components have a final content of 50-75%, low-energy / chemical carbonate components have a final content of 25-50%, and biogenic calcareous components have a final content of <25%. The resulting triangulation of the three-terminal element is low-energy / chemical carbonate clastic rock. According to the naming rules in step S4, since the final content of biogenic calcareous components is less than 10% and the final content of low-energy / chemical carbonate components is 25-50%, the basic name of the rock is low-energy / chemical carbonate clastic rock. Because the micritic content in the low-energy / chemical carbonate components is much higher than the spar crystal content, and based on the rock fragment grain size, it is classified as silty mudstone. Therefore, the final classification of the depth rock in this embodiment is micritic silty mudstone.
[0090] Example 7 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2924.95m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 10 As shown, where Figure 10 a is a microscopic image observed under single-polarized light. Figure 10 b is a microscopic observation image under crossed polarized light. Statistical data on the three components of the rock and the foraminiferal infilling components (steps S1 and S2) are shown in Table 8.
[0091] Table 8. Statistical data on rock composition in Example 7 according to Figure 10 The rock contains abundant foraminiferal fossils, but no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily foraminiferal. Based on Table 8, the initial values for the terrigenous clastic component are 56%, the low-energy / chemical carbonate component is 13%, and the biogenic calcium component is 25%. After correction calculations in step S3, the initial values for the contents of the terrigenous clastic component, low-energy / chemical carbonate component, and biogenic calcium component are 63.69%, 13.94%, and 12.99%, respectively. After normalization, the final values for the contents of the three components are 70.28%, 15.38%, and 14.34%, respectively.
[0092] The final values of the three components are consistent with the following: terrigenous clastic components have a final content of 50-75%, low-energy / chemical carbonate components have a final content of 15-25%, and biogenic calcareous components have a final content of <15%. The resulting triangulation of the three-terminal element indicates a low-energy / chemical carbonate-bearing clastic rock. According to the naming rules in step S4, since the biogenic calcareous component has a final content exceeding 10%, it is included in the naming process. The low-energy / chemical carbonate component has a final content of 15-25%, so the basic name of the rock is biogenic calcareous low-energy / chemical carbonate clastic rock. Because the biogenic calcareous component in the rock is mainly composed of foraminifera, and the micritic content in the low-energy / chemical carbonate component is much higher than the spar content, and based on the rock clastic grain size, it is classified as argillaceous siltstone. Therefore, the final classification of the deep rock in this embodiment is foraminifera-bearing micritic argillaceous siltstone.
[0093] Example 8 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2927.14 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 11 As shown, where Figure 11 a is a microscopic image observed under single-polarized light. Figure 11 b is a microscopic observation image under crossed polarized light. Statistical data on the three components of the rock and the foraminiferal infilling components (steps S1 and S2) are shown in Table 9.
[0094] Table 9. Rock composition statistics for Example 8 according to Figure 11 It is evident that the rock contains abundant foraminiferal fossils, and no other biogenic calcium was observed, indicating that the biogenic calcium component is primarily composed of foraminifera. Based on Table 9, the initial values for the terrigenous detrital component are 32%, the low-energy / chemical carbonate component is 22%, and the biogenic calcium component is 40%. After correction calculations in step S3, the initial values for the contents of the terrigenous detrital component, low-energy / chemical carbonate component, and biogenic calcium component are 33.39%, 27.36%, and 32.66%, respectively. After normalization calculations, the final values for the contents of the three components are 35.75%, 29.29%, and 34.96%, respectively.
[0095] The final values of the three components are consistent with the final values of terrigenous clastic components (25-50%), low-energy / chemical carbonate components (25-50%), and biogenic calcareous components (25-50%). The projection results of the three-end-member triangulation diagram show that none of these components exceed 50% in the mixed sedimentary rock. According to the naming rules in step S4, since the final values of the three components are all greater than 10% and less than 25%, all three components can participate in the naming. Therefore, the basic naming of the rock can be terrigenous low-energy / chemical biogenic calcareous mixed sedimentary rock. Since the biogenic calcareous component in the rock is mainly foraminifera, and the micritic content in the low-energy / chemical carbonate component is much lower than the spar content, and based on the rock clastic grain size, it is classified as silty mudstone. Therefore, the final classification of the depth rock in this embodiment is silty mudstone with spar and foraminifera.
[0096] Example 9 The foraminiferous mixed sedimentary rocks of this invention were classified and named at a depth of 2927.96 m in the study well using the classification and naming method of this invention. Microscopic images of the rocks in this embodiment are shown below. Figure 12 As shown, where Figure 12 a is a microscopic image observed under single-polarized light. Figure 12 b is a microscopic observation image under crossed polarized light. Statistical data on the three rock components and foraminiferal infilling components (steps S1 and S2) are shown in Table 10.
[0097] Table 10 Statistical data on rock composition of Example 9 according to Figure 12 The rock contains abundant foraminiferal fossils, but no other biogenic calcium deposits were observed. Based on Table 10, the initial values for the terrigenous clastic component were 28%, the low-energy / chemical carbonate component was 6%, and the biogenic calcium component was 60%. After correction calculations in step S3, the initial values for the contents of the terrigenous clastic component, low-energy / chemical carbonate component, and biogenic calcium component were 29.77%, 62.72%, and 0.8%, respectively. After normalization calculations, the final values for the contents of the three components were 31.93%, 67.27%, and 0.80%, respectively.
[0098] The final values of the three components are consistent with the following: terrigenous clastic components have a final content of 25-50%, low-energy / chemical carbonate components have a final content of 50-75%, and biogenic calcareous components have a final content of <25%. The resulting triangulation of the three-terminal element indicates a terrigenous low-energy / chemical carbonate rock. According to the naming rules in step S4, since the biogenic calcareous component has a final content of less than 10%, it is not included in the naming. The terrigenous clastic components have a final content of 25-50%, so the basic name of the rock is terrigenous low-energy / chemical carbonate rock. Because the micritic content in the low-energy / chemical carbonate component is much lower than the spar content, and the calcite content is much higher than the dolomite content, and based on the rock fragment grain size, it is classified as silty mudstone. Therefore, the final classification of the deep rock in this embodiment is silty mudstone sparry limestone.
[0099] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.
Claims
1. A method for classifying and naming foraminiferal mixed sedimentary rocks, characterized in that, Includes the following steps: S1. The rock is identified and its components are classified to obtain the initial values of the contents of three types of components, namely, terrigenous clastic components, low-energy / chemical carbonate components, and biological calcareous components; the low-energy / chemical carbonate components include mud, and the biological calcareous components include foraminifera. S2. Identify, classify and statistically analyze the filling components of the foraminifera to obtain statistical data on the filling components and calculate the foraminifera filling rate. S3. Based on the initial values of the contents of the three types of components, combined with the statistical data of the filling components and the foraminifera filling rate, calculate the final values of the contents of the three types of components. S4. Based on the final content values of the three types of components, the final classification and naming of the rock is determined using a pre-established triangular diagram with the three types of components as end members.
2. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 1, characterized in that, In step S1, the component identification includes grain size analysis and rock and mineral identification; the component classification is to classify the rock and minerals according to their genesis into the terrigenous clastic component, the low-energy / chemical carbonate component, and the biological calcium component. The terrigenous clastic components include quartz, feldspar, mica, rock fragments, and argillaceous material; the low-energy / chemical carbonate components include carbonate shards and carbonate mud crystals, the carbonate shards include calcite shards and dolomite shards, and the carbonate mud crystals include mud and dolomite mud crystals; the biogenic calcareous components include bioclastic material, the bioclastic material includes foraminifera, and the foraminifera include coccidioides.
3. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 1, characterized in that, In step S2, the filling components are classified into the three categories according to their origin. The filling components classified as terrestrial detrital components are the terrestrial detrital portion, the filling components classified as low-energy / chemical carbonate components are the low-energy / chemical carbonate portion, and the filling components classified as biological calcium components are the biological calcium portion.
4. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 3, characterized in that, In step S3, based on the statistical data of the filling components and the foraminifera filling rate, the initial values of the contents of the three types of components are corrected and calculated to obtain the corrected values of the contents of the three types of components respectively. Then, normalization calculations are performed to obtain the final values of the contents of the terrigenous detrital component, the low-energy / chemical carbonate component, and the biological calcium component respectively.
5. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 4, characterized in that, In step S3, the content correction values of the three types of components are calculated using equations (1)-(3): Corrected value of terrigenous detrital component content = Initial value of terrigenous detrital component content + Initial value of biological calcium component content × Foraminifera infill rate × Statistical data of terrigenous detrital component (1) Corrected value of low-energy / chemical carbonate content = Initial value of low-energy / chemical carbonate content + Initial value of biological calcium content × Foraminifera infill rate × Statistical data of low-energy / chemical carbonate component (2) Corrected value of biological calcium content = Initial value of biological calcium content × (1 - foraminifera infill rate) (3).
6. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 3, characterized in that, In steps S2 and S3, the filling components include glauconite, slate, clay, calcite crystals, dolomite crystals, mortar, dolomite mud crystals, quartz, and unfilled cavities; wherein glauconite, slate, clay, and 50% quartz are classified as the terrigenous detrital components, calcite crystals, dolomite crystals, mortar, and dolomite mud crystals are classified as the low-energy / chemical carbonate components, and the cavities are classified as the biological calcium components.
7. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 1, characterized in that, In step S4, after projecting the final values of the contents of the three types of components onto the triangular diagram, the name of the area where the projection is located is determined as the basic name of the rock; then, based on the grain size and composition of the rock, the basic name is updated to the final classification name.
8. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 7, characterized in that, In step S4, the basic naming includes a main name and at least one prefix name; The main name is determined by the component with a final content of more than 50% in the rock. If the final content of the three types of components does not exceed 50%, the main name is mixed sedimentary rock. The prefix name is determined by the component with a final content of 10-50% in the rock. If the basic name includes two prefix names, the prefix name determined by the component with the lower final content is written first.
9. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 7, characterized in that, In step S4, the basic names are clastic rocks, low-energy / chemical carbonate clastic rocks, low-energy / chemical carbonate clastic rocks, biogenic calcareous low-energy / chemical clastic rocks, low-energy / chemical biogenic calcareous clastic rocks, biogenic calcareous clastic rocks, terrigenous low-energy / chemical carbonate rocks, terrigenous low-energy / chemical carbonate rocks, terrigenous biomass low-energy / chemical carbonate rocks, terrigenous-low-energy / chemical mixed rocks, terrigenous-biogenic mixed rocks, low-energy / chemical-biogenic mixed rocks, rocks with less than 50% mixed sedimentary content, terrigenous biogenic limestone, terrigenous biogenic limestone, terrigenous low-energy / chemical biogenic limestone, microcrystalline / sparkling carbonate rocks, or biogenic grain limestone.
10. The method for classifying and naming foraminiferal mixed sedimentary rocks according to claim 8, characterized in that, In step S4, if the main name or the prefix name is determined by the terrigenous clastic component, then the main name or the prefix name is updated according to the grain size of the rock. And / or, If the main name is determined by the low-energy / chemical carbonate component, the contents of calcite and dolomite in the low-energy / chemical carbonate component are compared, and the main name is updated according to the comparison results.