Method and device for judging carbonate rock sedimentary landform by using carbon isotope

Abstract

The invention discloses a method and a device for judging the sedimentary landform of carbonate rocks by using carbon isotopes. The method comprises the following steps: selecting a carbonate rock sample; preparing carbonate rock sample slices and carbonate rock powder samples from the carbonate rock samples; carrying out slice identification and analysis on the carbonate rock sample slices to obtain corresponding carbonate rock deposition characteristics of each sample slice; performing carbon and oxygen isotope test on the carbonate rock powder sample to obtain carbon and oxygen isotope test data; determining a first characteristic of the carbonate rock sedimentary ancient landform by using carbon and oxygen isotope test data; and determining carbonate sedimentary landform features of the target area according to the carbonate sedimentary features and the first features of the carbonate sedimentary ancient landform.

Description

Technical Field

[0001] This article relates to the field of geological exploration technology, and in particular to a method and apparatus for determining the sedimentary landforms of carbonate rocks using carbon isotopes. Background Technology

[0002] Paleogeography of carbonate rocks is of multifaceted importance for oil and gas exploration. This is mainly reflected in the following aspects: ① Controlling the distribution of sedimentary facies zones: Paleogeography influences the sedimentary environment of carbonate rocks, with different geomorphic locations forming different types of sedimentary facies zones. For example, reef-shoal facies deposits may develop at the edge of a platform, which is often a favorable area for the formation of high-quality reservoirs. In other words, by studying paleogeography, the distribution range of some favorable reservoirs controlled by high geomorphic facies can be indirectly predicted. ② Influencing reservoir development: The undulation of paleogeography in carbonate rocks leads to varying degrees of exposure of carbonate rocks, thus affecting the development of pores and fractures. For example, in high parts or slopes of paleogeography, dissolution, weathering, and erosion may form more pores, caves, and fractures, thereby improving reservoir properties and providing good storage space for oil and gas. That is, by studying paleogeography, the distribution area of ​​exposed karst reservoirs can be directly identified. ③ Forming oil and gas traps: Certain features of paleogeography can constitute oil and gas traps. Ancient uplifts and slopes, for example, can form structural or stratigraphic traps, which are conducive to the accumulation and preservation of oil and gas. In conclusion, the identification and prediction of carbonate sedimentary paleogeography is crucial.

[0003] Therefore, how to develop an accurate method for determining carbonate sedimentary landforms using carbon isotopes is an urgent problem to be solved. Summary of the Invention

[0004] This application provides a method and apparatus for determining carbonate sedimentary landforms using carbon isotopes. This method utilizes carbon isotope δ¹³C‰ (VPDB) analysis data combined with microscopic thin section identification results to quickly and efficiently determine paleogeomorphisms, improve the efficiency and accuracy of identifying landforms during carbonate sedimentary periods, and provide a theoretical basis for the distribution patterns of carbonate sedimentary landforms.

[0005] In a first aspect, this application provides a method for determining carbonate sedimentary landforms using carbon isotopes. The method includes: selecting carbonate rock samples; preparing carbonate rock sample thin sections and carbonate rock samples using the carbonate rock samples; performing thin section identification analysis on the carbonate rock sample thin sections to obtain the corresponding carbonate sedimentary characteristics of each sample thin section; performing carbon and oxygen isotope testing on the carbonate rock samples to obtain carbon and oxygen isotope test data; determining the first feature of carbonate sedimentary paleogeography using the carbon and oxygen isotope test data; and determining the carbonate sedimentary landform characteristics of a target area based on the carbonate sedimentary characteristics and the first feature of carbonate sedimentary paleogeography.

[0006] Secondly, embodiments of the present invention also provide an apparatus for determining carbonate sedimentary landforms using carbon isotopes, the apparatus comprising: a memory and a processor; the memory is used to store a program for determining carbonate sedimentary landforms using carbon isotopes, and the processor is used to read and execute the program for determining carbonate sedimentary landforms using carbon isotopes, and execute the method described in any one of the above embodiments.

[0007] Thirdly, embodiments of the present invention also provide a computer-readable storage medium storing a data processing program, wherein the data processing program is executed by a processor using the method for determining carbonate sedimentary landforms based on carbon isotopes as described in any of the above embodiments.

[0008] Compared with related technologies, this application provides a method and apparatus for determining carbonate sedimentary landforms using carbon isotopes. The method includes: selecting carbonate rock samples; preparing carbonate rock sample thin sections and carbonate rock powder samples using the carbonate rock samples; performing thin section identification analysis on the carbonate rock sample thin sections to obtain the corresponding carbonate rock sedimentary characteristics of each sample thin section; performing carbon and oxygen isotope testing on the carbonate rock powder samples to obtain carbon and oxygen isotope test data; determining the first feature of carbonate rock sedimentary paleogeography using the carbon and oxygen isotope test data; and determining the carbonate sedimentary landform characteristics of the target area based on the carbonate rock sedimentary characteristics and the first feature of carbonate rock sedimentary paleogeography. This application uses carbon isotope δ¹³C‰ (VPDB) data for analysis to determine carbonate sedimentary landforms, and combines it with microscopic thin section identification, which can quickly and efficiently determine paleogeography, improve the efficiency and accuracy of carbonate rock sedimentary landform identification, and provide a theoretical basis for the distribution law of carbonate rock sedimentary landforms.

[0009] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the solutions described in the description and the accompanying drawings. Attached Figure Description

[0010] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0011] Figure 1 This is a flowchart illustrating the method for determining carbonate sedimentary landforms using carbon isotopes, as described in an embodiment of this application.

[0012] Figure 2 This is a schematic diagram of an apparatus for determining carbonate sedimentary landforms using carbon isotopes, according to an embodiment of this application.

[0013] Figure 3 Flowchart of a method for determining carbonate sedimentary landforms using carbon isotopes in some exemplary embodiments;

[0014] Figure 4 This is a schematic diagram of carbon and oxygen isotope scattering in some exemplary embodiments;

[0015] Figure 5 This is a schematic diagram of a box plot of carbon isotopes in different regions in some exemplary embodiments;

[0016] Figure 6 This is a schematic diagram of a sample under a microscope in the HJL cross-section in some exemplary embodiments;

[0017] Figure 7 This is a schematic diagram of a sample under a microscope in the cross-section of a BJP in some exemplary embodiments. Detailed Implementation

[0018] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0019] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive scheme as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive schemes to form another unique inventive scheme as defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0020] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0021] The main methods for restoring ancient landforms of carbonate rocks are as follows:

[0022] ① Stratigraphic Thickness Method: During deposition, the elevation changes of paleogeomorphism affect the thickness distribution of sediments. Generally, sediments are relatively thinner where paleogeomorphism is higher and thicker where it is lower. This method is more reliable for clastic rocks dominated by mechanical deposition. However, carbonate rocks exhibit both mechanical and chemical precipitation, leading to greater ambiguity in stratigraphic thickness interpretation, making this method less applicable. ② Sedimentological Method: Different paleogeomorphic units form different sedimentary facies types and exhibit different sedimentary characteristics. By analyzing the distribution of sedimentary facies, some paleogeomorphism can be indirectly reconstructed. This method requires detailed sedimentary facies analysis of core, well, and seismic data to determine sedimentary facies types and characteristics, and to infer the division of paleogeomorphic units. It is relatively complex and has high ambiguity. ③ Imprint Method: This method uses paleogeomorphic-related features in the overlying strata (such as overlying stratum thickness) to infer paleogeomorphic morphology. A drawback of this method is that it only reflects residual paleogeomorphism and not the geomorphism during the depositional period. If large-scale erosion, karstification, or other erosion occurs after deposition, leading to strata thinning, it will significantly affect the results. ④ Residual Thickness Trend Surface Method: In the process of paleogeographic reconstruction, the effects of stratigraphic compaction and subsequent tectonic deformation are considered. The paleogeographic features are reconstructed by calculating the residual thickness trend surface. This method is quite challenging, and the parameters vary greatly across different regions, so the results may have some errors compared to the actual situation. ⑤ Thin Section Identification Method: This method uses microscopic sedimentary characteristics to determine sedimentary paleogeographic features, but it has certain ambiguities. For example, the presence of a distinct granular structure in the rock under the microscope could be due to wave erosion at higher elevations or deposition by storm-borne fluids at lower elevations.

[0023] δ 13 C‰ (VPDB) refers to the carbon isotope content in the sample. 13 C / 12C) The deviation of the ratio from the carbon isotope ratio in the Vienna Basin belemnites (VPDB), an international standard reference. It has wide applications in geology, ecology, and environmental science, especially in geology, where it can be used for research on paleoclimate and paleoenvironment. δ¹⁸O₂ in carbonate rocks... 13 Variations in C‰ values ​​are primarily related to biological processes, diagenesis, water chemistry, paleooceanic environments, global carbon cycling, and hydrothermal activity. Recent studies have shown that δ 13 The C‰ (VPDB) value can reflect the relative elevation of paleogeography during the carbonate rock deposition period to a certain extent. When the paleogeography is relatively high, frequent changes in sea level lead to repeated exposure of sedimentary strata. During this period, carbonate rocks are more susceptible to weathering than clastic rocks. Atmospheric carbon dioxide participates in the diagenesis of high-elevation carbonate rocks, and organic carbon also has the opportunity to participate in the diagenesis process during weathering. All of these factors contribute to the increase in δ¹⁴ (vertical peak density). 13 The C‰ (VPDB) value is significantly negative; therefore, the carbon isotope δ 13 C‰ (VPDB) can be used as a method to identify carbonate sedimentary landforms, and this has been confirmed through years of experiments.

[0024] To address the difficulty in restoring the aforementioned carbonate sedimentary landforms, the inventors discovered:

[0025] Using carbon isotope δ¹³C‰ (VPDB) analysis as a method to identify carbonate sedimentary landforms, combined with microscopic thin section identification, can quickly and efficiently identify paleogeomorphs, improve the efficiency and accuracy of identifying landforms during carbonate rock deposition periods, and provide a theoretical basis for the distribution patterns of carbonate sedimentary landforms.

[0026] This invention provides a method for determining carbonate sedimentary landforms using carbon isotopes, such as... Figure 1 As shown, the method includes steps S100-S150:

[0027] S100: Select carbonate rock samples;

[0028] S110: Using the carbonate rock sample, prepare carbonate rock sample thin sections and carbonate rock powder samples;

[0029] S120: Perform thin section identification analysis on the carbonate rock sample thin sections to obtain the corresponding carbonate rock sedimentary characteristics of each sample thin section;

[0030] S130: Perform carbon and oxygen isotope testing on the carbonate rock powder sample to obtain carbon and oxygen isotope test data.

[0031] S140: Determining the first paleogeographic feature of carbonate sedimentary rocks using carbon and oxygen isotope test data;

[0032] S150: Determine the carbonate sedimentary geomorphic features of the target area based on the aforementioned carbonate sedimentary characteristics and the first feature of carbonate sedimentary paleogeography.

[0033] In one exemplary embodiment, the process of selecting carbonate rock samples is as follows:

[0034] Step 1: Divide the study area into multiple target regions;

[0035] The study area was divided into multiple target areas according to the needs, and several core and cuttings samples from field profiles or wells were selected from each area.

[0036] If drilling cores are present in the target area, thin rock sections of the core samples are prepared, with a thickness of approximately 0.03 mm. These sections are then finely ground, polished, and covered with coverslips for microscopic observation and identification. Simultaneously, during the thin section preparation process, any remaining carbonate powder samples are selected and ground to a particle size of 200 mesh; this ensures that the carbonate rock sample thin sections and carbonate rock powder samples belong to the same target area.

[0037] Step 2: Select unaltered carbonate rock samples from each target region.

[0038] Select relatively pure carbonate rock samples that have not been altered by diagenetic fluids from each target area, and avoid selecting samples filled in fractures or cavities.

[0039] Step 3: When selecting samples, record necessary geological background information, such as the occurrence, thickness, color, and crystal size of the strata.

[0040] In one exemplary embodiment, thin section identification analysis is performed on the carbonate rock sample thin sections to obtain the corresponding carbonate rock sedimentary characteristics of each sample thin section. This includes: taking microscopic photographs of the sample, then preparing a rock thin section with a thickness of approximately 0.03 mm, and after fine grinding and polishing, covering it with a cover glass slide for microscopic observation and identification. The identification mainly focuses on the lithology, structure, paleontological type, and sedimentary characteristics of the rock.

[0041] In one exemplary embodiment, determining the first paleogeographic feature of carbonate sedimentary rocks using carbon and oxygen isotope testing data includes:

[0042] Step 1: Construct scatter plots and box plots based on carbon and oxygen isotope test data of carbonate rock samples; the scatter plot is constructed using carbon isotope (δ¹⁸O) as the plotting factor. 13 C‰(VPDB)) is used as the x-axis, and oxygen isotopes (δ) are used as the x-axis. 18Using carbon isotope data (δ¹³C‰(VPDB)) as the ordinate, scatter plots are created for carbon and oxygen isotope test data from different target areas. Data points within the same target area use the same color scale. A reference frame can also be placed on the base map to indicate the range of global seawater carbon and oxygen isotope values ​​for the same period. In addition to comparing carbon isotope values, scatter plots can also reference oxygen isotope values ​​and global seawater carbon and oxygen isotope values ​​for the same period. Box plots use different target areas as the x-axis and carbon isotope (δ¹³C‰(VPDB)) data as the y-axis.

[0043] The second step is to conduct comparative analysis based on scatter plots and box plots to determine the primary feature of carbonate sedimentary paleogeography.

[0044] In one exemplary embodiment, the first paleogeographic feature of carbonate sedimentary rocks is determined by comparative analysis of scatter plots and box plots, including:

[0045] The first step is to divide the scatter plot into two regions based on the carbon isotope data characteristics; for example... Figure 4 As shown, the left side belongs to the first region, and the right side belongs to the second region; the first region corresponds to a relatively high position of ancient landforms, and the second region corresponds to a relatively low position of ancient landforms.

[0046] The second step involves determining the primary paleogeographic feature of carbonate sedimentary rocks for each target region based on the carbon isotope data range for each area. If carbonate thin-section analysis results are available in the study area, these results are cross-validated to ultimately determine the primary paleogeographic feature of carbonate sedimentary rocks for each target region. For example, a lower carbon isotope level generally indicates a higher paleogeographic location, as carbonate thin-section samples typically show a granular structure. If no carbonate thin-section samples are available, carbon and oxygen isotopes from seawater of the same period can be considered. By comparing these values ​​with the global average carbon and oxygen isotope ranges for each period, if the carbon isotope data range for the target region is lower than the average for seawater of the same period, the paleogeographic location of the target region is determined to be lower; if the carbon isotope data range is higher than the average for seawater of the same period, the paleogeographic location of the target region is determined to be higher.

[0047] In one exemplary embodiment, determining the first feature of carbonate sedimentary paleogeography by comparing and analyzing the scatter plot and the box plot includes:

[0048] The first step is to divide the box plot into two regions based on the carbon isotope data characteristics of the box plot and the region division values ​​of the scatter plot.

[0049] The second step is to determine the primary paleogeographic features of carbonate sedimentary rocks in each target area based on the division results.

[0050] Box plots and scatter plots can be used to verify the division of regions.

[0051] Two comparison methods can be used in the comparative analysis of box plots and scatter plots:

[0052] The first method involves comparing multiple sets of data from multiple target regions.

[0053] Comparing multiple sets of data from various target areas can reflect the interrelationship of paleogeography during different sedimentary periods. Specifically, areas with lower δ13C‰ (VPDB) have relatively higher paleogeography, while areas with higher δ13C‰ (VPDB) have relatively lower paleogeography.

[0054] The second method is to compare with global seawater carbon isotope big data from the same period.

[0055] When there are few carbon isotope data points or only a single set of data for the target area, a comparison with global seawater carbon isotope big data of the same period can be used. If the carbon isotope data value of the target area is lower than that of global seawater carbon isotope data of the same period, the target area is considered to have a higher paleogeography. Conversely, if the carbon isotope data value of the target area is higher than that of global seawater carbon isotope data of the same period, the target area is considered to have a lower paleogeography.

[0056] Based on the above comparative analysis results, if the analysis results of carbonate rock thin sections exist in this study area, the analysis results of the carbon isotope data can be used to cross-verify the two. If the results are consistent with the thin section data verification, the geomorphological conclusions are reliable and can be used directly; if the results are inconsistent with the thin section data verification, it is necessary to check whether the sample data is affected by complex factors such as diagenetic fluid cementation. The sedimentary geomorphology of the target area is determined based on the final analysis and verification results.

[0057] Secondly, embodiments of the present invention also provide a device for determining carbonate sedimentary landforms, such as... Figure 2 As shown, the device includes a memory 200 and a processor 210; the memory is used to store a program for determining carbonate sedimentary landforms using carbon isotopes, and the processor is used to read and execute the program for determining carbonate sedimentary landforms using carbon isotopes, and execute the method described in any of the above embodiments.

[0058] Thirdly, embodiments of the present invention also provide a computer-readable storage medium storing a data processing program, wherein the data processing program is executed by a processor using the method for determining carbonate sedimentary landforms based on carbon isotopes as described in any of the above embodiments.

[0059] Example 1

[0060] This example demonstrates an efficient and rapid method for identifying carbonate sedimentary landforms, such as... Figure 3 As shown, the specific implementation process is as follows:

[0061] Step 1: Select carbonate rock samples:

[0062] In this step, the conditions for selecting carbonate rock samples are as follows:

[0063] For different regions where comparative sedimentary paleogeography is required, relatively pure carbonate rock samples are selected from field outcrops, drill cores, or rock cuttings. These relatively pure carbonate rock samples are those that have not been altered by diagenetic fluids. There are no specific restrictions on lithology, but the main goal is to avoid selecting fillings in cracks or cavities.

[0064] For the selected carbonate rock samples, record relevant geological background information: the occurrence, thickness, color, crystal size, etc. of the strata.

[0065] Step 2: Prepare thin sections of carbonate rock samples:

[0066] In the laboratory, firstly, microscopic photographs were taken of carbonate rock samples from different regions to record their characteristics.

[0067] Secondly, small samples were separated and thin sections of rock samples were made for later verification of the conclusions. The remaining samples (>300 μg) in the same area as the thin sections were ground into powder (200 mesh) for geochemical experimental analysis.

[0068] Finally, the selected small carbonate rock samples were cut and ground to make thin rock sections with a thickness of about 0.03 mm. After fine grinding and polishing, they were covered with coverslips for observation and identification under a microscope.

[0069] Step 3: Identification of thin sections of carbonate rock samples

[0070] Thin sections of carbonate rock samples were observed and identified under a microscope. The identification mainly focused on the lithology, structure, paleontological types, and sedimentary characteristics of the rocks, especially some special phenomena that represent water depth, such as exposed karst breccia, well-sorted bioclastic and sand particles that represent high-energy shoals.

[0071] Step 4: Geochemical Experimental Analysis - Carbon and Oxygen Isotope Testing

[0072] Carbon and oxygen isotope analysis was performed according to the standard SY / T 5238-2019. Sample powder (>300 μg) corresponding to the thin section was selected for carbon (δ¹⁴ oz) analysis. 13 C‰(VPDB))Oxygen(δ) 18 The corresponding values ​​were obtained from isotope analysis of O‰ (VPDB).

[0073] Step 5: Create scatter plots and box plots for the data from different regions that need to be compared and analyzed in terms of ancient geomorphology, according to the regional grouping method.

[0074] Scatter plots and box plots were created for the data from different regions that required paleogeographic comparison.

[0075] ①Based on carbon isotopes (δ) 13 C‰(VPDB)) is used as the x-axis, and oxygen isotopes (δ) are used as the x-axis.

[0076] 18 Using O‰(VPDB) as the ordinate, scatter plots are created for data from different regions, with data points in the same target area using the same color code.

[0077] ②Based on carbon isotopes (δ¹⁸) from different regions 13 Box plots were created based on C‰(VPDB) data.

[0078] Step 6: Compare and analyze the above scatter plots and box plots.

[0079] Step 7: Verify the carbon isotope analysis results with the sample thin section analysis results.

[0080] The conclusions drawn can be randomly verified with previous thin section data. Based on practical experience, the degree of agreement is relatively high. If there is a significant difference between the microstructure characteristics under the thin section and the experimental conclusions, it is advisable to check whether the sample data is affected by complex factors such as diagenetic fluid cement.

[0081] This invention provides an efficient and rapid experimental method for determining the relative elevation of paleogeography in carbonate sedimentary rocks in different regions, which has the following technical advantages:

[0082] First, this method involves fewer experimental steps. Especially in areas lacking 3D seismic data and a large amount of drilling data, it is impossible to conduct extensive stratigraphic correlation, sedimentological studies, and trend surface reconstruction. A preliminary understanding of sedimentary paleogeography can be obtained using only a small number of field outcrops or drilling cuttings, which greatly saves time, manpower, and resources.

[0083] II. To provide theoretical support for the distribution patterns of carbonate sedimentary paleogeomorphology.

[0084] Example 2

[0085] This example focuses on the Permian Qixia Formation in the northwestern Sichuan Basin. It utilizes an efficient and rapid method for identifying carbonate sedimentary landforms to determine the sedimentary landforms of a localized area within the Qixia Formation. The specific implementation process is as follows:

[0086] Step 1: Selecting Samples

[0087] Eight different field profiles (BJP, LDB, HJL, MDY, DMY) and well core samples (LT2, K2, ST18) in the northwestern Sichuan Basin were selected for paleogeographic analysis during the carbonate sedimentary period.

[0088] Step 2: Prepare sample thin sections and observe the rock thin sections.

[0089] First, microscopic photographs were taken of the sample. Then, a thin rock section with a thickness of about 0.03 mm was prepared and observed and identified under a microscope for later verification of the conclusions.

[0090] Step 3: Perform carbon and oxygen isotope testing.

[0091] Step 1: Select the remaining sample (>300μg) from the same area as the thin slice in Step 2 and grind it into powder (200 mesh).

[0092] The second step involves performing carbon and oxygen isotope testing and analysis according to the SY / T 5238-2019 standard to obtain the carbon (δ¹⁸O) content. 13 C‰(VPDB))Oxygen(δ) 18 The corresponding values ​​of isotopes of O‰(VPDB)).

[0093] Step 4: Create scatter plots and box plots based on the carbon and oxygen isotope test results.

[0094] Scatter plots and box plots were created according to different field profiles or drilling grouping methods, such as... Figure 4 The carbon and oxygen isotope scatter plot shown is as follows: Figure 5 Box plots of carbon isotopes for different regions are shown.

[0095] Step 5: Scatter plot and box plot analysis

[0096] Scatter plot analysis:

[0097] As can be seen from the scatter plot, there are 8 groups of δ 13 C‰ (VPDB) data can be divided into two distinct regions, such as Figure 4 As shown, there are two areas: the red area and the blue area. Within the red area, the data from five sets of data (δ) from field profiles (HJL, MDY, DMY) and drill core samples (K2, ST18) are included. 13 The C‰ (VPDB) values ​​are relatively low, ranging from 0.31 to 2.88, indicating a relatively high sedimentary topography. In the blue area, the δ values ​​of the three data sets from the field profiles (BJP, LDB) and the drill core sample (LT2) are... 13 Except for one outlier (1.98), the C‰ (VPDB) values ​​are all relatively high, ranging from 2.86 to 4.99, indicating that the sedimentary landforms are relatively low.

[0098] Box plot analysis:

[0099] From such Figure 5 As shown in the boxed chart, the eight data sets can be clearly divided into two zones: the upper red section (5 data sets) represents high terrain, and the lower blue section (3 data sets) represents low terrain, in contrast to the scatter plots. Figure 1 The values ​​were the lowest in the HJL section box area, indicating the highest sedimentary landform, followed by ST18 and MDY sections, then DMY and K2. The carbon isotope box values ​​in the LDB section were significantly higher than the previous five sets of data, and the corresponding paleogeography was significantly lower. The same was true for the BJP section and LT2 well, both of which belonged to low-geomorphic areas.

[0100] Step 6: Verify the carbon and oxygen isotope analysis results with the sample thin section data.

[0101] Two sets of data were randomly selected from the previous backup of sample thin section data for verification:

[0102] (1) HJL section: Sample A, under a microscope, is lithology of sparry bioclastic dolomite, such as Figure 6 As shown in the middle left image, the sparry bioclastic dolomite exhibits high roundness of the bioclastic material, with sparry cementing predominating between the bioclastic fragments, reflecting the characteristics of a high paleogeographical level and strong water energy. Sample B is a fine-grained dolomite, as... Figure 6 As shown in the middle right figure, the original rock grain structure can be clearly seen. Judging from the phantom of the grain residue, the grains should mainly be bioclastic or sandy debris, with good sorting, reflecting the characteristics of strong water energy and repeated washing, and relatively high sedimentary landforms.

[0103] (2) BJP section: The lithology of sample A under the microscope is argillaceous microcrystalline bioclastic limestone, such as... Figure 7 As shown in the middle left figure, the bioclastic sorting and roundness are poor, and the cement is mainly composed of micritic matrix, suggesting that the sedimentary water energy was medium to low, and the sedimentary landform was relatively low. Sample B is a micritic microcrystalline bioclastic sandstone-limestone, such as... Figure 7 As shown in the middle right figure, some bioclastics are relatively well preserved but poorly sorted and have low roundness, suggesting that the energy of the sedimentary water was medium to low and the sedimentary landforms were relatively low.

[0104] The two sets of data, verified against the corresponding thin section microscopic features, yielded consistent conclusions. The conclusions regarding the sedimentary geomorphology of carbonate rocks obtained from this carbon isotope analysis are indeed reliable and can be directly applied.

[0105] Carbonate samples from the Permian Qixia Formation in the northwestern Sichuan Basin indicate that the Qixia period in this region is generally considered to have developed a NE-trending platform margin. The Qixia Formation in the Shuangyushi area has already yielded proven natural gas reserves of approximately 50 billion cubic meters. Overall, the region is a high-topography area during the carbonate sedimentary period, demonstrating considerable exploration potential. However, some areas likely contain relatively low-topography zones, requiring further in-depth research. Therefore, determining the relative elevation of sedimentary landforms in different areas is crucial for predicting lithofacies paleogeographic distribution and the distribution of reservoirs associated with high-topography areas. The methods described above can more accurately identify carbonate sedimentary landforms and address issues in this region.

[0106] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A method for determining the sedimentary landforms of carbonate rocks using carbon isotopes, characterized in that, The method includes: Select carbonate rock samples; Carbonate rock sample thin sections and carbonate rock powder samples were prepared using the carbonate rock samples; Thin section analysis was performed on the carbonate rock samples to obtain the corresponding carbonate rock sedimentary characteristics for each sample thin section; Carbon and oxygen isotope tests were performed on the carbonate rock powder sample to obtain carbon and oxygen isotope test data. The first feature of paleogeography in carbonate sedimentary rocks was determined using carbon and oxygen isotope testing data. The carbonate sedimentary geomorphological features of the target area are determined based on the aforementioned carbonate sedimentary characteristics and the first feature of the carbonate sedimentary paleogeography.

2. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 1, characterized in that, The process of selecting carbonate rock samples is as follows: The study area was divided into multiple target regions; Select unaltered carbonate rock samples from each target region.

3. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 2, characterized in that, The carbonate rock sample section and the carbonate rock powder sample are located in the same target area; The carbonate rock sample section was a 0.03 mm thin rock section. The carbonate powder sample has a diameter of 200 mesh.

4. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 1, characterized in that, The thin section identification analysis of the carbonate rock samples yields the corresponding carbonate rock sedimentary characteristics for each sample thin section, including: Thin section identification analysis was performed on the carbonate rock samples to obtain the corresponding sedimentary lithology, rock structure, paleontological type and sedimentary characteristics of each sample thin section.

5. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 2, characterized in that, The determination of the first paleogeographic feature of carbonate sedimentary rocks using carbon and oxygen isotope testing data includes: Scatter plots and box plots were constructed based on the carbon and oxygen isotope test data of all carbonate rock samples. The first feature of the carbonate sedimentary paleogeography was determined by comparing and analyzing the scatter plot and the box plot. The first feature of the carbonate rock sedimentary paleogeography includes a paleogeographic high position and a paleogeographic low position.

6. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 5, characterized in that, The scatter plot is a two-dimensional graph with carbon isotope data as the horizontal axis and oxygen isotope data as the vertical axis. The box plot is a two-dimensional plot with the target area on the horizontal axis and carbon isotope data on the vertical axis.

7. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 6, characterized in that, The determination of the first feature of carbonate sedimentary paleogeography based on the comparative analysis of the scatter plot and the box plot includes: Based on the distribution characteristics of carbon isotope data in the scatter plot, the scatter plot is divided into a first region and a second region. The primary paleogeographic feature of carbonate sedimentary rocks in each target area was determined based on the range of carbon isotope data values ​​for each region.

8. The method for determining carbonate sedimentary landforms using carbon isotopes according to claim 7, characterized in that, The determination of the first feature of carbonate sedimentary paleogeography based on the comparative analysis of the scatter plot and the box plot includes: Based on the carbon isotope data characteristics of the box plot and the regional division values ​​of the scatter plot, the box plot is divided into a first region and a second region; Based on the division results, the primary paleogeographic feature of carbonate sedimentary rocks in each target area was determined.

9. A device for determining the sedimentary landforms of carbonate rocks using carbon isotopes, characterized in that, The apparatus includes a memory and a processor; the memory is used to store a program for determining carbonate sedimentary landforms using carbon isotopes, and the processor is used to read and execute the program for determining carbonate sedimentary landforms using carbon isotopes, and to execute the method according to any one of claims 1-8.

10. A computer-readable storage medium storing a data processing program, the data processing program being executed by a processor according to any one of claims 1-8, the method for determining carbonate sedimentary landforms using carbon isotopes.

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