Isochronous stratigraphic correlation method based on sporopollenin paleoclimate thermal event response

Abstract

This invention discloses an isochronous stratigraphic correlation method based on the paleoclimate thermal event response of sporopollenins. This method utilizes the sensitive response of sporopollenins to thermal evolution and their resistance to degradation. Fourier transform infrared spectroscopy is used to extract and quantify the evolutionary sequences of their chemical functional groups (such as carboxyl and aromatic groups) with high sensitivity. Changes in these functional groups directly record the paleoclimate thermal events experienced by the strata. By utilizing the synchronicity of thermal event responses in multiple wells, a high-precision isochronous stratigraphic framework can be established. This invention overcomes the bottleneck of traditional stratigraphic correlation methods being limited in low-exploration areas such as deep water, deep layers, and complex structures due to scarce fossils and strong diagenesis, providing a new chemostratigraphic approach for regional tectonic-thermal evolution history analysis and oil and gas exploration.

Description

Technical Field

[0001] This invention relates to the fields of oil and gas exploration and stratigraphy, and in particular to an isochronous stratigraphic correlation method based on the response of sporophyll paleoclimate thermal events. Background Technology

[0002] In oil and gas exploration, stratigraphic division and correlation are fundamental for source rock evaluation, reservoir prediction, and comprehensive understanding of petroleum geological conditions. Currently, the analytical methods for stratigraphic correlation in oil and gas basins mainly rely on marker fossils and geochemical indicators. However, with increasing exploration difficulty and the continuous expansion of exploration areas, traditional stratigraphic methods face significant limitations in some low-exploration areas, such as deep-water, deep-layered, structurally complex, and multi-stage altered marginal sea basins. These limitations stem from factors such as limited drilling, the dominance of sandy strata at the basin margins, and strong diagenetic alteration. For example, traditional biostratigraphic division and correlation rely on index fossils (such as foraminifera), but in deep-water, deep-layered, or structurally complex areas, fossil preservation is often poor or species is limited, leading to reduced resolution in the division and correlation. Traditional chemical stratigraphic division and correlation (such as elemental ratios and isotopes) are easily affected by diagenetic processes (such as hydrothermal activity), resulting in distorted original signals and limiting their application in cross-regional depression or basin-level stratigraphic correlation. Isotope dating (such as zircon U-Pb) is difficult to accurately reflect the age of clastic strata in the absence of volcanic rock interlayers, and it is also costly and time-consuming. Therefore, there is a need for a stratigraphic correlation method that is widely distributed, cross-regionally comparable, highly resistant to interference, and has high accuracy, and is suitable for complex, low-exploration areas. Summary of the Invention

[0003] This invention addresses the technical challenges of stratigraphic division and correlation in low-exploration areas such as deep water, deep layers, and complex geological structures, where scarcity of fossils, strong diagenetic alteration, and the susceptibility of traditional geochemical indicators to distortion lead to difficulties. It provides an isochronous stratigraphic correlation method based on the paleoclimate thermal event response of sporopollenins. Sporopollenins, as major components of plant spores and pollen exoskeletons, are resistant to high temperatures (>300°C), strong acids and alkalis, and microbial erosion. Even in basins with complex burial histories, they retain relatively good information on chemical alteration caused by paleoclimate thermal events, significantly reducing interference from later alterations. This provides a unique advantage for stratigraphic correlation. Based on this characteristic, this invention utilizes Fourier transform infrared spectroscopy to analyze the composition and type changes of compounds in sporopollenins. The identified thermal evolution parameters of sporopollenins (such as functional group distribution and changes in carboxyl absorption peaks) can directly correlate with the thermal events and tectonic activities experienced by the strata. Studies have shown that the study of sporophytin thermal event sequences not only improves the accuracy of longitudinal correlation, but also makes it easier to compare zones with different provenance and diagenetic evolution characteristics, and establish a continuous stratigraphic framework. This can, to some extent, make up for the shortcomings, applicability and resolution problems of traditional methods.

[0004] In the first aspect, the present invention provides an isochronous stratigraphic correlation method based on the response of sporophyll paleoclimate thermal events, which is achieved by the following technical solution.

[0005] A time-series stratigraphic correlation method based on the response of sporophyll paleoclimate-thermal events includes the following steps: S1: Perform pretreatment on core or rock fragment samples from the target layer to enrich pollen fossils using physical and chemical methods, while avoiding the use of oxidizing reagents; S2: Prepare a sample for Fourier transform infrared spectroscopy testing, wherein the sample is a selected collection of single-genus species multi-grained pollen fossils or a mixed powder of multi-genus species pollen from representative strata. S3: Analyze the sample using a Fourier transform infrared spectrometer to obtain its wavelength range of 4000-1333 cm⁻¹. -1 Infrared absorption spectra in the wavenumber range were used to identify absorption peaks of key functional groups that characterize the chemical composition of sporopollenins. S4: Based on the functional group absorption peak intensity data obtained in step S3, construct a continuous curve of its variation with stratigraphic depth. By analyzing the anomalous variation characteristics of specific functional group absorption peaks in the curve, identify the paleoclimate thermal events recorded in the stratigraphic records. S5: Compare the paleoclimate thermal event response curves identified in step S4 in different wells, and use the synchronous anomaly segments with similar morphology and amplitude that appear in multiple wells as isochronous comparison interfaces to establish a regional stratigraphic division and comparison scheme.

[0006] Furthermore, avoiding the use of oxidizing agents in step S1 means not using nitric acid, concentrated sulfuric acid, or Schultz's reagent during the treatment process, and using diluted hydrochloric acid and hydrofluoric acid for mineral dissolution.

[0007] Furthermore, in step S3, the absorption peak of the key functional group includes at least the peaks located in the 1900-1650 cm⁻¹ range. -1 The C=O stretching vibration peak of the carboxyl group is located in the wavenumber range of 3400-3000 cm⁻¹. -1 The hydroxyl (OH) stretching vibration peak in the wavenumber range is located at 3000-2800 cm⁻¹. -1 Aliphatic CH stretching vibration peaks in the wavenumber range, and the main body located at 1610-1560 cm⁻¹ -1 Aromatic C=C stretching vibration peaks within the wavenumber range.

[0008] Furthermore, in step S4, a significant negative anomaly of the carboxyl absorption peak is used as the core indicator for identifying paleoclimate thermal events.

[0009] Furthermore, the carboxyl absorption peak is specifically located at 1652.7230 cm⁻¹. -1 The peak value at that location was analyzed.

[0010] Furthermore, before analyzing the carboxyl absorption peak, the spectrum needs to be standardized, and the highest peak within the characteristic peak range or the fitted main peak value should be selected to eliminate background interference and ensure the comparability of data between different samples.

[0011] Furthermore, the key functional group absorption peak also includes: located at 3122 cm⁻¹ -1 The absorption peak is located at 1559 cm⁻¹ and is attributed to hydroxyl groups or nitrogen-containing functional groups with strong hydrogen bonding. -1 The absorption peaks at 1070 cm⁻¹ belong to the aromatic C=C skeleton vibrations; and the absorption peak at 1070 cm⁻¹ is also present. -1 The absorption peaks are mainly attributed to the COC ether bond or the S=O vibration of sulfur-containing functional groups.

[0012] Furthermore, a volcanic disturbance screening step is included between steps S4 and S5: if the volcanic glass content in the target section is greater than 5% or the mercury concentration is greater than 200 ppb, the section is marked as a volcanically disturbed area and is not included in the stratigraphic correlation based on paleoclimate thermal events.

[0013] Furthermore, in step S5, while establishing an isochronous comparison interface by comparing the synchronous negative anomaly segments of the carboxyl absorption peak curves in multiple wells, the thermal event type and intensity are comprehensively identified by combining the combination and change patterns of hydroxyl, aliphatic CH, aromatic C=C, and the aforementioned characteristic absorption peak curves, in order to assist and verify the formation division scheme.

[0014] Secondly, the present invention provides a computer-readable storage medium, which is achieved by the following technical solution.

[0015] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements steps S3 to S5 of the isochronous stratigraphic correlation method based on the sporophyll paleoclimate thermal event response described above.

[0016] Thirdly, the present invention provides an isochronous stratigraphic correlation device based on the response of sporophyll paleoclimate thermal events, which is achieved by the following technical solution.

[0017] A time-series stratigraphic correlation instrument based on sporophyll paleoclimate thermal event response includes: The spectral analysis unit is used to perform sample preparation as described above and to obtain infrared absorption spectra as described above using a Fourier transform infrared spectrometer. The data processing and comparison unit includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it is used to implement the isochronous stratigraphic correlation steps of the paleoclimate thermal event response as described above.

[0018] This application has the following beneficial effects: The method of this invention utilizes the characteristics of sporophytin that are sensitive to thermal events and resistant to degradation. By using Fourier transform infrared spectroscopy, the evolution sequence of its chemical functional groups is obtained, which enables high-precision isochronous stratigraphic correlation in areas lacking index fossils and affected by strong diagenesis. This provides a new technical means for stratigraphic framework construction and oil and gas exploration in complex basins. Attached Figure Description

[0019] Figure 1 This is an overall flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the prepared pollen fossil sample in an embodiment of the present invention. It shows the pollen fossil particles that have been picked out and placed on a calcium fluoride glass slide, waiting for drying and testing. It is used to illustrate the final state of sample preparation in step S2, and to help explain the sample enrichment and preparation process in steps S1 and S2. Figure 3 This is a schematic diagram of observing and selecting single pollen fossils for testing using the microscope lens of a Fourier transform infrared spectrometer (FTIR) in an embodiment of the present invention. It corresponds to the selection of specific samples in step S2 and the positioning operation before testing in step S3, and intuitively shows the core analysis link in step S3. Figure 4 This is a schematic diagram of the main infrared spectral features of sporophytin and its corresponding main functional group feature regions obtained by Fourier transform infrared spectroscopy analysis in this embodiment of the invention. It intuitively shows the analysis results of step S3 and is an intuitive basis for identifying the absorption peaks of key functional groups such as carboxyl groups. Figure 5 The peak value of carboxyl uptake from multiple wells in the target study area of ​​the Qiongdongnan Basin in this embodiment of the invention is 1652.7230 cm⁻¹. -1 The curves showing changes with depth and the stratigraphic division comparison map are based on data from steps S4 and S5, and the map marks three major thermal events. Figure 6 This embodiment of the invention is based on absorption peaks of other characteristic functional groups (including but not limited to approximately 3122 cm⁻¹). -1 The hydroxyl / amino peak at approximately 1559 cm⁻¹ -1 The aromatic C=C peak at approximately 1070 cm⁻¹ -1 A comparison chart of the characteristic peaks at a given depth as a function of depth is used as an auxiliary basis for the multi-index comprehensive identification method, to verify and enhance its effectiveness. Figure 5 The reliability of the comparison schemes shown. Detailed Implementation

[0020] The present patent application will be further described below with reference to the accompanying drawings and embodiments.

[0021] like Figure 1As shown, an isochronous stratigraphic correlation method based on the response of sporophyll paleoclimate-thermal events includes the following steps: S1: Sample pretreatment.

[0022] The sample pretreatment process was basically consistent with the requirements of the petroleum industry analytical standard SY / T 5915-2018, using conventional acid-base methods and heavy liquid flotation to enrich pollen fossils. The difference lies in the fact that the pretreatment process for Fourier transform infrared spectroscopy (FTIR) experiments must not involve oxidizing reagents (such as nitric acid, concentrated sulfuric acid, Schultz's reagent, etc.), and diluted hydrochloric acid and hydrofluoric acid should be used whenever possible. Although heavy liquid flotation theoretically does not oxidize pollen, sieving and sodium hexametaphosphate treatment were used to remove clay and other impurities. Based on these methods, a suspension enriched with organic debris (containing pollen fossils, plant cuticle, lignocellulosic organic matter, algae, and other potentially pollutants) was finally obtained. Subsequently, the suspension was sieved using a 6 μm sieve by placing the sieve containing the suspension into an ultrasonic cleaner filled with ultrapure water (for 15 minutes) to remove clay and other impurities.

[0023] S2: Sample preparation.

[0024] The processed samples were divided into two categories. The first category consisted of multiple samples from a single genus or species: after sieving, the samples were transferred to a glass dish, and approximately 5-10 individual pollen fossils to be tested were selected under a stereomicroscope and placed on a sealed stage for testing. The second category consisted of mixed pollen samples from multiple genera and species: the selected samples were transferred to 10 ml glass (or plastic) test tubes, freeze-dried, ground into powder, and finally a small amount of organic powder was taken for testing. The pollen fossil samples prepared using the above steps were as follows: Figure 2 As shown; a scenario for observing and selecting single pollen grains using a Fourier transform infrared spectrometer's microscopic system, such as... Figure 3 As shown.

[0025] S3: Conduct Fourier transform infrared spectroscopy analysis of sporopyramin.

[0026] Fourier transform infrared spectroscopy was used to test continuous samples from the formation to obtain raw infrared absorption spectra of sporophytin. Through analysis of the spectral data, the following can be obtained: Figure 4The infrared spectral characteristics of sporopollenins shown are clearly marked, with characteristic absorption peaks corresponding to key functional groups such as carboxyl and hydroxyl groups. This is fundamental for identifying compound composition and structure and extracting thermal evolution parameters. The principle is as follows: when different sporopollenin compounds in a sample are irradiated with infrared light, their molecular vibrations absorb infrared light of specific wavelengths, producing specific absorption peaks. These peaks are mainly determined by their chemical bond kinetic constants and the reduced masses of the atoms at both ends, i.e., by the structural characteristics of the compound. Based on the compound structure reflected by these different absorption peaks, the compound composition and type of sporopollenin can be indicated. By using the characteristic values ​​of all absorption peaks within a certain wavenumber range, functional groups can be identified, thereby determining the type of sporopollenin compound and the characteristics of the continuous curve of stratigraphic change.

[0027] S4: Construct variation curves based on the absorption peak intensity of functional groups to identify paleoclimate thermal events.

[0028] Taking a Paleogene well in a certain area of ​​the Qiongdongnan Basin as an example, samples were continuously screened in step S1, obtained using the method in step S2, and sporophytin analysis was conducted in step S3. The results are as follows: a. Observe 4000-1333 cm -1 Based on the wavenumber range, it is believed that the sporophytin composition in the pollen fossils tested in the drilling is mainly saturated hydrocarbons, with lower levels of unsaturated hydrocarbons, and even lower levels or almost no preserved aromatic hydrocarbons containing benzene rings. Although the pollen fossil samples experienced high diagenetic temperatures in the host rock strata, resulting in strong thermal decomposition of the sporophytin in the pollen walls, a small number of high absorption peaks can still be obtained. These high absorption peaks are considered to be the chemical information retained in the tested pollen fossil remnants. The indicative significance of the absorption peaks of key functional groups is as follows: (1) Characteristic range of C=O stretching vibration of carboxyl group (1900-1650 cm⁻¹) -1 A significant decrease in the intensity of this peak typically indicates that sporopollenins have undergone decarboxylation, making it a key indicator that is highly sensitive to paleoclimate thermal events such as high temperatures, drought, high UV radiation, or high-oxygen environments. The typical peak position within this range is approximately 1700 cm⁻¹. -1 The stable characteristic peak observed and used in this study is located nearby, while it is at 1652.7230 cm⁻¹. -1 (As described in point c below), indicating that it is a conjugated carboxylic acid structure.

[0029] (2) Absorption peaks of hydroxyl (-OH) and possibly present amino groups (3400-3000 cm⁻¹) -1 Hydrogen bonding can cause the peak position to shift down to approximately 3122 cm⁻¹. -1 The weakening of the signal is often associated with high-temperature dehydration or oxidation processes, and can also help indicate heat or drought events.

[0030] (3) Absorption peak of aliphatic CH bond (3000-2800cm) -1 As a fundamental skeletal signal of organic matter, the change in the relative ratio of its intensity to that of the carbonyl or aromatic peaks is a classic indicator for assessing the overall thermal maturity of organic matter. In this study, the evolution trend of this ratio provides background information for determining the stage of thermal degradation.

[0031] (4) Absorption peak of stretching vibration of aromatic C=C skeleton (typical range 1610-1560 cm⁻¹) -1 The measured value in this study is approximately 1559 cm. -1 The characteristic peaks (clearly distinct from the C=O absorption peak of the carboxyl group) belong to this category, and their appearance or significant enhancement is direct spectroscopic evidence of aromatization under strong thermal / oxidative conditions. This process often occurs concurrently with decarboxylation, jointly indicating the chemical restructuring of organic matter under thermal stress.

[0032] Furthermore, at approximately 1070 cm -1 The stable absorption peaks observed at the point (whose absorption is mainly attributed to the vibrations of COC ether bonds or S=O groups) can provide additional information for understanding the breaking and formation of specific chemical bonds in thermal events.

[0033] Therefore, the significant negative anomaly of the carboxyl peak is a core criterion for identifying thermal events. The combination and variation patterns of absorption peaks from different functional groups can be further used to determine the type and intensity of thermal events. Plotting these peaks in a line graph reveals the longitudinal evolution sequence and identifies important thermal events, and then correlating these thermal events horizontally forms the basis for subsequent comparisons.

[0034] b. Rapid screening using volcanic disturbance: If volcanic glass >5% (XRD) or Hg concentration >200 ppb is detected, the layer is marked as a volcanic disturbance zone and will not be included in climate event comparisons. (This step is only required for local sections of two wells in this area and is not a necessary condition for regional zone comparisons.) c. Six wells were selected, with the most significant one located at wave number 1652.7230 cm⁻¹. -1 The characteristic absorption peak at that location was analyzed. The obtained infrared absorption spectrum was analyzed, and based on the basic principles of organic spectroscopy (see Ning Yongcheng's "Structural Identification of Organic Compounds and Organic Spectroscopy," etc.), this peak is located in the characteristic broad range of the C=O stretching vibration of the carboxyl group (1900-1650 cm⁻¹). -1 Within a given range, the specific wavenumber indicates that it may be a conjugated carboxylic acid structure. For common saturated carboxylic acids, the peak position is typically between 1720 and 1680 cm⁻¹. -1 When the carboxyl group is conjugated with structures such as aromatic rings, its absorption peak shifts significantly to lower wavenumbers, reaching 1690-1650 cm⁻¹. -1 Range. The range observed in this study is 1652.7230 cm.-1 This stable peak value falls within the typical range of conjugated carboxylic acids, indicating that the carboxyl structure of the sporophytin it represents may be linked to the aromatic system. The peak is sharp, minimally affected by other functional groups, and remains stable after diagenesis. It is extremely sensitive to paleoclimate thermal events (initiating decarboxylation reactions), and therefore was selected as a key correlation parameter in this method. Linear plots were created using its vertical content variation to conduct analogies (its multi-well correlation results are compared with stratigraphic division schemes, as shown in...). Figure 5 (As shown).

[0035] It is worth noting that to ensure the comparability of sample data from different depths and wells, the raw spectra must be standardized (e.g., area normalization of the entire spectrum). Afterward, the target characteristic peak (e.g., 1652.7230 cm⁻¹) should be determined. -1 The intensity of the curve is the basic data for constructing the curve and conducting comparative analysis.

[0036] S5: Using the changes in paleoclimate thermal events identified by sporophyll compounds in the stratigraphy, conduct comparisons between different wells to determine a stratigraphic correlation and division scheme.

[0037] Taking the Paleogene drilling analysis in the Qiongdongnan Basin as an example, based on the identification of single-well thermal events in step S4, wells B and C, with continuous stratigraphic records and complete records, were selected as comparative benchmarks. This is because, through a comprehensive analysis of regional tectonic evolution and drilling and seismic stratigraphy, wells D, E, and F, while identifying at least one thermal event, are located in relatively thin strata at higher levels of Oligocene deposition. Their surrounding areas experienced large-scale tectonic uplift at the end of the Early Oligocene, and the Yacheng Formation exhibits significant angular unconformity in seismic stratigraphy, suggesting a large amount of exposed and eroded strata. Therefore, they are insufficient to serve as typical wells for regional stratigraphic correlation and can be used as auxiliary wells. Wells B and C, as wells revealing continuous, relatively complete, and less eroded strata in the study area, can serve as benchmarks for regional stratigraphic correlation. While well A exhibits moderate erosion intensity, its larger exposed strata thickness allows it to be used as a reference well. Furthermore, comparative studies can be conducted by tracing seismic stratigraphy in conjunction with the calibration of thermal events on the wells.

[0038] During the study, the carboxyl peak value (1652.7230 cm⁻¹) of each well was analyzed. -1 Linear plotting of changes over depth (time) is used to indicate the evolutionary sequence of paleoatmospheric environment and illumination conditions. The core of stratigraphic correlation lies in identifying synchronous changes with isochronous significance in the carboxyl peak curves of multiple wells, especially significant negative anomalies (i.e., peak reduction segments). For example, in well C, the change in carboxyl absorption peak content at this wavenumber shows a relatively significant decrease in the middle, falling below the baseline value, and persisting for a certain period (see reference). Figure 5The blue dashed line (representing the second thermal event) indicates strong thermal decomposition of carboxyl components in the central formation, potentially indicating a regional thermal event. By meticulously comparing peak curves with other wells, negative anomaly segments with comparable morphology and amplitude, and corresponding locations within the same relative geological timeframe, can be identified and used as the basis for isochronous stratigraphic correlation and division. Based on the aforementioned sporophyll characteristics, comparisons revealed that wells A, B, and D all exhibited negative anomalies with similar morphology and amplitude in comparable intervals, indicating regional isochronous nature of the thermal event and serving as marker layers for stratigraphic division.

[0039] Based on this isochronous interface constraint, the study found that in addition to the middle part of the Yacheng Formation, there are two secondary content abrupt changes and persistently low peak value bands in the upper and lower parts (see reference). Figure 5 The red and purple dashed lines (representing the first and third thermal events, respectively) also indicate the presence of strong thermal decomposition of carboxyl groups, resulting in a significant decrease in their content. Due to the varying degrees of stratigraphic integrity revealed in different areas and the influence of unconformities and other tectonic events (e.g., wells at the T70 unconformity surface often lack the first or part of the cliff section, and wells E and F only reveal the third cliff section, with the first and second cliff sections completely eroded), this first-order event is mainly clearly revealed and well-contrasted among the three wells. The finger-like undulations or peaks in certain sections of the third cliff section at well B, combined with thin section and XRD analysis, are attributed to interbedded andesite and clastic rocks, suggesting that this represents more of the influence of a local volcanic event. This could serve as supplementary evidence for stratigraphic division in this tectonic zone (strike-slip tectonic zone) but is not suitable as a basis for isochronous correlation of regional thermal events within the basin.

[0040] To compare thermal events more precisely at the regional scale, the study selected several characteristic infrared absorption peaks sensitive to thermal evolution from three typical wells for tracking and mapping. Figure 6 These indicators include: at 3122.2 cm. -1 (approximately 3122cm) -1 The absorption peak appearing at ) (attributed to hydroxyl groups or nitrogen-containing functional groups with strong hydrogen bonding); at 1558.709 cm⁻¹ -1 (approximately 1559cm) -1 The aromatic C=C skeleton vibration peak appears at 1069.834 cm⁻¹; and combined with the high sulfur content in elemental analysis, the peak is located at 1069.834 cm⁻¹. -1 (approximately 1070cm) -1The characteristic peaks appearing at (their absorption is mainly attributed to the vibrations of COC ether bonds or S=O groups) show a consistent and significant decrease or change in intensity in the upper part of the Yacheng Formation. This confirms that not only unstable carboxyl groups, but also normally more stable aromatic structures and specific bonding forms are generally affected by strong thermal degradation in this stratum. The comprehensive application of multiple indicators effectively improves the accuracy and reliability of cross-regional stratigraphic correlation.

[0041] Based on comprehensive infrared spectral evidence: core decarboxylation indicators ( Figure 5 The significant decrease in the carboxyl peak (and the synchronous degradation of the tolerance component) is related to the simultaneous degradation of the tolerance component. Figure 6 These findings collectively confirm that the strata underwent multiple thermal events. Among them, the thermal event in the second cliff section is a regional landmark event. Figure 5 The revealed two secondary anomalies of carboxyl groups (phase I and phase III thermal events), and Figure 6 The synchronous response of multiple functional group indicators revealed suggests the existence of three phases of thermogeological events in this stratigraphic segment. The isochronous stratigraphic framework established in this way is in good agreement with existing biostratigraphic and seismic stratigraphic divisions.

[0042] This invention comprehensively considers the low exploration level and complex tectonic zones in deep water and deep layers. It establishes a high-precision thermochronology framework based on the thermal evolution characteristics of sporophyll, enabling lateral stratigraphic correlation and overcoming the limitations of traditional biostratigraphic analysis. Because sporophyll exhibits significantly better resistance to degradation than traditional organic markers (such as kerogen), it effectively avoids the damage to stratigraphic signals caused by diagenesis, enhancing its anti-interference capability. By comparing the sporophyll thermal event sequences revealed by different wells, it is possible to determine stratigraphic correlation schemes for oil and gas basins and simultaneously reveal the stages of tectonic activity within the basin, thereby better promoting the study of the coupling relationship between tectonic and thermal history.

[0043] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A time-series stratigraphic correlation method based on the response of sporophyll paleoclimate-thermal events, characterized in that, Includes the following steps: S1: Perform pretreatment on core or rock fragment samples from the target layer to enrich pollen fossils using physical and chemical methods, while avoiding the use of oxidizing reagents; S2: Prepare a sample for Fourier transform infrared spectroscopy testing, wherein the sample is a selected collection of single-genus species multi-grained pollen fossils or a mixed powder of multi-genus species pollen from representative strata. S3: using a Fourier transform infrared spectrometer to analyze the sample, obtaining its infrared absorption spectrum in the 4000-1333 cm -1 wavenumber range, identifying the key functional group absorption peaks characteristic of sporopollenin chemical composition; S4: Based on the functional group absorption peak intensity data obtained in step S3, construct a continuous curve of its variation with stratigraphic depth. By analyzing the anomalous variation characteristics of specific functional group absorption peaks in the curve, identify the paleoclimate thermal events recorded in the stratigraphic records. S5: Compare the paleoclimate thermal event response curves identified in step S4 in different wells, and use the synchronous anomaly segments with similar morphology and amplitude that appear in multiple wells as isochronous comparison interfaces to establish a regional stratigraphic division and comparison scheme.

2. The isochronous stratigraphic correlation method based on the paleoclimate thermal event response of sporophyll as described in claim 1, characterized in that, In step S3, the key functional group absorption peaks at least include: carboxyl C=0 stretching vibration peak in the wave number range of 1900-1650 cm -1 -1, hydroxyl O-H stretching vibration peak in the wave number range of 3400-3000 cm -1 -1, aliphatic C-H stretching vibration peak in the wave number range of 3000-2800 cm -1 -1, and aromatic C=C stretching vibration peak in the wave number range of 1610-1560 cm -1 -1.

3. The isochronous stratigraphic correlation method based on the paleoclimate-thermal event response of sporophyll as described in claim 2, characterized in that, In step S4, the significant negative anomaly of the carboxyl absorption peak is used as the core indicator for identifying paleoclimate thermal events.

4. The isochronous stratigraphic correlation method based on the paleoclimate thermal event response of sporophyll as described in claim 3, characterized in that, The specific absorption peak for the carboxyl group is 1652.7230 cm⁻¹. -1 The peak value at that location was analyzed.

5. The isochronous stratigraphic correlation method based on the paleoclimate thermal event response of sporophyll as described in claim 3, characterized in that, Before analyzing the carboxyl absorption peak, the spectrum needs to be standardized, and the highest peak within the characteristic peak range or the fitted main peak value should be selected to eliminate background interference and ensure the comparability of data between different samples.

6. The isochronous stratigraphic correlation method based on the paleoclimate thermal event response of sporophyll as described in claim 2, characterized in that, The key functional group absorption peak also includes: located at 3122 cm⁻¹ -1 The absorption peak is located at 1559 cm⁻¹ and is attributed to hydroxyl groups or nitrogen-containing functional groups with strong hydrogen bonding. -1 The absorption peaks at 1070 cm⁻¹ belong to the aromatic C=C skeleton vibrations; and the absorption peak at 1070 cm⁻¹ is also present. -1 The absorption peaks are mainly attributed to the COC ether bond or the S=O vibration of sulfur-containing functional groups.

7. The isochronous stratigraphic correlation method based on the paleoclimate-thermal event response of sporophyll as described in claim 1, characterized in that, Between steps S4 and S5, there is also a volcanic disturbance screening step: if the volcanic glass content in the target section is greater than 5% or the mercury concentration is greater than 200 ppb, then the section is marked as a volcanic disturbance area and will not participate in the stratigraphic correlation based on paleoclimate thermal events.

8. The isochronous stratigraphic correlation method based on the response of sporophyll paleoclimate thermal events according to claim 1, characterized in that, In step S5, while establishing an isochronous comparison interface by comparing the synchronous negative anomaly segments of the carboxyl absorption peak curves in multiple wells, the combination and variation patterns of hydroxyl, aliphatic CH, aromatic C=C, and characteristic absorption peak curves according to claim 6 are also combined to comprehensively identify the type and intensity of thermal events, in order to assist and verify the formation division scheme.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements steps S3 to S5 in the isochronous stratigraphic correlation method based on the response of a sporophyll paleoclimate thermal event as described in any one of claims 1-8.

10. A time-series stratigraphic correlation instrument based on the response of sporophyll paleoclimate thermal events, characterized in that, include: A spectral analysis unit is used to perform the sample preparation as described in claim 1 and to obtain the infrared absorption spectrum as described in claim 2 using a Fourier transform infrared spectrometer; The data processing and comparison unit includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it is used to implement the isochronous stratigraphic correlation step of the paleoclimate thermal event response as described in any one of claims 3-8.

Images