A method and system for recovering a paleogeomorphology of a sedimentary period based on a siliceous rock thickness

Abstract

The present application belongs to the field of palaeogeomorphology restoration, and particularly relates to a method and system for palaeogeomorphology restoration in a sedimentary period based on siliceous rock thickness, which specifically comprises the following steps: establishing a crossplot of a plurality of standardized logging curves and a siliceous rock content curve; screening a siliceous rock sensitive curve sensitive to siliceous content according to the crossplot; carrying out a curve fitting reconstruction identification experiment according to the siliceous rock sensitive curve to obtain a reconstructed curve; selecting an inversion method with the highest coincidence degree with the actual siliceous rock to perform inversion to obtain siliceous rock inversion data; converting time thickness into depth by using time-depth conversion to obtain a siliceous rock thickness planar distribution map; and optimizing the siliceous rock thickness planar distribution map to obtain a final three-dimensional palaeogeomorphology map. The method can successfully solve the problem of the tracking accuracy of conventional methods depending on specific stratigraphic combinations and seismic horizons, and breaks the limitation that if there is no continuous reflection interface above and below the target layer, the palaeogeomorphology of the target layer cannot be accurately restored.

Description

Technical Field

[0001] This invention belongs to the field of paleogeographic restoration, and specifically relates to a method and system for paleogeographic restoration during sedimentary periods based on the thickness of siliceous rocks. Background Technology

[0002] Traditionally, siliceous rocks are sedimentary rocks composed of rocks rich in SiO2 (generally >70%). Since the concentration of silica in natural water bodies is usually very low, silica precipitation often requires unusual external conditions to alter the solubility of silica in the water. Large-scale siliceous rock formations originate from sediments provided by regional submarine volcanic eruptions or other volcanic deposits. According to sedimentary principles, when silica-rich fluids are abundant in seawater, and the water body is relatively high-energy, the silica-rich seawater frequently flows and exchanges materials with surrounding water bodies, making it difficult for silica to be stored for long periods. Therefore, the deposited siliceous rocks are thinner and smaller in scale, such as those found on platform margins or inland highlands. Conversely, in areas with relatively low-energy water, silica-rich seawater is less likely to flow and dissipate, providing better enrichment conditions, resulting in thicker and larger deposited siliceous rocks. Therefore, the thickness of the target layer of siliceous rocks can reflect the morphology of the sedimentary period. Thin siliceous rocks correspond to high-energy sedimentary paleogeographic areas, while thick siliceous rocks correspond to low-energy sedimentary paleogeographic areas.

[0003] Currently, the mainstream paleogeomorphological restoration methods both domestically and internationally can be summarized as follows: imprinting method, residual thickness method, back-exfoliation method, and sequence stratigraphy paleogeomorphological restoration method (including high-resolution sequence stratigraphy paleogeomorphological restoration method). Among these, the imprinting method and residual thickness method mainly utilize seismic and well data to restore the paleogeomorphology of the target layer, and their accuracy is relatively high, with reliable results. In practical applications, they are often combined with well data with high vertical resolution and seismic data with a wide lateral distribution to restore paleogeomorphology. The "imprinting method" often involves selecting a stratigraphic boundary above the target layer and "flattening" it; the morphology of the target layer after flattening is considered to be the paleogeomorphology of the depositional period. The principle for evaluating whether the target layer can be restored using the "imprinting method" is that the depositional process from the target layer to the flattened layer during the depositional period was a "filling and leveling" process, meaning that the regional tectonic activity during the depositional period was relatively stable, and syn-depositional faults were not well developed. The "residual thickness method" uses the residual thickness of the target layer to map the paleogeomorphic conditions during the depositional period. It assumes that the strata were relatively uniform in thickness during deposition, but were thinned by weathering and erosion after deposition. The thickness variation between the top and bottom interfaces of the target layer reflects the paleogeomorphic morphology after deposition. Both of these methods require finding a reflection interface with a relatively stable seismic phase axis. If an interface that meets these requirements cannot be found in practical applications, reliable paleogeomorphic reconstruction results cannot be obtained.

[0004] Therefore, paleogeographic reconstruction is often limited by geological conditions, resulting in significant differences between the reconstruction results and actual drilling. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a method for paleogeographic reconstruction during the sedimentary period based on the thickness of siliceous rocks, comprising the following steps:

[0006] Establish a cross-plot of various standardized logging curves and siliceous rock content curves;

[0007] Based on the cross-sectional chart, sensitive curves for siliceous rocks with sensitive silica content are selected, and curve fitting and reconstruction identification experiments are carried out based on the sensitive curves for siliceous rocks to obtain reconstructed curves;

[0008] The inversion method with the highest consistency with the actual siliceous rocks was selected to invert the target layer of siliceous rocks, and the siliceous rock inversion data was obtained. The time thickness was converted into depth using time-depth conversion to obtain a planar distribution map of siliceous rock thickness.

[0009] The planar distribution map of the siliceous rock thickness is optimized, including correction, three-dimensional visualization, and verification, to obtain the final three-dimensional paleogeographic map.

[0010] Furthermore, the following steps are included before establishing a cross-plot of multiple well logging curves and siliceous rock content curves:

[0011] Collect conventional well data and seismic data for the study area, including well logging curves;

[0012] The seismic data of the study area is loaded to create a synthetic record. The well logging curves are then standardized and displayed on the seismic profile through the synthetic record.

[0013] The characteristics of isochronous siliceous rocks and the well logging identification characteristics of target layer siliceous rocks were clearly defined. At the same time, the rock electrical response model of siliceous rocks was established, and the siliceous rocks were calibrated on single-well seismic synthetic records.

[0014] Furthermore, the conventional well data also includes logging data, drilling data, core sampling data, and regional geological data;

[0015] The seismic data for the study area include post-stack migrated seismic bodies and seismic interpretation horizons of the target layer within the study area.

[0016] Furthermore, the characteristics of isochronous siliceous rocks were clarified through sequence stratigraphy and petrography analysis;

[0017] The logging characteristics of the target layer of siliceous rock were clearly identified through core calibration.

[0018] Furthermore, the intersection chart includes an intersection chart of natural gamma, P-wave velocity, resistivity, wave impedance curves and silicon content curves.

[0019] Furthermore, the reconstructed curve is obtained by performing curve fitting and reconstruction to identify siliceous rocks after using machine learning neural network clustering analysis on the sensitive curve of siliceous rocks.

[0020] The reconstructed curve is sensitive to silica content and has no effect on special rock masses.

[0021] Furthermore, selecting the inversion method that best matches the actual siliceous rocks includes the following steps:

[0022] Different inversion algorithms were used to test siliceous rocks, and the inversion results of siliceous rocks under different inversion algorithms were obtained;

[0023] The results were matched with the fine calibration and inversion of the siliceous rocks from the actual well.

[0024] An inversion method was selected that showed a high degree of matching between the wellbore waveform and the actual logging curve, and whose planar regularity was consistent with that of actual siliceous rock drilling.

[0025] Furthermore, the step of converting time thickness into depth using time-depth conversion to obtain a planar distribution map of siliceous rock thickness includes the following steps:

[0026] The impedance profile uses a set impedance value as a threshold value to extract the time thickness sampling of the target layer in the siliceous rock inversion body.

[0027] The time-depth conversion method is used to convert the time thickness of the target layer into depth, thus obtaining a planar distribution map of the thickness of siliceous rocks.

[0028] Furthermore, the correction, three-dimensional visualization, and verification of the siliceous rock thickness distribution map specifically include the following steps:

[0029] In the planar distribution map of siliceous rock thickness, areas with thick siliceous rock are converted into low paleogeographic value areas, and areas with thin siliceous rock are converted into high paleogeographic value areas, thus obtaining a paleogeographic map to characterize the target layer before deposition.

[0030] A trend surface is fitted onto a plane using the single-well siliceous rock thickness data. The trend surface is then used to correct the paleogeographic map, which is then visualized in three dimensions.

[0031] Verify the visualized paleogeographic maps.

[0032] Furthermore, the verification of the visualized paleogeographic maps includes:

[0033] The paleogeographic map was verified based on regional geological data and the characteristics of siliceous rocks from a single well.

[0034] Paleogeomorphic maps are evaluated using parameters that reflect the geomorphic characteristics of the target layer during its depositional period.

[0035] On the other hand, this invention also proposes a paleogeographic reconstruction system based on the thickness of siliceous rocks during the sedimentary period, comprising:

[0036] The intersection chart creation module is used to create intersection charts of various standardized logging curves and siliceous rock content curves.

[0037] The fitting module is used to screen siliceous rock sensitive curves that are sensitive to silica content based on the intersection chart, and to carry out curve fitting reconstruction and identification experiments based on the siliceous rock sensitive curves to obtain the reconstructed curves;

[0038] The inversion module is used to select the inversion method with the highest consistency with the actual siliceous rock to invert the target layer of siliceous rock, obtain siliceous rock inversion data, and use time-depth conversion to convert time thickness into depth to obtain a siliceous rock thickness planar distribution map;

[0039] The optimization module is used to optimize the planar distribution map of the siliceous rock thickness, including correction, three-dimensional visualization, and verification, to obtain the final three-dimensional paleogeographic map.

[0040] Furthermore, the system also includes:

[0041] The data collection module collects conventional well data and seismic data of the study area, including well logging curves.

[0042] The loading module is used to load seismic data from the study area to create synthetic records, and to display the standardized well logging curves on the seismic profile through the synthetic records.

[0043] The calibration module is used to identify the characteristics of siliceous rocks with isochronous significance and the well logging identification characteristics of siliceous rocks in the target layer. At the same time, it establishes the rock electrical response model of siliceous rocks and calibrates the siliceous rocks on the single-well seismic synthetic record.

[0044] The beneficial effects of this invention are:

[0045] This invention uses the thickness of siliceous rock to restore the paleomorphological trend, which is in line with the principles of sedimentology. When traditional methods are not applicable to the work area, it can simply and effectively restore the paleomorphological trend of the work area. When compared with the actual situation of a single well, it has a high degree of matching and is more in line with the actual geological conditions.

[0046] The restoration method proposed in this invention can successfully solve the problem that conventional methods rely on specific stratigraphic combinations and the tracking accuracy of seismic horizons. It overcomes the limitation that if there are no continuously trackable reflection interfaces above and below the target layer, the sedimentary paleogeography of the target layer cannot be accurately restored.

[0047] This invention does not require the addition of new seismic interpretation horizons; it is completed based on the existing interpretation results of the target horizon, which can effectively reduce the workload of seismic interpretation.

[0048] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 A flowchart of a method for paleogeographic reconstruction based on siliceous rock thickness during sedimentary periods, as illustrated in an embodiment of the present invention, is shown.

[0051] Figure 2 This invention illustrates a composite columnar section of a single well in the target layer of the study area, as shown in this embodiment of the invention.

[0052] Figure 3a This invention illustrates the intersection of siliceous rock content and impedance curves before and after reconstruction in an embodiment of the invention.

[0053] Figure 3b The following are histograms of silica rock content and impedance curves before and after reconstruction in an embodiment of the present invention;

[0054] Figure 4 This diagram illustrates the effect of identifying silica content using a single-well reconstructed impedance curve in an embodiment of the present invention.

[0055] Figure 5 The experimental results of different inversion methods used in embodiments of the present invention are shown in the figure.

[0056] Figure 6 This invention presents a comparison diagram of the well-connected profile and the inverted profile developed in the target layer of siliceous rock in an embodiment of the invention.

[0057] Figure 7 A planar distribution diagram of the thickness of the target layer of siliceous rock is shown in an embodiment of the present invention;

[0058] Figure 8 The image shows a three-dimensional geomorphological display of the target layer during its depositional period, obtained in an embodiment of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] This invention aims to propose a reliable paleogeographic reconstruction method that does not require finding a reflection interface with a relatively stable phase along the seismic phase axis, such as... Figure 1 As shown, the specific steps include:

[0061] A method for paleogeographic reconstruction during the sedimentary period based on the thickness of siliceous rocks includes the following steps:

[0062] (1) Basic data collection and organization: Collect conventional well data and seismic data of the study area;

[0063] Specifically, conventional well data includes: conventional logging curves and silica content curves, logging data, drilling data, core sampling data, and regional geological data;

[0064] Seismic data for the study area include post-stack migrated seismic bodies and seismic interpretation horizons of the target layer.

[0065] Furthermore, the conventional logging curves are standardized. Standardization involves taking standard wells as a basis, comparing the logging curves of the same formation in the same oilfield with similar geological and geophysical characteristics, calculating the correction value, and then standardizing and correcting abnormal wells.

[0066] (2) Data loading and seismic interpretation work area establishment: Load the seismic data in the study area, that is, load the post-stack migrated seismic bodies and the seismic interpretation horizons of the target layer in the study area, and make synthetic records. The collected well logging curves are displayed on the seismic profile through the synthetic records. Specifically, the synthetic records are converted into seismic records by artificial synthesis based on conventional well logging data, and are mainly used for horizon interpretation and calibration.

[0067] (3) Isochronous siliceous rock characteristic analysis: Clarify the characteristics of siliceous rocks with isochronous significance and the well logging identification characteristics of siliceous rocks in the target layer. At the same time, establish the rock electrical response model of siliceous rocks to facilitate the summary of the well logging response characteristics of siliceous rocks, lay the foundation for subsequent rock physical analysis, and mark the siliceous rock strata on the single-well seismic synthetic record.

[0068] Specifically, through sequence stratigraphy and petrographic analysis, the characteristics of isochronous siliceous rocks were identified; and through core calibration, the well logging identification characteristics of the target layer of siliceous rocks were identified.

[0069] (4) Petrophysical analysis of siliceous rocks: Establishing a cross-plot of various well logging curves and siliceous rock content;

[0070] Specifically, the various logging curves include natural gamma, P-wave velocity, resistivity, and wave impedance curves;

[0071] The intersection chart refers to the intersection chart of the natural gamma curve, P-wave velocity curve, resistivity curve, wave impedance curve, and silicon content curve.

[0072] (5) Selection of sensitive parameters for identifying siliceous rocks: Based on the cross-plot reflecting the sensitivity of each logging curve parameter to silica content, analyze and select curve parameters sensitive to silica content;

[0073] Specifically, the sensitivity of each logging curve parameter to silica content can be arranged in a certain order, and the sensitive curve parameters can be selected.

[0074] (6) Reconstruction and fitting test of sensitive curve of siliceous rock: The curve fitting and reconstruction test of sensitive curve of siliceous rock is carried out to identify siliceous rock, and the reconstructed curve is obtained. The accuracy of the reconstructed curve is verified by comparing it with the logging interpretation results of actual wells.

[0075] Specifically, machine learning neural network clustering analysis was used to perform curve fitting and reconstruction experiments to identify siliceous rocks based on the sensitivity curves of siliceous rocks. The reconstructed curves were compared and analyzed with the measured curves to determine if the trends were consistent, and the error was controlled within 1%. This yielded a reconstructed curve that was sensitive to siliceous content and eliminated the influence of special rock masses.

[0076] (7) Siliceous rock inversion and verification of inversion results: Inversion matching is performed based on conventional well data, seismic data and seismic interpretation layer data of the target layer, and an inversion method that matches the actual siliceous rock drilling is selected;

[0077] The specific steps are as follows:

[0078] Different inversion algorithms were tested to obtain the inversion results of siliceous rocks under different inversion algorithms;

[0079] By matching the fine calibration of siliceous rocks in actual wells with the inversion results, the fine calibration in this study is of the seismic response characteristics of siliceous rocks;

[0080] An inversion method was selected that showed a high degree of matching between the wellbore waveform and the actual logging curve, and whose planar regularity was consistent with that of actual siliceous rock drilling.

[0081] (8) Recovery of the planar distribution of siliceous rock thickness: The target layer of siliceous rock is inverted to obtain siliceous rock inversion data. The time thickness of the target layer segment of the siliceous rock inversion body is sampled, and the time thickness is further converted into depth using time-depth conversion to obtain the planar distribution map of siliceous rock thickness. The time thickness is obtained based on the seismic interpretation layer of the target layer.

[0082] Specifically, the geostatistical inversion method is used to invert siliceous rocks based on existing post-stack seismic data to obtain siliceous rock inversion data. According to the rock physical analysis results in steps (1)-(7), the impedance profile is set with the impedance value as the threshold value. The time thickness of the target layer of the siliceous rock inversion body is sampled using the threshold value. The time thickness is further converted into depth using time-depth conversion to obtain the siliceous rock thickness plane distribution map.

[0083] The time conversion formula is as follows:

[0084] H = t * V

[0085] Where H represents depth, t represents time thickness, and V represents the time-depth transition velocity field.

[0086] (9) Geomorphological map correction and three-dimensional visualization of geomorphological map: The planar distribution map of the thickness of siliceous rock is corrected and then three-dimensional visualization is performed to characterize the sedimentary paleogeography before the deposition of the target layer;

[0087] Specifically, it includes the following steps:

[0088] (9.1) Based on the principle of sedimentology, areas with thick siliceous rocks are converted into low paleogeographic value areas, and areas with thin siliceous rocks are converted into high paleogeographic value areas, so as to obtain the sedimentary paleogeography that characterizes the target layer before deposition.

[0089] (9.2) Then fit a trend surface on the plane to the single-well siliceous rock thickness data, use the trend surface to correct the paleogeographic map transformed in 9.1, and then perform three-dimensional visualization display.

[0090] (10) Verification of geomorphological restoration results: The geomorphological restoration results are verified based on regional geological data and the situation of siliceous rocks in single wells. The paleogeomorphological map is evaluated by other parameters that reflect the geomorphological characteristics of the target layer during the deposition period, including parameters such as stratigraphic thickness and properties, and finally an accurate three-dimensional paleogeomorphological map is obtained.

[0091] Based on the above method, this invention proposes a paleogeographic reconstruction system for sedimentary periods based on the thickness of siliceous rocks, comprising:

[0092] The data collection module collects conventional well data and seismic data of the study area, including well logging curves.

[0093] The loading module is used to load seismic data from the study area to create synthetic records, and to display the standardized well logging curves on the seismic profile through the synthetic records.

[0094] The calibration module is used to clarify the characteristics of siliceous rocks with isochronous significance and the well logging identification characteristics of siliceous rocks in the target layer. At the same time, it establishes the rock electrical response model of siliceous rocks and calibrates siliceous rocks on single-well seismic synthetic records.

[0095] The intersection chart creation module is used to create intersection charts of various standardized logging curves and siliceous rock content curves.

[0096] The fitting module is used to screen siliceous rock sensitive curves that are sensitive to silica content based on the intersection chart, and to carry out curve fitting reconstruction and identification experiments based on the siliceous rock sensitive curves to obtain the reconstructed curves;

[0097] The inversion module is used to select the inversion method with the highest consistency with the actual siliceous rock to invert the target layer of siliceous rock, obtain siliceous rock inversion data, and use time-depth conversion to convert time thickness into depth to obtain a siliceous rock thickness planar distribution map;

[0098] The optimization module is used to optimize the planar distribution map of the siliceous rock thickness, including correction, three-dimensional visualization display, and verification, to obtain the final three-dimensional paleogeographic map.

[0099] The system also includes:

[0100] The above steps will be described in detail below with reference to specific embodiments and corresponding drawings.

[0101] (1) Collection and organization of basic data.

[0102] Conventional logging curves and silica content curves, logging data, drilling data, core data and regional geological data were collected. Seismic data such as post-stack migrated seismic bodies and seismic interpretation horizons of the target layer in the study area were also collected, and the logging curves were standardized.

[0103] (2) Data loading and seismic interpretation work area establishment. Load the well logging data and seismic interpretation horizon of the target layer in the study area, create a composite record, and display the well logging curves on the seismic profile through the composite record.

[0104] (3) Analysis of isochronous siliceous rock characteristics. Through sequence stratigraphy and petrographic characteristics of siliceous rocks, it was determined that the relatively stable siliceous rocks have isochronous significance and are developed from the maximum transgression of the target layer in the study area to the early highstand zone. Their thickness and distribution are closely related to the geomorphology during the depositional period.

[0105] The results of its feature analysis are as follows Figure 2 As shown, Figure 2This is a comprehensive columnar section of a single well in the target formation of the study area. From left to right, the section includes the formation, well logging curves, depth, lithological profile, third-order sequence stratigraphy, deep double lateral resistivity (RLLD) and deep double lateral resistivity logging curves (RLLS), silica content, physical properties (including porosity and permeability), lithological description, core and microscopic images, sedimentary facies, and sea level. As can be seen from the figure, the siliceous rock section of this example is the marked area, with formation depths of 5168-5194m and 5208-5217m. The 5168-5194m section consists of algal-agglomerated dolomite, with intermediate interlayered siliceous algal stromatolites and a bottom layer of micritic dolomite; the 5208-5217m section consists of siliceous algal stromatolites and micritic dolomite.

[0106] The strata are divided into three types: system, group, and section. The system includes the Cambrian and Sinian systems; the group is divided into the Qiongzhusi Formation and the Dengying Formation; the section is divided into Deng 43, Deng 42 and Deng 41; the logging curves include natural gamma (GR), sonic logging (AC), density logging (DEN), compensated neutron logging (CNL), and caliper logging (CAL); the sedimentary facies are divided into microfacies, subfacies and facies.

[0107] (4) Petrophysical analysis of siliceous rocks. Establish a cross-plot of various well logging curves with siliceous rock content, and establish a cross-plot of natural gamma, P-wave velocity, resistivity and wave impedance curves with siliceous rock content curves.

[0108] (5) Optimization of Sensitive Parameters for Siliceous Rock Identification. Based on the sensitivity of each curve parameter to silica content as reflected in the cross-plots, the curve parameters sensitive to silica content are analyzed and optimized. The results of each cross-plot are as follows: Figure 3a and 3b As shown, 3a is the intersection of siliceous rock content and impedance curve before and after reconstruction, with the vertical axis representing siliceous content; Figure 3b The histograms before and after reconstruction of the siliceous rock content and impedance curves are shown, with the vertical axis representing percentages. From the cross-sectional results, siliceous content shows a good correlation with wave impedance. However, the existing impedance curves with a single impedance threshold are insufficient to effectively remove the influence of special low-resistivity rock bodies (reservoirs), such as dolomite and reservoirs.

[0109] (6) Siliceous Rock Sensitivity Curve Reconstruction and Fitting Experiment. In this embodiment, to effectively predict siliceous rocks, machine learning neural network clustering analysis was used to conduct a curve fitting and reconstruction experiment to identify siliceous rocks, obtaining a reconstructed curve sensitive to silica content while eliminating the influence of special rock masses. The reconstructed curve is shown below. Figure 4 As shown, after reconstructing the curve, the intersection analysis with the original curve shows that the reconstructed wave impedance retains the response characteristics of siliceous rocks. At the same time, by limiting the resistance value, the influence of other low-resistivity rock masses can be effectively eliminated.

[0110] Based on the actual logging interpretation and well calibration results, the reconstructed curves were adjusted according to a certain threshold (impedance less than 17500 g·m / cm). 3 The ·s) curve can effectively distinguish siliceous rocks, with low impedance corresponding to high-siliceous rock sections. Through curve reconstruction, the characteristics of low impedance and high silica content are more pronounced, and the impedance fit is better (upper limit of the reconstructed curve impedance is 17500 g·m / cm). 3 ·s), through the cross-analysis of silica content and reconstructed wave impedance, a clear linear relationship between silica content and wave impedance is shown, such as Figure 3a and 3b As shown.

[0111] (7) Siliceous rock inversion and verification of inversion results. Different inversion algorithms were tested to obtain siliceous rock inversion data under different algorithms. The inversion results were matched with the fine calibration of siliceous rock in actual wells. The inversion method with high matching degree between the wellbore waveform and the actual logging curve, and whose plane regularity matches the actual drilling, was selected. The results are as follows: Figure 5 As shown, Figure 5 The experimental results of relative impedance inversion, sparse pulse inversion, maximum likelihood inversion, neural network inversion, and geostatistical inversion are shown. The results indicate that the relative impedance method < sparse pulse method < maximum likelihood method < neural network method < geostatistical inversion. The geostatistical inversion results show the best match with the actual drilling, and the wellbore waveform has the highest matching degree with the actual logging curve. Therefore, geostatistical inversion was used in this study. A comparison of the well profile and the inverted profile of the target siliceous rock formation is shown below. Figure 6 As shown, the inversion analysis matches the actual drilling data.

[0112] (8) Recovery of the planar distribution of siliceous rock thickness. Using geostatistical inversion methods, based on existing post-stack seismic data, siliceous rock inversion data was obtained. Based on the rock physical analysis results from steps (1-7), the impedance profile was constructed with an impedance value of 17500 g·m / cm. 3 ·s is a threshold value. The time thickness sampling of the target layer in the siliceous rock inversion body is extracted using this threshold value. Further time-depth conversion is then used to transform the time thickness into depth, resulting in the following: Figure 7 The diagram shown is a planar distribution of the thickness of the target layer of siliceous rock. Figure 7 For example, GS-119 and GS-127 are well numbers for the study area.

[0113] (9) Geomorphological Map Correction and 3D Visualization. According to sedimentological principles, when silica-rich fluids are developed in seawater and the water body is relatively high-energy, the silica-rich seawater frequently flows and exchanges materials with the surrounding water body, making it difficult for silica to be stored for a long time. Therefore, the deposited siliceous rocks are relatively thin and small in scale, such as platform margins or intraplatform highlands. Conversely, in areas with relatively low water energy, silica-rich seawater is not easily dissipated, resulting in good enrichment conditions and thicker, larger deposited siliceous rocks. Therefore, the depositional thickness of the target layer's siliceous rocks can reflect the geomorphological morphology during the depositional period. Thin siliceous rocks correspond to high-energy paleogeographic regions. Therefore, areas with thick siliceous rocks need to be converted into low-value paleogeographic regions, and areas with thin siliceous rocks need to be converted into high-value paleogeographic regions to obtain the paleogeographic features before the deposition of the target layer. Furthermore, a trend surface is fitted onto the single-well siliceous rock thickness data on a plane. This trend surface is used to correct the paleogeographic map, reducing errors, and then a 3D visualization is performed. The 3D geomorphological display map of the target layer's depositional period is shown below. Figure 8 As shown.

[0114] (10) Verification of geomorphological restoration results. The geomorphological restoration results are verified based on the regional geological data and the situation of siliceous rocks in single wells. Furthermore, the results can be evaluated by other parameters that reflect the geomorphological characteristics of the target layer during the deposition period, and finally, an accurate three-dimensional paleogeomorphology of the deposition period can be obtained.

[0115] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for paleogeographic reconstruction during the sedimentary period based on the thickness of siliceous rocks, characterized in that, Includes the following steps: Establish a cross-plot of various standardized logging curves and siliceous rock content curves; Based on the cross-sectional chart, sensitive curves for siliceous rocks with sensitive silica content are selected, and curve fitting and reconstruction identification experiments are carried out based on the sensitive curves for siliceous rocks to obtain reconstructed curves; The inversion method with the highest consistency with the actual siliceous rocks was selected to invert the target layer of siliceous rocks, and the siliceous rock inversion data was obtained. The time thickness was converted into depth using time-depth conversion to obtain a planar distribution map of siliceous rock thickness. The planar distribution map of the siliceous rock thickness is optimized, including correction, three-dimensional visualization, and verification, to obtain the final three-dimensional paleogeographic map.

2. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 1, characterized in that, Before establishing a composite chart of multiple well logging curves and siliceous rock content curves, the following steps are also included: Collect conventional well data and seismic data for the study area, including well logging curves; The seismic data of the study area is loaded to create a synthetic record. The well logging curves are then standardized and displayed on the seismic profile through the synthetic record. The characteristics of isochronous siliceous rocks and the well logging identification characteristics of target layer siliceous rocks were clearly defined. At the same time, the rock electrical response model of siliceous rocks was established, and the siliceous rocks were calibrated on single-well seismic synthetic records.

3. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 2, characterized in that, The conventional well data also includes logging data, drilling data, core sampling data, and regional geological data; The seismic data for the study area include post-stack migrated seismic bodies and seismic interpretation horizons of the target layer within the study area.

4. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 2, characterized in that, The characteristics of isochronous siliceous rocks were clarified through sequence stratigraphy and petrography analysis; The logging characteristics of the target layer of siliceous rock were clearly identified through core calibration.

5. The method for paleogeographic reconstruction based on siliceous rock thickness during sedimentary periods according to claim 1 or 2, characterized in that, The intersection chart includes an intersection chart of natural gamma, P-wave velocity, resistivity, wave impedance curves and silicon content curves.

6. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 1, characterized in that, The reconstructed curve was obtained by performing curve fitting and reconstruction to identify siliceous rocks after using machine learning neural network clustering analysis on the sensitive curve of siliceous rocks. The reconstructed curve is sensitive to silica content and has no effect on special rock masses.

7. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 1, characterized in that, Selecting the inversion method that best matches the actual siliceous rocks includes the following steps: Different inversion algorithms were used to test siliceous rocks, and the inversion results of siliceous rocks under different inversion algorithms were obtained; The results were matched with the fine calibration and inversion of the siliceous rocks from the actual well. An inversion method was selected that showed a high degree of matching between the wellbore waveform and the actual logging curve, and whose planar regularity was consistent with that of actual siliceous rock drilling.

8. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 1, characterized in that, The process of converting time thickness into depth using time-depth conversion to obtain a planar distribution map of siliceous rock thickness includes the following steps: The impedance profile uses a set impedance value as a threshold value to extract the time thickness sampling of the target layer in the siliceous rock inversion body. The time-depth conversion method is used to convert the time thickness of the target layer into depth, thus obtaining a planar distribution map of the thickness of siliceous rocks.

9. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 1, characterized in that, The correction, three-dimensional visualization, and verification of the siliceous rock thickness distribution map specifically include the following steps: In the planar distribution map of siliceous rock thickness, areas with thick siliceous rock are converted into low paleogeographic value areas, and areas with thin siliceous rock are converted into high paleogeographic value areas, thus obtaining a paleogeographic map to characterize the target layer before deposition. A trend surface is fitted onto a plane using the single-well siliceous rock thickness data. The trend surface is then used to correct the paleogeographic map, which is then visualized in three dimensions. Verify the visualized paleogeographic maps.

10. The method for paleogeographic reconstruction based on siliceous rock thickness during the sedimentary period according to claim 1, characterized in that, Verification of visualized paleogeographic maps includes: The paleogeographic map was verified based on regional geological data and the characteristics of siliceous rocks from a single well. Paleogeomorphic maps are evaluated using parameters that reflect the geomorphic characteristics of the target layer during its depositional period.

11. A paleogeographic reconstruction system based on the thickness of siliceous rocks during the sedimentary period, characterized in that, include: The intersection chart creation module is used to create intersection charts of various standardized logging curves and siliceous rock content curves. The fitting module is used to screen siliceous rock sensitive curves that are sensitive to silica content based on the intersection chart, and to carry out curve fitting reconstruction and identification experiments based on the siliceous rock sensitive curves to obtain the reconstructed curves; The inversion module is used to select the inversion method with the highest consistency with the actual siliceous rock to invert the target layer of siliceous rock, obtain siliceous rock inversion data, and use time-depth conversion to convert time thickness into depth to obtain a siliceous rock thickness planar distribution map; The optimization module is used to optimize the planar distribution map of the siliceous rock thickness, including correction, three-dimensional visualization, and verification, to obtain the final three-dimensional paleogeographic map.

12. The paleogeographic reconstruction system based on siliceous rock thickness during the sedimentary period according to claim 11, characterized in that, The system also includes: The data collection module collects conventional well data and seismic data of the study area, including well logging curves. The loading module is used to load seismic data from the study area to create synthetic records, and to display the standardized well logging curves on the seismic profile through the synthetic records. The calibration module is used to identify the characteristics of siliceous rocks with isochronous significance and the well logging identification characteristics of siliceous rocks in the target layer. At the same time, it establishes the rock electrical response model of siliceous rocks and calibrates the siliceous rocks on the single-well seismic synthetic record.

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