Method for improving accuracy of sedimentary facies boundary and drawing sedimentary facies plane distribution diagram

Abstract

The invention relates to the technical field of oil-gas exploration, and discloses a method for improving the accuracy of a sedimentary facies boundary and drawing a sedimentary facies plane distribution diagram. The method for improving the accuracy of the sedimentary facies boundary comprises the following steps of: delimiting threshold values of dolomite and limestone proportions of different phase belts; on the basis of a large number of single factors and related sedimentary facies statistical analysis, lithofacies single factor characteristics and sedimentary facies corresponding models are established. The method for drawing the sedimentary facies plane distribution diagram comprises the following steps: drawing a dolomite ratio and limestone ratio contour map; and based on a sedimentary facies corresponding model, determining the related sub-facies boundary of the tidal plateau facies, and comprehensively drawing a planar distribution diagram of the sedimentary facies of the lagoon, the in-platform beach and the whole basin in combination with the gypsum rock proportion contour map and the granular rock content. According to the technical scheme, the lithofacies single-factor feature and sedimentary phase corresponding model is established, and the accuracy of the sedimentary facies boundary is improved. The method accords with the actual condition of oil-gas geology research and is suitable for quickly and accurately analyzing the sedimentary facies boundary plane distribution rule so as to assist in judging oil-gas distribution.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration, and in particular to a method for improving the accuracy of sedimentary phase boundaries and drawing a sedimentary phase plane distribution map. Background Art

[0002] The prior art search and analysis of the present invention is as follows:

[0003] Wei Yanping et al. (2016) invented a method for identifying the nearshore underwater fan sedimentary facies belt in the steep slope zone of the faulted lake basin (application number CN201610909062.3), comprising: step 1, obtaining the seismic data of the block, conventional logging data of the drilling, and logging lithological data; step 2, determining the sedimentary facies of the single well by calibrating the synthetic records of the single well; step 3, summarizing the seismic facies characteristics of the nearshore underwater fan conglomerate body through the seismic profile of the connected wells based on the calibration of the synthetic seismic records of each single well; step 4, identifying the sedimentary facies belt interface of the conglomerate body based on the seismic facies characteristics of the nearshore underwater fan conglomerate body; step 5, dividing the sedimentary facies belt interface; step 6, determining the planar distribution of the sedimentary facies belt of the nearshore underwater fan conglomerate body based on the combination of the seismic profile and the sedimentary phase comparison profile of the connected wells.

[0004] Li Ling et al. (2012) compiled 10 lithofacies paleogeographic maps of the sedimentary period of the fourth-order sequence based on single well core, logging and electrical curve data, field profile stratigraphy and sedimentary facies analysis, combined with the paleotopography, paleoclimate and tectonic evolution of the Middle Triassic, through the analysis of the plane regularity of the thickness of grainstone and gypsum, assisted by the plane distribution characteristics of dolomite and limestone, and using the fourth-order sequence as the mapping unit. It is pointed out that during the Leikoupo Formation period, the Sichuan Basin developed restricted platform, restricted-evaporite platform facies and platform margin facies, as well as subfacies types such as restricted lagoon, evaporite lagoon, tidal flat, platform flat, platform intra-platform beach and platform margin beach.

[0005] Sun Chunyan et al. (2018) classified the Middle Triassic Leikoupo Formation in the Sichuan Basin into a carbonate platform sedimentary system based on core marks, logging marks, sedimentary rock types, primary sedimentary structures and sedimentary microfacies marks. The Middle Triassic Leikoupo Formation in the Sichuan Basin developed a set of shallow-water carbonate platform facies sedimentary systems, as well as four types of phase belts, including restricted-evaporative platform, platform edge, and open platform, as well as sub-facies such as restricted tidal flat, intra-platform beach, restricted lagoon, and evaporative lagoon (gypsum flat). The phase belts are clearly differentiated from west to east on the plane.

[0006] Based on the paleogeographic background and paleoclimate conditions of the Sichuan Basin, combined with the observation of field profiles, cores and thin sections of the Middle Triassic Leikoupo Formation and the analysis of single well and connected well sedimentary phases, Lv Yuzhen et al. (2013) believed that the barrier effect of the surrounding underwater uplift and the dry and hot climate conditions jointly affected the sedimentary phase characteristics of the Leikoupo Formation in the Sichuan Basin. The Leikoupo Formation is generally a set of barrier evaporative lagoon deposits, which can be divided into four sedimentary subfacies types: lagoon edge flat, lagoon, tidal flat and platform barrier. The lagoon edge flat can be further divided into dolomite flat, muddy gypsum dolomite flat, limestone flat and gypsum limestone flat. The lagoon phase is mainly composed of gray lagoon and gypsum salt lake deposits.

[0007] Lin Liangbiao et al. (2007) divided the Leikoupo Formation in the study area into one sedimentary phase, three subphases and several sedimentary microphases based on the analysis of sedimentary petrology, paleontology and logging phase characteristics. They pointed out that the Leikoupo Formation in the middle Triassic in the northwestern Sichuan Basin mainly developed three sedimentary subphases: evaporation platform, restricted platform and open platform, among which the restricted platform is the main sedimentary subphase. The development and spatial distribution of the Leikoupo sedimentary phases from the first to the fifth phases were mainly controlled by the rise and fall of the sea level: from the first to the third phase, the water body gradually deepened, the sedimentary environment changed from restricted platform and evaporation platform to restricted platform and open platform, the clastic shoal gradually became larger, and the gypsum lake gradually disappeared. In the fourth phase, the water body became shallower, the sedimentary environment was restricted platform and evaporation platform, gypsum basin deposits developed in the Zitong area, and the clastic shoal shrunk. In the fifth phase, the water body deepened again, forming an open platform deposit. Grain-clastic shoals were widely developed in Majiaoba, Jiangyou and Hanwang, Mianzhu, and the thickness of the shoals increased.

[0008] Yang Wei et al. (2021) used outcrop, core, drilling, logging and other data to believe that the Leikoupo Formation in the Sichuan Basin mainly developed sedimentary facies such as platform margin, open platform, restricted platform and evaporative platform. The Lei 1 and 2 segments formed a weakly rimmed closed platform sedimentary system, dominated by restricted platform facies; the Lei 3 and 4 segments formed a rimmed carbonate platform sedimentary system, indicating that seawater mainly entered from the west during the deposition of the Leikoupo Formation in the Sichuan Basin, and was closed in the south, east and north directions, forming a relatively closed carbonate platform. The Lei 1 and 2 segments were weakly rimmed carbonate platforms during their deposition, and the Lei 3 and 4 segments were rimmed carbonate platforms during their deposition. The basin mainly developed sedimentary facies such as platform margin, open platform, restricted platform and evaporative platform, with the restricted platform facies being the most widely distributed, including subfacies such as lagoons, intra-platform beaches and tidal flats.

[0009] He Wenyuan et al. (2020) invented a method for well-seismic coordinated division of sedimentary microfacies based on a high-precision sequence framework model (application number CN202011181858.4). This method is based on the seismic response characteristics of the lithology combination and cyclic characteristics of the sedimentary body under the high-precision sequence stratigraphic shelf, establishes a matching relationship between well-seismic sedimentary facies characteristics, and selects seismic attributes that are sensitive to the type of sedimentary facies of the stratum. Through well-seismic coordinated simulation, a three-dimensional data body of sedimentary subfacies and microfacies of the target layer is established. The reliability and accuracy of the three-dimensional data body of the sedimentary facies are verified by the phase sequence law, and finally the sedimentary facies division results that meet industrial standards are obtained.

[0010] In the prior art, the basis for the division of sedimentary phases is mainly based on single well cores and thin sections, logging and electrical curve data, field profile strata and primary sedimentary structures. After the sedimentary phases are divided according to single wells and earthquakes, when plane mapping is carried out, the boundaries of the sedimentary phases will be drawn more arbitrarily and the accuracy will be reduced in the areas where data points are missing. Summary of the invention

[0011] The present application provides a method for improving the accuracy of sedimentary phase boundaries and drawing a sedimentary phase plane distribution map to solve the above-mentioned technical problems in the prior art.

[0012] According to one aspect of the present application, an embodiment provides a method for improving the accuracy of sedimentary facies boundaries, dividing the boundary of the tidal flat facies according to the correlation between the content of limestone and dolomite, wherein when dividing the boundary of the lagoon facies and the inner platform beach, the content of gypsum, mudstone and algae sand fragments is introduced for comprehensive delineation; the method for improving the accuracy of sedimentary facies boundaries comprises the following steps:

[0013] S1. Delineate the thresholds of dolomite and limestone proportions in different phase zones;

[0014] S2. Based on the statistical analysis of a large number of single factors and related sedimentary phases, a corresponding model of lithofacies single factor characteristics and sedimentary phases is established.

[0015] In one embodiment, the threshold for delineating the proportion of dolomite and limestone in different phase zones is obtained by first determining the phase zone affiliation based on core observations, drilling dissections and thin section identifications of multiple typical wells, and then comparing it with the statistical data of limestone, dolomite and gypsum to further determine the comparison scheme.

[0016] In one embodiment, in the sedimentary correspondence model, the boundary of 40% limestone content and 60% dolomite content is the boundary threshold for quantitatively distinguishing the upper intertidal zone and the lower intertidal zone.

[0017] In one embodiment, in the sedimentary corresponding model, the dolomite content is 80%, and the content of gypsum and mud is less than 20%, which is the boundary mark of the supratidal zone.

[0018] In one embodiment, in the sedimentary corresponding model, the dolomite content is 20%-60%, while the limestone content is 40%-80% and the presence of gypsum and mudstone is a boundary marker of a confined lagoon.

[0019] In one embodiment, in the sedimentary corresponding model, dolomite content <40% and rich in gypsum are the boundary marks of evaporative lagoons.

[0020] In one embodiment, in the paste-rich form, the paste content is greater than 60%.

[0021] In one embodiment, in the sedimentary phase corresponding model, the boundary mark of the inner beach is in the tidal flat phase and contains algae and sand debris.

[0022] According to one aspect of the present application, an embodiment provides a method for drawing a sedimentary phase plane distribution map, comprising the following steps:

[0023] S1. Draw a dolomite proportion contour map based on the ratio of dolomite to stratum thickness;

[0024] S2. Based on the ratio of limestone to stratum thickness, draw a contour map of limestone proportion;

[0025] S3. Apply the map formed by steps S1 and S2, determine the relevant subphase boundaries of the tidal flat phase based on the sedimentary phase correspondence model described in any of the methods for improving the accuracy of sedimentary phase boundaries described in the above, and combine the contour map of gypsum proportion and grainstone content to comprehensively draw the plane distribution map of the sedimentary phases of the lagoon, platform beach and the entire basin.

[0026] In one embodiment, step S1 further includes the following sub-steps: counting the ratio of the dolomite to the stratum thickness at multiple data points; and / or,

[0027] Step S2 also includes the following sub-steps: Counting the ratio of the thickness of the stratum occupied by the limestone at multiple data points. The technical scheme of the above-mentioned embodiment of the present application clarifies the single-factor statistical data characteristics of the lithofacies that are well correlated with the sedimentary phase through multi-faceted and multi-indicator research. In terms of sedimentary phase boundary division, a single-factor characteristic of the lithofacies and a corresponding model of the sedimentary phase boundary are established to improve the accuracy of the sedimentary phase boundary. The technical scheme of the above-mentioned embodiment of the present application conforms to the actual situation of oil and gas geological research, is suitable for quickly and accurately analyzing the planar distribution law of sedimentary phase boundaries, and thus assists in judging the distribution of oil and gas, and has an optimistic application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a technical roadmap for a method of improving the accuracy of sedimentary phase boundaries in an embodiment;

[0029] Figure 2 is a schematic diagram of a single factor characteristic of lithofacies and a corresponding model of sedimentation in an embodiment;

[0030] Figure 3 is a contour map of dolomite proportion in the upper Leisan sub-member of the Sichuan Basin in an embodiment;

[0031] Figure 4 is a contour map of limestone proportion in the upper Leisan sub-member of the Sichuan Basin in an embodiment;

[0032] Figure 5 is a contour map of the proportion of gypsum in the upper sub-member of Leisan in the Sichuan Basin in an embodiment;

[0033] Figure 6 The sedimentary facies distribution map of the upper subsection of Leisan in Sichuan Basin is an embodiment. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0036] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, method, system, product or equipment comprising a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0037] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element. Moreover, in this application, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element through a third element.

[0038] Embodiment 1

[0039] An embodiment provides a method for improving the accuracy of sedimentary facies boundaries. Based on single-factor statistics of lithofacies, the statistical results of different lithology data of drilling are used to determine the sedimentary facies boundaries, which can improve the accuracy of sedimentary facies plane maps. Furthermore, the method for improving the accuracy of sedimentary facies boundaries divides the boundaries of tidal flat facies according to the correlation between the content of limestone and dolomite. When dividing the boundaries of lagoon facies and inner platform beaches, the content of gypsum, mudstone and algae sand fragments is introduced for comprehensive delineation. The method for improving the accuracy of sedimentary facies boundaries includes the following steps:

[0040] S1. Delineating the thresholds for the proportions of dolomite and limestone in different phase zones; generally, the thresholds for delineating the proportions of dolomite and limestone in different phase zones are obtained by first determining the phase zone attribution based on core observations, drilling dissections and thin section identifications of multiple typical wells, and then comparing them with the statistical data of limestone, dolomite and gypsum to further determine the comparison plan.

[0041] S2. Based on the statistical analysis of a large number of single factors and related sedimentary phases, a corresponding model of lithofacies single factor characteristics and sedimentary phases is established.

[0042] Regarding the sedimentary corresponding model, the boundary of 40% limestone content and 60% dolomite content is the boundary threshold for quantitatively distinguishing the upper intertidal zone and the lower intertidal zone; and / or, the dolomite content is 80%, and the content of gypsum and mud is less than 20%, which is the boundary mark of the supratidal zone; and / or, the dolomite content is 20%-60%, and the limestone content is 40%-80% and contains gypsum and mudstone, which is the boundary mark of the confined lagoon; and / or, the dolomite content is less than 40% and rich in gypsum is the boundary mark of the evaporative lagoon.

[0043] In one embodiment, in the paste-rich form, the paste content is greater than 60%.

[0044] In one embodiment, in the sedimentary phase corresponding model, the boundary mark of the inner beach is in the tidal flat phase and contains algae and sand debris.

[0045] Embodiment 2

[0046] Please refer to Figure 2 An embodiment provides a method for improving the accuracy of sedimentary phase boundaries. The following will explain the technical solution of the present invention with the ideas of the inventor, which will help those skilled in the art to be familiar with the ideas of the present invention. Among them, some technical points are explained in detail so that those skilled in the art can fully understand the technical solution of the present invention.

[0047] Methods to improve the accuracy of sedimentary facies boundaries include quantitative determination of dolomite and limestone and qualitative determination of sedimentary facies boundaries by gypsum, mudstone and particles; the technical route is basin-wide stratigraphic framework comparison - single-factor sedimentary characteristic analysis - lithofacies combination and sedimentary facies analysis.

[0048] The following is an explanation using the Leikoupo Formation strata (including data) in the Sichuan Basin as an example.

[0049] By applying the method of the present invention, this example uses sub-sections as units, divides lithology into 4 major categories and 17 minor categories, and counts 13,280 single-factor drilling data for the entire basin and key zones.

[0050] Among them, the facies characteristics and paleogeographic environment presented on the plane of the lithofacies paleogeographic map represent the sedimentary environment of a certain area in a certain period of time. The method of determining the boundary of sedimentary facies based on single-factor statistics of lithofacies is based on the idea of ​​quantitative lithofacies paleogeography. The current common phase belt identification mark does not consider the origin of dolomite for the time being, but considers the content of dolomite. In the process of studying the sedimentary facies of the Leikoupo Formation in the Sichuan Basin, it was found that the content of limestone and dolomite was obviously controlled by the depth of sedimentary water in the sedimentary facies belt. In the subtidal subfacies of the tidal flat facies, the sedimentary water body is deeper and the limestone content is larger; while in the supratidal zone, the sedimentary water body is shallower and the dolomite content increases. In the supratidal subfacies, due to the further enhancement of the evaporation environment, the dolomitization process is significantly realized, and the dolomite content reaches the peak of the tidal flat facies. The correlation between the content of limestone and dolomite can be used to divide the boundary of the tidal flat facies, while to divide the boundary of the lagoon facies and the inner platform beach, it is necessary to introduce the content of gypsum, mudstone and algae sand fragments for comprehensive delineation (Table 1).

[0051] Table 1 Lithological combination characteristics of different sedimentary facies of the Leikoupo Formation in the Sichuan Basin

[0052]

[0053] The thresholds for the proportion of dolomite and limestone in different phases are determined based on core observations, drilling anatomy, and thin section identification of multiple typical wells. The phases are first determined, and then compared with the statistical data of limestone, dolomite, and gypsum to determine the comparison scheme. For example, the core and thin section characteristics at 5688.72 m in the AF1 well can be identified as the intertidal lime flat, where the proportion of limestone is greater than 60%. Based on a large number of single factor and related sedimentary facies statistical analyses, a corresponding model of lithofacies single factor characteristics and sedimentary phases is established ( Figure 2 ). The 40% / 60% boundary of limestone and dolomite is the threshold for quantitatively distinguishing the upper intertidal zone and the lower intertidal zone. 80% dolomite and containing gypsum and mud (<20%) are the boundary marks of the supratidal zone. 20%-60% dolomite content and 40%-80% limestone content with gypsum and mudstone are the boundary marks of confined lagoons. Dolomite with a proportion of less than 40% and rich in gypsum (>60%) is the boundary mark of evaporative lagoons. Being in the tidal flat phase and containing algae and sand debris is the boundary mark of the inner platform beach.

[0054] The method of the present invention is in line with the actual situation of oil and gas geological research in the Leikoupo Formation of the Sichuan Basin, can provide a basis for judging oil and gas distribution, and has an optimistic application prospect.

[0055] Embodiment 3

[0056] Please refer to Figure 3-Figure 6 , an embodiment provides a method for drawing a sedimentary phase plane distribution map, comprising the following steps:

[0057] S1. Draw a dolomite proportion contour map based on the ratio of dolomite to stratum thickness;

[0058] S2. Based on the ratio of limestone to stratum thickness, draw a contour map of limestone proportion;

[0059] S3. Apply the map formed by steps S1 and S2, based on the sedimentary phase correspondence model described in the method for improving the accuracy of sedimentary phase boundaries described in any one of the above embodiments, determine the relevant subphase boundaries of the tidal flat phase, combine the contour map of gypsum proportion and grainstone content, and comprehensively draw the plane distribution map of the sedimentary phases of the lagoon, platform beach and the entire basin.

[0060] In one embodiment, step S1 further includes the following sub-step: counting the ratio of the dolomite to the stratum thickness at multiple data points. Figure 3 Taking the upper Leisan submember in the Sichuan Basin as an example, the ratio of dolomite to stratum thickness at 91 data points was counted, and a dolomite proportion contour map was drawn.

[0061] In one embodiment, step S2 further includes the following sub-step: counting the ratio of the limestone to the stratum thickness at multiple data points. Figure 4 Taking the upper Leisan submember in the Sichuan Basin as an example, the ratio of limestone to stratum thickness at 91 data points was counted, and a contour map of limestone proportion was drawn.

[0062] According to the above steps, we implemented them step by step and obtained better results of sedimentary facies plane distribution, such as Figure 6 .

[0063] This method is based on the single-factor statistical results of lithofacies, and then draws a single-factor contour map. By establishing the corresponding relationship between sedimentary facies and lithological combinations, the single-factor contour map is used to determine the sedimentary facies boundary, which can overcome the limitations and shortcomings of the above-mentioned sedimentary facies boundary drawing.

[0064] Embodiment 4

[0065] In order to overcome the shortcomings of the prior art and more accurately delineate sedimentary facies boundaries, the present invention aims to provide a method for improving the accuracy of sedimentary facies boundaries based on lithofacies single factor statistics.

[0066] This method analyzes the correlation between different types of lithofacies data and sedimentary facies, establishes and optimizes the model, starts from the statistical analysis of lithology, combines quantitative and qualitative methods, and implements them step by step. The method comprehensively analyzes and obtains a relatively accurate boundary method for sedimentary facies, which can more objectively reflect the planar distribution characteristics of sedimentary facies and obtain a relatively accurate sedimentary facies boundary. The method of the present invention is suitable for boundary demarcation requirements for large-scale sedimentary facies research when point-like lithology data has been obtained. The method of the present invention conforms to the actual situation of oil and gas geological research and can assist in determining oil and gas distribution.

[0067] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for improving the accuracy of sedimentary phase boundaries, characterized in that: The boundary of the tidal flat phase is divided according to the correlation of the content of limestone and dolomite, wherein when dividing the boundary of the lagoon phase and the inner platform beach, the content of gypsum, mudstone and algae sand fragments is introduced for comprehensive delineation; the method for improving the accuracy of the sedimentary phase boundary comprises the following steps: S1. Delineate the thresholds of dolomite and limestone proportions in different phase zones; S2. Based on the statistical analysis of a large number of single factors and related sedimentary phases, a corresponding model of lithofacies single factor characteristics and sedimentary phases is established.

2. A method for improving the accuracy of sedimentary phase boundaries according to claim 1, characterized in that: The thresholds for delineating the proportions of dolomite and limestone in different phase zones are obtained by first determining the phase zone attribution based on core observations, drilling dissections and thin section identification of multiple typical wells, and then comparing them with statistical data of limestone, dolomite and gypsum to further determine the comparison plan.

3. A method for improving the accuracy of sedimentary phase boundaries according to claim 1 or 2, characterized in that: In the sedimentary correspondence model, the boundary of 40% limestone content and 60% dolomite content is the boundary threshold for quantitatively distinguishing the upper intertidal zone and the lower intertidal zone.

4. A method for improving the accuracy of sedimentary phase boundaries according to claim 1 or 2, characterized in that: In the sedimentary corresponding model, the dolomite content is 80%, and the content of gypsum and mud is less than 20%, which is the boundary mark of the supratidal zone.

5. A method for improving the accuracy of sedimentary phase boundaries according to claim 1 or 2, characterized in that: In the sedimentary corresponding model, the dolomite content is 20%-60%, while the limestone content is 40%-80% and the gypsum and mudstone are the boundary marks of the confined lagoon.

6. A method for improving the accuracy of sedimentary phase boundaries according to claim 1 or 2, characterized in that: In the sedimentary correspondence model, dolomite content <40% and rich in gypsum are the boundary marks of evaporative lagoons.

7. A method for improving the accuracy of sedimentary phase boundaries according to claim 6, characterized in that: In the cream-enriched form, the cream content is > 60%.

8. A method for improving the accuracy of sedimentary phase boundaries according to claim 1 or 2, characterized in that: In the sedimentary phase correspondence model, the boundary mark of the inner shoal is in the tidal flat phase and contains algae and sand debris.

9. A method for drawing a sedimentary phase plane distribution map, characterized in that: The following steps are involved: S1. Draw a dolomite proportion contour map based on the ratio of dolomite to stratum thickness; S2. Based on the ratio of limestone to stratum thickness, draw a contour map of limestone proportion; S3. The drawing formed by applying steps S1 and S2 is based on the improvement described in any one of claims 1 to 8. The sedimentary phase correspondence model described in the method for accuracy of sedimentary phase boundaries is used to determine the relevant subphase boundaries of the tidal flat phase. Combined with the contour map of gypsum proportion and grainstone content, the plane distribution map of sedimentary phases of the lagoon, platform beach and the entire basin is comprehensively drawn.

10. A method for drawing a sedimentary phase plane distribution map according to claim 9, characterized in that: Step S1 also includes the following sub-steps: counting the ratio of the dolomite to the stratum thickness at multiple data points; and / or, Step S2 also includes the following sub-steps: counting the ratio of the limestone to the stratum thickness at multiple data points.

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