A three-dimensional lithofacies modeling method for marine-continental transitional shale under stratigraphic framework

Abstract

The invention discloses a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework, comprising: collecting seismic data and evaluation well data of a study area, and determining a modeling boundary of a three-dimensional geological modeling of a shale reservoir according to the seismic data and the evaluation well data of the study area; establishing a bottom plane model of a seismic fine interpretation layer according to the seismic data, the evaluation well data of the study area and the determined modeling boundary of the three-dimensional geological modeling of the shale reservoir, establishing a top and bottom surface model under the constraint of the bottom plane model, and setting a vertical grid according to the average stratigraphic thickness and lithology thickness of each layer under a five-level layer plane model; establishing lithofacies models of corresponding lithofacies types according to the lithofacies types of the study area and the distribution of the lithofacies under the five-level layer plane model, and each lithofacies model constitutes a lithofacies model of the study area.

Description

Technical Field

[0001] The invention relates to the field of geology, and in particular to a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework. Background Art

[0002] The thin pay layers and strong heterogeneity of transitional shale have created many difficulties for the large-scale and efficient development of shale gas. Therefore, a clear understanding of the heterogeneity of transitional shale can improve the efficiency of exploration and development of shale gas reservoirs. The establishment of a three-dimensional geological model is precisely to quantitatively characterize the heterogeneity of transitional shale reservoirs, which is of great significance to the exploration and development of oil and gas reservoirs.

[0003] At present, there are few studies on 3D geological modeling of shale gas reservoirs. 2 3 There are no reports on modeling of high-quality shale in the sub-segment of marine-continental transition phase. There are two main reasons for this. First, my country's shale research is mostly biased towards the development stage. Most scholars focus on large-scale fracturing and acidizing, collection efficiency and other engineering aspects of shale gas, but their understanding of geology is not accurate enough. Second, my country's marine-continental transition phase shale is still in the early stage of exploration. The research on the marine-continental transition phase shale strata of the Shanxi Formation on the eastern edge of the Ordos Basin mainly includes sedimentary environment, reservoir characteristics, source rock types, etc.

[0004] In view of the characteristics of thin marine-continental transitional shale pay layers and strong heterogeneity, constructing a detailed three-dimensional geological model is the key to understanding the three-dimensional spatial distribution of the gas reservoir. Reservoir three-dimensional geological modeling mainly includes structural models, lithofacies models and attribute models. This study mainly includes the construction of structural models, lithofacies models and attribute models based on a high-precision stratigraphic framework. The construction of detailed structural models and lithofacies models has certain reference significance for reservoir evaluation, well site optimization and horizontal well trajectory guidance design, and provides a scientific basis for oil and gas field development. Conventional three-dimensional geological modeling technology is no longer applicable to shale gas reservoirs, especially mountain 2 3 The high-quality shale interval at the bottom of the subsection is relatively thin and difficult to identify using seismic data. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework, which is characterized by comprising the following processes:

[0006] Step 1: Collect seismic data and evaluation well data in the study area, and determine the modeling boundary of shale reservoir three-dimensional geological modeling based on the seismic data and evaluation well data in the study area;

[0007] Step 2: According to the seismic data, evaluation well data and the modeling boundary of the 3D geological modeling of the shale reservoir in the study area, a bottom layer model of the seismic fine interpretation layer is established, and the top and bottom surface models are established under the constraint of the bottom layer model. The modeling layers of the top and bottom surface models are the four-level layer models of PSQ1, PSQ2, PSQ3 and PSQ4 from bottom to top, and the five-level layer models of FSQ1-FSQ11 are established based on the four-level layer model, and the vertical grid is set according to the average stratigraphic thickness and lithology thickness of each layer under the five-level layer model;

[0008] Step three, according to the lithofacies types of the study area and the distribution of lithofacies under the five-level stratigraphic model, lithofacies models of corresponding lithofacies types are established respectively, and each lithofacies model constitutes the lithofacies model of the study area.

[0009] 2. According to the three-dimensional lithofacies modeling method of marine-continental transitional shale under the stratigraphic framework of claim 1, it is characterized in that the seismic data and evaluation well data of the study area are collected, including: obtaining the well location coordinates and well trajectory data of the evaluation wells in the study area; fine logging interpretation data of the evaluation wells in the study area; stratified data of the evaluation wells, including fourth-level and fifth-level sequences and top and bottom surface structural maps of the study area.

[0010] 3. According to the three-dimensional lithofacies modeling method of marine-continental transitional shale under the stratigraphic framework of claim 2, it is characterized in that the modeling boundary of the three-dimensional geological modeling of the shale reservoir is determined based on the seismic data of the study area and the evaluation well data, wherein the modeling boundary is the range of the three-dimensional seismic data.

[0011] 4. According to the three-dimensional lithofacies modeling method of marine-continental transitional shale under the stratigraphic framework of claim 3, it is characterized in that, according to the seismic data of the study area, the evaluation well data and the modeling boundary of the determined three-dimensional geological modeling of the shale reservoir, a seismic fine interpretation layer bottom layer model is established, and the top and bottom layer surface models are established under the constraints of the bottom layer model, including: based on the seismic interpretation data, the top and bottom layer surface models are established under the constraints of the bottom layer model in combination with the logging stratification data.

[0012] 5. According to a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework as described in claim 4, it is characterized in that the top and bottom surface model modeling layers are four-level layer surface models of PSQ1, PSQ2, PSQ3 and PSQ4 from bottom to top, and a five-level layer surface model of FSQ1-FSQ11 is established based on the four-level layer surface model, including: the four-level layers of PSQ1, PSQ2, PSQ3 and PSQ4 are divided into 11 five-level layers such as FSQ1-FSQ11 from bottom to top, and a five-level layer surface model of FSQ1-FSQ11 is established based on the four four-level layer surface models.

[0013] 6. According to the three-dimensional lithofacies modeling method of marine-continental transitional shale under the stratigraphic framework described in claim 1, it is characterized in that the vertical grid is set according to the average stratigraphic thickness and lithological thickness of each layer under the five-level stratigraphic layer model, wherein the vertical grid is: to ensure that the thinnest lithological thickness of each stratum can be characterized, and the vertical grid is set proportionally.

[0014] 7. According to a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework as described in claim 1, it is characterized in that according to the lithofacies type of the study area and the lithofacies distribution under the fifth-order sequence, lithofacies models of corresponding lithofacies types are established respectively, including: cluster analysis of seismic attribute fusion, Pearson correlation analysis based on Bayesian statistical theory, calculating the correlation between the attributes of the lithofacies and each seismic attribute, obtaining the correlation coefficient R, selecting the seismic attributes with a correlation coefficient within a set threshold range according to the size of the correlation coefficient, establishing the relationship between the lithofacies and the seismic attributes, and calculating the plane phase diagram of the lithofacies to obtain the distribution characteristics of the lithofacies and establish a lithofacies model.

[0015] The beneficial effect of the present invention is that through the technical solution provided by the present invention, it is possible to achieve hierarchical characterization of mountain formations through a high-precision stratigraphic framework, using well logging interpretation data as hard data and three-dimensional seismic data as soft data. 2 3 Three-dimensional spatial distribution of marine-continental transitional shale in the sub-section. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the principle of a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework;

[0017] Figure 2 A schematic diagram of the three-dimensional lithofacies modeling flow chart;

[0018] Figure 3 Study Area Mountain 2 3 Relationship diagram between sub-segment seismic attribute multivariate model fitting results and logging interpretation results;

[0019] Figure 4 Study Area Mountain 2 3 Schematic diagram of the sub-section shale model;

[0020] Figure 5 For the study area 2 3 Plane phase diagram of coal seam in subsection FSQ3;

[0021] Figure 6 This is a schematic diagram of the limestone model of the top of the Taiyuan Formation in the study area;

[0022] Figure 7 For the study area2 3 Plane phase diagram of silty shale in subsection FSQ1

[0023] Figure 8 For the study area 2 3 Planar phase diagram of carbonaceous shale in submember FSQ1;

[0024] Fig. 9 For the study area 2 3 Grid diagram of the sub-section lithofacies model. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. It should be noted that relational terms such as the terms "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0028] Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a list of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of more restrictions, an element defined by the phrase "comprises a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0029] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0030] like Figure 1As shown, a three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework includes the following processes:

[0031] Step 1: Collect seismic data and evaluation well data in the study area, and determine the modeling boundary of shale reservoir three-dimensional geological modeling based on the seismic data and evaluation well data in the study area;

[0032] Step 2: According to the seismic data, evaluation well data and the modeling boundary of the 3D geological modeling of the shale reservoir in the study area, a bottom layer model of the seismic fine interpretation layer is established, and the top and bottom surface models are established under the constraint of the bottom layer model. The modeling layers of the top and bottom surface models are the four-level layer models of PSQ1, PSQ2, PSQ3 and PSQ4 from bottom to top, and the five-level layer models of FSQ1-FSQ11 are established based on the four-level layer model, and the vertical grid is set according to the average stratigraphic thickness and lithology thickness of each layer under the five-level layer model;

[0033] Step three, according to the lithofacies types of the study area and the distribution of lithofacies under the five-level stratigraphic model, lithofacies models of corresponding lithofacies types are established respectively, and each lithofacies model constitutes the lithofacies model of the study area.

[0034] Furthermore, the acquisition of seismic data and evaluation well data in the study area includes: obtaining the well location coordinates and well trajectory data of the evaluation wells in the study area; fine logging interpretation data of the evaluation wells in the study area; and stratification data of the evaluation wells, including fourth-order and fifth-order sequences and top and bottom surface structural maps of the study area.

[0035] Furthermore, the modeling boundary of the three-dimensional geological modeling of the shale reservoir is determined based on the seismic data and the evaluation well data of the study area, wherein the modeling boundary is the range of the three-dimensional seismic data.

[0036] Furthermore, according to the seismic data of the study area, the evaluation well data and the modeling boundary of the determined three-dimensional geological modeling of the shale reservoir, a seismic fine interpretation layer bottom layer model is established, and the top and bottom layer surface models are established under the constraints of the bottom layer model, including: based on the seismic interpretation data, in combination with the logging stratification data, the top and bottom layer surface models are established under the constraints of the bottom layer model.

[0037] Furthermore, the top and bottom surface modeling layers are four-level layer model of PSQ1, PSQ2, PSQ3 and PSQ4 from bottom to top, and a five-level layer model of FSQ1-FSQ11 is established based on the four-level layer model, including: the four-level layers of PSQ1, PSQ2, PSQ3 and PSQ4 are divided into 11 five-level layers such as FSQ1-FSQ11 from bottom to top, and a five-level layer model of FSQ1-FSQ11 is established based on the four four-level layer models.

[0038] Furthermore, the vertical grid is set according to the average stratigraphic thickness and lithologic thickness of each layer under the five-level stratigraphic plane model, wherein the vertical grid is: a vertical grid set proportionally to ensure that the thinnest lithologic thickness of each stratum can be characterized.

[0039] Furthermore, according to the lithofacies type of the study area and the lithofacies distribution under the fifth-level sequence, lithofacies models of corresponding lithofacies types are established respectively, including: using cluster analysis to fuse seismic attributes, and Pearson correlation analysis based on Bayesian statistical theory to calculate the correlation between lithofacies attributes and each seismic attribute to obtain the correlation coefficient R; according to the size of the correlation coefficient, seismic attributes with a correlation coefficient within a set threshold range are selected to establish a relationship between lithofacies and seismic attributes, and calculate the planar phase diagram of the lithofacies to obtain the distribution characteristics of the lithofacies and establish a lithofacies model.

[0040] Specifically, there are 6 evaluation wells in the study area. According to the data format requirements of the modeling software Petrel, the seismic and logging data required for modeling are collected and sorted. The data sorting of the study area mainly includes the following tasks:

[0041] 1) Organize the well location coordinates and well trajectory data of 6 evaluation wells in the study area;

[0042] 2) Organize the detailed logging interpretation data of 6 evaluation wells in the study area;

[0043] 3) Organize the stratification data of 6 appraisal wells, including the fourth-order and fifth-order sequences;

[0044] 4) Organize the Shanxi Mountains in the study area 2 3 Structural diagrams of the top and bottom surfaces of the subsection.

[0045] Based on the existing seismic data and well information in Well A, the modeling boundary of the shale reservoir 3D geological modeling was determined in combination with the research content. The modeling area this time is about 100km 2 . The modeling layers are four fourth-order sequences, PSQ1, PSQ2, PSQ3 and PSQ4, and 11 fifth-order sequences, FSQ1-FSQ11, from bottom to top. The Dongdayao limestone at the top of the Taiyuan Formation in the study area is stably distributed, so the bottom of the model is designed to be the top limestone of the Taiyuan Formation. Fine grid simulation can more accurately characterize the smaller geological units of the target layer in the study area. Although the smaller the grid size means the finer the model, it should be designed according to the actual situation, otherwise it will increase the model operation time and reduce efficiency. The modeling grid design for this study is: the plane grid spacing is 25m×25m, the vertical grid accuracy is 0.7m, and the total number of grids is 22 million. Since the source direction of the study area is from north to south, the grid direction is due north.

[0046] The establishment of a three-dimensional structural model can better express the spatial distribution relationship of the vertical and horizontal stratum thickness distribution, stratum strike trend, fault development and other characteristics. The structural model mainly consists of two parts, namely the layer model and the fault model. However, there are few faults in the study area and it is not affected by faults, so only layer modeling is performed. When performing layer modeling, the structural surface of the fine interpretation of seismic data should be used as a constraint, and the mountain should be established through the combination of well and seismic data. 2 3 Therefore, in the modeling process, the first step is to establish the seismic fine interpretation of the stratigraphic mountain. 2 3 The bottom layer model of the sub-segment is then used to establish the mountain 2 3 The top and bottom surface models of the sub-section and the four stratigraphic models of PSQ1, PSQ2, PSQ3 and PSQ4 were constructed, and 11 stratigraphic models such as FSQ1-FSQ11 were further constructed to build a bridge for the subsequent lithofacies model. This structural surface can not only accurately reflect the accuracy of the stratigraphic depth of each well position, but also intuitively reflect the changes in the structural trend between wells in the study area and the structural characteristics of each small layer. According to the established structural model, it can be seen that the A well area is high in the southeast and low in the northwest in the structural model as a whole, and there are micro-structures in some parts.

[0047] The vertical grid is set up in proportion. To ensure that the thinner rock properties are characterized vertically, the vertical grid size is set to 0.7m in this study. According to the average stratigraphic thickness and lithology thickness of each layer under the five-level sequence, the vertical grids of each layer are set as follows: 9 for FSQ1 layer, 13 for FSQ2 layer, 15 for FSQ3 layer, 7 for FSQ4 layer, 10 for FSQ5 layer, 13 for FSQ6 layer, 10 for FSQ7 layer, 7 for FSQ8 layer, 8 for FSQ9 layer, 8 for FSQ10 layer, and 10 for FSQ11 layer. Since the top of the Taiyuan Formation only involves limestone, the vertical grid is set to 1 (Table 5-1).

[0048] Table 5-1A Well Area Shanxi Formation Mountains 2 3 Number of vertical grids in each sub-layer of the sub-segment

[0049]

[0050]

[0051] The same isochronous modeling layer can have a multi-level structure. Therefore, when modeling, it should be modeled in layers, that is, first establish the distribution of large-scale target bodies, and then control them in a hierarchical manner to establish smaller-scale target body distribution models in turn. The basic idea is: under the high-precision stratigraphic framework, the lithofacies distribution characteristics of different levels are used, and the deterministic modeling method (assignment method) is used to carry out lithofacies modeling of each small layer in the study area step by step, such as Figure 2 shown.

[0052] According to the research results of the subject, the Shanxi group mountain 2 3 Five typical lithofacies types were identified in the subsection, namely, silty shale, carbonaceous shale, gray-black shale, coal seam and sandstone. The top of the Taiyuan Formation is the Dongdayao limestone with stable distribution.

[0053] Lithofacies division:

[0054] 1. Coastal sandstone facies

[0055] This lithofacies is fine sandstone and siltstone. The rock is gray as a whole, with general sorting, good roundness, mostly sub-original, medium sorting, and mud cementation. Its main components are quartz, with a content of about 80%, a certain amount of feldspar and a small amount of other rock fragments, with feldspar accounting for about 15%, and debris and other minerals accounting for about 5%. Calcite is developed to fill the cracks.

[0056] 2. Coal seam

[0057] The coal seam is black, has a high degree of carbonization, is brittle, can stain hands, has well-developed cleavage, and the cleavage surface is rich in luster. The coal seam is formed by the accumulation of plant debris and peat.

[0058] 3. Carbonate rocks

[0059] This lithofacies is limestone, the whole rock is gray-black, with general sorting, good roundness and strong density. Calcite accounts for about 48.2-52.1%, dolomite accounts for about 21.4-23.0%, and mud and other insolubles account for about 26.5-29.2%, of which calcite fills the cracks.

[0060] 4. Gray-black shale phase

[0061] Sedimentary rocks of different colors represent formations under different sedimentary environments, and the depth of color indicates the amount of organic matter in the rock. This shale phase is gray-black to black, does not stain hands, has relatively developed foliation, and is partially filled with calcite film. Microscopically, the main minerals are clay minerals, which account for about 60%, and their surfaces are mostly attached to dark organic matter. The second mineral component is quartz, which accounts for about 40%. The black shale has a high organic matter content, with a maximum value of 11.21%. Authigenic minerals such as siderite and pyrite can also be seen, reflecting the deeper water bodies in a strongly reducing environment.

[0062] 5. Silty shale facies

[0063] This lithofacies is mainly composed of silty shale, which is gray to dark gray in color, with muddy structure, hard nature, and uneven distribution of silt. Carbonized plant stem fossils can be seen in the cross section. The main mineral components are clay minerals, sandy debris and a very small amount of pyrite. The clay mineral content is mostly between 60% and 70%. The sandy debris content accounts for about 30%-40%, and the composition is mostly quartz. The pyrite content is rare, and the TOC content is between 2% and 3%.

[0064] 6. Carbonaceous shale phase

[0065] The overall lithofacies is gray-black to black, pure, with a low degree of carbonization, slightly dirty, gray-black carbonaceous shale often appears at the same time as coal seams, and coal laminae are seen locally, which is a transition from the lower carbonaceous shale to the upper coal seams. Common carbonaceous plant fossils.

[0066] 5.2.1 Sandstone lithofacies model

[0067] To establish a lithofacies model, we can first use three-dimensional seismic data to identify and analyze the spatial variation characteristics of lithology on the plane. High-precision three-dimensional seismic data can be used to identify lithology boundary characteristics, which is one of the main constraints in the lithofacies modeling process.

[0068] However, in the modeling process, it is necessary to analyze the correlation between the seismic data body and the lithology first. If there is a relatively obvious correlation, the data can be used as a constraint condition for lithofacies modeling. When analyzing the relationship between the seismic data body and the lithology, it is necessary to measure the statistical characteristics of the seismic data to reflect the underground geological information. Therefore, extracting relevant seismic attributes can better determine the distribution characteristics of the lithology in three-dimensional space. There are various classifications of seismic attributes. The most commonly used one is Quincy Chen et al. (1997) who classified seismic attributes into 8 categories and 91 types, such as amplitude, waveform, and frequency, based on the characteristics of seismic waves and reservoir characteristics. Among them, the three attributes of amplitude, frequency, and phase are the most basic attributes (Zhang Kebao et al., 2007), and the amplitude-related attributes are closely related to the lithology information. The amplitude-related seismic attributes mainly include root mean square amplitude, average amplitude, maximum amplitude, minimum amplitude, and arc length. After the optimization of various attributes, this study selected the root mean square amplitude attribute to judge and divide each lithology. There are four types of lithology in the study area, including sandstone, coal seam, limestone and shale. First, taking sandstone as an example, the distribution characteristics of sand bodies in the study area are characterized by seismic attributes.

[0069] 1. Single attribute analysis

[0070] First, the mountain was extracted using Petrel software. 2 3The root mean square amplitude of each seismic attribute in the sub-section is calculated, and then the root mean square amplitude value of each well passing through the well is calculated. The work area contains 5 types of seismic data volumes, and their root mean square amplitude values ​​are extracted accordingly to comprehensively judge the relationship between each seismic attribute and lithology. Secondly, according to the formation division results on the well, the mountain range of the target layer section of each well is calculated. 2 3 The thickness of the sub-section stratum and the thickness of the sand body. The sand content of the stratum is calculated by the stratum thickness and the sand body thickness. Finally, a scatter plot of the statistical root mean square amplitude value of the well point and the calculated sand content of the stratum above the well passing the well is made. The results show that the sand content has a certain correlation with the root mean square amplitude value of each seismic attribute, among which the instantaneous frequency root mean square amplitude has a better correlation with the sand content, R 2 It is 0.4743. This shows that the amplitude attribute can effectively predict sandstone to a certain extent.

[0071] 2. Multi-attribute fusion analysis

[0072] This scheme adopts cluster analysis for seismic attribute fusion. SPSS software is used to establish the correlation between sand content and various seismic attributes through Pearson correlation analysis based on Bayesian statistical theory, as shown in Table 5-2. Among them, the superposition attribute has a good correlation with the instantaneous frequency attribute and the oil and gas detection attribute, with correlation coefficients R of 0.529 and -0.704 respectively, and has a poor correlation with the velocity attribute and the fracture attribute; the instantaneous frequency has a good correlation with the oil and gas detection attribute, with a correlation coefficient R of -0.626; the fracture attribute has a good correlation with the velocity attribute, with a correlation coefficient R of -0.530. Therefore, according to the principle of cluster analysis, those with good correlation will be classified into one category. This study divides seismic attribute bodies into two categories, of which the superposition attribute, instantaneous frequency attribute and oil and gas detection attribute are classified into one category (category I), and the velocity attribute and the fracture attribute are classified into one category (category II).

[0073] Table 5-2 Shanxi Mountains in the Study Area 2 3 Correlation analysis between sub-section sand content and seismic attributes

[0074]

[0075] After the cluster analysis, the attributes with good correlation between seismic attributes and sand content are selected for fusion attribute analysis. Among the Class I attributes, the instantaneous frequency attribute and the oil and gas detection attribute have a good correlation with the sand content, and the correlation coefficients are R of 0.689 and -0.400, respectively. The instantaneous frequency attribute has a better correlation, so the instantaneous frequency attribute is preferred among the Class I attributes. Among the Class II attributes, the fracture attribute has a good correlation with the sand content, with a correlation coefficient R of -0.508, while the velocity attribute has a poor correlation with the sand content, so the fracture attribute is preferred among the Class II attributes. Based on SPSS software, the relationship between sand content and seismic attributes is established with sand content as the dependent variable, and instantaneous frequency attributes and fracture attributes as independent variables. After the fusion attribute analysis, the correlation between sand content and seismic attributes is significantly improved, with R of 0.774, as shown in Figure 2. Figure 3 The plane phase diagram of the sand body was calculated by Petrel software to characterize the plane distribution characteristics of the sand body. The sand body is distributed from north to south as a whole. The source direction of the study area is north, which is consistent with the source direction. The sand body in the northern part is distributed in an east-west direction, gradually shrinking to the south, and then the sand body in the south gradually increases.

[0076] Secondly, according to the results of the stratigraphic division on the well, the stratigraphic thickness and sand body thickness of the target layer PSQ1, PSQ2, PSQ3 and PSQ4 of each well were counted, and the relationship between the sand content of each small layer and the seismic attributes was established through SPSS software, and the plane phase diagram of the sand body of each small layer was depicted. The sand body is distributed from north to south as a whole, which is consistent with the mountain. 2 3 The sub-sections are basically consistent. The sand content of the two sub-layers PSQ1 and PSQ2 is relatively high, and the sand content of the PSQ3 and PSQ4 sub-layers gradually decreases as they evolve upward, which is consistent with the evolution characteristics of the actual formation sandstone from bottom to top.

[0077] Based on Petrel software, the mountain is depicted 2 3 The plane phase diagram of the sand body under the sub-section and the fourth-level sequence framework, but at the same time, it is necessary to verify the correctness of the plane phase diagram based on three-dimensional seismic data. According to the lithology information on the well, the consistency rate of the sand body distribution at each well in each sub-layer and the plane phase diagram of each sub-layer was statistically calculated. Among them, the PSQ1 sub-layer has an on-well consistency rate of 80%, the PSQ2 sub-layer has an on-well consistency rate of 80%, the PSQ3 sub-layer has an on-well consistency rate of 50%, and the PSQ4 sub-layer has an on-well consistency rate of 60%. The sand content predicted by the seismic interpretation is generally consistent with the sand content interpreted by the well logging. The seismic data may not be able to accurately identify the lithology and other problems. The target layer section of the study area is the mountain 2 3 The thickness of the sub-section strata is about 40m, and the thickness of the strata below the fifth-order sequence stratigraphic framework is about 2m-3m. The lithology is relatively thin, and there are problems such as insufficient accuracy in seismic interpretation.

[0078] Since seismic data cannot accurately identify the distribution characteristics of sand bodies, and the well-surface coincidence rate is poor, the plane distribution characteristics of sand bodies can be established based on the well-surface interpretation results. Based on the high-precision stratigraphic framework, according to the lithology thickness and well-surface distribution characteristics, the distribution characteristics of sand bodies are roughly drawn, and the three-dimensional spatial distribution characteristics of sand bodies are depicted in stages. First, according to the mountain in the study area, 2 3 The sub-segment structural model is used to establish the lithofacies model of the study area, and then the model is uniformly assigned to mud shale, such as Figure 4 , and on this basis, the distribution characteristics of each lithology are characterized.

[0079] (1) Interpretation of PSQ1 sandstone distribution characteristics based on well logging

[0080] 1) Distribution characteristics of FSQ1 sandstone

[0081] The main lithology of the FSQ1 layer is the marine shale distributed at the top of the Taiyuan Formation. The lithology is mainly divided into mudstone, silty shale, and carbonaceous shale. Among them, the A2 well FSQ1 contains mudstone and sandstone, and the sandstone is distributed at the bottom with a thickness of 3.68m. According to the lithology thickness and downhole lithology interpretation, the spatial distribution characteristics of the sand body are characterized. First, in the vertical direction, FSQ1 sets 9 grid divisions, from top to bottom, respectively, layer1-layer9, and the accuracy of a single grid is 0.7m. According to the lithology thickness and vertical grid accuracy, the sand body is distributed vertically in layer5-layer9. In the plane, according to the uphole lithology interpretation and lithology thickness, the distribution characteristics of the sand body in the plane are roughly characterized. The source direction of the study area is from north to south. Only the A2 well has sandstone distribution in the FSQ1 layer, so the sandstone gradually tapers from north to south at the A2 well.

[0082] 2) Distribution characteristics of FSQ2 sandstone

[0083] The sand bodies at the bottom of the FSQ2 layer are distributed stably, which is the Beichagou sandstone, the landmark layer in the study area. The thickness of the sandstone in Well A1, Well A2, Well A3, Well A4, Well A5 and Well A6 are 1.29m, 1.25m, 2.58m, 1.7m, 3.52m and 1.56m respectively. Vertically, FSQ2 sets 13 grid divisions, from top to bottom, respectively, layer1-layer13, and layer1-layer13 are all distributed with sand bodies. In the plane, the distribution of layer13 sand bodies is very extensive, basically covering the entire study area, the distribution range of layer11-12 sand bodies begins to decrease, and the distribution range of layer10 sand bodies is further reduced until it is locally distributed (layer9), and layer1-8 are mostly distributed with shale, and sandstone is distributed at the A2 well, gradually tapering from north to south.

[0084] 3) Distribution characteristics of FSQ3 sandstone

[0085] Sandstone is distributed in some wells at the bottom of the FSQ3 layer, and the overall distribution of sandstone is less during the upward evolution process. The thickness of sandstone in Well A3, Well A4 and Well A6 are 3.7m, 2.76m and 1.48m respectively. Vertically, FSQ3 is divided into 15 grids, from top to bottom, layer1-layer15, layer5-layer15 has sandstone distribution, and sandstone is mainly distributed in the lower part of FSQ3. In the plane, layer12-15 sandstone is distributed on the east and west sides. During the upward evolution process, the distribution range of layer8-11 sandstone begins to increase, and then the sandstone disappears at Well A6, and layer6-7 sandstone is distributed on the east and west sides again, until layer5 is only partially distributed on the west side, and layer1-4 are all distributed with shale.

[0086] (2) Interpretation of PSQ2 sandstone distribution characteristics based on well logging

[0087] 1) Distribution characteristics of FSQ4 sandstone

[0088] The overall distribution of sandstone in FSQ4 is uneven, with a wide distribution range in the middle and less distribution in the upper and lower parts. The thickness of sandstone in Well A4, Well A5 and Well A6 is 0.8m, 2.8m and 0.97m respectively. Vertically, FSQ3 has 7 grid divisions, from top to bottom, namely layer1-layer7. Sandstone is distributed in layer1-laye7, and sandstone is mainly distributed in the middle of FSQ4. In the plane, layer5-7 sandstone is distributed in strips. During the upward evolution process, the distribution range of layer4 sandstone begins to increase, and then the distribution range of sandstone begins to decrease. Layer1-3 sandstone is only distributed locally on the east side.

[0089] 2) Distribution characteristics of FSQ5 sandstone

[0090] There are fewer sandstones in the FSQ5 layer as a whole, and they are mainly distributed locally in the middle of the study area. Among them, only the A1 well has sandstones, with a thickness of 1.32m. Vertically, FSQ5 has 10 grid divisions, from top to bottom, layer1-layer10, layer3-layer6, all of which have sandstones distributed, and sandstones are mainly distributed in the middle of FSQ4. In the plane, only the A1 well layer3-6 has sandstones, and the sandstones gradually taper out from the northeast to the southwest.

[0091] (3) Interpretation of PSQ3 sandstone distribution characteristics based on well logging

[0092] 1) Distribution characteristics of FSQ6 sandstone

[0093] The overall distribution of sandstone in FSQ6 is relatively extensive, mainly characterized by almost no sandstone in the lower part of FSQ6 and more sandstone in the middle and upper parts. The thickness of sandstone in Well A1, Well A2, Well A5 and Well A6 are 1.65m, 4.17m, 2.73m and 1.95m respectively. Vertically, FSQ6 has 13 grid divisions, from top to bottom, respectively, layer1-layer13, layer1-layer9 has sandstone distribution, and sandstone is mainly distributed in the middle and upper parts of FSQ4. In the plane, layer6-9 sandstone is widely distributed. In the upward evolution process, the distribution range of layer5 sandstone begins to decrease, and the distribution range of layer1-4 sandstone begins to increase. Sandstone is widely distributed in the southeast, while sandstone is less distributed in the northwest, mostly mudstone.

[0094] 2) Distribution characteristics of FSQ7 sandstone

[0095] Sandstone is distributed throughout the FSQ7 layer, but the distribution is small, mainly showing the distribution characteristics in the southeast of the study area. The thickness of A5 sandstone is 3.61m. Vertically, FSQ7 has 10 grid divisions, from top to bottom, layer1-layer10, and sandstone is distributed in layer1-layer10. In the plane, the distribution of layer1-10 sandstone is relatively stable, and the distribution range of sandstone has hardly changed during the upward evolution process. Sandstone is mainly distributed in the eastern part of the study area, with an overall north-south distribution, and the western part is mostly mud shale.

[0096] 3) Distribution characteristics of FSQ8 sandstone

[0097] The thickness of the sandstone in the FSQ8 layer is relatively thin, mainly showing local distribution in the upper part of FSQ8, and almost no sandstone distribution in the middle and lower parts. The thickness of the sandstone in well A3 and A5 is 1.11m and 1.06m respectively, and the thickness does not change much. Vertically, FSQ8 is set up with 7 grid divisions, from top to bottom, respectively, layer1-layer7, layer1-laye3 has sandstone distribution, and sandstone is mainly distributed in the middle and upper parts of FSQ4. In the plane, the distribution of layer1-3 sandstone is small, and the distribution range of sandstone remains stable during the upward evolution process.

[0098] (4) Interpretation of PSQ4 sandstone distribution characteristics based on well logging

[0099] 1) Distribution characteristics of FSQ9 sandstone

[0100] The sandstone distribution in the FSQ9 layer is uneven, mainly showing the local distribution in the middle of the FSQ9 layer, and the sandstone distribution in the upper and lower parts is less. Among them, the thickness of the sandstone in Well A1, Well A2 and Well A5 is 1.02m, 4.82m and 1.04m respectively, and the thickness varies greatly. Vertically, FSQ9 has 8 grid divisions, from top to bottom, respectively, layer1-layer8, and layer1-7 are all distributed with sandstone. In the plane, the distribution of layer7 sandstone is small. In the upward evolution process, the distribution range of layer5-6 sandstone increases, and it is distributed in strips from north to south in the study area. The distribution range of layer4 sandstone is reduced, which is similar to layer7, and the range of layer1-3 sandstone increases locally.

[0101] 2) Distribution characteristics of FSQ10 sandstone

[0102] The distribution of sandstone in FSQ10 is relatively stable. The thickness of sandstone in Well A4 is 3.48m. Vertically, FSQ9 sets 8 grid divisions, layer1-layer8 from top to bottom, and there are sandstones in layers1-8. In the plane, the distribution of sandstone is relatively stable, distributed in the study area in strips from north to south, and gradually tapers off.

[0103] 5.2.2 Coal seam lithofacies model

[0104] Based on the sandstone plane phase characterization method, the distribution characteristics of coal seams in the study area are further characterized by seismic attributes.

[0105] (1) Single attribute analysis

[0106] Based on the mountain extracted by Petrel software 2 3 The root mean square amplitude of each seismic attribute in the sub-section is further analyzed to analyze the relationship between the root mean square amplitude of each seismic attribute and the coal seam. According to the formation division results on the well, the mountain range of the target layer section of each well is counted. 2 3 Sub-segment stratum thickness and coal seam thickness. The coal content of the stratum is calculated by the stratum thickness and coal seam thickness. Finally, a scatter plot of the statistical RMS amplitude of the well point and the calculated coal seam thickness and coal content of the stratum above the well passing through the well is made. The results show that the correlation between the coal content and the RMS amplitude of each seismic attribute is poor, while the correlation between the coal seam thickness and the RMS amplitude of each seismic attribute is good. Therefore, this study mainly describes the distribution characteristics of the coal seam through the correlation between the coal seam thickness and the seismic attribute value. Among them, the velocity RMS amplitude has a good correlation with the coal seam thickness, R 2 It is 0.6375. This shows that the amplitude attribute can also effectively predict coal seams to a certain extent.

[0107] (2) Multi-attribute fusion analysis

[0108] Cluster analysis of seismic attribute fusion was used, and Pearson correlation analysis based on Bayesian statistical theory was used to establish the correlation between coal seam thickness and various seismic attributes (Table 5-3). According to the cluster analysis principle and the previous division results, superposition attributes, instantaneous frequency attributes and oil and gas detection attributes were classified into one category (Class I), and velocity attributes and fracture attributes were classified into one category (Class II).

[0109] Table 5-3 Shanxi Mountains in the Study Area 2 3 Correlation analysis between sub-section coal seam thickness and seismic attributes

[0110]

[0111] After cluster analysis, the attributes with good correlation between seismic attributes and coal seam thickness are selected for fusion attribute analysis. Among the type I attributes, the superposition attribute and instantaneous frequency attribute have good correlation with the coal seam thickness, with correlation coefficients R of 0.485 and 0.616 respectively, while the instantaneous frequency attribute has better correlation, so the instantaneous frequency attribute is preferred among the type I attributes. Among the type II attributes, the velocity attribute and fracture attribute have good correlation with the coal seam thickness, with correlation coefficients R of -0.798 and 0.600 respectively, while the velocity attribute has better correlation with the coal seam thickness, so the velocity attribute is preferred among the type II attributes. Based on SPSS software, the relationship between coal seam and seismic attributes is established with coal seam thickness as the dependent variable, instantaneous frequency attribute and velocity attribute as independent variables. After fusion attribute analysis, the correlation between coal seam thickness and seismic attributes is significantly improved, with R of 0.878. The plane phase diagram of the coal seam is calculated by Petrel software to characterize the plane distribution characteristics of the coal seam. The overall distribution characteristics of coal seams in the study area are similar to those of sandstone. The coal seams in the northern part are distributed in an east-west direction, gradually shrinking to the south, and then the distribution of coal seams in the south gradually increases. Based on this phenomenon, it is believed that seismic attributes can identify the distribution characteristics of sandstone and coal seams, but cannot distinguish them.

[0112] Secondly, according to the results of the stratigraphic division on the well, the stratigraphic thickness and coal seam thickness of each sub-layer PSQ1, PSQ2, PSQ3 and PSQ4 of the target layer section of each well were counted. Among them, the PSQ1 sub-layer contains less coal, and the statistics of the data points on the well are insufficient, so it is impossible to establish the correlation between seismic attributes and coal seam thickness. The PSQ4 coal seam is distributed at the top, which is 5 # The coal seams are distributed stably in the study area. The relationship between the thickness of PSQ2 and PSQ3 coal seams and seismic attributes was established by SPSS software, and the plane phase diagram of each small coal seam was depicted. The coal seams are distributed from north to south as a whole, which is consistent with the mountain. 2 3The characteristics of the belly of the sub-section coal seams are basically the same, and the PSQ2 coal seams are thin, and the PSQ3 coal seams that evolve upward are thicker and have a wider distribution range. However, the distribution characteristics of the coal seams are similar to those of the sandstones, and seismic attributes cannot completely distinguish the two lithologies of sandstone and coal seams.

[0113] Based on Petrel software, the mountain is depicted 2 3 The thickness of the coal seams under the sub-section and the fourth-level sequence framework is plane map, but at the same time, the correctness of the plane phase map based on the three-dimensional seismic data needs to be verified. According to the lithology information on the well, the coincidence rate of the coal seam distribution at each well passing through each sub-layer and the plane phase map of each sub-layer is counted. Among them, the coincidence rate of the PSQ2 sub-layer on the well is 60%, and the coincidence rate of the PSQ3 sub-layer on the well is 40%. It can be seen that seismic data may not be able to accurately identify lithology and other problems.

[0114] Since seismic data cannot accurately identify the distribution characteristics of sandstone and coal seams, and the well-surface coincidence rate is poor, the plane distribution characteristics of coal seams can be established based on the well-surface interpretation results. Based on the high-precision stratigraphic grid, the distribution characteristics of coal seams are roughly drawn, and the three-dimensional spatial distribution characteristics of coal are characterized in stages. Although coal seams are widely distributed in the study area, they are not necessarily distributed in every stratum, so the strata where coal seams are distributed are selected for characterization.

[0115] (1) Interpretation of PSQ1 coal seam distribution characteristics based on well logging

[0116] 1) Distribution characteristics of FSQ3 coal seams

[0117] The distribution of coal seams in FSQ3 is relatively stable. The thickness of the coal seam in Well A2 is 1.83m. Vertically, FSQ9 sets 8 grid divisions, from top to bottom, layer1-layer8, layer1-4 distribution of coal seams. In the plane, the distribution of coal seams is relatively stable, distributed from north to south in the study area, such as Figure 5 ;

[0118] (2) Interpretation of PSQ2 coal seam distribution characteristics based on well logging

[0119] 1) Distribution characteristics of FSQ5 coal seams

[0120] The distribution of coal seams in FSQ5 is relatively stable. The thickness of coal seams in Well A1, Well A3 and Well A5 is 0.83m, 0.76m and 1.48m respectively. Vertically, FSQ9 sets 8 grid divisions, from top to bottom, they are layer1-layer8, layer1-4 distribution coal seams. In the plane, layer6 coal seams are distributed on the east side of the study area, and the distribution range of evolved coal seams increases upward. Layer1 coal seams are the most widely distributed, distributed in the study area from north to south.

[0121] (3) Interpretation of PSQ3 coal seam distribution characteristics based on well logging

[0122] 1) Distribution characteristics of FSQ7 coal seam

[0123] The distribution range of coal seams in FSQ7 layer varies greatly, showing the characteristics of wide distribution range of coal seams in the middle and lower parts of the layer and narrow distribution range in the upper part. The thickness of coal seams in A3 well and A6 well is 1.94m and 1.38m. Vertically, FSQ7 sets 10 grid divisions, layer1-layer10 from top to bottom, and coal seams are evenly distributed in layer1-10. In the plane, layer5-10 coal seams are distributed on the west side of the study area. In the upward evolution process, the distribution range of layer3-4 coal seams increases, and then the distribution range of layer1-2 coal seams decreases, mainly distributed in the south side of the study area.

[0124] 2) Distribution characteristics of FSQ8 coal seams

[0125] The FSQ8 coal seams are scattered in the study area. The thickness of the coal seams in Well A1, Well A2 and Well A3 is 0.9m, 1.27m and 0.78m. Vertically, FSQ8 sets 7 grid divisions, from top to bottom, the coal seams are layer1-layer7, layer1-2 and layer6-7. In the plane, the layer6-7 coal seams are distributed in the west of the study area, with a small distribution range; in the upward evolution process, the layer1-2 coal seams are distributed in the north of the study area, the thickness of the coal seams changes little, and the distribution is stable. .

[0126] (4) Interpretation of PSQ4 coal seam distribution characteristics based on well logging

[0127] 1) Distribution characteristics of FSQ11 coal seam

[0128] FSQ11 coal seams are widely distributed and are the landmark layer in the study area. # Coal seams. The thickness of coal seams in Well A1, Well A2, Well A3, Well A4, Well A5 and Well A6 are 1.33m, 1.21m, 0.97m, 2m, 1.42m and 1.02m respectively. Vertically, FSQ11 sets 10 grid divisions, layer1-layer10 from top to bottom, and FSQ11 mainly distributes coal seams in the upper part (layer1-4). In the plane, the layer4 coal seams are distributed in pieces. In the upward evolution process, the distribution range of the layer3 coal seams gradually increases, and then the distribution range of the layer1-2 coal seams is distributed in the entire study area.

[0129] 5.2.3 Carbonate rock facies model

[0130] The Taiyuan Formation in the study area has developed multiple limestones, including Maoergou limestone, Xiedao limestone and Dongdayao limestone from bottom to top. Dongdayao limestone is developed at the top of the Taiyuan Formation and belongs to carbonate platform deposits in the study area. Dongdayao limestone is a regional marker layer and the boundary between the Taiyuan Formation and the Shanxi Formation. It is widely and stably distributed in the underground profile in the study area, but its thickness is uneven, ranging from 6m to 13m.

[0131] Based on the stable distribution of Dongdayao limestone in the study area, when establishing the carbonate rock lithofacies model, the Taiyuan Formation at the bottom of the model was assigned as limestone. Figure 6 .

[0132] 5.2.4 Shale lithofacies model

[0133] Since seismic data cannot accurately identify the distribution characteristics of sandstone and coal seams, and the well-surface coincidence rate is poor, when establishing the shale lithofacies model, the plane distribution characteristics of shale are roughly determined based on the well interpretation results. Based on the high-precision stratigraphic framework, the plane phase characteristics of silty shale, carbonaceous shale and mud shale are depicted.

[0134] 1. Silty shale

[0135] (1) Distribution characteristics of PSQ1 silty shale based on well logging interpretation

[0136] 1) Distribution characteristics of FSQ1 silty shale

[0137] The main lithology of the FSQ1 layer is the marine shale distributed at the top of the Taiyuan Formation. The lithology is mainly divided into mudstone, siltstone and carbonaceous shale. The thickness of the siltstone in Well A1, Well A4 and Well A6 are 1.39m, 3.03m and 2.94m respectively. Vertically, FSQ1 has set up 9 grid divisions, from layer1 to layer9 from top to bottom. Silty shale is distributed in Layer1-layer9, and the distribution is stable. In the plane, the siltstone is distributed in strips from north to south. Figure 7 .

[0138] 2) Distribution characteristics of FSQ2 silty shale

[0139] The distribution range of silty shale in the FSQ2 layer varies greatly, with a wide distribution in the middle of the layer and a small distribution in the upper and lower parts. The thickness of the silty shale in Well A1, Well A2 and Well A4 are 2.37m, 3.07m and 2.4m respectively. In the vertical direction, silty shale is distributed in Layer1-layer13. In the plane, the distribution of silty shale in layer13 is small. In the upward evolution process, the range of silty shale gradually increases, and then gradually decreases and is distributed in the north of the study area.

[0140] 3) Distribution characteristics of FSQ3 silty shale

[0141] The distribution range of silty shale in the FSQ3 layer varies greatly, showing the characteristics of wide distribution in the upper part of the layer and less distribution in the middle and lower parts. The thickness of silty shale in Well A1, Well A3, Well A4, Well A5 and Well A6 are 0.7m, 1.24m, 2.26m, 1.55m and 1.26m respectively. In the vertical direction, silty shale in Layer1-layer15 is distributed. In the plane, the silty shale in layer12-15 is distributed in strips from north to south. In the upward evolution process, the range of silty shale gradually decreases, and then gradually stabilizes and is distributed on the east and west sides of the study area.

[0142] (2) Distribution characteristics of PSQ2 silty shale based on well logging interpretation

[0143] 1) Distribution characteristics of FSQ4 silty shale

[0144] The distribution range of FSQ4 silty shale varies greatly, with a wide distribution in the upper part of the layer and a small distribution in the middle and lower parts. The thickness of silty shale in Well A1, Well A3, Well A5 and Well A6 are 1.06m, 3.76m, 1.46 and 1.47m respectively. Vertically, silty shale in Layer1-layer7 is distributed. In the plane, silty shale in layer6-7 is distributed on the east and west sides of the study area. In the upward evolution process, the range of silty shale gradually decreases, and then it is distributed in the middle of the study area and gradually shrinks.

[0145] 2) Distribution characteristics of FSQ5 silty shale

[0146] The distribution range of silty shale in the FSQ5 layer is relatively small. The thickness of silty shale in wells A3 and A4 is 2.58m and 3.34m respectively. Vertically, silty shale is distributed in Layer3-layer10, and silty shale is not developed at the top of the layer. In the plane, silty shale in layer8-10 is distributed in the north of the study area. In the upward evolution process, the range of silty shale gradually expanded, and then it was stably distributed in the middle of the study area.

[0147] (3) Distribution characteristics of PSQ3 silty shale based on well logging interpretation

[0148] 1) Distribution characteristics of FSQ6 silty shale

[0149] The distribution range of silty shale in the FSQ6 layer is significantly reduced. The thickness of silty shale in wells A1 and A4 is 1.05m and 1.96m respectively. Vertically, silty shale is distributed in layer5-layer9, and silty shale is not developed at the top of the layer. In the plane, silty shale in layer10-13 is locally developed in the north of the study area. The distribution range of silty shale increases during the upward evolution process. Silty shale in layer6-9 is distributed in the middle of the study area, and silty shale in layer5 is only locally developed in the northeast of the study area.

[0150] 2) Distribution characteristics of FSQ7 silty shale

[0151] The distribution range of silty shale in FSQ7 layer is small, and it is only locally developed in Well A1. The thickness of silty shale in Well A1 is 3.9m. In the vertical direction, silty shale is distributed in Layer1-layer10. In the plane, the distribution of silty shale is stable in the study area.

[0152] 3) Distribution characteristics of FSQ8 silty shale

[0153] FSQ8 silty shale is developed in the south of the study area, and its distribution range is stable. The thickness of silty shale in Well A6 is 1.74m. Vertically, silty shale is distributed at the top of the layer (layer1-layer3), and silty shale is not developed in the middle and lower parts. In the plane, silty shale is stably distributed in the south of the study area, and the range of silty shale does not change much during the upward evolution process.

[0154] (4) Distribution characteristics of PSQ4 silty shale based on well logging interpretation

[0155] 1) Distribution characteristics of FSQ9 silty shale

[0156] The distribution range of silty shale in the FSQ9 layer varies greatly. The thickness of silty shale in wells A3 and A4 is 0.84m and 2.56m respectively. Vertically, silty shale is distributed in layer1-layer8. In the plane, silty shale in layer8 is distributed in the north of the study area. In the upward evolution process, the range of silty shale gradually expanded, and then it was stably distributed in the west of the study area.

[0157] 2. Carbonaceous shale

[0158] (1) Distribution characteristics of PSQ1 carbonaceous shale based on well logging interpretation

[0159] 1) Distribution characteristics of FSQ1 carbonaceous shale

[0160] The distribution range of carbonaceous shale in the FSQ1 layer varies little and is basically developed in the east of the study area. The thickness of carbonaceous shale in Well A5 is 1.19m. In the vertical direction, carbonaceous shale is distributed in layer1-layer9. In the plane, carbonaceous shale is distributed in the north of the study area and is relatively stable in the upward evolution process. Figure 8 .

[0161] 2) Distribution characteristics of FSQ2 carbonaceous shale

[0162] The distribution range of carbonaceous shale in the FSQ2 layer changes little, and it is also basically developed on the east side of the study area. The thickness of carbonaceous shale in Well A1, Well A5 and Well A6 are 1.05m, 4.71m and 1.18m respectively. In the vertical direction, carbonaceous shale is distributed in layer1-layer8. In the plane, carbonaceous shale is distributed on the east side of the study area. In the upward evolution process, the development range of carbonaceous shale increases, and the distribution is relatively stable.

[0163] 3) Distribution characteristics of FSQ3 carbonaceous shale

[0164] The distribution range of carbonaceous shale in FSQ3 layer is relatively small, and it is basically developed in the north of the study area. The thickness of carbonaceous shale in Well A4 is 1.72m. In the vertical direction, carbonaceous shale is distributed in layer1-4 and layer5-6. In the plane, carbonaceous shale is distributed in the north of the study area. In the upward evolution process, the development range of carbonaceous shale increases, and the distribution is relatively stable.

[0165] (2) Distribution characteristics of PSQ2 carbonaceous shale based on well logging interpretation

[0166] 1) Distribution characteristics of FSQ4 carbonaceous shale

[0167] The distribution range of carbonaceous shale in the FSQ4 layer varies greatly, with less carbonaceous shale in the middle and lower parts and more in the upper part. The thickness of carbonaceous shale in wells A3 and A4 is 0.88m and 3m respectively. In the vertical direction, carbonaceous shale is distributed in layer1-2 and layer5-7. In the plane, carbonaceous shale is mainly distributed in the north of the study area. In the upward evolution process, the distribution range of carbonaceous shale increases and is mainly distributed in the west of the study area.

[0168] 2) Distribution characteristics of FSQ5 carbonaceous shale

[0169] The distribution range of carbonaceous shale in FSQ5 layer is small and only developed at the top of the layer. The thickness of carbonaceous shale in A6 well is 0.68m. Vertically, the thickness of carbonaceous shale in this layer is thin, and carbonaceous shale is distributed in layer1. In plane, carbonaceous shale is mainly distributed in the south of the study area.

[0170] (3) Distribution characteristics of PSQ3 carbonaceous shale based on well logging interpretation

[0171] 1) Distribution characteristics of FSQ6 carbonaceous shale

[0172] The distribution range of carbonaceous shale in the FSQ6 layer varies greatly. There are more carbonaceous shale in the lower part of the layer, and basically no carbonaceous shale in the upper part. The thickness of carbonaceous shale in wells A3 and A5 is 0.98m and 1.05m respectively. In the vertical direction, carbonaceous shale is distributed in layer9-13. In the plane, carbonaceous shale is mainly distributed on the east and west sides of the study area. During the upward evolution process, the carbonaceous shale on the east side gradually disappears and is mainly distributed on the west side of the study area.

[0173] 2) Distribution characteristics of FSQ7 carbonaceous shale

[0174] The distribution range of carbonaceous shale in the FSQ7 layer is relatively stable, and carbonaceous shale is developed at the top of the layer. The thickness of carbonaceous shale in Well A3 is 0.54m. Vertically, the thickness of carbonaceous shale in this layer is relatively thin, and carbonaceous shale is only distributed in layer1-2. In the plane, carbonaceous shale is mainly distributed on the west side of the study area. In the upward evolution process, the development of carbonaceous shale is relatively stable.

[0175] 3) Distribution characteristics of FSQ8 carbonaceous shale

[0176] The distribution range of carbonaceous shale in the FSQ8 layer is relatively small, and carbonaceous shale is distributed in the upper and lower parts of the layer. The thickness of carbonaceous shale in wells A1 and A4 is 0.74m and 2.18m respectively. In the vertical direction, carbonaceous shale is distributed in layer2-3 and layer6-7. In the plane, carbonaceous shale is mainly distributed in the north of the study area. In the upward evolution process, carbonaceous shale is locally developed in well A1 and distributed in a continuous area with carbonaceous shale in well A4.

[0177] (4) Distribution characteristics of PSQ4 carbonaceous shale based on well logging interpretation

[0178] 1) Distribution characteristics of FSQ9 carbonaceous shale

[0179] The thickness of carbonaceous shale in FSQ10 layer is relatively thin and distributed in the upper and lower parts of the layer. The thickness of carbonaceous shale in Well A2 and Well A5 is 0.7m and 0.76m respectively. In the vertical direction, carbonaceous shale is distributed in layer1 and layer8. In the plane, the lower carbonaceous shale is distributed in the north of the study area. In the upward evolution process, the carbonaceous shale in the north disappears and is mainly distributed in the east of the study area.

[0180] 2) Distribution characteristics of FSQ10 carbonaceous shale

[0181] The thickness of carbonaceous shale in FSQ10 layer is relatively thin, and the distribution range is relatively stable. It is mainly distributed at the top of the layer, and the rest is not developed. The thickness of carbonaceous shale in Well A6 is 0.82m. In the vertical direction, carbonaceous shale is distributed in layer1-2. In the plane, carbonaceous shale is mainly distributed in the north of the study area, and the distribution is stable.

[0182] 3) Distribution characteristics of FSQ11 carbonaceous shale

[0183] The distribution range of carbonaceous shale in FSQ11 layer varies greatly. Carbonaceous shale is distributed more frequently. Carbonaceous shale is developed almost throughout the layer, and the top layer is marked with 5 # Coal seams. The thickness of carbonaceous shale in Well A1, Well A2 and Well A4 are 1.12m, 4.93m and 1.12m respectively. Vertically, carbonaceous shale is distributed in layer3-10. In the plane, carbonaceous shale is mainly distributed in the north of the study area. During the upward evolution, the distribution range of carbonaceous shale in the north gradually increases, and then gradually disappears, and finally develops locally in the north of the study area.

[0184] 3. Shale

[0185] The model is based on mudstone, and depicts the distribution characteristics of sandstone, coal seam, siltstone and carbonaceous shale in three-dimensional space under a high-precision stratigraphic framework, and the rest is assigned to mudstone.

[0186] Through deterministic lithofacies modeling of each sublayer, the Shanxi Formation in the A well area on the eastern margin of the Ordos Basin was established. 2 3 The lithofacies model of the sub-member is as follows Fig. 9 The three-dimensional spatial distribution characteristics of each lithofacies will lay a more reliable foundation for the establishment of subsequent attribute models.

[0187] From the Shanxi Formation in the A well area on the eastern edge of the Ordos Basin 2 3 The three-dimensional geological model of the lithofacies of the sub-section shows that the entire mountain 2 3 The sandstone of the sub-section is mainly distributed on the east and west sides of the study area, with less sandstone in the middle. The thickness and plane distribution of sandstone are opposite to those of mudstone. 2 3 In the area where sandstone is developed, the mudstone is thin and distributed in thin interlayers of sand and mud. In the area where sandstone is relatively undeveloped, the sandstone is thin. The two are distributed in the study area in a trend of one increasing while the other decreasing. 2 3The bottom and upper part of the sub-section, of which the bottom is Beichagou sandstone, is relatively stable and distributed in the study area, but Beichagou sandstone is not developed in some areas. For example, in the north of the study area, mud shale is developed in its lower part and is in unconformable contact with carbonate rocks. The upper sandstone is mainly distributed in the north and east of the study area, and the sandstone in the A5 well in the east is thicker, with good connectivity in the direction of the source, and mud shale is mostly developed in thin layers inside it.

[0188] The thickness of the coal seams in the study area is relatively thin, ranging from 0.7m to 2m. They are mostly developed in coal lines and interbedded with carbonaceous shales in the study area. 2 3 The top and middle of the subsection, of which the top is the landmark layer 5 of the study area # Coal, with a thickness ranging from 0.97m to 2m, is stably and continuously distributed in the study area. The thickness of the central coal seam is relatively thin and is mostly distributed in the western part of the study area.

[0189] The shale is well developed in the A1 well in the middle of the study area, and in the A2 and A4 wells in the north. The thickness is between 20 and 30 m, and the vertical connectivity is good. Among them, the silty shale is well developed in the A2 and A4 wells in the north, and is distributed in the mountains. 2 3 At the bottom of the sub-member, in the middle of the study area, the silt shale is relatively thin overall, mostly mud shale, and the silt shale at the bottom is no longer developed, but mainly Beichagou sandstone. In the southern A6 well, the silt shale gradually develops and is distributed in the mountain. 2 3 The carbonaceous shale is relatively thin overall, not only thin in thickness, but also poor in vertical continuity. 2 3 The carbonaceous shale is most developed in the A5 well in the eastern part of the study area. The thickness of the carbonaceous shale gradually decreases and disappears in the process of evolution to the middle part. The carbonaceous shale gradually develops in the A3 well in the west and is distributed in the mountains. 2 3 The middle of the sub-section is interbedded with coal seams. The carbonaceous shale is thicker in the east and west and thinner in the middle. The mud shale is thicker in the middle and thinner in the east and west, with a thickness of 10m-26m, which is the opposite trend of sandstone and silty shale. The A2 and A4 wells in the north are mostly distributed in the mountains. 2 3 In the middle and upper parts of the sub-member, mud shale is relatively developed in the middle area, with thin layers of sand stably distributed. In the southern A6 well, mud shale gradually develops and is distributed in the mountain. 2 3 Middle and upper parts of the subsegment.

[0190] In summary, the lithofacies model constructed in the study area is consistent with the actual evolution law of the strata, providing a more reliable basis for subsequent exploration and development.

[0191] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A three-dimensional lithofacies modeling method for marine-continental transitional shale under the stratigraphic framework, It is characterized in that The process includes the following: Step 1: Collect seismic data and evaluation well data in the study area, and determine the modeling boundary of shale reservoir three-dimensional geological modeling based on the seismic data and evaluation well data in the study area; The acquisition of seismic data and evaluation well data in the study area includes: obtaining the well location coordinates and well trajectory data of the evaluation wells in the study area; fine logging interpretation data of the evaluation wells in the study area; stratified data of the evaluation wells, including the fourth-order sequence and the fifth-order sequence and the top and bottom structural maps of the study area; Step 2: According to the seismic data, evaluation well data and the modeling boundary of the 3D geological modeling of the shale reservoir in the study area, a bottom layer model of the seismic fine interpretation layer is established, and the top and bottom surface models are established under the constraint of the bottom layer model. The modeling layers of the top and bottom surface models are the four-level layer models of PSQ1, PSQ2, PSQ3 and PSQ4 from bottom to top, and the five-level layer models of FSQ1-FSQ11 are established based on the four-level layer model, and the vertical grid is set according to the average stratigraphic thickness and lithology thickness of each layer under the five-level layer model; Step three, according to the lithofacies type of the study area and the distribution of lithofacies under the five-level stratigraphic model, establish lithofacies models of corresponding lithofacies types respectively, and each lithofacies model constitutes the lithofacies model of the study area; including: using cluster analysis to fuse seismic attributes, Pearson correlation analysis based on Bayesian statistical theory, calculating the correlation between lithofacies attributes and each seismic attribute, obtaining the correlation coefficient R, selecting seismic attributes with correlation coefficients within the set threshold range according to the size of the correlation coefficient, establishing the relationship between lithofacies and seismic attributes, and calculating the plane phase diagram of the lithofacies to obtain the distribution characteristics of the lithofacies and establish a lithofacies model.

2. A three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework according to claim 1, It is characterized in that The modeling boundary of the three-dimensional geological modeling of the shale reservoir is determined based on the seismic data of the study area and the evaluation well data, wherein the modeling boundary is the range of the three-dimensional seismic data.

3. A three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework according to claim 2, It is characterized in that The method is to establish a bottom layer model of a seismic fine interpretation layer based on the seismic data, evaluation well data of the study area and the modeling boundary of the determined three-dimensional geological modeling of the shale reservoir, and to establish top and bottom layer surface models under the constraints of the bottom layer model, including: based on the seismic interpretation data, in combination with the logging stratification data, to establish top and bottom layer surface models under the constraints of the bottom layer model.

4. A three-dimensional lithofacies modeling method for marine-continental transitional shale under a stratigraphic framework according to claim 3, It is characterized in that The top and bottom surface model modeling layers are PSQ1, PSQ2, PSQ3 and PSQ4 four-level layer model from bottom to top, and the FSQ1-FSQ11 five-level layer model is established based on the four-level layer model, including: PSQ1, PSQ2, PSQ3 and PSQ4 four-level layers are divided into FSQ1-FSQ11, 11 five-level layers from bottom to top, and the FSQ1-FSQ11 five-level layer model is established based on the four four-level layer models.

5. The three-dimensional lithofacies modeling method of marine-continental transitional shale under the stratigraphic framework according to claim 1, It is characterized in that The vertical grid is set according to the average stratigraphic thickness and lithologic thickness of each layer under the five-level stratigraphic plane model, wherein the vertical grid is: a vertical grid set proportionally to ensure that the thinnest lithologic thickness of each stratum can be characterized.

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