Quantitative evaluation method and system for connectivity of river channel sand body

Abstract

The invention belongs to the technical field of oil-gas exploration and development, and relates to a river channel sand body connectivity quantitative evaluation method and system, and the method comprises the steps: building a sand body thickness map and a sedimentary microfacies plane graph based on obtained core, logging, three-dimensional earthquake and modern delta outcrop analogy data of a target interval of a research area; determining node and branch types according to the sand body thickness map and the sedimentary microfacies planar graph; according to data in the sand body thickness map, performing stratigraphic framework division on a target interval of the research area based on an isochronous interface, and generating a sand body distribution model; extracting river channel plane distribution vector data from the sand body distribution model; the method comprises the following steps: importing river channel plane distribution vector data into ArcGIS software for spatial connection to obtain a node and branch spatial connection distribution diagram, performing grid division on the distribution diagram, and counting the number of nodes and branches in each grid; the development proportion of the nodes and the branches is calculated according to the number of the nodes and the branches, and the sand body connectivity is determined according to connectivity indexes calculated according to the development proportion. The method can quantitatively depict the communication relation of the complex split-flow river channels.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development technology, and relates to the oil and gas development technology of river-controlled deltaic reservoirs. Specifically, it relates to a method and system for quantitative evaluation of the connectivity of river sand bodies. Background Technology

[0002] Deltaic reservoirs are an important type of oil and gas reservoir in continental oil and gas reservoirs. Among them, river-controlled deltaic reservoirs are characterized by small channel size, strong heterogeneity, and complex reservoir connectivity, often leading to problems such as ineffective injection and production during oil and gas development, severely restricting the efficient exploitation of oil and gas resources. Therefore, accurately conducting connectivity analysis of sand bodies in river-controlled deltaic distributary channels is of significant practical importance for optimizing oil and gas reservoir development strategies and improving development efficiency.

[0003] Effective identification of reservoir connectivity is crucial for solving the aforementioned development challenges. It can clearly reveal the water injection development path and provide a scientific basis for targeted adjustments to development plans. However, the spatial structure of sand bodies in distributary channels of river-controlled deltas is extremely complex, posing a significant challenge to the accurate identification of reservoir connectivity. Topology, as an important branch of science describing the shape properties of mathematical space, excels at analyzing the continuity and connectivity of geometric elements. Through geometric analysis of the relationships between river branching and nodes in the river channel plane, it can provide new ideas and important guidance for studying the spatial connectivity of complex distributary channels. Therefore, methods and devices for determining the connectivity of distributary channels in river-controlled deltas based on topological analysis have become a research focus, aiming to more clearly resolve the connectivity of sand bodies in distributary channels with different spatial structures, explore the distribution of dominant seepage channels, and provide key guidance for water injection development.

[0004] Currently, there are various methods for studying sand body connectivity, mainly including static connectivity analysis, chemical tracer analysis, interference well analysis, production dynamic data analysis, and inter-well single sand layer connectivity analysis. However, in practical applications, existing technologies still have significant shortcomings: First, they rely on manual experience for identification. This method is based on geological outcrops, cores, well logging curves, seismic profiles, and two-dimensional plan maps. Geological experts make manual inferences and connections based on regional sedimentary background and patterns. This method is highly dependent on expert experience, subjective, and inefficient. When facing large-area, high-density, and multi-phase complex channel networks, it is difficult to guarantee the objectivity, consistency, and accuracy of the results, and problems such as missing minor channel connections or misjudging abandoned channels are prone to occur. Secondly, there are limitations to simple spatial analysis methods. While using geographic information systems (such as ArcGIS) for river centerline extraction, buffer zone analysis, or simple distance calculations improves efficiency to some extent, it can only reflect the spatial proximity or rough parallel relationships of rivers. It cannot deeply analyze the topological connectivity attributes between rivers (such as node connectivity, path connectivity, and network structure), making it difficult to distinguish between adjacent rivers belonging to different periods or abandoned rivers, and also unable to accurately identify the true confluence and divergence points between rivers. Thirdly, there are shortcomings in the interpretation of seismic attribute volumes. While using the coherence volume and curvature volume attributes of 3D seismic data to assist in identifying river boundaries can provide a 3D perspective, resolution limitations make it challenging to finely characterize and determine the connectivity of thin underground layers and small-scale distributary rivers (especially the dense terminal channels in complex river control systems). Furthermore, the interpretation process requires significant manual intervention.

[0005] As a powerful geographic information system (GIS) software, ArcGIS has been widely used in geological modeling and reservoir characterization due to its rich tools for spatial data processing, analysis, and visualization. Its topology function is primarily used to ensure the logical consistency of spatial relationships between vector data (such as points, lines, and polygons), serving as a crucial means of data quality control. However, existing technologies for determining river connectivity using ArcGIS have significant shortcomings: First, there is a lack of targeted topology analysis tools. The core of standard ArcGIS topology tools lies in constraint rule checking and error correction, rather than specifically designed for systematic topology modeling, automatic extraction of connectivity relationships, and quantitative analysis of connectivity in complex river networks. Second, topology rules have limitations. Preset topology rules are often treated as "errors" requiring correction in river analysis, but in the actual geological context of river deltas, river terminals are a common natural phenomenon, not data errors. Blindly applying standard topology rules can distort the true geological structure information. Furthermore, the depth of topological connectivity analysis is insufficient. Existing methods fail to fully utilize topological relationships such as node connections and edge connections to achieve automated or semi-automated reconstruction of river network connectivity maps, identification of key connection nodes, calculation of connectivity paths, and output of structured river connectivity relationship matrices or graph models. Existing ArcGIS functions are insufficient to meet the needs of characterizing the overall connectivity structure and local connectivity details of complex branching systems.

[0006] In summary, existing technologies for determining the spatial connectivity of complex distributary channel systems in river-controlled deltas suffer from drawbacks such as over-reliance on manual methods, low efficiency, insufficient analytical depth, and difficulty in adapting to complex geological structures. Consequently, they are unable to effectively, objectively, and accurately determine the spatial connectivity of complex distributary channel systems in river-controlled deltas. Summary of the Invention

[0007] This invention addresses the aforementioned problems in existing technologies, such as the difficulty in effectively and accurately determining the spatial connectivity of complex distributary channels in river-controlled deltas. It provides a method and system for quantitatively evaluating the connectivity of channel sand bodies. Based on the geomorphological pattern system observation and parameter statistics of modern deltaic distributary channels, combined with the fine sedimentary microfacies study of ancient deltaic reservoirs, high-resolution sand body thickness maps, well logging curve morphology, and production dynamic data, a deltaic reservoir configuration characterization technology system is established, which can quantitatively characterize the connectivity of complex distributary channels.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a method for quantitatively evaluating the connectivity of river channel sand bodies, the steps of which are as follows: Data acquisition steps: Acquire core, well logging, 3D seismic, and modern delta outcrop analog data for the target stratigraphic interval in the study area; Map construction steps: Based on core, well logging, 3D seismic and modern delta outcrop analog data, establish sand body thickness maps and sedimentary microfacies plane maps; Type determination steps: Based on the sand body thickness map and sedimentary microfacies planar map, determine the node and branch types; Model generation steps: Based on the data in the sand body thickness map, the stratigraphic framework of the target layer in the study area is divided according to the isochronous interface to generate a sand body distribution model; Vector data extraction steps: Extract the channel centerline and channel boundary polygons in vector format from the sand body distribution model to obtain the channel planar distribution vector data; Quantitative statistics steps: Import the river channel planar distribution vector data into ArcGIS software to obtain a spatial connection distribution map of nodes and branches. Divide the spatial connection distribution map of nodes and branches into grids and count the number of different types of nodes and branches in each grid. Calculation steps: Calculate the development ratio of nodes and branches based on the number of nodes and branches in each grid, and calculate the connectivity index based on the development ratio; Evaluation steps: Determine the connectivity of sand bodies based on the connectivity index.

[0009] In some embodiments, during the model generation step, a high-resolution sand body distribution model is generated using a sequential instruction simulation method or a multi-point geostatistical method.

[0010] In some embodiments, the method for importing river channel planar distribution vector data into ArcGIS software for spatial connection to obtain a spatial connection distribution map of nodes and branches in the quantity statistics step is as follows: Import the river channel planar distribution vector data into ArcGIS software to generate a topological dataset of nodes and branches; The nodes and branches in the topology dataset are spatially connected using the spatial connectivity tool in ArcGIS software to obtain a spatial connectivity distribution map of nodes and branches.

[0011] In some embodiments, the node types include type I nodes, type Y nodes, and type X nodes; type I nodes are isolated nodes with 1 connecting branch; type Y nodes are oblique / derived nodes with 3 connecting branches; type X nodes are cross nodes with 4 connecting branches; the branches include type II branches, type CI branches, and type CC branches, type II branches are branches with type I nodes on both sides, type CI branches are branches with type I nodes on one side and connecting nodes on the other side, and type CC branches are branches with connecting nodes on both sides.

[0012] In some embodiments, the method for calculating the development ratio of nodes and branches based on the number of nodes and branches in each grid during the calculation step is as follows: The development ratio of nodes is:

[0013]

[0014]

[0015] in,

[0016] In the formula, The developmental proportion of type I nodes. The developmental proportion of Y-shaped nodes. The developmental proportion of X-shaped nodes. The number of type I nodes. The number of Y-shaped nodes. The number of X-shaped nodes; The branching development ratio is:

[0017]

[0018]

[0019] in,

[0020] In the formula, The developmental proportion of type I nodes. The developmental proportion of Y-shaped nodes. The developmental proportion of X-shaped nodes. The number of type I nodes. The number of Y-shaped nodes. This represents the number of X-shaped nodes.

[0021] In some embodiments, during the calculation step, the connectivity index is calculated based on the development ratio using the following formula:

[0022] In the formula, This is the connectivity index.

[0023] In some embodiments, the method for determining sand body connectivity based on the connectivity index is as follows: When the connectivity index is less than 0.3, the sand body is considered to be weakly connected; when the connectivity index is greater than or equal to 0.3 and less than or equal to 0.6, the sand body is considered to be moderately connected; when the connectivity index is greater than 0.6, the sand body is considered to be strongly connected.

[0024] In a second aspect, the present invention provides a quantitative evaluation system for the connectivity of river sand bodies, used to implement the quantitative evaluation method for the connectivity of river sand bodies described in the first aspect of the present invention, comprising: Data acquisition module: Acquires core, well logging, 3D seismic, and modern delta outcrop analog data for the target stratigraphic interval in the study area; Map construction module: Based on core, well logging, 3D seismic and modern delta outcrop analog data, establish sand body thickness maps and sedimentary microfacies plane maps; Type determination module: Determines node and branch types based on sand body thickness map and sedimentary microfacies planar map; Model generation module: Based on the data in the sand body thickness map, the stratigraphic framework of the target layer in the study area is divided according to the isochronous interface, and a sand body distribution model is generated. Vector data extraction module: Extracts the channel centerline and channel boundary polygons in vector format from the sand body distribution model to obtain the channel planar distribution vector data; The quantity statistics module imports the river channel planar distribution vector data into ArcGIS software, performs spatial connection to obtain a spatial connection distribution map of nodes and branches, divides the spatial connection distribution map of nodes and branches into grids, and counts the number of different types of nodes and branches in each grid. Calculation module: Calculates the development ratio of nodes and branches based on the number of nodes and branches in each grid, and calculates the connectivity index based on the development ratio; Evaluation module: Determines sand body connectivity based on connectivity index.

[0025] Compared with the prior art, the advantages and positive effects of the present invention are as follows: (1) The quantitative evaluation method and system for channel sand body connectivity provided by this invention introduces topology into delta reservoir research for the first time, abstracting complex distributary channels into a "node-branch" network. By constructing and gridding the channel node-branch topological spatial connection diagram, a quantitative relationship of "number of nodes - number of branches (i.e., connecting channels) - connectivity strength" is directly established. This topological-quantitative relationship eliminates empirical coefficients, making the connectivity evaluation results unique and repeatable. This invention achieves rapid, batch, and quantitative identification of complex connectivity relationships through spatial connection, grid division, and quantity statistics.

[0026] (2) The quantitative evaluation method and system for river sand body connectivity provided by the present invention divides the entire study area into grids in the ArcGIS software environment, realizes “pixel-level” sampling of the planar distribution of river sand bodies, and improves the spatial resolution of connectivity evaluation by at least one order of magnitude.

[0027] (3) The quantitative evaluation method and system for river sand body connectivity provided by this invention can complete the connectivity quantification of hundreds of square kilometers of area in a single run in 5-30 minutes by using ArcGIS software for spatial connection, grid division, node-branch identification and quantity statistics. The labor cost is reduced by more than 80%, and the test cycle is shortened from "month" to "hour". Compared with the traditional method, which requires manual placement of tracers and repeated well opening and closing tests, and the test cycle of a single well group is 2 to 6 months, this invention significantly improves the evaluation efficiency. (4) Compared with the existing technology that relies on the actual injection and production response and can only identify invalid cycles after water injection development, the quantitative evaluation method and system for river sand body connectivity provided by this invention can distinguish connectivity during the oilfield development scheme design stage. Attached Figure Description

[0028] Figure 1 This is a flowchart of the quantitative evaluation method for river sand body connectivity according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the branch and node types described in an embodiment of the present invention; Figure 3 This is a flowchart illustrating the method for importing river channel planar distribution vector data into ArcGIS software to obtain a spatial connection distribution map of nodes and branches, as described in an embodiment of the present invention. Figure 4 This is a structural block diagram of the quantitative evaluation system for river sand connectivity according to an embodiment of the present invention; Figure 5 This is a plan view of the sedimentary microfacies of the river-controlled delta in the Shahejie Formation of the Dongying Depression as described in an embodiment of the present invention; Figure 6 This is a topological diagram of the river-controlled delta distributary channel node types in the Shahejie Formation of the Dongying Depression, identified using the quantitative evaluation method and system for river sand connectivity of this invention. Figure 7 This is a topological diagram of the branching channel types of the river-controlled delta in the Shahejie Formation of the Dongying Depression, identified using the quantitative evaluation method and system for river sand connectivity of this invention. Figure 8 This is a schematic diagram of the topology of the river-controlled delta distributary channel node-branch type in the Shahejie Formation of the Dongying Depression, identified using the quantitative evaluation method and system for river sand connectivity of this invention. Figure 9 This is a diagram showing the connectivity of river sand bodies in the river-controlled delta of the Shahejie Formation in the Dongying Depression, obtained using the quantitative evaluation method and system for river sand body connectivity of this invention.

[0029] In the diagram, 1 is the data acquisition module, 2 is the graph construction module, 3 is the type determination module, 4 is the model generation module, 5 is the vector number extraction module, 6 is the quantity statistics module, 7 is the calculation module, and 8 is the evaluation module. Detailed Implementation

[0030] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0031] Existing methods for evaluating channel sand body connectivity mostly rely on empirical formulas or indirect monitoring data (tracer concentration curves, pressure disturbance curves, and production dynamic decline curves) to infer channel connectivity relationships. These methods are highly susceptible to human interpretation and have low resolution. This invention provides a quantitative evaluation method and system for channel sand body connectivity. For the first time, topology is introduced into delta reservoir research, abstracting complex distributary channels into a "node-branch" network. By identifying node-branch types, a quantitative relationship is established between the number of nodes connected to branches and the connectivity strength. This topological-quantitative relationship eliminates empirical coefficients, ensuring the uniqueness and repeatability of connectivity evaluation results, and enabling quantitative evaluation of channel sand body connectivity. The following detailed description, in conjunction with the accompanying drawings, provides a quantitative evaluation method and system for channel sand body connectivity provided by this invention.

[0032] See Figure 1 According to a first aspect of the present invention, a method for quantitatively evaluating the connectivity of river sand bodies is provided, the steps of which are as follows: S1. Data acquisition steps: Acquire core, well logging, 3D seismic, and modern delta outcrop analog data of the target strata in the study area.

[0033] S2. Map construction steps: Based on core, well logging, 3D seismic and modern delta outcrop analog data, establish sand body thickness maps and sedimentary microfacies plane maps.

[0034] Specifically, based on core, well logging, 3D seismic, and modern delta outcrop analog data, we conducted work such as identifying sedimentary structures, finely classifying the microfacies types of underwater distributary channels, mouth bars, distal sand bars, and interdistributary bays at the delta front, and identifying channel boundaries. We integrated the data to generate sand body thickness maps and sedimentary microfacies plane maps to avoid misclassifying non-channel parts as distributary channels, ensure that the topological network contains only effective connected units, distinguish between active channels (main sand transport) and abandoned channels (no connectivity value), and prevent the introduction of invalid branches in the topological analysis.

[0035] S3. Type determination steps: Determine the node and branch types based on the sand body thickness map and sedimentary microfacies planar map.

[0036] Specifically, see Figure 2The node types include type I nodes, type Y nodes, and type X nodes; type I nodes are isolated nodes with 1 connecting branch; type Y nodes are oblique / derived nodes with 3 connecting branches; type X nodes are cross nodes with 4 connecting branches; the branches include type II branches, type CI branches, and type CC branches, type II branches are branches with type I nodes on both sides, type CI branches are branches with type I nodes on one side and connecting nodes on the other side, and type CC branches are branches with connecting nodes on both sides.

[0037] Based on the above definition, the topological relationships existing in the branching channels can be clearly defined as follows: type I nodes connect to 1 branch of the channel, type Y nodes connect to 3 branches of the channel, and type X nodes connect to 4 branches of the channel. Therefore, there is a quantitative relationship between the number of channel branches and the number of nodes in a certain region.

[0038] S4. Model generation steps: Based on the data in the sand body thickness map, the stratigraphic framework of the target layer in the study area is divided according to the isochronous interface to generate a sand body distribution model.

[0039] Specifically, a high-resolution sand body distribution model is generated using sequential indicator simulation or multi-point geostatistical methods.

[0040] Based on isochronous interfaces (such as lacustrine flooding surfaces), the stratigraphic framework of the target strata in the study area is divided to generate a sand body distribution model, ensuring the timeliness of the sand body distribution model.

[0041] S5. Vector data extraction steps: Extract the channel centerline and channel boundary polygons in vector format from the sand body distribution model to obtain the channel planar distribution vector data.

[0042] S6. Quantity statistics steps: Import the river channel plane distribution vector data into ArcGIS software to obtain a spatial connection distribution map of nodes and branches. Divide the spatial connection distribution map of nodes and branches into grids and count the number of different types of nodes and branches in each grid.

[0043] It should be noted that when dividing the grid, the size of the grid is set according to the average width of the river channel (50-100m), and its range is 10m×10m~50m×50m. For example, it can be 10m×10m, 30m×30m, or 50m×50m.

[0044] Specifically, see Figure 3 The method for importing river channel planar distribution vector data into ArcGIS software and performing spatial connection to obtain a spatial connection distribution map of nodes and branches is as follows: S61. Import the river channel planar distribution vector data into ArcGIS software to generate a topological dataset of nodes and branches; S62. Using the spatial connection tool in ArcGIS software, spatial connections are made between nodes and branches in the topology dataset to obtain a spatial connection distribution map of nodes and branches.

[0045] Specifically, when performing spatial joins, set the parameters Join Operation = JOIN_ONE_TO_MANY and Match Option = Contains.

[0046] Specifically, in ArcGIS software, under the Analysis Tools toolbox, click the Spatial Tools option under the Overlay option. In Target Features, grid the complex distributary channels developed in the study area. Use the Summary Statistics tool to count the number of X / Y / I type nodes and CC / CI / II type branches within each grid. Set the core parameters as follows: Statistics Field = Join_Count, Statistics Type = SUM, and Case Field = TARGET_FID (grouped by grid).

[0047] S7. Calculation steps: Calculate the development ratio of nodes and branches based on the number of nodes and branches in each grid, and calculate the connectivity index based on the development ratio.

[0048] It should be noted that the development ratio refers to the percentage of each type of node or branch within a given study area, relative to the total number of nodes or branches. Node type determines the "theoretical total number" of branches, while branch type is simply a reclassification of branches according to the type of the breakpoint node. The two have a whole-part relationship, rather than a one-to-one binding relationship such as "X-type nodes necessarily correspond to CC-type branches." In a closed river network, the sum of the number of connected branches of all nodes is equal to twice the total number of branches, meaning that each branch is counted once by each of its two endpoints.

[0049] Specifically, the method for calculating the development ratio of nodes and branches based on the number of nodes and branches in each grid is as follows: The development ratio of nodes is:

[0050]

[0051]

[0052] in,

[0053] In the formula, The developmental proportion of type I nodes. The developmental proportion of Y-shaped nodes. The developmental proportion of X-shaped nodes. The number of type I nodes. The number of Y-shaped nodes. The number of X-shaped nodes; The branching development ratio is:

[0054]

[0055]

[0056] in,

[0057] In the formula, The developmental proportion of type I nodes. The developmental proportion of Y-shaped nodes. The developmental proportion of X-shaped nodes. The number of type I nodes. The number of Y-shaped nodes. This represents the number of X-shaped nodes.

[0058] Specifically, the connectivity index is calculated based on the development ratio using the following formula:

[0059] In the formula, This is the connectivity index.

[0060] The first part of the above formula This is the weighted proportion of strongly connected components, directly measuring the weight share of high-quality connected channels (CC type) and medium-quality channels (CI type) in a given grid. The latter part of the formula... It is the development ratio of X-type nodes, which measures the density of the most critical intersection points (X-type nodes) in a certain grid.

[0061] S8. Evaluation steps: Determine the connectivity of sand bodies based on the connectivity index.

[0062] Specifically, the method for determining the connectivity of sand bodies based on the connectivity index is as follows: When the connectivity index is less than 0.3, the sand body is considered to be weakly connected; when the connectivity index is greater than or equal to 0.3 and less than or equal to 0.6, the sand body is considered to be moderately connected; when the connectivity index is greater than 0.6, the sand body is considered to be strongly connected.

[0063] It should be noted that this invention transforms topological parameters (node ​​type / branch type) into a spatial connectivity strength index (i.e., connectivity index). For areas with different connectivity levels, different development strategies can be adopted based on the development ratio of nodes and branches. For example, when the proportion of CC-type intersecting branches in a certain area is >60% and the density of X-type nodes is >0.05 per hectares, it can be determined that there are high-permeability dominant channels in this area, and water channeling is likely to occur during development. Based on this, injection, profile control, or infill wells can be deployed in advance during the well placement stage.

[0064] The method described in this invention is based on accurate distributary channel identification and uses ArcGIS software to identify connectivity relationships. It transforms complex distributary channels from abstract sensory features into images with quantitative characteristics, thus completing a quantitative study of the connectivity of complex distributary channels. This provides a new method for the study and evaluation of channel sand reservoir connectivity relationships during oil and gas field development and has important guiding significance for the development of deltaic facies reservoirs.

[0065] See Figure 6 According to a second aspect of the present invention, a quantitative evaluation system for river channel sand body connectivity is provided to implement the quantitative evaluation method for river channel sand body connectivity described in the first aspect of the present invention, comprising: Data acquisition module 1 acquires core, well logging, 3D seismic, and modern delta outcrop analog data for the target strata in the study area; Module 2, based on core, well logging, 3D seismic and modern delta outcrop analog data, establishes sand body thickness maps and sedimentary microfacies plane maps; Type determination module 3 determines the node and branch types based on the sand body thickness map and sedimentary microfacies planar map; Model generation module 4, based on the data in the sand body thickness map, divides the stratigraphic framework of the target layer in the study area based on the isochronous interface, and generates a sand body distribution model. Vector data extraction module 5 extracts the channel centerline and channel boundary polygons in vector format from the sand body distribution model to obtain the channel planar distribution vector data. Module 6, the quantity statistics module, imports the vector data of the river's planar distribution into ArcGIS software to obtain a spatial connection distribution map of nodes and branches, divides the spatial connection distribution map of nodes and branches into grids, and counts the number of different types of nodes and branches in each grid. Calculation module 7 calculates the development ratio of nodes and branches based on the number of nodes and branches in each grid, and calculates the connectivity index based on the development ratio; Evaluation module 8 determines the connectivity of sand bodies based on the connectivity index.

[0066] This embodiment describes the quantitative evaluation system for the connectivity of river sand bodies described above.

[0067] The effectiveness of the above-mentioned quantitative evaluation method and system for river sand connectivity is explained below with reference to specific embodiments.

[0068] Example: This study evaluates the connectivity of channel sand bodies in the river-controlled delta of the Shahejie Formation in the Dongying Depression. The structural units within the study area can be divided into a southern gentle slope zone, a central nose-shaped structural zone, and a northern sloping zone. Within this zone, Zone 4 is located in the middle of the central nose-shaped structural zone. Along the Bamianhe strike-slip fault zone, a left-handed oblique fault extending in a near-NE-East and East-West direction develops, forming a well-formed structural trap and supporting multiple oil-bearing strata, primarily composed of the Paleogene Shahejie Formation. The study area currently has over 750 wells, a high well density, and abundant data, providing a data foundation for conducting high-precision quantitative characterization of deltaic reservoir configurations.

[0069] The evaluation method is as follows: Obtain core, well logging, 3D seismic, and modern delta outcrop analog data for the target stratigraphic interval in the study area.

[0070] Based on core, well logging, 3D seismic, and modern deltaic outcrop analog data, this study identifies sedimentary structures, refines the microfacies types of underwater distributary channels, mouth bars, distal sand bars, and interdistributary bays at the delta front, and identifies channel boundaries. The data is then integrated to generate sand body thickness maps and sedimentary microfacies plans (see [reference]). Figure 5 ).

[0071] In ArcGIS software, the study area with complex distributary channels was gridded, and the number of X / Y / I type nodes in each grid was extracted (see [link]). Figure 6 ) and the number of CC / CI / II type branches (see Figure 7 ), further obtaining the node and branch topology graph as follows Figure 8 As shown, the final connectivity image of the study area is obtained as follows: Figure 9 As shown.

[0072] After adopting the above-mentioned method and system of the present invention, the proportion of ineffective water circulation in the river-controlled delta of Shahejie Formation in Dongying Depression was reduced from 18% to 7%, and the final recovery rate is expected to be increased by 3.2%.

[0073] The above embodiments are used to explain the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for quantitatively evaluating the connectivity of river channel sand bodies, characterized in that, The steps are as follows: Data acquisition steps: Acquire core, well logging, 3D seismic, and modern delta outcrop analog data for the target stratigraphic interval in the study area; Map construction steps: Based on core, well logging, 3D seismic and modern delta outcrop analog data, establish sand body thickness maps and sedimentary microfacies plane maps; Type determination steps: Based on the sand body thickness map and sedimentary microfacies planar map, determine the node and branch types; Model generation steps: Based on the data in the sand body thickness map, the stratigraphic framework of the target layer in the study area is divided according to the isochronous interface to generate a sand body distribution model; Vector data extraction steps: Extract the channel centerline and channel boundary polygons in vector format from the sand body distribution model to obtain the channel planar distribution vector data; Quantitative statistics steps: Import the river channel planar distribution vector data into ArcGIS software to obtain a spatial connection distribution map of nodes and branches. Divide the spatial connection distribution map of nodes and branches into grids and count the number of different types of nodes and branches in each grid. Calculation steps: Calculate the development ratio of nodes and branches based on the number of nodes and branches in each grid, and calculate the connectivity index based on the development ratio; Evaluation steps: Determine the connectivity of sand bodies based on the connectivity index.

2. The method for quantitatively evaluating the connectivity of river sand bodies as described in claim 1, characterized in that, In the model generation step, a high-resolution sand body distribution model is generated using sequential indicator simulation methods or multi-point geostatistical methods.

3. The method for quantitatively evaluating the connectivity of river sand bodies as described in claim 1, characterized in that, In the quantitative statistics step, the method for importing the river channel planar distribution vector data into ArcGIS software and performing spatial connection to obtain the spatial connection distribution map of nodes and branches is as follows: Import the river channel planar distribution vector data into ArcGIS software to generate a topological dataset of nodes and branches; The nodes and branches in the topology dataset are spatially connected using the spatial connectivity tool in ArcGIS software to obtain a spatial connectivity distribution map of nodes and branches.

4. The method for quantitatively evaluating the connectivity of river sand bodies as described in claim 1, characterized in that, The node types include Type I nodes, Type Y nodes, and Type X nodes; Type I nodes are isolated nodes with 1 connecting branch; Type Y nodes are oblique / derived nodes with 3 connecting branches; Type X nodes are cross nodes with 4 connecting branches; the branches include Type II branches, Type CI branches, and Type CC branches. Type II branches are branches with Type I nodes on both sides; Type CI branches are branches with Type I nodes on one side and connecting nodes on the other side; and Type CC branches are branches with connecting nodes on both sides.

5. The method for quantitative evaluation of river channel sand connectivity as described in claim 4, characterized in that, In the calculation steps, the method for calculating the development ratio of nodes and branches based on the number of nodes and branches in each grid is as follows: The development ratio of nodes is: in, In the formula, The developmental proportion of type I nodes. The developmental proportion of Y-shaped nodes. The developmental proportion of X-shaped nodes. The number of type I nodes, The number of Y-shaped nodes. The number of X-shaped nodes; The branching development ratio is: in, In the formula, The developmental proportion of type I nodes. The developmental proportion of Y-shaped nodes. The developmental proportion of X-shaped nodes. The number of type I nodes, The number of Y-shaped nodes. This represents the number of X-shaped nodes.

6. The method for quantitatively evaluating the connectivity of river sand bodies as described in claim 5, characterized in that, In the calculation step, the connectivity index is calculated based on the development ratio using the following formula: In the formula, This is the connectivity index.

7. The method for quantitatively evaluating the connectivity of river sand bodies as described in claim 1, characterized in that, In the evaluation process, the method for determining sand body connectivity based on the connectivity index is as follows: When the connectivity index is less than 0.3, the sand body is considered to be weakly connected; when the connectivity index is greater than or equal to 0.3 and less than or equal to 0.6, the sand body is considered to be moderately connected; when the connectivity index is greater than 0.6, the sand body is considered to be strongly connected.

8. A quantitative evaluation system for the connectivity of river channel sand bodies, used to implement the quantitative evaluation method for the connectivity of river channel sand bodies as described in any one of claims 1 to 7, characterized in that, include: Data acquisition module: Acquires core, well logging, 3D seismic, and modern delta outcrop analog data for the target stratigraphic interval in the study area; Map construction module: Based on core, well logging, 3D seismic and modern delta outcrop analog data, establish sand body thickness maps and sedimentary microfacies plane maps; Type determination module: Determines node and branch types based on sand body thickness map and sedimentary microfacies planar map; Model generation module: Based on the data in the sand body thickness map, the stratigraphic framework of the target layer in the study area is divided according to the isochronous interface, and a sand body distribution model is generated. Vector data extraction module: Extracts the channel centerline and channel boundary polygons in vector format from the sand body distribution model to obtain the channel planar distribution vector data; The quantity statistics module imports the river channel planar distribution vector data into ArcGIS software, performs spatial connection to obtain a spatial connection distribution map of nodes and branches, divides the spatial connection distribution map of nodes and branches into grids, and counts the number of different types of nodes and branches in each grid. Calculation module: Calculates the development ratio of nodes and branches based on the number of nodes and branches in each grid, and calculates the connectivity index based on the development ratio; Evaluation module: Determines sand body connectivity based on connectivity index.

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