Sedimentary characterization method of braided river delta based on genetic sand body structural model constraints

Abstract

The present invention relates to a braided river delta sedimentary characterization method based on genetic sand body structural pattern constraints, comprising the following steps: determining the vertical development characteristics of distributary channel genetic sand bodies and river mouth bar genetic sand bodies in a braided river delta, and identifying the thick sand body type of a single well; statistically analyzing the vertical development ratios of different types of genetic sand bodies in single wells at different locations of the braided river delta to be mapped, and determining the genetic sand body structural pattern of the single well based on the vertical development ratios of the different types of genetic sand bodies; combining the genetic sand body structural patterns of the single well and the profile, and using a sedimentary concept model to guide the drawing of a zoning and planar distribution map of the genetic sand bodies, thereby achieving braided river delta sedimentary characterization based on the genetic sand body structural pattern constraints; and adding the genetic sand body type and structural pattern into the factors guiding the braided river delta sedimentary facies mapping, thereby solving the problem that the existing braided river delta sedimentary facies mapping technology does not consider the genetic sand body type and structural pattern.

Description

Technical Field

[0001] The present invention relates to the field of oilfield exploration research, and in particular to a braided river delta sediment characterization method based on genetic sand body structure model constraints. Background Art

[0002] Braided river deltas are an important reservoir sedimentary type in continental petroliferous basins. Delta distributary channel sand bodies and mouth bar sand bodies are the primary sites of oil and gas reservoir development. Planar sedimentary facies mapping of braided river deltas can demonstrate the distribution and patterns of deltaic sand bodies, making it an important tool for sedimentary characterization of braided river deltas. Describing and mapping the distribution patterns of deltaic sand bodies is a crucial technical step in oil and gas exploration, playing a crucial role in guiding oilfield exploration research.

[0003] Existing methods for characterizing braided delta sedimentation primarily rely on sedimentary models, using sand-to-formation ratios to determine the distribution of sedimentary facies. Typical braided delta sedimentary models are used as a reference in developing conceptual models. This characterization approach focuses on the distribution patterns of braided delta sedimentary facies belts and the application of sand-to-formation ratios. However, in practical applications, braided delta sediments are often characterized by overlapping and continuous sand bodies, rapid sedimentary facies transitions, and strong reservoir heterogeneity. Reservoirs with high sand-to-formation ratios are widely distributed, and within larger-scale studies, the distribution differences in sedimentary sand bodies within different zones are difficult to distinguish using sand-to-formation ratios. Because braided delta sand bodies have a variety of different genetic types, existing techniques for mapping large-scale braided delta sedimentary facies primarily rely on sand-to-formation ratios to distinguish sedimentary facies belts, without distinguishing between deltaic sand body types. Particularly in distributary bar-type braided deltas, sedimentary characterization methods that specifically address the distribution patterns of sand bodies of different genetic origins remain lacking. Therefore, there are problems such as insufficient accuracy of sedimentary facies mapping, inconsistency with the actual distribution of sand bodies, and difficulty in guiding oil and gas exploration and development practices. Summary of the Invention

[0004] The present invention addresses the technical problems existing in the prior art and provides a braided river delta sedimentary characterization method based on the constraints of the genetic sand body structure pattern. The method adds two factors, genetic sand body type and structure pattern, to the factors guiding the braided river delta sedimentary facies mapping, thereby solving the problem that the existing braided river delta sedimentary facies mapping technology does not take the genetic sand body type and structure pattern into consideration.

[0005] According to a first aspect of the present invention, a method for characterizing braided river delta sedimentation based on genetic sand body structural model constraints is provided, comprising:

[0006] Step 1: Determine the provenance direction based on the sedimentary background of the braided river delta to be mapped; obtain the sedimentary characteristics of the braided river delta core encountered by the coring well and the development characteristics of the well logging curve;

[0007] Step 2: Determine the vertical development characteristics of distributary channel-derived sand bodies and estuary bar-derived sand bodies in the braided river delta based on the provenance direction, core sedimentary characteristics, and well logging curve development characteristics, and identify the type of thick sand bodies in a single well based on the vertical development characteristics of the distributary channel-derived sand bodies and estuary bar-derived sand bodies;

[0008] Step 3, based on the thick sand body type identification of the single well, statistically analyzing the vertical development ratios of different types of genetic sand bodies in the single well at different locations of the braided river delta to be mapped, and determining the genetic sand body structure pattern of the single well based on the vertical development ratios of the different types of genetic sand bodies;

[0009] Step 4: Prepare a well-connected genetic sand body analytical section along the propagation direction of the braided river delta during its depositional period. Obtain the genetic sand body structural model of the section based on the different types and structural models of the genetic sand bodies of each single well on the section.

[0010] Step 5: combining the genetic sand body structure model of the single well and the profile, and using the sedimentary concept model to guide the drawing of the genetic sand body zoning planar distribution map, to achieve the braided river delta sedimentary characterization based on the genetic sand body structure model constraint.

[0011] On the basis of the above technical solution, the present invention can also make the following improvements.

[0012] Optionally, the process of identifying the thick sand body type of a single well in step 2 includes:

[0013] The sand bodies with box-funnel shape and repeated anti-rhythm in the natural gamma-ray curve are interpreted as the sand bodies of estuary bar origin.

[0014] The sand bodies with bell-shaped natural gamma-ray curves and local repetitive positive rhythmic sawtooth shapes are interpreted as distributary channel sand bodies.

[0015] The thick sand bodies with composite rhythmic characteristics of natural gamma-ray curves are formed by repeated superposition of distributary channel-induced sand bodies and estuary bar-induced sand bodies of different periods. The sand bodies with local anti-rhythmic characteristics are estuary bar-induced sand bodies, and the sand bodies with local positive rhythm characteristics are distributary channel-induced sand bodies.

[0016] Optionally, step 3 includes:

[0017] Calculate the genetic sand body structure parameter A=H1 / H2; H1 represents the thickness of the distributary channel genetic sand body, and H2 represents the thickness of the mouth bar genetic sand body.

[0018] Optionally, step 3 includes:

[0019] Set thresholds a<0, b>0;

[0020] When the value of the parameter A-1 is greater than b, the single well genetic sand body structure model is determined to be the superposition of multi-stage distributary channel sand bodies, in which a small part of the well area during the deposition period transitions to the estuary bar deposition area;

[0021] When the value of the parameter A-1 is within the range of (a, b), the single well genetic sand body structure model is determined to be a continuous transition between estuary bar deposition and distributary channel deposition in the well area;

[0022] When the value of the parameter A-1 is less than a, the structural model of the single well genetic sand body is determined to be located in the estuary area, with the development of distributary channel end deposits and estuary bar deposits.

[0023] Optionally, the genetic sand body structure pattern of the cross section obtained in step 4 includes:

[0024] The variation pattern of genetic sand body structure parameter A from the near provenance well area to the far provenance well area was analyzed, the variation pattern of genetic sand body types was summarized, and the genetic sand body structure model of braided river delta was established based on the variation pattern of genetic sand body types.

[0025] Optionally, step 5 includes:

[0026] Based on the interpretation results of the genetic sand bodies of single wells and profiles, the plane is divided into zones in combination with the sedimentary facies belts. Then the boundaries of different zones are clarified, and the genetic sand bodies are divided into three zones from the upstream to the downstream of the delta.

[0027] Optionally, step 5 includes:

[0028] Combined with the distribution of the sand body structure parameter A at the well points, the zone boundary ranges of different types of genetic sand body structure patterns are determined.

[0029] Optionally, step 5 includes:

[0030] Carry out sedimentary mapping through single well division, section comparison and plane fitting to depict the plane distribution pattern of genetic sand bodies.

[0031] The present invention provides a method for characterizing braided river delta sedimentation based on the constraints of genetic sandbody structural patterns. Combining well logging identification analysis with the interpretation of genetic sandbodies in individual wells, this method calculates genetic sandbody structural parameters and analyzes the cross-sectional distribution characteristics and variations in these parameters along the provenance water system to summarize the structural patterns of the genetic sandbodies. Finally, a sedimentary conceptual model is used to guide the creation of a final planar distribution map of the genetic sandbodies, which is zoned and divided. This method can increase the amount of information carried by sedimentary mapping and, based on existing large-scale regional sedimentary mapping, more accurately describe the distribution patterns of different types of sandbodies in braided river deltas. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of an embodiment of a braided river delta sediment characterization method based on genetic sand body structure model constraints provided by the present invention;

[0033] Figure 2 A single-well distribution characteristic map of a braided river delta-derived sand body provided by an embodiment of the present invention;

[0034] Figure 3 A cross-sectional diagram of a braided river delta-derived sand body interpretation provided in an embodiment of the present invention;

[0035] FIG4( a ) is a schematic diagram of a first embodiment of a braided river delta-derived sand body structure model provided by an embodiment of the present invention;

[0036] FIG4( b ) is a schematic diagram of a second embodiment of a braided river delta-derived sand body structure model provided by an embodiment of the present invention;

[0037] FIG4( c ) is a schematic diagram of a third embodiment of a braided river delta-derived sand body structure model provided by an embodiment of the present invention;

[0038] Figure 5 A detailed characterization result diagram of a braided river delta-derived sand body provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0040] Figure 1 The present invention provides a flow chart of a braided river delta sediment characterization method based on genetic sand body structure model constraints, such as Figure 1 As shown, the characterization method includes:

[0041] Step 1: Determine the provenance direction based on the sedimentary background of the braided river delta to be mapped; obtain the sedimentary characteristics of the braided river delta core encountered by the coring well and the development characteristics of the well logging curve.

[0042] Step 2: Determine the vertical development characteristics of distributary channel-derived sand bodies and mouth bar-derived sand bodies within the braided river delta by combining the provenance direction, core sedimentary characteristics, and well logging curve development characteristics. Identify the thick sand body type in a single well based on the vertical development characteristics of the distributary channel-derived sand bodies and mouth bar-derived sand bodies.

[0043] Step 3: Based on the identification of thick sand body types in single wells, the vertical development ratios of different types of genetic sand bodies in single wells at different locations of the braided river delta to be mapped are counted, and the genetic sand body structure pattern of the single well is determined based on the vertical development ratios of different types of genetic sand bodies.

[0044] Step 4: Prepare a well-connected genetic sand body analytical profile along the propagation direction of the braided river delta deposition period. According to the different types and structural patterns of genetic sand bodies of each single well on the profile, obtain the genetic sand body structural pattern of the profile.

[0045] Step 5: Combine the genetic sand body structure patterns of single wells and profiles, and use the sedimentary concept model to guide the drawing of the genetic sand body zoning planar distribution map, so as to realize the braided river delta sedimentary characterization based on the constraints of the genetic sand body structure pattern.

[0046] Existing techniques for mapping large-scale braided river delta sedimentary facies rely primarily on sand-to-ground ratios to distinguish sedimentary facies zones, without distinguishing the types of delta-forming sand bodies. Consequently, sedimentary facies mapping suffers from insufficient accuracy, misalignment with the actual distribution of sand bodies, and inability to guide oil and gas exploration and development practices. The present invention provides a braided river delta sedimentary characterization method based on constraints imposed by the structural pattern of the genetic sand bodies. This method incorporates both the genetic sand body type and the structural pattern into the factors guiding braided river delta sedimentary facies mapping, addressing the problem that existing braided river delta sedimentary facies mapping techniques fail to consider the genetic sand body type and structural pattern.

[0047] Example 1

[0048] Example 1 provided by the present invention is an embodiment of a braided river delta sediment characterization method based on genetic sand body structure model constraint provided by the present invention, combined with Figure 1 It can be seen that embodiments of the characterization method include:

[0049] Step 1: Determine the provenance direction based on the sedimentary background of the braided river delta to be mapped; obtain the sedimentary characteristics of the braided river delta core encountered by the coring well and the development characteristics of the well logging curve.

[0050] Step 2: Determine the vertical development characteristics of distributary channel-derived sand bodies and mouth bar-derived sand bodies within the braided river delta by combining the provenance direction, core sedimentary characteristics, and well logging curve development characteristics. Identify the thick sand body type in a single well based on the vertical development characteristics of the distributary channel-derived sand bodies and mouth bar-derived sand bodies.

[0051] like Figure 2 FIG4(a), FIG4(b), and FIG4(c) are schematic diagrams of three embodiments of a braided river delta-induced sand body structure model provided by an embodiment of the present invention, respectively. Figure 2 、 Figure 3 4(a), 4(b) and 4(c), in one possible embodiment, the process of identifying the thick sand body type of a single well in step 2 includes:

[0052] Under the constraints of delta development pattern, based on single well sedimentary microfacies identification and combined with logging identification template analysis, the sand bodies with box-funnel shape and repeated anti-rhythm on the natural gamma ray curve are interpreted as river mouth bar origin sand bodies (such as the attached Figure 2 shown in yellow).

[0053] The natural gamma ray curve is generally bell-shaped, and the sand bodies with repeated positive rhythmic serrations in some areas are interpreted as distributary channel sand bodies (such as the attached Figure 2 shown in orange).

[0054] The thick sand bodies with composite rhythmic characteristics of natural gamma-ray curves are formed by repeated superposition of distributary channel-induced sand bodies and estuary bar-induced sand bodies of different periods. The sand bodies with local anti-rhythmic characteristics are estuary bar-induced sand bodies, and the sand bodies with local positive rhythm characteristics are distributary channel-induced sand bodies.

[0055] In a specific application embodiment, it is determined that the sedimentary background and provenance of the braided river delta to be mapped come from the southeast and west, such as Figure 2 As shown, the sediment grain size of the sand body of single-stage river mouth bar origin shows the characteristics of anti-rhythm (coarsening upwards), and its natural gamma curve value gradually increases upwards; while the sediment grain size of the sand body of single-stage distributary channel origin shows the characteristics of positive rhythm (finer upwards), and its natural gamma curve value gradually decreases upwards. With the continuous change of hydrodynamic energy, the natural gamma value corresponding to the corresponding deposited sand body will also fluctuate. Overall, the Triassic braided river delta river mouth bar sand body develops repeated anti-rhythm, and the curve is box-funnel-shaped, forming an aggradation, retrogradation, and progradation type sedimentary sequence, which can form thick sand bodies. The distributary channel sand body develops positive rhythm, and the curve is bell-shaped. There can be multiple stages of vertical superposition, which can form thick sand bodies, such as Figure 3 shown.

[0056] Step 3: Based on the identification of thick sand body types in single wells, the vertical development ratios of different types of genetic sand bodies in single wells at different locations of the braided river delta to be mapped are counted, and the genetic sand body structure pattern of the single well is determined based on the vertical development ratios of different types of genetic sand bodies.

[0057] In one possible embodiment, step 3 includes:

[0058] Calculate the genetic sand body structure parameter A = H1 / H2; H1 represents the thickness of the distributary channel sand body, and H2 represents the thickness of the mouth bar sand body. Set the thresholds a < 0 and b > 0.

[0059] When the value of parameter A-1 is greater than b, the structural model of the genetic sand body of a single well is determined to be the superposition of multi-stage distributary channel sand bodies, among which a small part of the well area during the deposition period transitions to the estuary bar deposition area.

[0060] When the value of parameter A-1 is within the range of (a, b), the structural model of the single well genetic sand body is determined to be that the well area continuously switches between river mouth bar deposition and distributary channel deposition.

[0061] When the value of parameter A-1 is less than a, the single well genetic sand body structure model is determined to be located in the estuary area, with the development of distributary channel end deposits and estuary bar deposits.

[0062] In a specific application embodiment, the genetic sand body structure parameter A is calculated. Within the same stratigraphic unit, the genetic sand body structure pattern of a single well is summarized based on the presence of the genetic sand body structure parameter A, such as greater than 1, less than 1, and nearly equal to 1. The development ratio of distributary channel and estuary bar genetic sand bodies (the larger the parameter A, the higher the proportion of distributary channel genetic sand bodies; conversely, the smaller the parameter A, the higher the proportion of estuary bar genetic sand bodies). Figure 3 Based on the interpretation of different genetic sand bodies and the calculation of the structural parameter A of the genetic sand bodies in individual wells, the structural type and pattern of the genetic sand bodies in individual wells were determined. If parameter A is much greater than 1, the proportion of distributary channel-derived sand bodies increases, indicating the superposition of multiple distributary channel sand bodies, with a small portion of the well area transitioning to mouth-bar deposition during the depositional period. When parameter A is approximately 1, the thickness of mouth-bar and distributary channel-derived sand bodies is equal. Due to the constant oscillation of the distributary channel, the well area continuously switches between mouth-bar and distributary channel deposition. When parameter A is less than 1, the proportion of mouth-bar-derived sand bodies is relatively large, mainly located in the estuary area, with the development of distributary channel terminal deposits and mouth-bar deposits. Genetic sand body dissection based on genetic sand body identification and classification reveals significant differences in genetic sand body types and thicknesses across different zones.

[0063] Step 4: Prepare a well-connected genetic sand body analytical profile along the propagation direction of the braided river delta deposition period. According to the different types and structural patterns of genetic sand bodies of each single well on the profile, obtain the genetic sand body structural pattern of the profile.

[0064] Step 5: Combine the genetic sand body structure patterns of single wells and profiles, and use the sedimentary concept model to guide the drawing of the genetic sand body zoning planar distribution map, so as to realize the braided river delta sedimentary characterization based on the constraints of the genetic sand body structure pattern.

[0065] In one possible embodiment, step 5 includes:

[0066] Based on the interpretation results of the genetic sand bodies of single wells and profiles, the plane is divided into zones in combination with the sedimentary facies belts. Then the boundaries of different zones are clarified, and the genetic sand bodies are divided into three zones from the upstream to the downstream of the delta.

[0067] In one possible embodiment, step 5 includes:

[0068] Combined with the distribution of sand body structure parameter A at the well points, the zone boundary ranges of different types of genetic sand body structure patterns are determined.

[0069] Guided by the sedimentary model, the genetic sand body structure parameter A is introduced. If the thickness of the flowing channel-derived sand body H1 is much greater than the thickness of the mouth bar-derived sand body H2, it indicates the development location of the main distributary channel, and the distributary channel streamline is selected for delineation. If the thickness of the flowing channel-derived sand body H1 is much less than the thickness of the mouth bar-derived sand body H2, it indicates the deposition location of the mouth bar.

[0070] In one possible embodiment, step 5 includes:

[0071] Carry out sedimentary mapping through single well division, cross-section comparison and plane fitting to depict the plane distribution pattern of genetic sand bodies. Finally, complete the plane mapping of sedimentary representation of distributary sand bar type braided river delta constrained by the structural model of genetic sand bodies, such as Figure 5 Shown is a diagram showing the detailed characterization of a braided river delta-derived sand body provided by an embodiment of the invention.

[0072] The present invention provides a braided river delta sediment characterization method based on the constraints of the genetic sand body structure model. Combining well logging identification feature analysis with the interpretation of the genetic sand bodies in a single well, the method calculates the genetic sand body structure parameters, analyzes the cross-sectional distribution characteristics of the genetic sand bodies along the provenance water system, and analyzes the variation patterns of the sand body structure parameters to summarize the structural patterns of the genetic sand bodies. Finally, the sedimentary concept model is used to guide the drawing of the final genetic sand body zoning planar distribution map. This method can increase the amount of information carried by sedimentary mapping and, based on the original large-scale regional sedimentary mapping, more accurately describe the distribution patterns of different types of sand bodies in braided river deltas.

[0073] It should be noted that, in the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0074] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0076] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0078] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0079] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for characterizing braided river delta sedimentation based on genetic sand body structural model constraints, characterized by: The characterization method includes: Step 1: Determine the provenance direction based on the sedimentary background of the braided river delta to be mapped; obtain the sedimentary characteristics of the braided river delta core encountered by the coring well and the development characteristics of the well logging curve; Step 2: Determine the vertical development characteristics of distributary channel-derived sand bodies and estuary bar-derived sand bodies in the braided river delta based on the provenance direction, core sedimentary characteristics, and well logging curve development characteristics, and identify the type of thick sand bodies in a single well based on the vertical development characteristics of the distributary channel-derived sand bodies and estuary bar-derived sand bodies; Step 3, based on the thick sand body type identification of the single well, statistically analyzing the vertical development ratios of different types of genetic sand bodies in the single well at different locations of the braided river delta to be mapped, and determining the genetic sand body structure pattern of the single well based on the vertical development ratios of the different types of genetic sand bodies; Step 4: Prepare a well-connected genetic sand body analytical section along the propagation direction of the braided river delta during its depositional period. Obtain the genetic sand body structural model of the section based on the different types and structural models of the genetic sand bodies of each single well on the section. Step 5: combining the genetic sand body structure model of the single well and the profile, and using the sedimentary concept model to guide the drawing of the genetic sand body zoning planar distribution map, to achieve the braided river delta sedimentary characterization based on the genetic sand body structure model constraint.

2. The characterization method according to claim 1, characterized in that The process of identifying the thick sand body type of a single well in step 2 includes: The sand bodies with box-funnel shape and repeated anti-rhythm in the natural gamma-ray curve are interpreted as the sand bodies of estuary bar origin. The sand bodies with bell-shaped natural gamma-ray curves and local repetitive positive rhythmic sawtooth shapes are interpreted as distributary channel sand bodies. The thick sand bodies with composite rhythmic characteristics of natural gamma-ray curves are formed by repeated superposition of distributary channel-induced sand bodies and estuary bar-induced sand bodies of different periods. The sand bodies with local anti-rhythmic characteristics are estuary bar-induced sand bodies, and the sand bodies with local positive rhythm characteristics are distributary channel-induced sand bodies.

3. The characterization method according to claim 1, characterized in that The step 3 comprises: Calculate the genetic sand body structure parameter A=H1 / H2; H1 represents the thickness of the distributary channel genetic sand body, and H2 represents the thickness of the mouth bar genetic sand body.

4. The characterization method according to claim 3, characterized in that The step 3 comprises: Set thresholds a<0, b>0; When the value of the parameter A-1 is greater than b, the single well genetic sand body structure model is determined to be the superposition of multi-stage distributary channel sand bodies, in which a small part of the well area during the deposition period transitions to the estuary bar deposition area; When the value of the parameter A-1 is within the range of (a, b), the single well genetic sand body structure model is determined to be a continuous transition between estuary bar deposition and distributary channel deposition in the well area; When the value of the parameter A-1 is less than a, the structural model of the single well genetic sand body is determined to be located in the estuary area, with the development of distributary channel end deposits and estuary bar deposits.

5. The characterization method according to claim 3, characterized in that The genetic sand body structure model of the cross section obtained in step 4 includes: The variation pattern of genetic sand body structure parameter A from the near provenance well area to the far provenance well area was analyzed, the variation pattern of genetic sand body types was summarized, and the genetic sand body structure model of braided river delta was established based on the variation pattern of genetic sand body types.

6. The characterization method according to claim 1, characterized in that The step 5 comprises: Based on the interpretation results of the genetic sand bodies of single wells and profiles, the plane is divided into zones in combination with the sedimentary facies belts. Then the boundaries of different zones are clarified, and the genetic sand bodies are divided into three zones from the upstream to the downstream of the delta.

7. The characterization method according to claim 3, characterized in that The step 5 comprises: Combined with the distribution of the sand body structure parameter A at the well points, the zone boundary ranges of different types of genetic sand body structure patterns are determined.

8. The characterization method according to claim 3, characterized in that The step 5 comprises: Carry out sedimentary mapping through single well division, section comparison and plane fitting to depict the plane distribution pattern of genetic sand bodies.

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