Braided river delta deposition characterization method based on cause sand body structure mode constraint

Abstract

The invention relates to a braided river delta deposition characterization method based on cause sand body structure mode constraint, which comprises the following steps of: determining vertical development characteristics of shunt channel cause sand bodies and estuary dam cause sand bodies in a braided river delta, and identifying the type of a thick-layer sand body of a single well; counting vertical development proportions of different types of cause sand bodies of the single well at different positions of the to-be-mapped braided river delta, and determining a cause sand body structure mode of the single well based on the vertical development proportions of the different types of cause sand bodies; in combination with a cause sand body structure mode of a single well and a section, a cause sand body zoning and zoning plane distribution diagram is drawn under guidance of a deposition concept mode, and braided river delta deposition characterization based on cause sand body structure mode constraint is achieved; two factors of cause sand body types and structural modes are added into factors for guiding braided river delta sedimentary facies mapping, and the problem that the cause sand body types and the structural modes are not considered in an existing braided river delta sedimentary facies mapping technology is solved.

Description

Technical Field

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

[0002] Braided river delta is an important reservoir sedimentary type in continental petroliferous basins. Delta distributary channel sand bodies and estuary bar sand bodies are the main sites for the development of oil and gas reservoirs. The planar sedimentary facies mapping of braided river delta can show the distribution range and distribution law of delta sand bodies, which is an important means of sedimentary characterization of braided river delta. In the oil and gas exploration stage, the description and mapping prediction of delta sand body distribution law are important technical links, which can play an important guiding role in oilfield exploration and research.

[0003] The existing braided river delta sedimentary characterization method mainly relies on the guidance of sedimentary model, and determines the distribution morphology of sedimentary facies according to the sand-to-land ratio. In the process of establishing the conceptual model, the typical braided river delta sedimentary model is referred to. This characterization method focuses on the distribution pattern of braided river delta sedimentary facies belt and the application of sand-to-land ratio. However, in the actual application process, it is found that braided river delta sediments often have the characteristics of superimposed and continuous development of sand bodies, rapid sedimentary facies change, strong reservoir heterogeneity, and a wide distribution range of reservoirs with high sand-to-land ratio. Within a large-scale research range, the distribution differences of sedimentary sand bodies in different zones are not easy to be distinguished by sand-to-land ratio. Since braided river delta sand bodies have many different genetic types, the existing technology mainly relies on sand-to-land ratio to distinguish sedimentary facies belts in the process of large-area sedimentary facies mapping of braided river deltas, and does not distinguish the types of delta-caused sand bodies. Especially in the diversion bar-type braided river delta, there is still a lack of sedimentary characterization research methods for the distribution laws of sand bodies of different genesis. 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 aims at the technical problems existing in the prior art and provides a braided river delta sedimentary characterization method based on the constraint of genetic sand body structure mode. The genetic sand body type and structure mode are added to the factors guiding the braided river delta sedimentary phase mapping, thereby solving the problem that the existing braided river delta sedimentary phase mapping technology does not take the genetic sand body type and structure mode 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 structure mode 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 logging curve;

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

[0008] Step 3, based on the thick-layer sand body type identification of the single well, 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 are counted, and the genetic sand body structure mode of the single well is determined 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 profile along the propagation direction of the braided river delta deposition period, and obtain the genetic sand body structure mode of the profile according to the different types and structural modes of the genetic sand bodies of each single well on the profile;

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

[0011] Based on 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-shaped natural gamma-ray curves and repeated anti-rhythms are interpreted as estuary-bar sand bodies.

[0014] The sand bodies with bell-shaped natural gamma-ray curves and repeated positive rhythmic sawtooth shapes in some areas are interpreted as distributary channel-derived 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 estuary bar genetic sand body.

[0018] Optionally, step 3 includes:

[0019] Set the threshold a<0, b>0;

[0020] When the value of the parameter A-1 is greater than b, it is determined that the single well genetic sand body structure mode is 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), it is determined that the single well genetic sand body structure mode is that the well area continuously switches between estuary bar deposition and distributary channel deposition;

[0022] When the value of the parameter A-1 is less than a, it is determined that the single well genetic sand body structure mode is located in the estuary area, with developed distributary channel end deposits and estuary bar deposits.

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

[0024] The variation law of genetic sand body structure parameter A from near-source well area to far-source well area is analyzed, the variation law of genetic sand body types is summarized, and the genetic sand body structure model of braided river delta is established based on the variation law 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 based on 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, profile comparison and plane fitting to depict the planar distribution pattern of genetic sand bodies.

[0031] The present invention provides a braided river delta sediment characterization method based on the constraint of the genetic sand body structure model. Under the conditions of combining the well logging identification feature analysis and completing the interpretation of the single well genetic sand body, the genetic sand body structure parameters are calculated, and the profile distribution characteristics of the genetic sand body and the change law of the sand body structure parameters in the direction of the source water system are analyzed to summarize the structural style of the genetic sand body. Finally, the sedimentary concept model is used to guide the drawing of the final genetic sand body zoning and zoning plane distribution map. The present invention can increase the amount of information carried by the sedimentary mapping, and at the same time, on the basis of the original large-area sedimentary mapping, more accurately describe the distribution law of different types of sand bodies in the braided river delta. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0033] Figure 2 A single well distribution characteristic map of a braided river delta-derived sand body provided in 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 in conjunction with 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 A flow chart of a braided river delta sediment characterization method based on genetic sand body structure model constraints provided by the present invention, 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 logging curve.

[0042] Step 2: Determine the vertical development characteristics of distributary channel-induced sand bodies and estuary bar-induced sand bodies in the braided river delta in combination with the provenance direction, core sedimentary characteristics and logging curve development characteristics, and identify the thick sand body type of a single well based on the vertical development characteristics of the distributary channel-induced sand bodies and estuary bar-induced sand bodies.

[0043] Step 3: Based on the identification of thick-layer 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 in the region, and obtain the genetic sand body structure model of the profile based on the different types and structural models of the genetic sand bodies of each single well on the profile.

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

[0046] In the process of braided river delta large-area sedimentary phase mapping, the prior art mainly relies on sand-to-ground ratio to distinguish sedimentary phase zones, but does not distinguish the types of delta-forming sand bodies. Therefore, there are problems such as insufficient accuracy of sedimentary phase mapping, inconsistency with the actual distribution of sand bodies, and difficulty in guiding oil and gas exploration and development practices. The present invention provides a braided river delta sedimentary characterization method based on genetic sand body structural pattern constraints, which adds two factors, genetic sand body type and structural pattern, to the factors guiding braided river delta sedimentary phase mapping, thereby solving the problem that the existing braided river delta sedimentary phase mapping technology does not 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 mode constraints 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 logging curve.

[0050] Step 2: Determine the vertical development characteristics of distributary channel-induced sand bodies and estuary bar-induced sand bodies in the braided river delta in combination with the provenance direction, core sedimentary characteristics and logging curve development characteristics, and identify the thick sand body type of a single well based on the vertical development characteristics of the distributary channel-induced sand bodies and estuary bar-induced sand bodies.

[0051] like Figure 2 FIG4( a ) is a schematic diagram of a braided river delta-induced sand body structure pattern according to an embodiment of the present invention, FIG4( b ) is a schematic diagram of a braided river delta-induced sand body structure pattern according to an embodiment of the present invention, and FIG4( c ) is a schematic diagram of three embodiments of a braided river delta-induced sand body structure pattern according to an embodiment of the present invention. Figure 2 , Figure 3 4(a), 4(b) and 4(c), it can be seen that in a 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 curve are interpreted as estuary bar-genetic 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 source water system of the braided river delta to be mapped come from the southeast and west, such as Figure 2 As shown in the figure, the sediment grain size of the sand body caused by a single-stage estuary bar presents the characteristics of anti-rhythm (becoming coarser upward), and its natural gamma curve value gradually increases upward; while the sediment grain size of the sand body caused by a single-stage distributary channel presents the characteristics of positive rhythm (becoming finer upward), and its natural gamma curve value gradually decreases upward. With the continuous change of hydrodynamic energy, the natural gamma value corresponding to the corresponding deposited sand body will also fluctuate. In general, the Triassic braided river delta estuary bar sand body develops repeated anti-rhythm, and the curve is box-funnel-shaped, constituting an aggradational, retrogradational, and progradational sedimentary sequence, which can form thick sand bodies. The distributary channel sand body develops positive rhythm, and the curve is bell-shaped. There may 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-layer 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 a possible implementation manner, step 3 includes:

[0058] 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 estuary bar genetic sand body. Set the threshold a<0, b>0.

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

[0060] When the value of parameter A-1 is within the range of (a, b), the single well genetic sand body structure model is judged to be a continuous transition between estuary bar deposition and distributary channel deposition in the well area.

[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, and within the same stratigraphic unit, the genetic sand body structure mode of a single well is summarized according to the presence of the genetic sand body structure parameter A, which is greater than 1, less than 1, and nearly equal to 1. The development ratio of the 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), such as Figure 3 , based on the interpretation of different genetic sand bodies and the calculation of the structural parameter A of the genetic sand bodies of a single well, the structural type and structural mode of the genetic sand bodies of a single well are determined. If the parameter A is much greater than 1, the proportion of the distributary channel genetic sand bodies is larger, which is manifested as the superposition of multi-stage distributary channel sand bodies, among which a small part of the well area in the deposition period transitions to the estuary bar deposition area; when the parameter A is approximately equal to 1, the thickness of the estuary bar genetic sand body and the distributary channel genetic sand body is equal. Due to the continuous swing of the distributary channel, the well area continuously switches between the estuary bar deposition and the distributary channel deposition; and when the parameter A is less than 1, the proportion of the estuary bar genetic sand body is relatively large, mainly located in the estuary area, and the end of the distributary channel deposition and the estuary bar deposition are developed. According to the identification and division of genetic sand bodies, the section genetic sand body dissection shows that there are obvious differences in the types and thicknesses of genetic sand bodies in 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 in the region, and obtain the genetic sand body structure model of the profile based on the different types and structural models of the genetic sand bodies of each single well on the profile.

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

[0065] In a possible implementation manner, 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 based on 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 a possible implementation manner, step 5 includes:

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

[0069] Under the guidance of the sedimentation model, the genetic sand body structure parameter A is introduced. If the thickness of the flowing channel genetic sand body H1 is much greater than the thickness of the estuary bar genetic sand body H2, it is the development location of the main distributary channel, and the distributary channel streamline is selected for delineation. If the thickness of the flowing channel genetic sand body H1 is much less than the thickness of the estuary bar genetic sand body H2, it is the deposition location of the estuary bar.

[0070] In a possible implementation manner, step 5 includes:

[0071] Carry out sedimentary mapping of single well division, section comparison, and plane fitting to depict the plane distribution law 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 of the detailed characterization of a braided river delta-derived sand body provided by an embodiment of the invention.

[0072] The embodiment of the present invention provides a braided river delta sediment characterization method based on the constraint of the genetic sand body structure mode. Under the condition of combining the well logging identification feature analysis and completing the single well genetic sand body interpretation, the genetic sand body structure parameters are calculated, and the profile distribution characteristics of the genetic sand body and the change law of the sand body structure parameters in the direction of the source water system are analyzed to summarize the structural style of the genetic sand body. Finally, the sedimentary concept model is used to guide the drawing of the final genetic sand body zoning and zoning plane distribution map. The present invention can increase the amount of information carried by sedimentary mapping, and at the same time, on the basis of the original large-area sedimentary mapping, more accurately describe the distribution law 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 emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0074] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 generate 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 flowchart and / or block diagram. 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 capable of directing a computer or other programmable data processing device to operate 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 A 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 operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0078] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other 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 can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for characterizing braided river delta sedimentation based on genetic sand body structure model constraints, characterized in that: The characterization method comprises: 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 logging curve; Step 2, determining the vertical development characteristics of the distributary channel-induced sand bodies and the estuary bar-induced sand bodies in the braided river delta in combination with the provenance direction, core sedimentary characteristics and well logging curve development characteristics, and identifying the type of thick sand bodies in a single well based on the vertical development characteristics of the distributary channel-induced sand bodies and the estuary bar-induced sand bodies; Step 3, based on the thick-layer sand body type identification of the single well, 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 are counted, and the genetic sand body structure mode of the single well is determined based on the vertical development ratios of the different types of genetic sand bodies; Step 4: Prepare a well-connected genetic sand body analytical profile along the propagation direction of the braided river delta deposition period, and obtain the genetic sand body structure mode of the profile according to the different types and structural modes of the genetic sand bodies of each single well on the profile; Step 5, combining the genetic sand body structure model of the single well and the profile, using the sedimentary concept model to guide the drawing of the genetic sand body zoning and planar distribution map, to achieve the braided river delta sedimentary characterization based on the constraints of the genetic sand body structure model.

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-shaped natural gamma-ray curves and repeated anti-rhythms are interpreted as estuary-bar sand bodies. The sand bodies with bell-shaped natural gamma-ray curves and repeated positive rhythmic sawtooth shapes in some areas are interpreted as distributary channel-derived 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 estuary bar genetic sand body.

4. The characterization method according to claim 3, characterized in that: The step 3 comprises: Set the threshold a<0, b>0; When the value of the parameter A-1 is greater than b, it is determined that the single well genetic sand body structure mode is 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), it is determined that the single well genetic sand body structure mode is that the well area continuously switches between estuary bar deposition and distributary channel deposition; When the value of the parameter A-1 is less than a, it is determined that the single well genetic sand body structure mode is located in the estuary area, with developed distributary channel end deposits and estuary bar deposits.

5. The characterization method according to claim 3, characterized in that: The genetic sand body structure mode of the cross section obtained in step 4 includes: The variation law of genetic sand body structure parameter A from near-source well area to far-source well area is analyzed, the variation law of genetic sand body types is summarized, and the genetic sand body structure model of braided river delta is established based on the variation law 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 based on 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, profile comparison and plane fitting to depict the planar distribution pattern of genetic sand bodies.

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