A method for characterizing abandoned river channels and evaluating their lateral connectivity

Abstract

The present invention discloses a method for characterizing abandoned river channels and grading and evaluating lateral connectivity, including: obtaining geological background information, seismic data, and well logging data; performing well seismic calibration and seismic horizon interpretation of a single sand body in a target work area; establishing a seismic forward model based on the sedimentary characteristics of the abandoned river channel; completing RGB frequency division and fusion slicing of the sand body based on the seismic interpretation horizon of the single sand body, obtaining a plane distribution map of the abandoned river channel, and determining the genetic type of the abandoned river channel; obtaining a grayscale map of the plane distribution of the sand body through attribute fusion; performing sand body boundary characterization and lateral occlusion clustering evaluation to obtain a superimposed map of sand body distribution and boundary lateral occlusion evaluation; determining identification features of abandoned river channels of different genetic types based on geological models; and performing graded evaluation of the connectivity of abandoned river channels. The present invention, combined with the actual drilling results of the target work area, confirms that the results obtained by the method are accurate and reliable, and have strong operability, which has promoted an important step in the characterization of the lateral connectivity of abandoned river channels inside the continuous sand bodies of meandering rivers.

Description

Technical Field

[0001] The invention relates to an abandoned river channel characterization and lateral connectivity classification evaluation method, belonging to the technical field of petroleum exploration and development. Background Art

[0002] The abandoned channels of meandering rivers in a broad sense include the terminal channels and the abandoned channels formed during the migration of rivers. The terminal channel is the last stage of the active channel of the meandering river, and its interior is mainly composed of low-permeability mudstone, silty mudstone or muddy siltstone deposits. The terminal channel is located in the concave bank of the channel and the side of the steep bank. It often extends for a long time in the plane and has a medium to large curvature. The abandoned channel is a meandering channel abandoned due to river diversion and lack of sediment supply during the migration of the meandering river. It is mainly distributed in the concave bank of the meander section point bar. The interior is fine-grained sediments formed by flood overflow filling, mainly mudstone and silty mudstone. Actual drilling and configuration studies have confirmed that the terminal channel and the abandoned channel can form a good lateral shielding inside the continuous sand body due to their high internal mud sediment content, forming a large-scale lithologic trap boundary. Both of these channels are abandoned due to lack of material supply. In actual production and research, both can also be collectively referred to as abandoned channels.

[0003] Different types of abandoned channels have different genesis and abandonment processes, resulting in different planar morphology and internal sediment characteristics of abandoned channels, which in turn cause variable lateral connectivity of abandoned channels. How to accurately identify abandoned channels within contiguous sand bodies and further accurately characterize the lateral connectivity of abandoned channels has always been a difficult point in petroleum exploration and evaluation.

[0004] With the development and progress of geophysical exploration technology, the prediction accuracy of abandoned river channels in plane and profile can be improved through various technical means such as geophysical inversion; however, limited by the vertical resolution of seismic and the interference of surrounding rocks in seismic data volume, the location and internal structure of abandoned river channels cannot be clearly portrayed, and there is great uncertainty in the evaluation of lateral connectivity of abandoned river channels, which brings great difficulties to the actual exploration of oil fields. Summary of the invention

[0005] In order to overcome the defects in the prior art, the present invention aims to provide a method for characterizing abandoned river channels and grading and evaluating lateral connectivity.

[0006] The technical solution provided by the present invention to solve the above technical problems is: a method for characterizing abandoned river channels and grading lateral connectivity evaluation, comprising the following steps:

[0007] Step 1: Based on the genetic model data of abandoned meandering river channels, the sedimentary model diagrams of different types of abandoned river channels are obtained;

[0008] Step 2: Obtain geological background information, seismic data, and well logging data of the target work area;

[0009] Step 3: Conduct single sand body well seismic calibration and seismic horizon interpretation in the target work area;

[0010] Step 4: Establish a seismic forward model based on drilling and logging data and the sedimentary characteristics of different types of abandoned river channels;

[0011] Step 5: Based on the single sand body seismic interpretation horizon, complete the RGB frequency division fusion slice of the sand body, obtain the plane distribution map of the abandoned river channel, and determine the genesis type of the abandoned river channel;

[0012] Step 6: Extract and optimize seismic attributes based on the single sand body layer, and then fuse the attributes to obtain a grayscale map of the sand body plane distribution;

[0013] Step 7: Based on the attribute fusion result, the sand body boundary characterization and boundary lateral obstruction clustering evaluation are performed, and the sand body plane distribution map is superimposed to obtain the sand body distribution and boundary lateral obstruction evaluation superimposition map;

[0014] Step 8: Based on the geological model, determine the identification characteristics of abandoned river channels of different genetic types;

[0015] Step 9: Conduct a graded evaluation of the connectivity of abandoned river channels.

[0016] A further technical solution is that in step 3, by comparing the logging characteristics and seismic response of a single sand body, the seismic tracking interpretation characteristics of the top and bottom of the sand body are clarified, and the seismic horizon interpretation of the single sand body in the target work area is completed.

[0017] A further technical solution is to use the same depth of the river channel in step 4, set different mudstone thicknesses to represent different types of abandoned river channels, and perform forward simulation.

[0018] A further technical solution is that in step 5, a wavelet transform method is used to perform frequency division fusion.

[0019] A further technical solution is that the types of causes of abandoned river channels in step 5 include abandoned river channels with breaches near the breach point, abandoned river channels with breaches far from the breach point, abandoned river channels with severe sudden abandonment and straightening of ditches, abandoned river channels with moderate sudden abandonment and straightening of ditches, abandoned river channels with straightening of bends and terminal river channels.

[0020] A further technical solution is that the specific process of step 6 is:

[0021] Step 61, extracting seismic attributes based on a single sand body layer;

[0022] Step 62: Analyze the correlation between the thickness of a single sand body in the target work area and the seismic attribute by using the principal component analysis method, and select the seismic attribute;

[0023] Step 63: Use a multi-attribute fusion method based on machine learning to fuse attributes and obtain a grayscale map of the sand body plane distribution.

[0024] A further technical solution is that the seismic attributes include arc length, average energy, average instantaneous phase, average positive amplitude, total positive amplitude, maximum amplitude, root mean square amplitude, energy sum, waveform length, and waveform area.

[0025] A further technical solution is that the specific process of step 7 is:

[0026] Step 71, using an image edge extraction algorithm to identify the sand body boundary, by extracting the boundary center line, calculating the boundary width, and determining the sand body boundary type;

[0027] Step 72, inputting the boundary width and sand body thickness values ​​into an unsupervised fuzzy self-organizing neural network to obtain a clustering evaluation result of the boundary lateral obstruction;

[0028] Step 73: Overlay the cluster evaluation result of the boundary lateral obstruction with the grayscale map of the sand body plane distribution to obtain an overlay map of the sand body distribution and boundary lateral obstruction evaluation.

[0029] A further technical solution is that the specific process of step 8 is:

[0030] Step 81, determining the response characteristics of RGB frequency division slices of abandoned river channels of different genetic types;

[0031] Step 82, determining seismic phase identification characteristics of different types of abandoned river channels according to the seismic forward model;

[0032] Step 83, determining the mud content characteristics at the boundaries of different types of abandoned river channels according to the grayscale map of sand body plane distribution;

[0033] Step 84, determining the logging phase characteristics at the boundaries of different types of abandoned river channels according to the logging data;

[0034] Step 85: Determine the boundary types and lateral obstruction clustering evaluation characteristics of different types of abandoned river channels based on the sand body distribution and boundary obstruction evaluation superposition map.

[0035] A further technical solution is that in step 9, when the abandoned river channel type is identified as a breached abandoned river channel near the breach point, the abandoned river channel connectivity is good;

[0036] When the abandoned channel type is identified as a breach abandoned channel far from the breach point, its abandoned channel connectivity is poor;

[0037] When the abandoned river channel type is identified as a severe abrupt abandonment type abandoned river channel with straightened ditches, the abandoned river channel connectivity is poor;

[0038] When the abandoned river channel type is identified as a moderately abandoned type of channel straightening abandoned river channel, its abandoned river channel connectivity is medium;

[0039] When the abandoned river channel type is identified as a straightened abandoned river channel, its abandoned river channel connectivity is poor;

[0040] When the abandoned channel type is identified as a terminal channel, its abandoned channel connectivity is poor.

[0041] The present invention has the following beneficial effects: the present invention adopts a technical method that combines geological model guidance with geophysical joint drive, and qualitative characterization with semi-quantitative characterization, to accurately identify different types of abandoned river channels in meandering rivers, and conduct lateral connectivity classification evaluation; combined with the actual drilling results in the target work area, it is confirmed that the results obtained by this method are accurate and reliable, and have strong operability, which has taken an important step in promoting the characterization of lateral connectivity of abandoned river channels inside the continuous sand bodies of meandering rivers. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flowchart of the present invention;

[0043] Figure 2 It is a diagram of the planar sedimentary pattern and the cross-sectional sedimentary pattern of the final river channel;

[0044] Figure 3 It is a classification diagram of abandoned river channel plan morphology and genetic type;

[0045] Figure 4 It is a seismic forward model of abandoned river channels with different sedimentary characteristics.

[0046] Figure 5 It is the RGB frequency division fusion slice map of the sand body in the target work area;

[0047] Figure 6 It is the seismic attribute extraction and attribute fusion map of the sand body layers in the target work area;

[0048] Figure 7 It is the sand body boundary extraction map of the target work area;

[0049] Figure 8 It is the measurement map of the sand body boundary width in the target work area;

[0050] Fig. 9 This is the cluster evaluation result diagram of the lateral obstruction of the sand body boundary in the target work area;

[0051] Fig.10 It is an overlay map of sand body distribution and boundary obstruction evaluation in the target work area. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] like Figure 1 As shown, a method for characterizing abandoned river channels and evaluating lateral connectivity by graded evaluation according to the present invention comprises the following steps:

[0054] Step 1: Based on the genetic model data of abandoned meandering river channels, the sedimentary model diagrams of different types of abandoned river channels are obtained (e.g. Figure 2 , Figure 3 shown);

[0055] The last stage of the meandering river's active channel is the terminal channel, which is mainly composed of low-permeability mudstone, silty mudstone or muddy siltstone deposits, and the hydrodynamic conditions are mainly medium to low energy. It often extends longer in plane, with medium to large curvature. Abandoned river channels are meandering river channels that are abandoned during the migration of meandering rivers due to river diversion and lack of sediment supply. According to the plane distribution pattern and abandonment process, they are divided into three categories: breach abandonment, ditch straightening abandonment and bend straightening abandonment. The corresponding sedimentary hydrodynamic conditions change from high-energy slow abandonment to low-energy rapid abandonment.

[0056] Step 2: Obtain geological background information, seismic data, and well logging data of the target work area;

[0057] Step 3: Conduct single sand body well seismic calibration and seismic horizon interpretation in the target work area;

[0058] On the basis of checking and correcting the synthetic records, by comparing the logging characteristics and seismic response of the single sand body, the seismic tracing interpretation characteristics of the top and bottom of the sand body are clarified, and the interpretation of the single sand body layer in the target work area is completed;

[0059] Step 4: Based on the drilling and logging data and the sedimentary characteristics of different types of abandoned river channels, different mudstone thicknesses are set to represent different types of abandoned river channels using the same depth of the river channel, and forward simulation is performed to establish a seismic forward model;

[0060] The abandoned river channel depth is set to 9m, and the model is set to sandstone-mudstone interlayers, with five layers from top to bottom: AE. Based on the logging data of the drilled point bar and abandoned river channel, the average velocity and density of different layers in the model are determined. The acoustic wave of the sandstone layer A is set to 412μs / m, and the density is 2.18g / m 3 The acoustic wave of mudstone layer B is set to 390μs / m, and the density is 2.19g / m 3 The acoustic wave of the river sandstone layer C is set to 426μs / m, and the density is 2.03g / m 3The D acoustic wave of the mudstone layer is set to 394μs / m, and the density is 2.18g / m 3 The E sound wave of the sandstone layer is set to 430μs / m and the density is 2.03g / m 3 The velocity of abandoned channel mudstone F is set to 397 μs / m and the density is 2.22 g / m 3 ( Figure 4 ). The wavelet used is 48Hz Ricker wavelet.

[0061] Step 5: Based on the single sand body seismic interpretation horizon, the wavelet transform method is used to complete the sand body RGB frequency division fusion slice ( Figure 5 ), obtain the plan distribution map of abandoned river channels and determine the cause type of abandoned river channels;

[0062] According to the original parameters of the seismic data body, the main frequency of the seismic data is determined to be about 60Hz, and the average velocity of the target layer is about 2400m / s. The thickness of the single-layer sand body is counted, and the appropriate low-frequency, medium-frequency and high-frequency single-frequency bodies are selected according to the distribution characteristics of the sand body thickness. The spectrum selects 30Hz, 60Hz and 110Hz as the frequency division body for fusion slicing;

[0063] Table 1 Classification of causes of abandoned river channels

[0064]

[0065]

[0066] Step 6: Extract and optimize seismic attributes based on the single sand body layer, and then fuse the attributes to obtain a grayscale map of the sand body plane distribution;

[0067] Step 61: Extract seismic attributes based on single sand body layer (e.g. Figure 6 a- Figure 6 e);

[0068] The properties between the top and bottom layers of a single sand body are extracted from the phase-shifted seismic data volume of the target work area. According to the characteristics of the corresponding crest event axis of the sand body in the target work area, more than ten interlayer properties such as arc length, average energy, average instantaneous phase, average positive amplitude, total positive amplitude, maximum amplitude, root mean square amplitude, energy sum, waveform length, and waveform area are extracted;

[0069] Step 62: Analyze the correlation between the thickness of a single sand body in the target work area and the seismic attribute by using the principal component analysis method, and select the seismic attribute;

[0070] The main features of the seismic data are extracted by principal component analysis, and the root mean square amplitude, total positive amplitude, maximum amplitude, waveform length, and waveform area with good correlation are preferably determined as the basic attributes of the fusion attributes;

[0071] Step 63: Use a multi-attribute fusion method based on machine learning to perform attribute fusion (such as Figure 6 f), and obtain the grayscale map of sand body plane distribution;

[0072] On the grayscale map of sand body plane distribution, black indicates thick mudstone with high mud content, while white indicates thick sandstone with low mud content;

[0073] Step 7: Based on the attribute fusion result, the sand body boundary characterization and boundary lateral obstruction clustering evaluation are performed, and the sand body plane distribution map is superimposed to obtain the sand body distribution and boundary lateral obstruction evaluation superimposition map;

[0074] Step 71: Figure 7 As shown ( Figure 7 a. Fusion attribute boundary gradient map, Figure 7 b. Fusion attribute boundary gradient denoising map, Figure 7 c. Boundary gradient binarization processing map, Figure 7 d. Binarization boundary refinement result diagram), the image edge extraction algorithm is used to identify the sand body boundary, and the boundary width is calculated by extracting the boundary center line (such as Figure 8 As shown in the figure), and determine the sand body boundary type (sand body boundaries are divided into double boundaries and single boundaries, and the lateral shielding ability of double boundaries is stronger than that of single boundaries);

[0075] Step 72: Input the boundary width and sand body thickness values ​​into the unsupervised fuzzy self-organizing neural network, set the number of clusters to 3, and obtain the clustering evaluation results of the boundary lateral obstruction. The results are as follows: Fig. 9 As shown (the lateral occlusion clustering evaluation results are divided into three levels, level I-strong lateral occlusion ability at the boundary, level II-medium lateral occlusion ability at the boundary, and level III-weak lateral occlusion ability at the boundary);

[0076] Step 73, superimpose the cluster evaluation result of the boundary lateral obstruction with the grayscale map of the sand body thickness plane distribution to obtain a superimposed map of sand body distribution and boundary obstruction evaluation (such as Fig.10 shown);

[0077] Step 8: Based on the geological model, determine the identification characteristics of abandoned river channels of different genetic types;

[0078] Step 81, determining the response characteristics of RGB frequency division slices of abandoned river channels of different genetic types;

[0079] Abandoned river channels that are straightened out appear as "Ω"-shaped black high-curvature channels on RGB frequency slices;

[0080] The abandoned river channel straightened by the ditch can be divided into severe abandonment type and moderate abandonment type. The severe abandonment type appears as a "C"-shaped medium-bend black meander on the plane, and the moderate abandonment type appears as a "C"-shaped medium-bend gray meander.

[0081] The final river channel is a black “S” shape, which is a long and medium-high sinuosity river channel;

[0082] The abandoned river channel at the breach appears as a low-bend gray-gray-black river channel with a long extension. The RGB color of the abandoned river channel in the downstream section is darker than that in the upstream section.

[0083] Step 82, determining seismic phase identification characteristics of different types of abandoned river channels according to the seismic forward model;

[0084] For abandoned river channels of straightening type, abandoned river channels of severe sudden abandonment type and late-stage river channels, the amplitude of seismic event axes in the corresponding forward model is significantly weakened, and the fault morphology is clear;

[0085] The amplitude of the corresponding event axis of the abandoned river channel in the middle-level abrupt abandonment type is weakened, the event axis is thinned, and the fault shape is blurred.

[0086] The continuity of the event axis corresponding to the abandoned river channel after the breach is good, with no obvious fault, and the overall change of the seismic phase is weak or no obvious change. In the downstream of the river channel far away from the breach point, the continuity of the event axis changes, the amplitude weakens, the fault morphology begins to appear, and the amplitude of the seismic phase change increases.

[0087] Step 83, determining the mud content characteristics at the boundaries of different types of abandoned river channels according to the grayscale map of sand body plane distribution;

[0088] According to the grayscale map of sand body plane distribution, the abandoned river channel of bend straightening type, the abandoned river channel of severe sudden abandonment type and the terminal river channel were determined. The grayscale map of sand body plane distribution showed mainly black-gray-black, indicating high content of muddy sediments and thick mudstone.

[0089] In the abandoned channel of the moderately abandoned type, the sand body plane distribution grayscale map is mainly gray, indicating that the muddy sediment content is medium;

[0090] At the breach abandoned channel, the sand body plane distribution grayscale map is mainly white to gray, indicating that the mud sediment content is low. In the downstream of the breach abandoned channel far away from the breach point, the boundary turns gray, indicating that the mud content of the sediment increases and the mudstone thickness increases.

[0091] Step 84, determining the logging phase characteristics at the boundaries of different types of abandoned river channels according to the logging data;

[0092] The well logging curves of abandoned river channels with straightening by cutting bends, abandoned river channels with straightening by severe abrupt abandonment and late-stage river channels all show a sudden change upwards, and the sediments change rapidly from coarse-grained sediments to thick-layer fine-grained or muddy sediments upwards.

[0093] The logging curve of the abandoned channel of the middle-level abandonment type changes gradually upward, and the sediments gradually transition from sandy conglomerate deposits at the bottom to medium-fine-grained deposits in the middle and mudstone at the top.

[0094] The logging curve of the abandoned channel near the breach point shows a gradual upward change in the upstream section, and a sudden upward change in the downstream section far from the breach point.

[0095] Step 85, determining the boundary types and lateral obstruction clustering evaluation characteristics of different types of abandoned river channels according to the sand body distribution and boundary obstruction evaluation superposition map;

[0096] Sand body boundaries are divided into two categories: double boundaries and single boundaries. The lateral shielding ability of double boundaries is stronger than that of single boundaries. The lateral shielding ability of boundaries is divided into grades I-III from strong to weak;

[0097] The sand body boundary types at the abandoned channel of straightening type, the abandoned channel of severe sudden abandonment type and the final channel are mainly double boundaries, and the lateral shielding evaluation is mainly level I.

[0098] The sand body boundary types at the abandoned channel of the middle-level abandonment type are mainly single-double boundaries, and the lateral shielding evaluation is mainly grade II.

[0099] The sand body boundary type at the breach abandoned channel is mainly single boundary, and the lateral shielding evaluation is mainly Class III. In the downstream section far from the breach point, the sand body boundary is mainly single-double boundary, and the lateral shielding becomes mainly Class II.

[0100] Step 9: Conduct hierarchical evaluation of the connectivity of abandoned river channels;

[0101] Table 2 Identification characteristics of abandoned river channels and their connectivity classification evaluation table

[0102]

[0103]

[0104] The above description is not intended to limit the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for characterizing abandoned river channels and evaluating their lateral connectivity, characterized in that: The following steps are involved: Step 1: Based on the genetic model data of abandoned meandering river channels, the sedimentary model diagrams of different types of abandoned river channels are obtained; Step 2: Obtain geological background information, seismic data, and well logging data of the target work area; Step 3: Conduct single sand body well seismic calibration and seismic horizon interpretation in the target work area; Step 4: Establish a seismic forward model based on drilling and logging data and the sedimentary characteristics of different types of abandoned river channels; Step 5: Based on the single sand body seismic interpretation horizon, complete the RGB frequency division fusion slice of the sand body, obtain the plane distribution map of the abandoned river channel, and determine the genesis type of the abandoned river channel; The types of abandoned river channel formation include abandoned river channels with breaches near breach points, abandoned river channels with breaches far from breach points, abandoned river channels with severe sudden abandonment and straightening of channels, abandoned river channels with moderate sudden abandonment and straightening of channels, abandoned river channels with straightening of channels, and terminal river channels. Step 6: Extract and optimize seismic attributes based on the single sand body layer, and then fuse the attributes to obtain a grayscale map of the sand body plane distribution; Step 61, extracting seismic attributes based on a single sand body layer; Step 62: Analyze the correlation between the thickness of a single sand body in the target work area and the seismic attribute by using the principal component analysis method, and select the seismic attribute; Step 63: Using a multi-attribute fusion method based on machine learning to fuse attributes, and obtaining a grayscale map of sand body plane distribution; Step 7: Based on the attribute fusion result, the sand body boundary characterization and boundary lateral obstruction clustering evaluation are performed, and the sand body plane distribution map is superimposed to obtain the sand body distribution and boundary lateral obstruction evaluation superimposition map; Step 71, using an image edge extraction algorithm to identify the sand body boundary, extracting the boundary center line, calculating the boundary width, and determining the sand body boundary type; Step 72, inputting the boundary width and sand body thickness values ​​into an unsupervised fuzzy self-organizing neural network to obtain a clustering evaluation result of the boundary lateral obstruction; Step 73, superimposing the cluster evaluation result of the boundary lateral obstruction property with the grayscale map of the sand body plane distribution to obtain a superimposed map of the sand body distribution and boundary obstruction property evaluation; Step 8: Based on the geological model, determine the identification characteristics of abandoned river channels of different genetic types; Step 81, determining the response characteristics of RGB frequency division slices of abandoned river channels of different genetic types; Abandoned river channels that are straightened out appear as "Ω"-shaped black high-curvature channels on RGB frequency division slices; The abandoned river channel straightened by the ditch can be divided into severe abandonment type and moderate abandonment type. The severe abandonment type is shown as a "C"-shaped medium-bend black meander on the plane, and the moderate abandonment type is shown as a "C"-shaped medium-bend gray meander. The river channel at the end of the period was in a black "S" shape, a long, medium-high sinuosity river channel; The abandoned river channel at the breach appears as a low-bend gray-gray-black river channel with a long extension. The RGB color of the abandoned river channel in the downstream section is darker than that in the upstream section. Step 82, determining seismic phase identification characteristics of different types of abandoned river channels according to the seismic forward model; For abandoned river channels of straightening type, abandoned river channels of severe sudden abandonment type and late-stage river channels, the amplitude of seismic event axes in the corresponding forward model is significantly weakened, and the fault morphology is clear; The amplitude of the corresponding event axis of the abandoned river channel with straightening of the ditch in the moderate abrupt abandonment type is weakened, the event axis is thinned, and the fault shape is blurred; The continuity of the event axis corresponding to the abandoned river channel after the breach is good, with no obvious fault, and the overall change of the seismic phase is weak or no obvious change. In the downstream of the river channel far away from the breach point, the continuity of the event axis changes, the amplitude weakens, the fault morphology begins to appear, and the amplitude of the seismic phase change increases. Step 83, determining the mud content characteristics at the boundaries of different types of abandoned river channels according to the grayscale map of sand body plane distribution; According to the grayscale map of sand body plane distribution, the abandoned river channel of bend straightening type, the abandoned river channel of severe sudden abandonment type and the terminal river channel were determined. The grayscale map of sand body plane distribution showed mainly black-gray-black, indicating high content of muddy sediments and thick mudstone. In the abandoned channel of the moderately abandoned type, the sand body plane distribution grayscale map is mainly gray, indicating that the muddy sediment content is medium; At the breach abandoned channel, the sand body plane distribution grayscale map is mainly white to gray, indicating that the mud sediment content is low. In the downstream of the breach abandoned channel far away from the breach point, the boundary turns gray, indicating that the mud content of the sediment increases and the mudstone thickness increases. Step 84, determining the logging phase characteristics at the boundaries of different types of abandoned river channels according to the logging data; The well logging curves of abandoned river channels with straightening by cutting bends, abandoned river channels with straightening by severe abrupt abandonment and late-stage river channels all show a sudden change upwards, and the sediments change rapidly from coarse-grained sediments to thick-layer fine-grained or muddy sediments upwards. The logging curve of the abandoned channel of the middle-level abandonment type changes gradually upward, and the sediments gradually change from sandy conglomerate deposits at the bottom to medium-fine-grained deposits in the middle and mudstone at the top. The logging curve of the abandoned channel near the breach point shows a gradual upward change in the upstream section, and a sudden upward change in the downstream section far from the breach point. Step 85, determining the boundary types and lateral obstruction clustering evaluation characteristics of different types of abandoned river channels according to the sand body distribution and boundary obstruction evaluation superposition map; Sand body boundaries are divided into two categories: double boundaries and single boundaries. The lateral shielding ability of double boundaries is stronger than that of single boundaries. The lateral shielding ability of boundaries is divided into grades I-III from strong to weak. The sand body boundary types at the abandoned channel of straightening type, the abandoned channel of severe sudden abandonment type and the final channel are mainly double boundaries, and the lateral shielding evaluation is mainly level I. The sand body boundary types at the abandoned channel of the middle-level abandonment type are mainly single-double boundaries, and the lateral shielding evaluation is mainly grade II. The sand body boundary type at the breach abandoned channel is mainly single boundary, and the lateral shielding evaluation is mainly Class III. In the downstream section far from the breach point, the sand body boundary is mainly single-double boundary, and the lateral shielding becomes mainly Class II. Step 9: Conduct hierarchical evaluation of the connectivity of abandoned river channels; When the abandoned channel type is identified as a breached abandoned channel near the breach point, its abandoned channel connectivity is good; When the abandoned channel type is identified as a breach abandoned channel far from the breach point, its abandoned channel connectivity is poor; When the abandoned river channel type is identified as a severe abrupt abandonment type abandoned river channel with straightened ditches, the abandoned river channel connectivity is poor; When the abandoned river channel type is identified as a moderately abandoned type of channel straightening abandoned river channel, its abandoned river channel connectivity is medium; When the abandoned river channel type is identified as a straightened abandoned river channel, its abandoned river channel connectivity is poor; When the abandoned channel type is identified as a terminal channel, its abandoned channel connectivity is poor.

2. A method for characterizing abandoned river channels and evaluating lateral connectivity according to claim 1, characterized in that: In step 3, by comparing the logging characteristics and seismic response of the single sand body, the seismic tracking interpretation characteristics of the top and bottom of the sand body are clarified, and the seismic horizon interpretation of the single sand body in the target work area is completed.

3. A method for characterizing abandoned river channels and evaluating lateral connectivity according to claim 1, characterized in that: In step 4, a river channel with the same depth is used, and different mudstone thicknesses are set to represent different types of abandoned river channels for forward simulation.

4. A method for characterizing abandoned river channels and evaluating lateral connectivity according to claim 1, characterized in that: In step 5, the wavelet transform method is used to perform frequency division fusion.

5. The method for characterizing abandoned river channels and evaluating lateral connectivity according to claim 1, characterized in that: The seismic attributes include arc length, average energy, average instantaneous phase, average positive amplitude, total positive amplitude, maximum amplitude, root mean square amplitude, energy sum, waveform length, and waveform area.

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