A method and system for quantitatively predicting the planar distribution and width-depth ratio of a river channel main stream line

Abstract

The application discloses a method and system for quantitatively predicting the planar distribution and width-thickness ratio of a river channel main flow line, relates to the technical field of reservoir prediction in oil geological exploration, and comprises the following steps: S1, griding according to the size of a research area and drilling data; S2, dividing the target layer stratum in the research area into single sand bodies or sand groups; S3, dividing the single sand bodies or sand groups into types according to a facies-controlled sand body structure method; S4, setting a research area source starting point according to the source direction of a large area, and quantitatively predicting the planar of the river channel main flow line according to a single grid mathematical model; S5, calculating the width-thickness ratio data of the river channel in the research area, and obtaining a mathematical model of the width-thickness ratio of the river channel main body; S6, determining the width and trend of the river channel main body; and S7, after the river channel main body is determined, quantitatively describing the envelope line of the river channel flanks and overbank facies, and completing the planar prediction of the river channel main flow line. The application achieves relatively accurate prediction of the trend of a single sedimentary period river channel dominant sand body, and achieves the purpose of predicting a high-quality river channel sand body.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum geological exploration reservoir prediction, and particularly relates to a method and system for quantitatively predicting planar distribution and width-thickness ratio of a river channel main flow line. BACKGROUND

[0002] At present, how to predict the river channel trend and high-quality sand body of the main part of the river channel is one of the key and difficult problems in the field of petroleum exploration. However, in the research, the river channel trend is generally depicted according to the sedimentary facies analysis method, and the river channel shape and trend drawn by different researchers are not the same due to different professional levels.

[0003] The traditional method for predicting the distribution of the river channel is mainly a seismic prediction method, but it has the characteristics of low precision and poor prediction of the advantage sand body. Moreover, due to the limitation of the resolution, the traditional sedimentary facies can only predict the river channel zone or the multi-period superimposed river channel (the longitudinal resolution is more than 30m), and the effect of predicting the single-period river channel trend is very poor. For example, the literatures disclosed by Mao Liqun and Liang Xiuli, namely, “Seismic prediction of underwater distributary channel: Taking S0 oil layer group in Xingxi-Haerweng area of Songliao Basin as an example”, and the literature disclosed by Bian Baoli, namely, “Research and application of reservoir prediction method of river channel sand body based on high-density three-dimensional seismic”, predict the river channel sand body by the seismic method, but the prediction precision and effect cannot meet the actual needs. In addition, although the traditional sedimentary facies can predict the single-period sand body distribution, it also has the shortcomings of low prediction precision and inability to finely depict the advantage sand body (the horizontal prediction width of the river channel is 1000-3000m), such as the literatures disclosed by Lan Zhaoli, He Shunli and Men Chengquan, namely, “Prediction of width of braided river channel zone by using thickness of cross-bedding set of core or outcrop: Taking Sulige gas field in Ordos Basin as an example”, and the literature disclosed by Xu Jie, He Zhili, Dong Ning and others, namely, “Prediction of facies-controlled reservoir of river channel sandstone in He3 section of Daniudi gas field in Ordos Basin”, which respectively predict the river channel by the traditional sedimentary facies characteristic method and the seismic prediction method under the control of the sedimentary facies, but the prediction precision is only the river channel zone level of the multi-period river channel superposition, and the prediction precision cannot meet the requirements in the early and development stages of development. The above two types of methods are qualitative prediction, have strong multi-solution and low accuracy. SUMMARY

[0004] The present application aims to provide a method and system for quantitatively predicting the planar distribution and width-thickness ratio of the river channel main flow line, which is based on the single-well type division of the facies-controlled sand body structure, establishes the corresponding geological model according to the principle of sedimentology, quantitatively predicts the river channel main flow zone and the internal structure of the river channel sand body, and thus achieves the purpose of predicting the advantage river channel sand body. In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] The present application provides a method for quantitatively predicting the planar distribution and width-thickness ratio of the river channel main flow line, which comprises the following steps:

[0006] Step S1: Gridding is performed based on the size of the study area and drilling data to obtain a gridded plan view of the study area;

[0007] Step S2: dividing the target stratum in the study area into single sand bodies or sand groups based on the gridded plan view of the study area;

[0008] Step S3: classify the single sand bodies or sand groups according to the phase-controlled sand body structure method and project them onto the gridded plan of the study area;

[0009] Step S4: Based on the divided types, the starting point of the study area's provenance is set according to the direction of the regional provenance, and a single grid mathematical model is used as a basis to perform a planar quantitative prediction of the river's main stream line;

[0010] Step S5: Based on the main stream line of the river channel, calculate the width-to-thickness ratio data of the river channel in the study area to obtain a mathematical model of the width-to-thickness ratio of the main body of the river channel;

[0011] Step S6: Determine the width and trend of the main body of the river channel based on a mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel;

[0012] Step S7: After the main body of the river channel is determined, the river channel flanks and the overflow phase envelope are quantitatively depicted according to the width and trend of the main body of the river channel to complete the plane prediction result of the main stream line of the river channel.

[0013] Furthermore, in step S1, the gridding formula is:

[0014] Z = Mix(|X*YS / N|);

[0015] Where Z represents the final gridding result, Mix represents the minimum grid after removing the manually specified redundant grids, X represents the manually specified number of horizontal grids, Y represents the manually specified number of vertical grids, S represents the area defined by the outermost well coordinates in the study area, and N represents the number of wells in the study area.

[0016] Furthermore, in step S2, the thickness of a single sand body is 3-5 m, and the thickness of a sand group is 5-10 m.

[0017] Furthermore, in step S3, the types include four types: river channel main body, flank, overflow and mudstone.

[0018] Furthermore, the step S5 of calculating the width-to-thickness ratio data of the river channel in the study area based on the main stream line of the river channel to obtain a mathematical model of the width-to-thickness ratio of the main body of the river channel includes:

[0019] Based on the river mainstream line, a river width-thickness ratio is statistically analyzed in a development area with similar sedimentary facies belts near the research area, so as to obtain the river width-thickness ratio data in the research area and obtain a mathematical model of the river main body width-thickness ratio.

[0020] Further, the step S6 comprises determining the river main body width and trend based on the river mainstream line and the mathematical model of the river main body width-thickness ratio, and comprises the following steps.

[0021] Based on the river mainstream line and the mathematical model of the river main body width-thickness ratio, well-seismic calibration and layer flattening are performed on the corresponding well-seismic profile, and the river main body width and trend are further determined in combination with the lens shape reflected by the seismic facies.

[0022] Further, the step S7 comprises quantitatively depicting the river flanks and overbank facies envelope based on the river main body width and trend after the river mainstream line is determined, and comprises the following steps.

[0023] After the river mainstream line is determined, the river main body development zone is obtained by widening the river main body width and trend by a set value on both sides of the river mainstream line, the flanks are enveloped on both sides, the river bed development range is depicted, and finally the overbank facies on both sides of the river bed is enveloped, and the remaining part is the shale development area.

[0024] The application further provides a system for quantitatively predicting the river mainstream line plane distribution and width-thickness ratio, which comprises a gridding unit, a first division unit, a second division unit, a calculation unit, a determination unit, a quantitative prediction unit and a prediction unit.

[0025] The gridding unit is used for gridding according to the size of the research area and drilling data to obtain a gridded plane map of the research area.

[0026] The first division unit is used for dividing the target layer stratum in the research area into single sand bodies or sand groups based on the gridded plane map of the research area.

[0027] The second division unit is used for dividing the single sand bodies or sand groups into types according to the facies-controlled sand body structure method and projecting them on the gridded plane map of the research area.

[0028] The quantitative prediction unit is used for quantitatively predicting the river mainstream line plane based on the divided types, setting a research area source starting point according to the source direction of the large area, and taking the single grid mathematical model as the basis.

[0029] The calculation unit is used for calculating the river width-thickness ratio data in the research area based on the river mainstream line to obtain a mathematical model of the river main body width-thickness ratio.

[0030] A determination unit for determining the width and trend of the main body of the river channel based on a mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel;

[0031] The prediction unit is used to quantitatively depict the channel flanks and overflow phase envelope lines based on the width and trend of the river channel after the main body of the river channel is determined, and complete the plane prediction results of the main stream line of the river channel.

[0032] Furthermore, the computing unit is specifically configured to:

[0033] Based on the mainstream line of the river channel, an analogy was made with the development areas of similar sedimentary facies near the study area to conduct statistics on the river channel width-to-thickness ratio, thereby obtaining the river channel width-to-thickness ratio data in the study area and obtaining a mathematical model of the river channel main body width-to-thickness ratio.

[0034] Furthermore, the determining unit is specifically configured to:

[0035] Based on the mathematical model of the mainstream line of the river channel and the width-to-thickness ratio of the main body of the river channel, well-seismic calibration and layer flattening are carried out on the corresponding through-well seismic profile. Combined with the lens morphology reflected by the seismic phase, the width and trend of the main body of the river channel are further determined.

[0036] Furthermore, the prediction unit is specifically configured to:

[0037] After the mainstream line of the river channel is determined, the widening value on both sides of the mainstream line is set according to the width and trend of the main body of the river channel. This is the main development zone of the river channel. The flank types are then enveloping lines on both sides to depict the development range of the riverbed. Finally, the overflow phases on both sides of the riverbed are enveloping on both sides. The remaining area is the mudstone development zone.

[0038] The technical effects and advantages of the present invention are as follows:

[0039] The present invention adopts main technical means such as gridding the study area, quantifying the width-to-thickness ratio of the river channel and the mathematical model for directional judgment of the direction, and creatively proposes a method for studying the sand body structure based on phase control. According to the principles of sedimentology, the corresponding sedimentary model is established, and the seismic phase reflection characteristics are combined to quantitatively predict the mainstream line and width of the river channel, thereby achieving the purpose of predicting the sand bodies of the dominant river channel. The new method well combines the advantages of traditional sedimentary phase methods and seismic prediction methods, and also solves the shortcomings of the above two methods. It achieves a relatively accurate prediction of the trend of the dominant sand bodies in the river channel in a single sedimentary period (3-5m vertically and 100-1000m horizontally), eliminates the uncertainty caused by human factors to the greatest extent possible, and improves the prediction accuracy, thereby achieving the purpose of predicting high-quality sand bodies in the river channel.

[0040] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 This is a flow chart of a method for quantitatively predicting the planar distribution and width-to-thickness ratio of a river main stream line according to the present invention;

[0043] Figure 2 This is a schematic diagram of the river channel trend using the MiG method of the present invention;

[0044] Figure 3 This is a schematic diagram of the mathematical model method for river channel trends of the present invention;

[0045] Figure 4 A schematic diagram of a method for predicting the width-to-thickness ratio of a river channel in a development zone according to the present invention;

[0046] Figure 5 This is a schematic diagram of the river channel trend prediction using the seismic phase method of the present invention;

[0047] Figure 6 This is a diagram showing the predicted planar distribution of the river main flow line of the present invention;

[0048] Figure 7 Schematic diagram of a system for quantitatively predicting the planar distribution and width-to-thickness ratio of a river mainstream line according to the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention 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 making creative efforts are within the scope of protection of the present invention.

[0050] In order to solve the deficiencies of the existing technology, the present invention discloses a method for quantitatively predicting the plane distribution and width-to-thickness ratio of the main stream line of a river channel. Figure 1 This is a flow chart of a method for quantitatively predicting the plane distribution and width-to-thickness ratio of a river mainstream line according to the present invention. Figure 1 As shown, the method includes the following steps:

[0051] Step S1: Gridding is performed based on the size of the study area and drilling data to obtain a gridded plan view of the study area;

[0052] In step S1 of the present invention, the gridding formula is:

[0053] Z = Mix(|X*YS / N|);

[0054] Where Z represents the final gridding result, Mix represents the minimum grid after removing the manually specified redundant grids, X represents the manually specified number of horizontal grids, Y represents the manually specified number of vertical grids, S represents the area defined by the outermost well coordinates in the study area, and N represents the number of wells in the study area.

[0055] Step S2: dividing the target stratum in the study area into single sand bodies or sand groups based on the gridded plan view of the study area;

[0056] In step S2 of the present invention, the target strata in the study area are divided into single sand bodies or sand groups according to the characteristics of the sedimentary cycles and marker layers; wherein the thickness of a single sand body in a single sedimentary period is about 3-5m, and the thickness of a sand group is about 5-10m.

[0057] Step S3: classify the single sand bodies or sand groups according to the phase-controlled sand body structure method and project them onto the gridded plan of the study area;

[0058] In step S3 of the present invention, there are four types and thirteen modes of mainstream line advance schemes in the entire grid plane of our study area. Among them, the types include: river channel, flank, overflow and mudstone. The dominant type results are respectively taken and represented by numbers 1-4, that is, 1 represents the river channel; 2 represents the flank; 3 represents the overflow; 4 represents the mudstone;

[0059] Step S4: Based on the divided types, the starting point of the study area's provenance is set according to the direction of the regional provenance, and a single grid mathematical model is used as a basis to perform a planar quantitative prediction of the river's main stream line;

[0060] In step S4 of the present invention, a single grid has multiple models such as "one type 1 main body in one grid, two type 1 main bodies in one grid, one type 1 main body and two type 2 flanks in one grid...";

[0061] Step S5: Based on the main stream line of the river channel, calculate the width-to-thickness ratio data of the river channel in the study area to obtain a mathematical model of the width-to-thickness ratio of the main body of the river channel;

[0062] In step S5 of the present invention, based on the main stream line of the river channel, analogy is made with development areas of similar sedimentary facies near the study area to perform river channel width-to-thickness ratio statistics, thereby obtaining river channel width-to-thickness ratio data within the study area and obtaining a mathematical model of the main stream channel width-to-thickness ratio;

[0063] Step S6: Determine the width and trend of the main body of the river channel based on a mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel;

[0064] In step S6 of the present invention, based on the mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel, well seismic calibration and layer flattening are performed on the corresponding through-well seismic section, and the width and trend of the river channel are further determined in combination with the lens morphology reflected by the seismic phase;

[0065] Step S7: After the main stream of the river is determined, the river flanks and the overtopping phase envelope are quantitatively depicted based on the width and trend of the main stream, thus completing the planar prediction result of the main stream of the river;

[0066] In step S7 of the present invention, after the mainstream line of the river channel is determined, the set value is widened on both sides of the mainstream line according to the width and trend of the main body of the river channel, which is the main development zone of the river channel. The flank types are then enveloping lines on both sides to roughly depict the development range of the riverbed. Finally, after the overflow phases on both sides of the riverbed are enveloping, the remaining is the mudstone development zone.

[0067] Example:

[0068] Taking the classification and evaluation of river channel microfacies reservoirs in a certain section of a sand layer group in a certain area of ​​a basin as an example, in the past, river channel trends were predicted manually based on sand body thickness and combined with provenance direction. This time, the method of the present invention predicts the main stream line of the river channel according to the development degree of the main body of the river channel, and then predicts the dominant reservoir. The specific steps of the method are as follows:

[0069] Step S1: Gridding is performed based on the size of the study area and drilling data. The gridded plan of the study area is usually obtained by the formula: Z = Mix(|X*YS / N|);

[0070] Where Z represents the final gridding result, Mix represents the minimum grid after removing the manually specified redundant grids, X represents the manually specified number of horizontal grids, Y represents the manually specified number of vertical grids, S represents the area defined by the outermost well coordinates in the study area, and N represents the number of wells in the study area.

[0071] Step S2: Divide the wells in the study area into single sand bodies or sand groups and compare them, trying to achieve a single sand body thickness of 3-5m or a sand group thickness of 5-10m in a single deposition period;

[0072] Step S3: Classify the single sand body or sand group into four types according to the facies-controlled sand body structure method, mainly including the main body of the river channel, the flank, the overflow and the mudstone. The dominant type results are respectively replaced by numbers 1-4 and projected on the grid plane map of the study area; Figure 2 The schematic diagram of the river course MiG method of the present invention is as follows: Figure 2 As shown, 1 represents the main body, 2 represents the flank, 3 represents the overflow, and 4 represents the mudstone. This is mainly based on the area controlled by the outermost drilling well as the maximum boundary of the study area;

[0073] Step S4, then set the source starting point of the study area according to the direction of the regional source. Based on the mathematical model of a single grid, as the river advances, there are four types and thirteen modes of mainstream line advancement schemes in each grid. Assuming that the average width of the river channel is 1 km based on the width-to-thickness ratio of the river channel, taking the second mode f as an example, when the river advances, it encounters two wells in the northwest direction that drill into the river channel. Because the distance between the two wells exceeds 1 km, and the angle between the line connecting the two wells and the source point (0 point) and the midpoint between the two wells is greater than 45°, it means that the two wells drilled into two different branch river channels. If the angle is less than 45°, it is a single river channel. Secondly, if the distance between the two wells in the northeast is less than 1 km, it can be considered as a main river channel. Similarly, the mainstream line of the river channel gradually advances until it runs through the entire work area. Figure 3 This is a schematic diagram of the mathematical model method for river channel trends of the present invention, as shown in FIG. Figure 3 As shown in the attached Figure 4 The mathematical model of the main trend of a single grid river channel has 1 to 1 single data point, 1 to 2 three data points, 1 to 3 multiple data points, etc. The river channel termination situation is not listed in the figure.

[0074] Step S5: Compare the river channel width-to-thickness ratio with the development areas with similar sedimentary facies near the study area, and calculate the river channel width-to-thickness ratio data in the study area; Figure 4 Schematic diagram of the method for predicting the width-to-thickness ratio of a river channel in a development zone of the present invention, as shown in FIG. Figure 4 As shown, it mainly consists of a cross-sectional view of the river channel, a cross-sectional plane position map, and a statistical graph of the correlation between the main thickness and width data obtained from the cross-sectional view. The entire set of maps is a mature development area near the study area, with a large number of wells and close distances. The drilling data can be used to finely characterize the various parameters of the river channel. First, a fine characterization of the cross-sectional direction of the river channel is carried out by comparing multiple well sections (the plane map in the upper right corner), and the main width and thickness values ​​of the river channel are calculated (the bottom cross-sectional view). Then, a correlation analysis is performed on all the cross-sectional data (the analysis map in the upper left corner), and a mathematical model for the width-to-thickness ratio of the main body of the river channel can be obtained;

[0075] Step S6: perform well-seismic calibration and layer flattening on the corresponding through-well seismic section, and further determine the width and trend of the river channel in combination with the lens morphology reflected by the seismic phase; Figure 5 Schematic diagram of river course prediction using the seismic phase method of the present invention, as shown in FIG. Figure 5As shown, it mainly consists of a seismic profile on the left that is flattened at the end of the study horizon, a comprehensive histogram of key well logging in the middle, and a two-dimensional seismic profile position and river channel trend prediction map on the right. The seismic phase profile on the left is a cross-section of the river channel direction. The yellow dotted line circled the river channel feature with a strong center and a pinch-out on both sides. By continuously cross-cutting the seismic profile in the river channel direction, the general direction of the river channel can be traced. A, B, C, and D in the figure are four wells that have passed through the seismic profile. As can be seen from wells B and D, thick layers of massive sandstone can be seen on the axis of the seismic profile lens, further proving the river channel attributes reflected by the seismic phase.

[0076] Step S7: After the main stream of the river is determined, the main stream is widened by 500 meters on both sides (the width of the main stream is set to 1 kilometer). This is the main stream development zone. The flank types are then enveloping lines on both sides to roughly depict the riverbed development range. Finally, after the overflow phases on both sides of the riverbed are enveloping lines on both sides, the remaining area is the mudstone development zone. Figure 6 This is the prediction result diagram of the river main flow line plane distribution of the present invention, as shown in Figure 6 As shown in the figure, the final channel prediction result is obtained based on the above steps. Its sedimentary background is the underwater distributary channel deposits at the delta front. The dark yellow part is the mainstream of the channel predicted by the quantitative sedimentary model combined with the seismic phase. It is mainly composed of medium-fine sandstone block structure, with uniform reservoir, good physical properties and oil content, and is the dominant channel sand body. The adjacent light yellow part is the flank of the channel, characterized by developed silt-fine sand bedding, strong reservoir heterogeneity, slightly poor physical properties and oil content. The outermost light yellow part is the overflow phase on both sides of the channel, mainly with developed or undeveloped muddy silt-siltstone bedding, poor reservoir physical properties, and little oil content. The blue background is mainly floodplain or lacustrine mudstone, which is a non-reservoir development area.

[0077] Based on the above method, the present invention also discloses a system for quantitatively predicting the plane distribution and width-to-thickness ratio of the main stream line of the river channel. Figure 7 Schematic diagram of a system for quantitatively predicting the plane distribution and width-to-thickness ratio of the main stream line of a river channel according to the present invention. Figure 7As shown, the system includes: a gridding unit 11, a first division unit 12, a second division unit 13, a calculation unit 14, a determination unit 15, a quantitative prediction unit 16 and a prediction unit 17; wherein the gridding unit 11 is used to perform gridding according to the size of the study area and drilling data to obtain a gridded plane map of the study area; the first division unit 12 is used to divide the target stratum in the study area into single sand bodies or sand groups based on the gridded plane map of the study area; the second division unit 13 is used to classify the single sand bodies or sand groups according to the phase-controlled sand body structure method and project them on the gridded plane map of the study area; the quantitative prediction unit 14 , used for setting the source starting point of the study area according to the direction of the regional source based on the type of division, and performing quantitative plane prediction of the mainstream line of the river channel based on the mathematical model of a single grid; the calculation unit 15 is used for calculating the width-to-thickness ratio data of the river channel in the study area based on the mainstream line of the river channel, and obtaining a mathematical model of the width-to-thickness ratio of the main body of the river channel; the determination unit 16 is used for determining the width and trend of the main body of the river channel based on the mathematical model of the width-to-thickness ratio of the main body of the river channel and the main body of the river channel; the prediction unit 17 is used for quantitatively depicting the river channel flanks and the overflow phase envelope according to the width and trend of the main body of the river channel after the mainstream line of the river channel is determined, and completing the plane prediction result of the mainstream line of the river channel.

[0078] Furthermore, the calculation unit 14 is specifically used to: based on the mainstream line of the river channel, make an analogy with the development area of ​​similar sedimentary facies near the study area, perform channel width-thickness ratio statistics, thereby obtaining the channel width-thickness ratio data in the study area and obtaining a mathematical model of the width-thickness ratio of the main body of the river channel. The determination unit 16 is specifically used to: based on the mainstream line of the river channel and the mathematical model of the width-thickness ratio of the main body of the river channel, perform well-seismic calibration and layer flattening on the corresponding through-well seismic profile, and further determine the width and trend of the main body of the river channel in combination with the lens morphology reflected by the seismic phase. The prediction unit 17 is specifically used to: after the mainstream line of the river channel is determined, according to the width and trend of the main body of the river channel, widen the set value on both sides of the mainstream line to form the main body development zone of the river channel, then envelop the flank type on both sides to characterize the range of riverbed development, and finally envelop the overflow phase on both sides of the riverbed to include it. The remaining is the mudstone development zone.

[0079] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for quantitatively predicting the planar distribution and width-to-thickness ratio of a river mainstream, characterized in that: The method comprises the following steps: Step S1: Gridding is performed based on the size of the study area and drilling data to obtain a gridded plan view of the study area; Step S2: Based on the gridded plan of the study area, the target layer in the study area is divided into single sand bodies or Sand group; Step S3: classify the single sand bodies or sand groups according to the phase-controlled sand body structure method and project them onto the gridded plan of the study area; Step S4: Based on the divided types, the starting point of the study area's provenance is set according to the direction of the regional provenance, and a single grid mathematical model is used as a basis to perform a planar quantitative prediction of the river's main stream line; Step S5: Based on the main stream line of the river channel, calculate the width-to-thickness ratio data of the river channel in the study area to obtain a mathematical model of the width-to-thickness ratio of the main body of the river channel; Step S6: Determine the width and trend of the main body of the river channel based on a mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel; Step S7: After the main body of the river channel is determined, the river flanks and the overtopping phase envelope are quantitatively depicted based on the width and trend of the main body of the river channel to complete the planar prediction result of the main stream of the river channel; The step S5, calculating the width-to-thickness ratio data of the river channel in the study area based on the main stream line of the river channel to obtain a mathematical model of the width-to-thickness ratio of the main body of the river channel, includes: Based on the main stream of the river channel, the river channel width-thickness ratio was statistically analyzed by analogy with the development areas with similar sedimentary facies near the study area, thereby obtaining the river channel width-thickness ratio data in the study area and obtaining a mathematical model for the width-thickness ratio of the main river channel. The step S6, determining the width and trend of the main body of the river channel based on a mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel, includes: Based on the mathematical model of the main stream line and the width-to-thickness ratio of the river channel, well seismic marking is carried out on the corresponding well seismic section. The width and direction of the main river channel are further determined by leveling the layers and combining them with the lens morphology reflected by the seismic phase.

2. A method for quantitatively predicting the planar distribution and width-to-thickness ratio of a river main flow line according to claim 1, characterized in that: In step S1, the gridding formula is: Z=Mix(|X*YS / N|); Where Z represents the final gridding result, Mix represents the minimum grid after removing the manually specified redundant grids, X represents the manually specified number of horizontal grids, Y represents the manually specified number of vertical grids, S represents the area defined by the outermost well coordinates in the study area, and N represents the number of wells in the study area.

3. A method for quantitatively predicting the planar distribution and width-to-thickness ratio of a river main flow line according to claim 1 or 2, characterized in that: In step S2, the thickness of a single sand body is 3-5 m, and the thickness of a sand group is 5-10 m.

4. The method for quantitatively predicting the planar distribution and width-to-thickness ratio of the main flow line of a river channel according to claim 2, characterized in that: In step S3, the types include four types: channel main body, flank, overflow and mudstone.

5. A method for quantitatively predicting the plane distribution and width-to-thickness ratio of a river main flow line according to claim 1, wherein The method is characterized in that, after the main stream line of the river channel is determined in step S7, the river channel flanks and the overtopping phase envelope are quantitatively depicted according to the width and trend of the main stream channel to complete the planar prediction result of the main stream line of the river channel, including: After the mainstream line of the river channel is determined, the widening value on both sides of the mainstream line is set according to the width and trend of the main body of the river channel. This is the main development zone of the river channel. The flank types are then enveloping lines on both sides to depict the development range of the riverbed. Finally, the overflow phases on both sides of the riverbed are enveloping on both sides. The remaining area is the mudstone development zone.

6. A system for quantitatively predicting the planar distribution and width-to-thickness ratio of a river mainstream, characterized by: The system includes: a gridding unit, a first dividing unit, a second dividing unit, a calculation unit, a determination unit, a quantitative prediction unit and a prediction unit; wherein, The gridding unit is used to perform gridding based on the size of the study area and drilling data to obtain a gridded plan view of the study area; The first division unit is used to divide the target layer in the study area into Single sand body or sand group; The second division unit is used to classify individual sand bodies or sand groups according to the facies-controlled sand body structure method and project them onto the gridded plane map of the study area; A quantitative prediction unit is used to set the source starting point of the study area based on the divided types and the direction of the regional source, and to perform a plane quantitative prediction of the main stream of the river channel based on a single grid mathematical model; a calculation unit, configured to calculate the width-to-thickness ratio data of the river channel in the study area based on the main stream line of the river channel, and obtain a mathematical model of the width-to-thickness ratio of the main body of the river channel; A determination unit for determining the width and trend of the main body of the river channel based on a mathematical model of the main stream line of the river channel and the width-to-thickness ratio of the main body of the river channel; The prediction unit is used to quantitatively depict the flanks and the river according to the width and trend of the river after the main body of the river is determined. The overflow phase envelope line completes the plane prediction result of the river mainstream line; The computing unit is specifically configured to: Based on the main stream of the river channel, the river channel width-thickness ratio was statistically analyzed by analogy with the development areas with similar sedimentary facies near the study area, thereby obtaining the river channel width-thickness ratio data in the study area and obtaining a mathematical model for the width-thickness ratio of the main river channel. The determining unit is specifically configured to: Based on the mathematical model of the main stream line and the width-to-thickness ratio of the river channel, well seismic marking is carried out on the corresponding well seismic section. The width and direction of the main river channel are further determined by leveling the layers and combining them with the lens morphology reflected by the seismic phase.

7. The system for quantitatively predicting the planar distribution and width-to-thickness ratio of the main flow line of a river channel according to claim 6, characterized in that: The prediction unit is specifically configured to: After the mainstream line of the river channel is determined, the widening value on both sides of the mainstream line is set according to the width and trend of the main body of the river channel. This is the main development zone of the river channel. The flank types are then enveloping lines on both sides to depict the development range of the riverbed. Finally, the overflow phases on both sides of the riverbed are enveloping on both sides. The remaining area is the mudstone development zone.

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