CN109856681B - Process analysis method for describing morphological change of water channel along direction of material source - Google Patents

Abstract

The invention discloses a process analysis method for describing the morphological change of a water channel along a provenance direction. ;C. Identify special landforms according to the slope difference of the longitudinal section; D. Use regression equation to calibrate the change of water channel scale; E. Express the symmetry of the water channel by calculating the average value of half parameters of the water channel; F. Use the Jaccard distance Characterize the degree of morphological evolution of water channels in different sections. The invention can effectively use different types of characterization parameters to divide the water channel into different sections along the flow direction and analyze the characteristics of the water channel shape evolution in the different sections. In the field of engineering, the data on overflow deposition and fluid migration in the analysis results of this method can show the distribution pattern of sediment on both sides of the channel and inside the channel, thereby helping to predict the distribution of favorable reservoirs on both sides of the channel and inside the channel.

Description

A process analysis method to describe the morphological changes of water channels along the provenance direction

technical field

The invention relates to geological resources and geological engineering, in particular to a process analysis method for describing morphological changes of water channels along the direction of provenance.

Background technique

Deep water channels are important channels for transporting sediments from continental shelves to sea basins, and deep water channels are also important places for storing oil and gas. Because the channel shape can reflect the deep-water deposition process and the movement mechanism of the turbidity current, the research on the evolution of the deep-water channel shape is very important in deep-sea energy exploration. As an important method in geophysical exploration, 3D seismic exploration technology can provide researchers with 3D morphological characteristics of deep water channels.

In recent years, a large number of researchers have used 3D seismic data to measure the plane and profile parameters of deep water channels, so as to analyze and study the geometric characteristics of deep water channels. Although the characterization parameters can represent the macroscopic morphological characteristics of the water channel, they cannot effectively reflect the morphological evolution trend and evolution scale of the water channel with the flow distance. In the field of geological resources and geological engineering, researchers only use characterization parameters to describe the shape and size of water channels at different locations. However, this traditional research method cannot efficiently use a large number of multi-type characterization parameters, that is, the use of characterization parameters is too single. And few valid connections are made between the different parameters.

At present, there is no method that can reflect the evolution process of deep water channel shape according to the characterization parameters. The analysis of the channel shape is limited to calibrating the changes of the channel characterization parameters at different positions of the water channel. The analysis of the relationship between the characterization parameters is too rough, which hinders the change trend of the water channel. and analysis of the degree of change.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a process analysis method for describing the morphological changes of water channels along the direction of the provenance. The method expresses the magnitude of the change of the channel shape.

The present invention adopts following technical scheme:

A process analysis method for describing the morphological changes of water channels along the provenance direction, comprising the following steps:

A. Divide the plane section according to the change of the track of the waterway centerline: According to the curvature change of the centerline of the waterway in the downstream direction, the waterway is divided into different sections on the plane according to the track of the centerline;

B. Divide the longitudinal section according to the change of the water channel valley line: according to the change of the water channel valley line in the downstream direction, divide the water channel section twice on the longitudinal section; calculate the distance between adjacent coordinate points on the valley line The sine value of the slope, the continuous coordinate points with similar sine values are grouped into one section, that is, the longitudinal section section;

C. Identify special landforms according to the slope difference of the longitudinal section section: according to the slope sine value of the longitudinal section section, identify the 'Nick point' section and the migratory bed sand form;

D. Use regression equation to calibrate the change of water channel scale: perform linear regression on the numerical changes of width and depth in each longitudinal section, and use a quadratic equation to characterize the regression results; calibrate the shape of the channel by calculating the derivative of the quadratic equation The magnitude of the change; by comparing the equation derivatives of the continuous longitudinal section sections, the influence of the slope change on the evolution of the channel shape is analyzed;

E. By calculating the average value of the half-side parameters of the water channel, the symmetry of the water channel is expressed: make the difference of all the half-side parameters of the cross section in each plane section, and by calculating and comparing the average value of the half-side parameter difference of the continuous plane sections, Analyze the effect of curvature change on the evolution of channel shape;

F. Use the Jaccard distance to characterize the degree of morphological evolution of the water channel in different longitudinal section sections: Calculate the Jaccard distance of the parameters representing the parameters of each two adjacent longitudinal section sections, and use the Jaccard distance to show the width, Differences or similarities in depth, slope morphological parameters.

Preferably, in step A, the vertical part of the midline trajectory is classified as a vertical waterway section; the part of the midline trajectory that is slightly curved and shows low amplitude fluctuations in shape is classified as a low-curved waterway section; the midline trajectory is very curved and U-shaped part is classified as a curved channel section.

Preferably, in step B, if the section divided by the longitudinal section passes through two plane sections, the longitudinal section section is divided into two longitudinal section sections.

Preferably, in step C, a longitudinal section with a larger gradient is sandwiched between two longitudinal sections with a smaller gradient, and the middle longitudinal section is identified as a 'Nick point'; a continuous longitudinal section Periodic variation occurs, and these continuous longitudinal sections are identified as migratory bed sand, ie: 'retrograde dunes' or 'gully and gully'.

The beneficial effects of the present invention are:

The invention discloses a process analysis method for describing the morphological changes of water channels along the provenance direction. The method can effectively use different types of characterization parameters to divide the water channels into different sections along the flow direction and analyze the morphological evolution of the water channels in different sections. feature. The relationship between the characterization parameters is established by mathematical statistics and data mining methods, so as to show the trend and amplitude of water channel morphological changes. In the field of engineering, the data on overflow deposition and fluid migration in the analysis results of this method can show the distribution pattern of sediment on both sides of the channel and inside the channel, thereby helping to predict the distribution of favorable reservoirs on both sides of the channel and inside the channel.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, rather than limit the present invention. .

Fig. 1 is the schematic diagram of the characterization parameter used in the present invention;

Fig. 2 is the schematic diagram of the parameter used for calculating curvature in the present invention;

Fig. 3 is the schematic diagram of plane section division in the present invention;

Fig. 4 is the schematic diagram of longitudinal section section division and gradient calculation in the present invention;

Fig. 5 is the schematic diagram of identifying Nick point according to segment gradient change in the present invention;

6 is a schematic diagram of identifying the form of migratory bed sand according to the section gradient change in the present invention;

Fig. 7 is the schematic diagram of dividing and demarcating the change trend of the characteristic parameter according to the longitudinal section section in the present invention;

FIG. 8 is a schematic diagram of the variation trend of the characterization parameter according to the plane section division and calibration in the present invention;

FIG. 9 is a schematic diagram of obtaining the variation range of the characteristic parameter between sections of the longitudinal section according to the Jaccard distance in the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Unless otherwise defined, technical or scientific terms used in this disclosure shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. As used in this disclosure, "comprises" or "comprising" and similar words mean that the elements or things appearing before the word encompass the elements or things recited after the word and their equivalents, but do not exclude other elements or things. "Up", "Down", "Left", "Right", etc. are only used to represent the relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

The present invention will be further described below with reference to the accompanying drawings and embodiments.

The types of characterization parameters used by this method to analyze and compare morphological evolution are shown in Figure 1. They are the maximum width of the channel, the minimum width of the channel, the maximum depth of the channel, the minimum depth of the channel, the left width of the channel, the right width of the channel, the left slope of the channel, and the right channel width. slope, etc. These characterization parameters can be manually interpreted from 3D seismic data.

A process analysis method for describing the morphological changes of water channels along the provenance direction, comprising the following steps:

A. Divide the plane section according to the change of the track of the waterway centerline: as shown in Figure 2, the plane track of the waterway is represented by the waterway centerline, and the curvature S of the waterway is determined by the centerline length L of the segment point on the waterway centerline and the straight line between the two points. N is calculated, and the expression is as follows:

S=L/N (1)

As shown in Figure 3, because the curvature of the centerline of the waterway in the downstream direction is very obvious and intuitive, the waterway in Figure 3 is divided into three plane sections according to the change of the curvature of the centerline, and the vertical part of the centerline trajectory is classified as the vertical waterway area. segment (segment A in the figure); the part with a slightly curved midline trajectory and a low-amplitude fluctuation in shape is classified as a low-curvature channel segment (segment C in the figure); the part with a very curved and U-shaped midline trajectory is classified as curved Waterway section (section B in the figure).

点的y坐标为

则中线长度L的计算公式表示如下：The curvature of different plane sections can be calculated by formula (1). In the formula, the length L of the midline is the sum of the distances of all adjacent points on the midline between the segment points. Assuming that there are n points between the segment points, the point is P _n means that the x-coordinate of the point is

The y coordinate of the point is

The formula for calculating the midline length L is as follows:

The straight line length N is calculated from the x and y coordinates of the two segment points. The start and end points of the segment are represented by P _s and P _e respectively. The calculation formula of the straight line length N is expressed as follows:

According to the calculated water channel curvature S, different plane sections are marked as vertical, low-curvature, and curved water channel sections. The plane section with the water channel curvature S less than 1.1 is the vertical section; the water channel curvature S between 1.1 and 1.3 is the low bending section, and such sections have low amplitude fluctuations on the plane; the water channel curvature S is greater than 1.3. Sections, which are approximately U-shaped in plan.

B. Divide the longitudinal section according to the change of the water channel valley line: according to the change of the water channel valley line in the downstream direction, divide the water channel section twice on the longitudinal section. Calculate the sine value of the slope between adjacent coordinate points on the valley line, and classify the continuous coordinate points with similar sine values as one section, namely the longitudinal section section. If the section divided by the longitudinal section passes through two plane sections, the longitudinal section section is divided into two longitudinal section sections. Generally, the length of the longitudinal section is much smaller than that of the plane section, so a plane section contains multiple longitudinal section sections. As shown in Figure 4, according to the change trend of the water channel slope, the longitudinal section is divided; the calculation of the slope in Figure 4 is calculated based on the coordinates of the points on the water channel valley line.

The segment points are obtained by a statistical method similar to iteration. The content of the iteration is the gradient G _p of two consecutive adjacent points. Let the two points be P ₁ and P ₂ respectively, and the y and z coordinates of the points are represented by D and Z. Then the point gradient _Gp is expressed as follows:

Taking the first longitudinal section of Fig. 4 as an example, the initial data point is used as the starting point of the segment, and the point gradient G _p of the adjacent points along the downstream direction is continuously calculated, and the point gradient G _p is increased by less than 1.5 (1.5 The points (similar points) whose gradients correspond to times of sine value are very obvious) (the decrease is greater than 0.66) are divided into a section, where the points refer to the points in the downstream direction used when calculating the point gradient _Gp ; Taking a small section of slope break in the first longitudinal section of Figure 4 as an example, if there is a point (surge point) with an increase of more than 1.5 (with a decrease of less than 0.66), but the number of subsequent surge points does not exceed 5 times and there is still a series of similar points after this small surge point, this small surge point will be classified as a segment with the similar points before and after its own appearance; if the surge point occurs more than 5 times, the last similar point appears It is the segment end point of the current segment and also the segment start point of the next segment.

After determining the segment start and end points of the longitudinal section section, the gradient G _s of the longitudinal section section can be calculated. The start point and end point are represented by P _a and P _b , and the y and z coordinates of the point are still represented by D and Z. Then the segment gradient G _s is expressed as follows:

Both the segment gradient G _s and the point gradient G _p are actually represented by the sine value of the gradient angle, which is a dimensionless and usually negative constant. When the segment slope is negative, it means that the terrain slopes downward; when the segment slope is positive, it means the landform is uplifted.

In addition, if a longitudinal section passes through two different plane sections, the longitudinal section is divided into two different sections. Generally speaking, the length of the plane section is much larger than that of the longitudinal section, Therefore, the longitudinal section can be regarded as a subsection of the plane section.

C. Identify special landforms according to the slope difference of the longitudinal section: As shown in Figure 5, a steeper longitudinal section is sandwiched between two gentler longitudinal sections. At this time, the steeper middle section is Sections are marked as 'Knickpoints'; the sign of judging steepness and gentleness is whether the increase in the segment gradient G _s is greater than 1.5 or the decrease is less than 0.66. As shown in Fig. 6, if there is periodic down dip and uplift in the longitudinal section, this series of sections is designated as migratory bed sand, that is, retrograde dunes or 'gully and gully'.

D. Use regression to calibrate the change of channel scale: as shown in Figure 7, according to the division of longitudinal section sections, perform linear regression on the numerical changes of the width (maximum width) and depth (maximum depth) along the flow direction in different sections, and use The quadratic equation of one variable is used to characterize the regression curve. The general expression of the quadratic equation of one variable is as follows:

f(x)=Ax ² +Bx+C (6)

A, B, and C in Expression 6 are the quadratic term coefficient, the linear term coefficient, and the constant of the quadratic equation in one variable, respectively.

According to expression (6), the first derivative expression of the quadratic equation in one variable is:

a=Ax+B (7)

According to formula (7) and the flow distances corresponding to the start and end points of the section, the derivative range of the characteristic parameters in the longitudinal section section can be obtained. By calculating the derivative range of the quadratic equation in one variable, the variation range of the characteristic parameters in this longitudinal section can be known, that is, the influence of the slope on the evolution of the channel shape. In Figure 7, the parameters of section 1 to section 6 are shown in Table 1. According to the relevant parameters of section 1 in Table 1, the derivative range of section 1 can be calculated to be 407.6-456.2 (through the first The quadratic equation of one variable and the parameters are calculated).

Table 1. Regression equations and derivatives of the parameters for the division and calibration of longitudinal sections

E. By calculating the average value of the half-side parameters of the water channel, the symmetry of the water channel is expressed: according to the division of the plane section, the average value of the left and right width, left and right depth, and left and right slope difference of the water channel in each plane section is calculated. Taking the average value of the left and right depth differences in Fig. 8 as an example, the depth difference D _sc on a single cross section in the section is equal to the difference between the left depth D _left and the right depth D _right , and the calculation formula of the depth difference is:

D _sc =D _left -D _right (8)

Assuming that there are i profiles (data points) in the segment, and the depth difference on each profile is D _sci , the calculation formula of the average depth difference D _s is as follows:

According to the calculation methods of formula (8) and formula (9), the average value of the left and right width difference W _s and the gradient difference S _s in the plane section can also be calculated. By averaging these half-side parameter differences, the effect of curvature on the evolution of channel morphology (especially symmetry) can be analyzed. As shown in Table 2 (process analysis table of channel evolution in different stages), different plane sections correspond to different mean values of half-edge parameters. By comparing the mean values, the influence of curvature on the symmetry of the channel can be analyzed; The bending creates a greater degree of asymmetry, with more turbidity currents migrating to the bank.

F. Using the Jaccard distance (Jaccard Distance): It is an indicator used to measure the difference between two sets. It is the complement of the Jaccard similarity coefficient and is defined as 1 minus Jaccard The Jaccard similarity coefficient (Jaccard similarity coefficient, also known as the Jaccard Index, is an index used to measure the similarity of two sets.) It characterizes the waterways of different longitudinal sections. Morphological evolution degree: According to the division of longitudinal section sections, the similarity of characteristic parameters between adjacent sections is calculated. The characterization parameters used are the ratio of the maximum width to the maximum depth of the channel (width-to-depth ratio), the ratio of the depth of the left and right banks, the ratio of the width of the left and right banks, and the ratio of the slope of the left and right banks. Among them, the ratio of the depth of the left and right banks represents the difference in the deposition of the overflow bank of the channel; the ratio of the width of the left and right banks represents the difference of the turbidity fluid deflection; the ratio of the slope of the left and right banks represents the morphological symmetry of the channel profile.

Taking the calculation of the similarity of the aspect ratio in Figure 9 as an example, first make a dot matrix diagram of the characterization parameters of the two longitudinal section sections, and the overlapping part of the circles (the figure includes a data set with larger overall data and a smaller overall data set). The number set, the minimum value of the larger number set to the maximum value of the smaller number set, the data within this range is the overlapping part of the figure) The number of data points in I represents the similar part of the characterizing parameter, the two circles The total number of data points in is U; the Jaccard distance is used to calculate the similarity of the aspect ratio J _A between the two segments, and the calculation formula is:

J _A = 1-I/U (10)

The greater the calculated Jaccard distance, the greater the difference in the characterization parameters between the two sections, that is, the degree or magnitude of the morphological evolution between sections.

According to the formula (10), the difference degree J _D of the overflow deposit, the difference degree J _W of the fluid deflection and the difference degree J _S of the profile shape can also be calculated. The obtained characterization parameter difference is for the previous longitudinal section, so there is no difference data for the first longitudinal section of the channel.

Finally, according to the derivative range of the regression equation obtained in steps D, E, and F, the average value of the half-side parameter difference, and the Jaccard distance of the characteristic parameter between the longitudinal section sections, the analysis table of the evolution process of the channel shape as shown in Table 2 is obtained. . This table divides the water channel into different stages by plane and longitudinal section sections, uses the average value of the half-side parameter difference to show the influence of the channel curvature on the shape during the evolution process, and uses the derivative range of the regression equation to show the slope's effect on the shape during the evolution process. Influence, and the Jaccard distance, which is a parameter between longitudinal section sections, is used to express the degree of change of channel shape in different evolution stages and the morphological similarity of channels in different evolution stages. The analysis table of the evolution process of the channel shape shown in Table 2 can not only show the control of the channel curvature and slope on the shape evolution, but also monitor and reflect the evolution characteristics and evolution degree of the channel in different stages. The statistics of the special landforms in the table help researchers to study the influence of the bottom shape on the evolution of the channel shape.

Table 2 Process analysis table of water channel evolution in different stages

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Technical personnel, within the scope of the technical solution of the present invention, can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content disclosed above, but any content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (4)

1. A process analysis method for describing the morphological change of a water channel along the direction of a material source is characterized by comprising the following steps:

A. dividing plane sections according to the change of the water channel midline locus: according to the curvature change of the center line of the water channel in the downstream direction, dividing the water channel into different sections on a plane according to the center line track;

B. dividing longitudinal section sections according to the change of a water course hong rice noodle: dividing sections of the water channel on the longitudinal section for the second time according to the change of the water channel hong grain line in the downstream direction; calculating the slope sine value between adjacent coordinate points on the hong millet line, and classifying the continuous coordinate points with similar sine values into a section, namely a longitudinal section;

C. identifying a special landform according to gradient difference of the longitudinal section: identifying a 'Nick point' section and a migrating bed sand form according to the slope sine value of the longitudinal section;

D. calibrating the change of the scale of the water channel by using a regression equation: performing regression on the numerical changes of the width and the depth in each longitudinal section, and representing the regression result by using a quadratic equation; calibrating the amplitude of the form change of the water channel by calculating the derivative of a quadratic equation; analyzing the influence of gradient change on the form evolution of the water channel by comparing equation derivatives of continuous longitudinal section sections;

E. the symmetry of the channel is represented by calculating the average value of the parameters of the half-edge of the channel: making difference values of half parameters of all cross sections in each plane section, and analyzing the influence of curvature change on the morphological evolution of the water channel by calculating and comparing the average value of the half parameter difference values of the continuous plane sections;

F. the Jacard distance is utilized to characterize the morphological evolution degree of the water channels of different longitudinal section sections: calculating the Jacard distance of the characteristic parameters of every two adjacent longitudinal section sections, and showing the difference or similarity of the morphological parameters of width, depth and gradient in the evolution process of the water channel through the Jacard distance.

2. The process analytic method for describing morphological changes of water course along the direction of a source according to claim 1, wherein in step a, the vertical part of the midline locus is classified as a vertical water course section; the part of the midline locus which is slightly curved and has low amplitude fluctuation in shape is classified as a low-curved water channel section; the very curved and U-shaped portion of the midline locus is referred to as the curved waterway section.

3. The method according to claim 1, wherein in step B, if the divided section crosses two plane sections, the divided section is divided into two longitudinal section sections.

4. The method according to claim 1, wherein in step C, the section with the larger gradient is sandwiched between the two sections with the smaller gradient, and the middle section is identified as the 'nike point'; periodic variation of the successive longitudinal section sections, these successive longitudinal section sections are identified as migrating bed sand, i.e.: 'retrograde dunes' or 'gullies and gullies'.

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