Coordinate correction method of shallow section position based on water depth matching

Abstract

The present invention discloses a shallow profile position coordinate correction method based on water depth matching, which firstly performs basic data sorting and unifies the file names of shallow profile original files and navigation original files; then extracts shallow profile key information and navigation and water depth data key information for the sorted data; after the key information is extracted, the shallow profile time is matched with the navigation time according to the time matching principle to achieve a preliminary match between the shallow profile water depth and the depth of the depth sounder; finally, the navigation position is relocated to eliminate the deviation, and the depth sounder position at this time is the corrected accurate shallow profile position. This scheme corrects the shallow profile position by matching the shallow profile water depth with the depth of the depth sounder, and the matched depth sounder position is the accurate shallow profile position after quality control, which can accurately and reliably determine the shallow profile position coordinates, and provides important technical support for the smooth conduct of marine geophysical surveys.

Description

Technical Field

[0001] The invention belongs to the technical field of shallow stratum profile measurement, and in particular relates to a shallow profile position coordinate correction method based on water depth matching. Background Art

[0002] Shallow layer profile measurement is a geophysical method based on acoustic principles to continuously detect the structure and structure of underwater shallow layers. It is one of the common means of marine geophysical surveys. It uses the propagation and reflection characteristics and laws of sound waves in seawater and seabed sediments to continuously detect the structure and structure of seabed sediments, thereby obtaining an intuitive shallow seabed stratigraphic structure profile. The shallow layer profile method can quickly detect the geological characteristics and distribution of underwater strata, and has a high vertical resolution, so it has been widely used in marine surveys.

[0003] Since the shallow section is towed behind the ship and sunk in the seawater during the collection process, it is impossible to accurately locate it by GPS positioning equipment. Currently, its actual position is mainly calculated by ship-borne GPS using formula (1):

[0004]

[0005] Among them, X1 is the horizontal coordinate of the shipborne GPS, Y1 is the vertical coordinate of the shipborne GPS, X is the horizontal coordinate of the shallow profile, Y is the vertical coordinate of the shallow profile, S is the distance between the shipborne GPS and the shallow profile, and α is the heading angle. Among them, S is generally obtained by measuring the distance between the shipborne GPS and the shallow profile through the rope method, but after big data statistics, nominally the general class report or field collection report will record this value, but in some cases the value will have a large error, mainly because the field collection is not standardized, resulting in the value not even being measured at all, but directly copying the results of the previous year's report. This wrong S value may have serious consequences. For example, in a sea sand survey project on an island, according to the results of the shallow profile survey, it was determined that a hole should be drilled at the top of the sand ridge, but because the S value was wrong, it deviated by about 70m, and the actual drilling position was drilled at the bottom of the sand ridge, causing serious problems in the resource quantity when evaluating sea sand resources.

[0006] Therefore, how to determine reliable shallow section position coordinates is extremely important, that is, there must be a quality control method that can calculate the correct shallow section coordinate position even without the S value. Summary of the invention

[0007] In view of the defects of the existing shallow section position coordinate calculation method, the present invention proposes a shallow section position coordinate correction method based on water depth matching, which realizes the verification of shallow section position coordinates based on water depth matching and ensures the accuracy of shallow section position coordinates.

[0008] The present invention is implemented by adopting the following technical scheme: a shallow profile position coordinate correction method based on water depth matching, comprising the following steps:

[0009] Step A, basic data arrangement: arrange and compare the shallow profile original file data and the navigation original file data, and unify the file names of the arranged shallow profile original files and navigation original files;

[0010] Step B, extracting key information of shallow section: extracting the time information of each shallow section from the shallow section data after the basic data is sorted;

[0011] Step C, extracting key information of navigation and water depth data: extracting the recorded navigation time, coordinate information and water depth data of the depth sounder from the navigation data after the basic data is sorted;

[0012] Step D, preliminary matching of shallow profile water depth and echo sounder water depth: taking each shallow profile data as a benchmark, matching the shallow profile time with the navigation time according to the time matching principle, and after successful matching, importing the echo sounder water depth data in navigation into the shallow profile data to achieve preliminary matching of shallow profile water depth and echo sounder water depth;

[0013] Step E, repositioning of navigation position: There is a deviation between the depth of the echo sounder after preliminary matching and the shallow profile seabed. The shallow profile data is moved horizontally and parallelly until the shallow profile depth matches the depth of the echo sounder to eliminate this deviation. The echo sounder position at this time is the accurate shallow profile position after correction.

[0014] Furthermore, step A is specifically implemented in the following manner:

[0015] Step A1: respectively statistically organize the original data of the shallow analysis file and the original data of the navigation file:

[0016] The data information of the shallow profile original file is sorted out, including the survey line file name, record length, sampling rate and the statistics of the first and last record time;

[0017] The data information of the original navigation file is sorted out, including the original navigation file name, the statistics of the start and end recording time of the navigation file;

[0018] Step A2: for the data collected in step A1, the one-to-one correspondence between the shallow profile data and the navigation data is re-divided according to the file names of the two, the continuity of the data records and the relative relationship between the start and end times, and the file names are unified.

[0019] Furthermore, the step A2 comprises the following steps:

[0020] (1) Preliminarily matching the shallow section data with the navigation data according to the file names of the shallow section original file data and the navigation original file data;

[0021] (2) Determine whether it is necessary to merge the segmented shallow section data or the segmented navigation data according to the continuity of the data records:

[0022] For the segmented data in the shallow profile original files, the shallow profile original files with similar recording time will be merged. If the recording time is significantly different, it is considered to be caused by instrument failure, and the shallow profile original files will not be merged.

[0023] For segmented data in the original navigation file, new files are automatically generated due to date changes. At this time, the segmented original navigation files are merged;

[0024] (3) Matching the start and end times of the shallow profile original file and the navigation original file;

[0025] (4) After the shallow analysis original file and the navigation original file are matched, the shallow analysis original file name and the navigation original file name corresponding to the match are renamed to a unified file name to complete the basic data sorting.

[0026] Furthermore, in step D, when performing a preliminary match between the shallow profile and the depth of the depth sounder, the time matching is performed according to the principle of complete matching of year, month, day, hour, minute and second, that is, the above parameters are considered to be completely equal and the match is successful.

[0027] Furthermore, in step D, if the shallow profile time cannot be found in the navigation time, the water depth value is set to zero. After all shallow profile times are matched with the navigation time, the zero water depth value is interpolated through the surrounding effective water depth values ​​to eliminate abnormal water depth values.

[0028] Furthermore, in step E, when performing offset correction, look for areas with undulating seabed topography, especially mutation points of seabed topography. Suppose the shallow section shot number at this time is D1, and find the mutation point of seabed topography of the depth of the echo sounder. The corresponding shallow section shot number at this time is D2, and the shallow section data moving distance D = D2-D1. If there is still a slight error after the movement, repeat the movement again until the shallow section water depth completely matches the echo sounder water depth.

[0029] Compared with the prior art, the advantages and positive effects of the present invention are:

[0030] This scheme corrects the shallow profile position by matching the shallow profile water depth with the depth of the echo sounder. The matched echo sounder position is the accurate shallow profile position after quality control. The shallow profile position coordinates can be accurately and reliably determined, providing important technical support for the smooth conduct of marine geophysical surveys. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1This is a schematic diagram of the shallow profile position coordinate correction process according to an embodiment of the present invention;

[0032] Figure 2 It is a statistical representation of the basic data of the embodiments of the present invention;

[0033] Figure 3 Schematic diagram of the process of matching shallow profiling and depth of a depth sounder in a certain work area of ​​a certain sea according to an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of matching the shallow profile water depth and the depth of the echo sounder at other positions of a survey line in a certain work area in a certain sea according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] The present invention proposes a shallow profile position coordinate correction method based on water depth matching, and its basic principle is introduced as follows: During the shallow profile acquisition process, water depth measurement is generally performed synchronously, and its water depth value is consistent with the shallow profile water depth. However, since the depth sounder is installed on the ship, that is, close to the ship-borne GPS position, the distance between the two is generally close, and the error between the two is within a controllable range. Therefore, the present invention creatively proposes to correct the shallow profile position by matching the shallow profile water depth with the depth of the depth sounder, and the matched depth sounder position is the accurate shallow profile position after quality control.

[0037] like Figure 1 As shown, the shallow profile position coordinate correction method based on water depth matching includes the following steps:

[0038] Step A, basic data arrangement: arrange and compare the shallow profile original file data and the navigation original file data, and unify the file names of the arranged shallow profile original files and navigation original files;

[0039] Step B, extracting key information from shallow profile: extracting the time information of each channel from the shallow profile data after the basic data is sorted;

[0040] Step C, extracting key information of navigation and water depth data: extracting the recorded navigation time, coordinate information and water depth of the depth sounder from the navigation data after the basic data is sorted;

[0041] Step D, preliminary matching of shallow profile and depth of echo sounder: taking each data of shallow profile as the benchmark, matching shallow profile time with navigation time according to the time matching principle, and after successful matching, importing the depth of echo sounder in navigation into shallow profile data, so as to achieve preliminary matching of shallow profile and depth of echo sounder;

[0042] Step E, repositioning of navigation position: there is a certain deviation between the depth of the echo sounder and the shallow profile seabed after preliminary matching, and this deviation is eliminated so that the shallow profile water depth matches the depth of the echo sounder. At this time, the echo sounder position is the accurate shallow profile position after quality control;

[0043] The following is a detailed description of each implementation step:

[0044] In step A, when collating basic data, the main focus is on collating and comparing shallow profile data and navigation data. Since the two belong to different acquisition systems, their file names, recording time lengths, and recording formats may be different. In order to smoothly carry out subsequent data analysis and processing, the file names are unified through basic data collation and the relevant information is further confirmed. This step can achieve standardized operations, such as Figure 2 The work content shown is to realize the data sorting of the shallow analysis original files and the data sorting of the navigation original files, as follows:

[0045] Step A1, respectively statistically arranging the shallow analysis original file data information and the navigation original file data information;

[0046] The information of shallow profile raw data mainly includes the survey line file name, record length, sampling rate and the statistics of the first and last record time; the special format of shallow profile raw data record is the month and day, which represents the total number of days that have passed from this year to that day. For example, 2011 / 12 / 20 is the same day as the 354th day of 2011, but the recording method is different. For convenience, the month and day are generally converted into the format of month and day.

[0047] The original navigation data information includes the original navigation file name, the start and end recording time of the navigation file, and the start and end recording time include date and hour, minute and second.

[0048] Step A2: After the raw data information of the shallow profile and the raw data information of the navigation are statistically sorted, the one-to-one correspondence between the shallow profile data and the navigation data is re-divided according to the corresponding relationships such as the file names of the two, the continuity of the data records, and the relative relationship between the start and end time, which specifically includes:

[0049] (1) First, the shallow profile data and the navigation data are preliminarily matched together according to the file names of the shallow profile raw data information and the navigation raw data information;

[0050] (2) Then, based on the continuity of the data records, determine whether the shallow profile data or navigation data needs to be merged. Specifically:

[0051] like Figure 2 As shown in , the segmented shallow-section original files may be caused by temporary offline due to instrument failure during the acquisition process and automatic segmentation due to data size limitation. Generally speaking, if the recording time difference is not large, such as a few seconds, it is generally necessary to merge the shallow-section original files (for segmented shallow-section original files, files with a small difference in recording time are merged). If the recording time difference is large, such as several hours, it is generally believed that it is caused by instrument failure, and the shallow-section original files cannot be merged at this time.

[0052] The segmented data in the original navigation file is often caused by date changes. For example, every day (starting at 0 o'clock), the navigation data will automatically generate a new file. At this time, the segmented navigation files need to be merged.

[0053] (3) Finally, the final match is determined based on the start and end time of the data in the shallow analysis original file and the navigation original file. Often, the two are not absolutely one-to-one corresponding in time, but generally there is a difference, but the difference is not large.

[0054] It should be noted that there are two types of time records in China: Beijing time and Greenwich time, which differ by 8 hours. If the time is difficult to match, it is often caused by the inconsistency of the recorded time type. In addition, the navigation file time is often prone to errors, that is, the date of the recorded file with the starting time of zero will jump, that is, one day more than the normal time. At this time, the date needs to be corrected, that is, subtract one day from the date.

[0055] (4) After the shallow analysis original file and the navigation original file are matched, the matched data files are renamed to a unified file name, for example, Figure 2 As shown, the corresponding shallow analysis original file names and navigation original file names after matching are unified into L01RE_1, L01RE_2, L01RE_3, ... L02_1, L02_2, etc., completing the basic data sorting work.

[0056] In the step B, the main thing is to extract each time information, including year, month, day, hour, minute, and second, where the year is located at bytes 157-158 of the SEGY data header, the month and day are located at bytes 159-160 of the SEGY data header, the hour is located at bytes 161-162 of the SEGY data header, the minute is located at bytes 163-164 of the SEGY data header, and the second is located at bytes 165-166 of the SEGY data header. Since the gun number arrangement order of different instruments and equipment is different, and may also be located at different bytes of SEGY, there is generally a problem of inconsistent standards when reading according to the original gun number. In order to unify and standardize, the gun number is renamed in sequence starting from 1.

[0057] In step C, the navigation record is generally a file of 1S, and the information of each file needs to be extracted. Although the navigation records contain information such as date and time, coordinate information and depth of the depth sounder, due to the non-uniform data formats of different navigation software, it is often necessary to redesign the reading program for different data formats. The specific data extraction is a relatively mature and conventional technology, which will not be described in detail here. The coordinate information has a projection coordinate format or a GPS coordinate format. If it is a projection format, the projection format needs to be converted to the GPS coordinate format. The commonly used projection transformations include Mercator projection, UTM projection, transverse Mercator projection, etc. The GPS coordinate unit uses the degree format.

[0058] In step D, when performing a preliminary match between the shallow profile and the depth of the depth sounder, the time matching is performed according to the principle of complete matching of year, month, day, hour, minute and second, that is, the above parameters are completely equal and the match is considered successful.

[0059] The month and day often need to be recalculated from the month and day in navigation. This algorithm is relatively common. The date modules (QDataTime) of major programming software platforms such as QT often have related algorithms, which will not be described in detail here. If the time in the shallow profile cannot be found in the navigation time, the water depth value needs to be set to zero. This situation is also quite common, mainly because the start recording time of the shallow profile is inconsistent with the start recording time of the navigation. When the shallow profile is recorded first and the navigation is not recorded, the time matching will inevitably fail.

[0060] In addition, the water depth value is affected by the depth sounder equipment and weather, and not every record has a normal value. Abnormal values ​​will also be represented by zero values. Because the water depth value after matching has zero values, if it is used directly, the water depth value changes will be chaotic, which is not conducive to water depth matching. Therefore, it is necessary to interpolate the zero-value water depth through the surrounding effective water depth values ​​to eliminate abnormal water depth values.

[0061] In step E, when relocating the navigation position, generally, there must be a certain offset between the depth of the echo sounder and the shallow profile seabed after preliminary matching according to the time relationship. This is mainly because there is a certain distance between the two. The shallow profile data is moved in parallel until it matches the depth value of the echo sounder. At this time, the navigation coordinates (echo sounder position coordinates) are the shallow profile position coordinates.

[0062] When performing offset correction, it is generally necessary to find the undulating areas of the seabed topography, especially the sudden change points of the seabed topography. Let the shallow profile shot number at this time be D1, and find the sudden change point of the seabed topography of the depth of the echo sounder. At this time, the corresponding shallow profile shot number is D2, and the shallow profile data moving distance D = D2-D1. If there is still a slight error after the movement, it can be repeated until the shallow profile depth and the echo sounder depth are completely matched. Since the depths obtained by the shallow profile system and the echo sounder system have been compared and verified as a whole, the coordinate value results obtained in this way are more reliable.

[0063] Specific examples

[0064] Figure 3 It is a shallow seismic survey line in a certain work area in the East China Sea. After sorting out the basic data, extracting the key information of the shallow profile, extracting the key information of the navigation and water depth data, the matching of the depth of the echo sounder and the water depth of the shallow profile was preliminarily completed ( Figure 3 Left figure). It can be seen that there are abnormal values ​​in the depth of the echo sounder after time matching, and the depth of the echo sounder and the depth of the shallow profile are not well matched, which is mainly caused by the certain distance between the echo sounder and the shallow profile. Figure 3 The middle picture shows the result after eliminating the abnormal data of the echo sounder. The trend of the seabed depth after eliminating the abnormal value of the echo sounder water depth is basically consistent with the trend of the shallow seabed depth, except that there is a lateral drift between the two. Figure 3 The picture on the right is the result of the final matching of the depth of the echo sounder and the shallow profile depth. It can be seen that the seabed trends of the two are completely consistent after matching. At this time, the shallow profile coordinates are the correct coordinates after correction.

[0065] The matching between the depth data of the echo sounder and the depth data of the shallow profile is more obvious in places with undulating terrain, and in the matching process, the complete matching of the entire survey line is taken as the standard ( Figure 4 ), the lateral drift of the shallow section coordinates after matching is about 140m. Obviously, if this drift is not eliminated, it will have a serious impact on the subsequent drilling well site selection, etc.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A shallow profile position coordinate correction method based on water depth matching, characterized in that: The following steps are involved: Step A, basic data arrangement: arrange and compare the shallow profile original file data and the navigation original file data, and unify the file names of the arranged shallow profile original files and navigation original files; Step B, extracting key information of shallow section: extracting the time information of each shallow section from the shallow section data after the basic data is sorted; Step C, extracting key information of navigation and water depth data: extracting the recorded navigation time, coordinate information and water depth data of the depth sounder from the navigation data after the basic data is sorted; Step D, preliminary matching of shallow profile water depth and echo sounder water depth: taking each shallow profile data as a benchmark, matching the shallow profile time with the navigation time according to the time matching principle, and after successful matching, importing the echo sounder water depth data in navigation into the shallow profile data to achieve preliminary matching of shallow profile water depth and echo sounder water depth; Step E, repositioning of navigation position: there is a deviation between the depth of the echo sounder after preliminary matching and the shallow profile seabed. The shallow profile data is moved horizontally and parallelly until the shallow profile depth matches the depth of the echo sounder to eliminate the deviation. The echo sounder position at this time is the accurate shallow profile position after correction.

2. The shallow profile position coordinate correction method based on water depth matching according to claim 1 is characterized by: The step A is specifically implemented in the following manner: Step A1: respectively statistically organize the original data of the shallow analysis file and the original data of the navigation file: The data information of the shallow profile original file is sorted out, including the survey line file name, record length, sampling rate and the statistics of the first and last record time; The data information of the original navigation file is sorted out, including the original navigation file name, the statistics of the start and end recording time of the navigation file; Step A2: for the data collected in step A1, the one-to-one correspondence between the shallow profile data and the navigation data is re-divided according to the file names of the two, the continuity of the data records and the relative relationship between the start and end times, and the file names are unified.

3. The shallow profile position coordinate correction method based on water depth matching according to claim 2 is characterized in that: The step A2 comprises the following steps: (1) Preliminarily matching the shallow section data with the navigation data according to the file names of the shallow section original file data and the navigation original file data; (2) Determine whether it is necessary to merge the segmented shallow section data or the segmented navigation data according to the continuity of the data records: For the segmented data in the shallow profile original files, the shallow profile original files with similar recording time will be merged. If the recording time is significantly different, it is considered to be caused by instrument failure, and the shallow profile original files will not be merged. For segmented data in the original navigation file, new files are automatically generated due to date changes. At this time, the segmented original navigation files are merged; (3) Matching the start and end times of the shallow profile original file and the navigation original file; (4) After the shallow analysis original file and the navigation original file are matched, the shallow analysis original file name and the navigation original file name corresponding to the match are renamed to a unified file name to complete the basic data sorting.

4. The shallow profile position coordinate correction method based on water depth matching according to claim 1 is characterized in that: In step D, when performing a preliminary match between the shallow profile and the depth of the depth sounder, the time matching is performed according to the principle of complete matching of year, month, day, hour, minute and second.

5. The shallow profile position coordinate correction method based on water depth matching according to claim 4 is characterized in that: In step D, if the shallow profile time cannot be found in the navigation time, the water depth value is set to zero. After all shallow profile times are matched with the navigation time, the zero water depth value is interpolated through the surrounding effective water depth values ​​to eliminate abnormal water depth values.

6. The shallow profile position coordinate correction method based on water depth matching according to claim 1 is characterized by: In step E, when performing offset correction, find the area with undulating seabed terrain, assume that the shallow profile shot number at this time is D1, find the seabed terrain mutation point of the depth of the echo sounder, and the corresponding shallow profile shot number at this time is D2. Then the shallow profile data moving distance D=D2-D1. If there is still a slight error after the movement, repeat the movement again until the shallow profile water depth completely matches the depth of the echo sounder.

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