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CN-120388100-B - Drawing method for seabed 1% sediment thickness point

CN120388100BCN 120388100 BCN120388100 BCN 120388100BCN-120388100-B

Abstract

The present disclosure provides a method of mapping a subsea 1% sediment thickness point. The method comprises the steps of interpreting and deriving horizon data of the seabed and a basal plane through Geoframe software, cleaning and sorting the horizon data to obtain horizon data of a single measuring line, then aligning the horizon data, interpolating and supplementing the horizon data, subtracting the horizon data from the interpolation, converting the depth of the horizon data to calculate sediment thickness of a depth domain, calculating 1% sediment thickness points on each measuring line, drawing sea bottom surface, basal plane, sediment thickness, FOS point coordinates and 1% sediment thickness points into a section view, and drawing a plane distribution map of the 1% sediment thickness points through QGIS software. According to the method, through interpretation of the long cable seismic section, the accuracy of calculation of 1% sediment thickness points is guaranteed to the maximum extent by utilizing a high-accuracy time-depth conversion relationship, and the requirement of 1% sediment thickness calculation in the seventy-sixth rule of the united nations ocean law is met.

Inventors

  • WANG ZHENG
  • TANG YONG
  • Guo Chufeng
  • LI HE
  • REN JIANYE

Assignees

  • 自然资源部第二海洋研究所

Dates

Publication Date
20260508
Application Date
20250310

Claims (7)

  1. 1. A method of mapping a 1% sediment thickness point on the seafloor, comprising: S1, collecting sgy seismic data, and importing sgy seismic data into Geoframe seismic interpretation software for interpretation to obtain time depth data of the seabed surface and the basal surface of all seismic lines; s2, using a multi-measuring line horizon data cleaning subsystem to clean time depth data of the seabed surface and the basal surface of all the seismic lines in S1, and removing error data lines generated during Geoframe export to obtain correct horizon data; S3, using a measuring line sorting subsystem to split the correct horizon data in the S2 one by one according to the measuring line names, and storing the split horizon data in a folder independently named by the measuring line names; S4, calculating the depth domain sediment thickness of each measuring line sorted in the S3 by using a stratum sediment thickness calculation subsystem; s5, determining the latitude and longitude coordinates of the FOS point corresponding to each measuring line by using Geocap software and high-precision actually measured topographic data; S6, using a 1% sediment thickness point calculating subsystem, and collecting points which meet the condition that the sediment thickness of each point on the measuring line is greater than 1% of the distance between the point and the FOS point according to the sediment thickness of each measuring line depth domain obtained in the S4 and the longitude and latitude coordinates of the corresponding FOS point obtained in the S5, wherein the points are 1% sediment thickness points; s7, drawing a sea bottom surface-substrate surface depth map, a sediment thickness map and a 1% sediment thickness point position map based on the data in S6 to show specific positions of FOS points and 1% sediment thickness points.
  2. 2. A method of mapping a 1% sediment thickness point on the ocean floor as defined in claim 1, The single line folder in S3 includes subsea surface line and basal surface line data.
  3. 3. A method of mapping a 1% sediment thickness point on the ocean floor as defined in claim 1, The calculation method in S4 comprises the following steps: s41, reading horizon data of sea bottom surface and basal surface data, selecting horizon data with continuous CDP (complementary data) or selecting horizon data with discontinuous but discontinuous less than 100m, and supplementing by adopting a segmented Hermite interpolation polynomial to ensure the continuity and the precision of the data; s42, cutting the sea floor and the base surface in the S41 to enable the sea floor and the base surface to be completely overlapped and aligned so as to obtain the sea floor and the base surface which are continuous and have the same length; S43, subtracting the sea bottom surface from the basal surface to obtain the sediment thickness of the time domain; s44, converting the sediment thickness of the time domain into the sediment thickness of the depth domain by using a time-depth conversion formula (1) of the ocean drilling well constraint; z = 0.000188295t 2 + 0.695896t(1) Where z is the depth domain deposit thickness and t is the time domain deposit thickness.
  4. 4. A method of mapping a 1% sediment thickness point on the sea floor as claimed in claim 3, When horizon data with a break of more than 100m appears in S41, the error is a horizon data error, and the original seismic data in Geoframe needs to be checked in S1.
  5. 5. A method of mapping a 1% sediment thickness point on the sea floor as claimed in claim 3, The sea floor and the base floor obtained in S42 are compared with the overlapping portions of the sea floor and the base floor in the geofame seismic interpretation software to determine the accuracy of the result of S42.
  6. 6. A method of mapping a 1% sediment thickness point on the ocean floor as defined in claim 1, The determination method of the 1% deposit thickness point in S6 includes: s61, reading longitude and latitude coordinates of all FOS points and corresponding line names, and matching the FOS point coordinates with the line according to the line names; s62, calculating the linear distance from each CDP corresponding point on the measuring line to the FOS point to obtain a first distance; S63, calculating the ratio of the depth domain sediment thickness of the point corresponding to each CDP to the first distance to obtain a plurality of first ratios, wherein all the points with the first ratios being larger than 0.01 are 1% sediment thickness points; s64, deriving x coordinates, y coordinates, time domain thickness, depth domain thickness, CDP number, first distance, first ratio and index number in the original coordinate column of all 1% sediment thickness points meeting the conditions, and deriving the 1% sediment thickness point farthest from the FOS point.
  7. 7. A method of mapping a 1% sediment thickness point on the ocean floor as defined in claim 1, The drawing method in S7 comprises the following steps: s71, automatically reading sediment thickness data of all the measuring lines, sea bottom surface and basal surface depth data, FOS point coordinates and 1% sediment thickness points meeting the conditions; s72, calculating azimuth angles of the measuring lines according to the increasing direction of CDP; wherein, the azimuth angle is a backhand section between 67.5 degrees and-112.5 degrees, and the drawing is carried out in a CDP decreasing mode, so that the final view is ensured to be in the direction of the normal hand section; S73, drawing an upper graph, wherein the upper graph comprises four pieces of information including FOS points, 1% sediment thickness points, sediment thickness and 1% thickness lines; s74, drawing a lower subgraph which comprises submarine surface depth and basal surface depth information; S75, drawing a plane distribution diagram of 1% sediment thickness points, and including plane distribution information of 1% sediment thickness points.

Description

Drawing method for seabed 1% sediment thickness point Technical Field The disclosure relates to the technical fields of ocean mapping, submarine topography mapping and submarine science, in particular to a mapping method for a submarine 1% sediment thickness point. Background According to the relevant regulations, the continental shelf of coastal countries includes all natural extension of the territory outside its territory, the seabed and the subsoil of the seabed area extended to the outer edge of the large Liu Bian, if the distance from the base line of territory to the outer edge of the large Liu Bian is less than 200 seas, i.e. extended to 200 seas, and if it exceeds 200 seas, the continental shelf outside 200 seas can be claimed, as shown in fig. 8. When coastal countries claim a continental shelf outside 200 seas, two modes can be adopted to define the outer limit of the continental shelf, namely, a sedimentary rock thickness formula method is adopted, namely, the thickness of sedimentary rock at each fixed point forming the outer limit is at least 1% of the shortest distance from the point to Liu Pojiao a, and a distance formula method is adopted, namely, the distance between each fixed point forming the outer limit and the continental slope foot is not more than 60 seas. Clearly, coastal countries want to expand continental shelves beyond 200 seas, calculation and determination of 1% sediment thickness points play a critical role therein. The deposition thickness can be determined by direct sampling and by indirect methods, the direct sampling being performed by drilling. Drilling, especially deep water drilling, is expensive and only a few point values are available. Indirect methods include multi-beam seismic measurements, gravity inversion, etc., which are relatively inexpensive, can be performed relatively quickly, and can obtain along-line or along-interface sediment distribution. The total quality and penetration degree of the multi-channel data are high, and the self speed information is beneficial to demarcating the outside of the continental sides, and the continental shelf boundary committee takes the multi-channel seismic reflection data as the most powerful evidence source for determining the deposition thickness. The current calculation means for the 1% sediment thickness point is from Geocap software developed by the company Geodata in Norway or CARISLOTS software developed by the company TELEDYNECARIS in Canada, but the algorithm of the two types of software is not disclosed. Moreover, when a large number of operations involving multiple seismic lines are involved, using Geocap software to perform time-depth conversion one by one and calculate 1% sediment thickness points can lead to significant effort. Furthermore, geocap software can only give plane coordinates of 1% sediment thickness points and cannot plot important information such as sea floor, substrate surface, sediment thickness points, 1% thickness lines, etc. onto a cross-section that facilitates analytical comparison. Therefore, in view of the problems and technical requirements existing in the prior art, the invention aims to provide an accurate, quick and convenient determination and drawing method of a 1% sediment thickness point. Disclosure of Invention One technical problem to be solved by the present disclosure is that the existing calculation method requires a lot of manpower and material resources, and cannot form a cross-sectional view capable of displaying the sea bottom surface, the substrate surface, the sediment thickness, 1% sediment thickness points, 1% thickness lines, and the like. To solve the above technical problems, an embodiment of the present disclosure provides a method for mapping a 1% sediment thickness point on the seabed, including: S1, collecting sgy seismic data, and importing sgy seismic data into Geoframe seismic interpretation software for interpretation to obtain time depth data of the seabed surface and the basal surface of all seismic lines; s2, using a multi-measuring line horizon data cleaning subsystem to clean time depth data of the seabed surface and the basal surface of all the seismic lines in S1, and removing error data lines generated during Geoframe export to obtain correct horizon data; s3, using a measuring line sorting subsystem to split the correct horizon data in the S2 one by one according to the measuring line names, and storing the split horizon data in a folder independently named by the measuring line names; S4, calculating the depth domain sediment thickness of each measuring line sorted in the S3 by using a stratum sediment thickness calculation subsystem; s5, determining the latitude and longitude coordinates of the FOS point corresponding to each measuring line by using Geocap software and high-precision actually measured topographic data; S6, using a 1% sediment thickness point calculating subsystem, and collecting points which meet the condition that the sedim