A seabed shallow geological disaster measuring system and method

Abstract

The application discloses a seabed shallow geological disaster measuring system and method, wherein a seismic source is towed behind the stern of a work ship and floats in seawater; a hydrophone is towed behind the stern of the work ship and floats in seawater; a sub-bottom profiler collecting system is arranged on the work ship and is connected with the seismic source and the hydrophone; a floating ball floats on the surface of seawater and is connected with the hydrophone; a ground wire floats in seawater and is connected with the sub-bottom profiler collecting system; a navigation positioning system is arranged on the work ship and is connected with the sub-bottom profiler collecting system; and a generator is arranged on the work ship and is connected with the seismic source, the sub-bottom profiler collecting system and the navigation positioning system. The seabed shallow geological disaster measuring system can effectively improve the stability and reliability of data collection during sub-bottom profiler operation and improve the positioning accuracy of the sub-bottom profiler.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of marine geophysical exploration, in particular to a system and method for measuring shallow seabed geological disasters. BACKGROUND

[0002] Currently, for high-precision measurement operations at sea, due to the characteristics of high technical requirements and complex measurement environment of shallow water measurement at sea, such as shallow seabed geological disaster measurement. Therefore, for shallow seabed geological disaster measurement, special equipment and methods need to be used to solve it. SUMMARY

[0003] The present application provides a system and method for measuring shallow seabed geological disasters, which can effectively improve the stability and reliability of data acquisition during shallow stratigraphic profiler operation.

[0004] The embodiment of the present application provides a system for measuring shallow seabed geological disasters, which comprises a work ship, a seismic source, a hydrophone, a shallow stratigraphic profiler acquisition system, a floating ball, a ground wire, a navigation positioning system and a generator. The seismic source is towed behind the stern of the work ship, and the seismic source floats in seawater, and the seismic source is used for emitting sound waves to the seabed. The hydrophone is towed behind the stern of the work ship, and the hydrophone floats in seawater, and the hydrophone is used for receiving sound waves reflected after the seismic source emits sound waves. The shallow stratigraphic profiler acquisition system is arranged on the work ship, the shallow stratigraphic profiler acquisition system is connected with the seismic source and the hydrophone, and the shallow stratigraphic profiler acquisition system is used for detecting the profile structure of the shallow seabed stratum. The floating ball floats on the surface of seawater, the floating ball is connected with the hydrophone, and the floating ball is used for marking the position of the hydrophone. The ground wire floats in seawater, the ground wire is connected with the shallow stratigraphic profiler acquisition system, and the ground wire is used for conducting current in seawater to ensure the normal operation of the shallow stratigraphic profiler acquisition system. The navigation positioning system is arranged on the work ship, the navigation positioning system is connected with the shallow stratigraphic profiler acquisition system, and the navigation positioning system is used for providing the horizontal position of the seismic source and the hydrophone in seawater and the horizontal position of the work ship. The generator is arranged on the work ship, the generator is connected with the seismic source, the shallow stratigraphic profiler acquisition system and the navigation positioning system, and the generator is used for providing power supply for the seismic source, the shallow stratigraphic profiler acquisition system and the navigation positioning system.

[0005] The embodiment of the present application also provides a method for measuring shallow seabed geological disasters, which uses the above-mentioned system for measuring shallow seabed geological disasters, and the method for measuring shallow seabed geological disasters comprises the following steps: ship navigation test. Length test of the seismic source and the hydrophone. Shallow stratigraphic profiler calibration. Measurement line layout. Traveling measurement. Data integrity check. Seabed stratum data processing and analysis. Preparing drawings and reports.

[0006] In some embodiments, during ship navigation tests, dual high-precision DGPS navigation software is installed, and ship type parameters and DGPS offsets are set in the navigation software Hypack, forming two DGPS systems. Both DGPS systems are used simultaneously for navigation, recording the tracking trajectory. East-west and north-south survey lines are laid out in the work area. The east-west survey lines are 1.5km long with a spacing of 50m, totaling two lines. The north-south survey lines are also 1.5km long with a spacing of 50m, totaling two lines. Guided by the navigation software, the ship runs along the survey lines at a speed of 2-4 knots, maintaining a deviation of ±2m. The offset of each survey line is analyzed, and a comparative report is generated.

[0007] In some embodiments, during the testing of the seismic source and hydrophone length, the seabed topography and test area are determined based on nautical charts. The seismic source and hydrophone are deployed and retrieved, cable length is tested, and layback positioning is controlled within ±2m. Ship speed and cable length are determined, and the stability of the seismic source and hydrophone during ship navigation is tested. The data from the shallow seismic profiler is also tested to ensure it is normal.

[0008] In some embodiments, during the shallow seismic profiler calibration process, a flat location without other obstacles is selected based on nautical chart results. A 20kg metal weight is placed on the seabed, and a beacon, release device, and buoy are connected sequentially from bottom to top, with the buoy approximately 2.5m above the seabed. The beacon's location is located using an underwater positioning system. Four survey lines are laid out around the beacon's location: two east-west lines and two north-south lines, with a spacing of 20m between lines and a line length of 100m. The vessel runs along the survey lines, recording data for different directions and survey lines. The location, depth, and distribution are then analyzed and compared with known data.

[0009] In some embodiments, during the survey line layout process, the survey line spacing is laid out according to the measurement scale requirements, the main survey line is laid out in an east-west direction, and the inspection survey line is laid out in a north-south direction.

[0010] In some embodiments, during the underway measurement, after the seismic source and hydrophone are submerged, the boat maintains a speed of 2-4 knots. Before the formal measurement operation, the shallow seismic profiler acquisition system is connected and debugged via GPS. After the instruments are connected, the seismic source and hydrophone are towed to both sides of the stern, at a distance of more than 15 meters from the stern. Different energy levels, excitation frequencies, and measurement ranges are selected for testing. The TVG is adjusted to achieve the best image quality from the shallow seismic profiler in order to select the optimal operating parameters.

[0011] In some embodiments, during the data integrity check process, the SonarWiz software checks the coverage and data quality of the survey area to ensure 100% coverage.

[0012] In some embodiments, during the seafloor stratigraphic data processing and analysis, the collected shallow stratigraphic profile data is processed, invalid data is deleted, gain adjustment, bandpass filtering, and overlay are performed on each survey line data to remove interference waves on the profile and achieve the best display effect. Ddelph interpretation post-processing software is used for bottom tracking, preliminary analysis of the spatial morphology of each sequence and the contact relationship between sequences, and finally the geological characteristics of each sequence are determined.

[0013] In some embodiments, the process of compiling maps and reports includes creating maps showing the characteristics and distribution of geological hazards and writing reports on the findings.

[0014] An embodiment of this application provides a seabed shallow geological hazard measurement system, comprising a workboat, a seismic source, a hydrophone, a shallow seismic profiling system, a buoy, a ground wire, a navigation and positioning system, and a generator. The seismic source is towed behind the stern of the workboat and floats in the seawater; the seismic source is used to emit sound waves towards the seabed. The hydrophone is also towed behind the stern of the workboat and floats in the seawater; the hydrophone is used to receive the sound waves reflected back from the seismic source. The shallow seismic profiling system is mounted on the workboat and connected to the seismic source and the hydrophone; the shallow seismic profiling system is used to detect the profile structure of the shallow seabed. The buoy floats on the seawater surface and is connected to the hydrophone; the buoy is used to mark the position of the hydrophone. The ground wire floats in the seawater and is connected to the shallow seismic profiling system; the ground wire is used to conduct current into the seawater to ensure the normal operation of the shallow seismic profiling system. The navigation and positioning system is mounted on the workboat and connected to the shallow seismic profiling instrument (SPR) data acquisition system. The navigation and positioning system provides the horizontal position of the seismic source and hydrophone in the seawater, as well as the horizontal position of the workboat. A generator is also mounted on the workboat and connected to the seismic source, the SPR data acquisition system, and the navigation and positioning system. The generator provides power to these systems. This proposed seabed shallow geological hazard measurement system effectively improves the stability and reliability of data acquisition during SPR operation, enhances the positioning accuracy of the SPR, and effectively controls the cable length of the seismic source and hydrophone to maintain a stable position. It offers flexible operability and can improve the quality of measurement data for geological hazards such as seabed oil and gas drilling operations, shallow gas, faults, paleochannels, and mud diapirs, further enhancing the accuracy of subsequent analysis. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the connection of the seabed shallow geological hazard measurement system in the embodiments of this application;

[0017] Figure 2 This is a flowchart of the method for measuring shallow seabed geological hazards in the embodiments of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] See Figure 1 The embodiments of this application provide a seabed shallow geological hazard measurement system, including a workboat 6, a seismic source 1, a hydrophone 2, a shallow seismic profiler acquisition system 3, a buoy 8, a ground wire 4, a navigation and positioning system 5, and a generator 7.

[0020] Workboat 6 is selected from vessels with a stern deck width greater than 10 meters.

[0021] Seismic source 1 is used to transmit sound waves to the seabed. Seismic source 1 is towed by a cable behind the stern of workboat 6. Seismic source 1 is located 15-25 meters from the stern. Seismic source 1 floats in the seawater.

[0022] Hydrophone 2 is used to receive the sound waves reflected back after the sound waves are emitted by the seismic source 1. Hydrophone 2 is towed by a cable behind the stern of the workboat 6. Hydrophone 2 is 15-25m from the stern. Hydrophone 2 floats in the seawater.

[0023] The shallow seismic profiler acquisition system 3 is used to detect the profile structure of shallow bottom strata. The shallow seismic profiler acquisition system 3 is mounted on the workboat 6. The shallow seismic profiler acquisition system 3 is connected to the seismic source 1 and the hydrophone 2 via a BNC cable. The shallow seismic profiler acquisition system 3 uses the SonarWiz acquisition software.

[0024] The buoy 8 is used to mark the position of the hydrophone 2. The buoy 8 floats on the seawater surface and is connected to the hydrophone 2. The buoy 8 is made of plastic, and the connecting rope between the buoy 8 and the hydrophone 2 is made of nylon rope, cotton rope, hemp rope, or hemp rope.

[0025] Ground wire 4 is used to conduct current into the seawater to ensure the normal operation of the shallow seismic profiler acquisition system 3. Ground wire 4 floats in the seawater and is connected to the shallow seismic profiler acquisition system 3. Ground wire 4 is made of copper wire with a diameter greater than 1.38 mm.

[0026] The navigation and positioning system 5 serves as a real-time positioning device, providing the horizontal positions of the seismic source 1 and hydrophone 2 in the seawater, as well as the horizontal position of the workboat 6. The navigation and positioning system 5 is mounted on the workboat 6. The navigation and positioning system 5 is connected to the shallow seismic profiler acquisition system 3. The navigation and positioning system 5 utilizes the BeiDou satellite navigation system and the GPS global positioning system.

[0027] Generator 7 provides power to the seismic source 1, the shallow seismic profiler acquisition system 3, and the navigation and positioning system 5. Generator 7 is mounted on the workboat 6. Generator 7 is connected to the seismic source 1, the shallow seismic profiler acquisition system 3, and the navigation and positioning system 5. Generator 7 is selected with a power output greater than 2.5 kW.

[0028] The seabed shallow geological hazard measurement system of this application can effectively improve the stability and reliability of data acquisition during shallow seismic profiling, enhance the positioning accuracy of the shallow seismic profiling instrument, and effectively control the cable length of the seismic source 1 and hydrophone 2 to maintain a stable length. It has flexible operability and can improve the quality of measurement data for geological hazards such as seabed oil and gas drilling operations, shallow gas, faults, paleochannels, and mud diapirs, further enhancing the accuracy of subsequent analysis. This seabed shallow geological hazard measurement system can be used on various small survey vessels and is easy to install. This seabed shallow geological hazard measurement system of this application is applied in the field of measurement technology for geological hazards such as seabed oil and gas drilling operations, shallow gas, faults, paleochannels, and mud diapirs.

[0029] See Figure 2 The embodiments of this application also provide a method for measuring shallow seabed geological hazards. Using the aforementioned shallow seabed geological hazard measurement system, the method includes the following steps:

[0030] (1) Background research

[0031] The above steps involve collecting basic data on wind, wave, current, tide level, water depth, and marine oil and gas operations in the work area.

[0032] (2) Equipment installation

[0033] In the above steps, the seismic source 1, hydrophone 2, shallow seismic profiler acquisition system 3, ground wire 4, navigation and positioning system 5, generator 7, and buoy 8 are installed and connected on the work vessel 6 to form a seabed shallow geological hazard measurement system.

[0034] (3) Ship navigation test

[0035] The above steps include a test of maintaining a deviation of ±2m at a speed of 4 knots or less. The completion standard is that the vessel should be able to maintain a deviation of approximately ±2m at a speed of 4 knots, whether sailing with the current, against the current, or not in the direction of the current.

[0036] In addition, the above steps include:

[0037] 1) Complete the installation of dual high-precision DGPS navigation software, and set the ship type parameters and DGPS offset in each navigation software Hypack to form two DGPS systems.

[0038] 2) Simultaneously use two DGPS systems for navigation and record the tracking points.

[0039] 3) Arrange east-west and north-south survey lines in the work area. The east-west survey lines are 1.5km long and 50m apart, for a total of 2 lines. The north-south survey lines are 1.5km long and 50m apart, for a total of 2 lines.

[0040] 4) Using navigation software, instruct the captain to run the survey line at a speed of 2-4 knots while maintaining a yaw distance of ±2m.

[0041] 5) Analyze the offset of each survey line and issue a comparison report.

[0042] Adjustments were made based on the comparison report, and the ship's navigation test was completed.

[0043] (4) Length (cable length) test of seismic source 1 and hydrophone 2

[0044] The above steps include testing the following: adjusting the boat speed and cable length to achieve stable positioning of the seismic source 1 and hydrophone 2. The completion standard is: under conditions of water depth greater than 5m and the distance between the seismic source 1 and hydrophone 2 and the stern of the boat, the layback positioning should be within ±2m.

[0045] In addition, the above steps include:

[0046] 1) Determine suitable seabed topography and test area based on nautical charts.

[0047] 2) Manually deploy and retrieve the seismic source 1 and hydrophone 2, conduct cable length tests, control the layback positioning within ±2m, determine the ship speed and cable length, and test whether the seismic source 1 and hydrophone 2 are stable during the ship's navigation.

[0048] 3) Test whether the data from the shallow seismic profiler is normal.

[0049] Adjustments were made based on the test results, and the cable length tests for seismic source 1 and hydrophone 2 were completed.

[0050] (5) Calibration of shallow seismic profiler

[0051] The above steps involve testing the location, depth, and distribution of known seabed targets using a shallow seismic profiler. The completion standard is: horizontal positioning accuracy within ±2m, and location, depth, and distribution accuracy reaching 100%.

[0052] In addition, the above steps include:

[0053] 1) Based on the nautical chart results, find a location with flat terrain and no other obstacles.

[0054] 2) Place a metal weight (iron frame) weighing about 20 kg on the seabed and connect the beacon, release device, and buoy 8 from bottom to top. The height of buoy 8 should be about 2.5 m above the seabed.

[0055] 3) Use an underwater positioning system to locate the beacon. Using the beacon as the center, set up 4 survey lines, including 2 east-west survey lines and 2 north-south survey lines, with a spacing of 20m between survey lines and a length of 100m for each survey line.

[0056] 4) Ship running line test: After recording data from different directions and measuring lines, analyze the location, burial depth, and distribution, and compare the data with known data.

[0057] Adjustments were made based on the comparative analysis results to complete the calibration of the shallow seismic profiler.

[0058] (6) Survey line layout

[0059] In the above steps, the spacing between survey lines is set according to the requirements of the measurement scale. For example, the spacing between survey lines at a scale of 1:1000 is 10m. The main survey lines are set in the east-west direction, and the inspection survey lines are set in the north-south direction.

[0060] (7) Mobile surveying

[0061] In the above steps, after the seismic source 1 and hydrophone 2 are submerged, the boat should maintain a speed of 2-4 knots to avoid stopping or reversing. Before the formal measurement operation, the shallow seismic profiler acquisition system should be connected and debugged via GPS. After the instruments are connected, the seismic source 1 (also known as the electromagnetic sound source) and hydrophone 2 should be towed to both sides of the stern, at a distance of more than 15 meters from the stern. Different energy levels, excitation frequencies, and measurement ranges should be selected for testing. The TVG should be adjusted to achieve the best image quality from the shallow seismic profiler in order to select the optimal operating parameters.

[0062] (8) Data integrity check

[0063] In the above steps, after the measurement is completed, check the coverage and data quality of the measurement area using SonarWiz software to ensure that the measurement area coverage is 100%.

[0064] (9) Submarine stratigraphic data processing and analysis

[0065] In the above steps, the direct measurement results of the stratigraphic profile are two-way reflection travel time profiles, which are physically interfaces with abrupt changes in acoustic impedance between stratigraphic interfaces. The collected shallow stratigraphic profile data are processed, invalid data is deleted, and gain adjustment, bandpass filtering, and overlay are performed on each survey line to remove interference waves on the profile and achieve optimal display results. Ddelph interpretation post-processing software is used for bottom tracking, preliminary analysis of the spatial morphology of each sequence and the contact relationships between sequences, and finally, the geological characteristics of each sequence are determined. The time-depth conversion sound velocity in the soil used in the data processing is 1550 m / s.

[0066] (10) Prepare maps and reports

[0067] In the above steps, the characteristics and distribution maps of geological hazards such as shallow seafloor gas, faults, paleochannels, and muddy diverticula are compiled, and a report on the results is written.

[0068] This application aims to improve the accuracy and quality of data measurement by using small survey vessels in shallow waters of sea state 4 and below for investigations of geological hazards such as subsea oil and gas drilling, shallow gas, faults, paleochannels, and mud diversions. It ensures that vessels traveling at speeds of 4 knots or less maintain a yaw rate of ±2m. Furthermore, it aims to ensure that in water depths greater than 5m and with the seismic source 1 and hydrophone 2 15-25m from the stern, the layback positioning is within ±2m. The application also aims to achieve a planar position accuracy of ±2m for subsea buried pipelines, with 100% accuracy in analyzing their location, depth, and distribution. This will improve data measurement accuracy and quality, providing more accurate and reliable data. The application has broad prospects for investigations of abandoned marine wellheads, marine well sites, and subsea pipeline and cable routes.

[0069] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0070] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of measuring a shallow geological disaster on the seabed, characterized by, It comprises the following steps: Ship navigation test; Length test of seismic source and hydrophone; Shallow seismic profiler calibration; Line layout; Running measurement; Data integrity check; Seafloor strata data processing analysis; Map drawing and report; In the ship navigation test process, the installation of double high-precision DGPS navigation software is completed, and the ship type parameters and DGPS offset are set in the navigation software Hypack to form two sets of DGPS systems; At the same time, two sets of DGPS systems are enabled for navigation, and the dotting track is recorded; East-west and north-south lines are arranged in the operation area, the east-west line is 1.5 km long, the interval is 50 m, and there are 2 lines, the north-south line is 1.5 km long, the interval is 50 m, and there are 2 lines; Run the line according to the command of the navigation software at 2-4 knots with a deviation of ±2m; The offset of each line is analyzed, and a comparison report is issued; In the length test of seismic source and hydrophone, the seafloor topography and test area are determined according to the chart; The seismic source and hydrophone are reeled in and out to test the cable length, the layback positioning is controlled within ±2m, the ship speed and cable length are determined, and whether the seismic source and hydrophone are stable during the ship running process is tested; Whether the shallow seismic profiler data is normal is tested; In the shallow seismic profiler calibration process, according to the chart result, find a place with flat terrain and no other obstacles; Put a 20kg metal weight on the seabed, connect the beacon, release device and float ball from bottom to top, and the height of the float ball is 2.5m away from the seabed; The position of the beacon is found by the underwater positioning system, and 4 lines are arranged around the beacon, of which 2 are east-west and 2 are north-south, the line spacing is 20m, and the line length is 100m; The ship runs the line, records the data of different directions and lines, and then analyzes the position, depth and distribution, and compares with the known data; In the line layout process, the line spacing is laid out according to the measurement scale requirement, the main line is laid out according to the east-west direction, and the inspection line is laid out according to the north-south direction; In the running measurement process, after the seismic source and hydrophone are put into water, keep the ship speed at 2-4 knots; Before formal measurement operation, the GPS connection of the shallow seismic profiler acquisition system instrument is debugged; After the instrument is connected, the seismic source and hydrophone are respectively dragged on both sides of the ship stern more than 15 meters away from the stern, and different energy size, excitation frequency and range are selected for test, and TVG is adjusted to make the image effect of the shallow seismic profiler best, so as to select the best working parameters; In the data integrity check process, the coverage degree and data quality of the measurement area are checked in the SonarWiz software to ensure that the coverage of the measurement area is 100%; In the seafloor strata data processing analysis process, the collected shallow seismic profile data is processed, invalid data is deleted, gain adjustment, band pass filtering and superposition are performed on the data of each line, interference waves on the profile are removed to achieve the best display effect, Ddelph interpretation post-processing software is used for bottom tracking, preliminary analysis of the spatial form of each sequence and the contact relationship between sequences, and finally the geological characteristics of each sequence are determined; Draw up the feature and distribution map of geological disasters and write the report.

2. A submarine shallow geological disaster measuring system using the submarine shallow geological disaster measuring method according to claim 1, characterized by It comprises: a work ship; a seismic source, which is towed behind the stern of the work ship, floats in seawater, and is used to emit sound waves to the seabed; a hydrophone, which is towed behind the stern of the work ship, floats in seawater, and is used to receive the sound waves reflected back after the sound waves are emitted by the seismic source; a shallow sub-surface profiler acquisition system, which is arranged on the work ship, is connected with the seismic source and the hydrophone, and is used to detect the profile structure of the shallow sub-surface; a float ball, which floats on the surface of seawater, is connected with the hydrophone, and is used to mark the position of the hydrophone; a ground wire, which floats in seawater, is connected with the shallow sub-surface profiler acquisition system, and is used to conduct electric current in seawater to ensure the normal operation of the shallow sub-surface profiler acquisition system; a navigation positioning system, which is arranged on the work ship, is connected with the shallow sub-surface profiler acquisition system, and is used to provide the horizontal positions of the seismic source and the hydrophone in seawater and the horizontal position of the work ship; a generator, which is arranged on the work ship, is connected with the seismic source, the shallow sub-surface profiler acquisition system, and the navigation positioning system, and is used to provide power supply for the seismic source, the shallow sub-surface profiler acquisition system, and the navigation positioning system.

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