Marine Seismic Offset Shift Correction via Trace Travel-Time Analysis
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Solution Overview
Problem
Current GPS and acoustic devices used in marine seismic surveys for determining offset accuracy are not sufficient, especially for 4D geophysical imaging, which requires high precision and reliability, and lack verification methods for ensuring data accuracy.
Innovation Solution
A method involving the calculation of an offset shift by selecting pairs of seismic traces, calculating quantities Y and X based on measured offsets and travel-times, and estimating the offset shift through a linear relation Y=aX+b, where 'a' is a constant and 'b' is related to the offset shift, to correct measured offsets and generate accurate subsurface images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS and acoustic devices are used to determine offset, then the offset can be measured, but the measurement precision is insufficient for 4D geophysical imaging
Solution Approach 1:
The patent applies feedback by using the seismic trace data itself to verify and correct the offset measurements. The method calculates expected travel times from seismic traces and compares them with measured travel times to determine offset shifts, creating a self-verifying system that improves both precision and reliability without requiring additional external measurement systems.
Solution Approach 2:
The patent substitutes the mechanical/GPS-based positioning system with an acoustic-based verification system. Instead of relying on GPS or acoustic positioning devices to determine offset, the method uses acoustic seismic waves and their travel times through the subsurface to calculate and verify offsets, replacing external mechanical measurement systems with an internal acoustic verification approach.
2Productivity
If traditional GPS and acoustic positioning methods are used, then the survey can be conducted, but verification of data accuracy is lacking
Solution Approach 1:
The patent implements self-service by enabling the seismic data itself to verify its own accuracy. The method uses the seismic traces and their travel times to automatically calculate and verify offsets, allowing the system to self-verify without requiring external verification equipment or manual checking processes, thus maintaining high productivity while adding reliability.
3Manufacturing precision
If high precision offset determination is required for 4D imaging, then imaging accuracy improves, but the complexity of the positioning system increases
Solution Approach 1:
The patent extracts the verification function from the complex positioning system. Instead of making the positioning system itself more complex to achieve high precision, the method extracts the verification capability and implements it separately through a simple algorithm that processes seismic trace data, achieving high imaging accuracy without increasing positioning system complexity.
Solution Approach 2:
The patent replaces complex mechanical positioning systems with a simpler acoustic-based verification method. Rather than using sophisticated GPS or acoustic positioning hardware to achieve high precision, the method substitutes these complex systems with a computational approach that uses seismic wave travel times to verify and correct offsets, achieving the same precision with much simpler technology.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a reliable and accurate means to determine offset shifts without relying on GPS or acoustic devices, enhancing the precision of marine seismic surveys and improving the accuracy of subsurface imaging, particularly for 4D geophysical imaging applications.
Implementation Method 1
The seismic wave 18 propagates downward toward the seafloor 20 and penetrates the seafloor until eventually a reflecting structure 22 (reflector) reflects the seismic wave
Implementation Method 2
a reflecting structure 22 (reflector) reflects the seismic wave. The reflected seismic wave 24 propagates upward until is detected by the receiver 11 on streamer 12
Implementation Method 3
The buoy 40 may have a GPS device 42 that determines the location of the buoy. The source 16 may include a GPS device 44. The same is true for the vessel 10, i.e., it also includes a GPS device 46
Implementation Method 4
an acoustic positioning network may be used to determine the underwater relative positions of the receivers, thus helping to measure the positions more accurately
Implementation Method 5
calculating a quantity Y that depends on measured offsets of receivers for which the traces were selected, and a quantity X that depends on travel-times and the measured offsets of the receivers for which the traces were selected
Data Source
AI summary
Computing device and method for generating an image of a subsurface. The method calculates an offset shift of measured offsets between a seismic source and plural receivers of a streamer. The method includes receiving seismic data recorded underwater by the plural receivers; selecting two pairs of traces from the plural traces and for each pair, calculating a quantity Y that depends on measured offsets of receivers for which the traces were selected, and a quantity X that depends on travel-times and the measured offsets of the receivers for which the traces were selected; calculating a linear relation Y=aX+b, where “a” is a constant and “b” is related to the offset shift; estimating the offset shift from “b”; correcting the measured offsets of the receivers based on the offset shift; and calculating the image of the subsurface based on the corrected offsets.