Underwater Acoustic Sound Velocity Estimation in Towed Streamers
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Solution Overview
Problem
Current seismic data acquisition in marine environments faces challenges in accurately estimating underwater acoustic sound velocity, leading to unreliable positioning of seismic streamers due to the use of velocimeters, which are prone to breakdown and assume constant sound velocity, resulting in errors in inter-node distance measurements and localization of sensors.
Innovation Solution
A method that estimates underwater acoustic sound velocity by forming groups of nodes into triangles, using propagation durations between nodes to calculate sound velocity, eliminating the need for velocimeters and improving accuracy through multiple estimations and statistical analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If velocimeters are used to measure sound velocity, then sound velocity can be obtained, but the system becomes unreliable due to velocimeter breakdown and constant velocity assumption
Solution Approach 1:
The patent extracts the sound velocity measurement function from the velocimeter hardware and implements it through a software-based algorithm using acoustic signal propagation time measurements between nodes. This eliminates the unreliable velocimeter hardware while maintaining measurement capability through distributed acoustic nodes and computational processing.
Solution Approach 2:
The patent replaces the mechanical velocimeter system with an acoustic-based measurement system. Instead of using mechanical instruments to directly measure sound velocity, the system uses acoustic signals transmitted between distributed nodes, measures propagation times, and calculates sound velocity through computational algorithms, thereby substituting mechanical measurement with acoustic and computational methods.
2Measurement precision
If velocimeters are used to control streamer depth and position, then positioning can be maintained, but system complexity increases and breakdowns occur
Solution Approach 1:
The patent extracts the sound velocity measurement and positioning control functions from centralized velocimeters and distributes them across multiple acoustic nodes along the streamer. Each node participates in measuring propagation times and contributing to the overall positioning calculation, thereby eliminating single-point failures and reducing system complexity through distribution.
Solution Approach 2:
The acoustic nodes serve multiple functions: they act as both sound velocity measurement points and positioning references. The same acoustic signals used for measuring propagation times also enable inter-node distance calculations and streamer positioning, thereby reducing the need for separate dedicated measurement devices and simplifying the overall system.
3Device complexity
If constant sound velocity is assumed, then calculations are simplified, but measurement precision deteriorates due to velocity variations
Solution Approach 1:
The patent transitions from assuming constant sound velocity to dynamically measuring and updating sound velocity values at different locations along the streamer. The system continuously measures propagation times between nodes and calculates local sound velocity values, allowing the velocity profile to vary spatially and adapt to changing underwater acoustic conditions rather than relying on a fixed constant value.
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 reliable sound velocity values, enhancing the precision of seismic data acquisition by reducing errors in inter-node distance measurements and streamer positioning, even in the absence of functional velocimeters, and is more robust and cost-effective.
Implementation Method 1
a first propagation duration of an acoustic signal transmitted between said first node and a third node placed along a second acoustic linear antenna
Data Source
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AI summary
A method for estimating an underwater acoustic sound velocity in a network of acoustic nodes arranged along towed acoustic linear antennas and in which a plurality of acoustic signals are transmitted between the nodes, the method comprising steps of: obtaining two predetermined distances each separating a couple of nodes ((A,B), (B,C)) placed along a same first acoustic linear antenna (31); for each couple of first and second nodes ((A,B), (B,C)), obtaining a first propagation duration of an acoustic signal transmitted between said first node and a third node (D) placed along a second acoustic linear antenna (32) and a second propagation duration of an acoustic signal transmitted between said second node and said third node (D); and estimating said underwater acoustic sound velocity, as a function of said two predetermined distances and said first and second propagation durations obtained for each couple of nodes.