Seismic Sensor Noise Filtering via Motion Reference Subtraction
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Solution Overview
Problem
Current seismic streamer technologies face challenges in effectively rejecting noise and achieving high-fidelity seismic signal acquisition, particularly due to the interference of ghost-notch effects and mechanical noise from towing and sea surface disturbances, which degrades the quality of seismic images.
Innovation Solution
The implementation of a system that includes multiple motion sensors and vibration sources to calculate transfer functions, allowing for the filtering of noise and enhancement of seismic signal quality by subtracting platform-motion responses from acoustic wave measurements, thereby improving signal-to-noise ratio and rejecting ghost notches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional temporal and spatial filtering is used to reduce noise, then some noise attenuation is achieved, but ghost-notch effects and mechanical noise from towing significantly degrade signal quality
Solution Approach 1:
A motion sensor acts as an intermediary device that measures platform motion separately. This motion sensor signal serves as a reference that characterizes the mechanical noise from towing and sea surface disturbances, enabling subsequent subtraction from the hydrophone signal to remove these harmful factors while preserving the seismic signal
Solution Approach 2:
The system uses transfer functions to establish a feedback relationship between the motion sensor signal and the expected noise component in the hydrophone signal. By continuously comparing and subtracting the referenced noise estimate from the actual signal, the system adaptively removes harmful noise while maintaining signal integrity
2Loss of information
If hydrophone arrays are used to record seismic waves, then seismic imaging capability is provided, but ghost reflections from the sea surface create notches in the frequency spectrum
Solution Approach 1:
The system converts the harmful ghost reflection problem into a beneficial solution by using the motion sensor to measure the actual platform motion that causes the ghosts. By referencing this motion and subtracting its effect, the system transforms the uncontrolled ghost interference into a measurable and removable component, recovering the lost low-frequency information
3Productivity
If streamers are towed near the sea surface for operational flexibility, then towing efficiency is improved, but noise from sea surface disturbances increases
Solution Approach 1:
The motion sensor serves as an intermediary that decouples the relationship between sea surface position and noise interference. By measuring platform motion at the actual towing depth and using it to reference-subtract noise, the system enables operation near the surface without suffering from increased sea surface noise, maintaining both productivity and signal quality
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 approach significantly enhances the signal-to-noise ratio of seismic data, allowing for more accurate seismic imaging by effectively filtering out noise and improving the fidelity of seismic wave components down to low frequencies.
Implementation Method 1
a first motion sensor and a second motion sensor spaced apart from the first motion sensor and each sensitive to vibrations of the streamer
Implementation Method 2
a first vibration source operably coupled to the streamer and configured to vibrate the streamer
Implementation Method 3
The acoustic energy travels downward through the sea, reflects off underlying structures or subsea strata 28, and returns upward through the sea to the hydrophone array
Implementation Method 4
Reflection of at least some of the sound-wave energy occurs whenever a change in acoustic impedance is encountered by the sound waves
Implementation Method 5
a processing device operably coupled to the first motion sensor and the second motion sensor, the processing device configured to calculate a transfer function at least partially based on information received from the first motion sensor and the second motion sensor
Data Source
AI summary
Methods, systems, and apparatuses are disclosed for sensing acoustic waves in a medium. One example system includes a first elongated member, a first motion sensor sensitive to vibrations of the first elongated member, a second motion sensor spaced apart from the first motion sensor and also sensitive to vibrations of the first elongated member, and a first vibration source operably coupled to the first elongated member and configured to vibrate the first elongated member.