Seismic Sweep Signal Design for Maximum Power and Frequency Profile
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Solution Overview
Problem
Existing seismic exploration methods using controllable sources struggle to generate seismic signals with optimal frequency properties, leading to suboptimal subsurface imaging due to physical limitations and unsatisfactory broadband data acquisition.
Innovation Solution
A method and system that determine limiting curves for piston displacement, velocity, and acceleration to design a sweep schedule for controllable seismic sources, allowing for the generation of seismic data with a desired frequency profile, maximizing power output while maintaining a preferred frequency profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a controllable source operates at maximum power output, then the power output is maximized, but the frequency profile becomes distorted due to physical limitations
Solution Approach 1:
The patent applies dynamics by making the sweep rate variable rather than constant. The sweep rate is dynamically adjusted according to the formula ds/dt ∝ 1/√f, allowing the system to operate at maximum power across the entire frequency band while maintaining an accurate frequency profile. This resolves the contradiction by enabling the source to adapt its operation dynamically rather than being constrained by a fixed sweep rate
Solution Approach 2:
The patent changes the parameter of sweep rate from a constant value to a frequency-dependent variable. By implementing the relationship ds/dt ∝ 1/√f, the system transforms the operating parameters to compensate for the physical limitations of the controllable source, thereby maintaining both maximum power output and accurate frequency profile across the swept band
2Ease of operation
If a constant sweep rate is used, then the source operation is simple, but the frequency profile becomes distorted at different frequencies
Solution Approach 1:
The patent transforms the sweep rate parameter from a constant to a frequency-dependent variable following the relationship ds/dt ∝ 1/√f. This parameter change enables the system to maintain accurate frequency profiles across the swept band while still using a systematic and controllable sweep mechanism, balancing operational simplicity with frequency accuracy
3Manufacturing precision
If the source amplitude is reduced to maintain flat spectrum, then the frequency profile accuracy is improved, but the power output decreases
Solution Approach 1:
Rather than reducing amplitude to maintain frequency profile accuracy, the patent dynamically adjusts the sweep rate according to ds/dt ∝ 1/√f. This dynamic approach allows the source to operate at maximum amplitude across the entire frequency band while naturally maintaining a flat spectrum through the optimized sweep rate, thereby preserving both power output and frequency profile accuracy
Data Source
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AI summary
The output spectrum of a controllable swept- frequency acoustic source at a given frequency can be controlled by making the rate of change of frequency equal to the desired output power spectrum divided by the squared envelope amplitude of the source output signal, both measured at the time after the start of its frequency sweep at which the sweep frequency passes through the given frequency. The system and method can also be used to correct for propagation effects outside the source by dividing the desired spectrum by the propagation effect. The method can further be used either to obtain an output spectrum of a desired shape from a source operating at maximum output or to design a sweep of a minimum feasible duration that will result in an output spectrum of a specified shape and with a specified amplitude.