Marine Seismic Source With Variable-Depth Shuttle Frequency Control
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Solution Overview
Problem
Conventional seismic sources produce undesirable very high frequencies that interfere with the identification of subsurface geological structures, and can cause damage to marine life and equipment due to high-pressure discharge interactions.
Innovation Solution
A seismic source with multiple discharge ports, a varying depth shuttle assembly shaft, and a firing seal sealing ring to adjust frequency content, forming a round output pulse bubble, and positioning suspension lines and umbilical cables away from discharge ports to prevent interference and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional seismic sources discharge compressed air at high pressure (1500-3000 psi) to generate seismic energy, then the power and penetration capability are improved, but very high frequency sound components are produced that are harmful to marine life and useless for geological identification
Solution Approach 1:
The single discharge port is segmented into multiple discharge ports (at least three, preferably four or more) arranged in a circular pattern. This segmentation distributes the compressed air discharge across multiple smaller openings, which reduces the very high frequency components while maintaining the overall power output. The segmented discharge geometry creates a more controlled expansion pattern that eliminates harmful frequencies.
Solution Approach 2:
The discharge ports are positioned at specific locations around the periphery of the operating head, creating localized discharge zones. The shaft with varying depth longitudinal channel provides different acceleration distances for different portions of the compressed air charge, allowing optimization of frequency content while maintaining power. This local quality control enables selective suppression of very high frequencies.
2Object-affected harmful factors
If the rise time of the primary pressure pulse is reduced to eliminate very high frequencies, then the harmful effects on marine life are reduced, but the penetration capability through challenging geological structures (salt, basalt) may be compromised
Solution Approach 1:
The shaft is designed with a varying depth longitudinal channel that changes the acceleration distance for the compressed air charge. By adjusting the depth of the channel at different locations, the acceleration distance is optimized to control the rise time of the pressure pulse. This parameter change allows the rise time to be extended sufficiently to eliminate very high frequencies while maintaining low frequency content (10-40 Hz) necessary for penetrating challenging geological structures.
3Ease of operation
If suspension lines and umbilical cables are positioned close to discharge ports for ease of operation, then the device complexity is reduced, but they are damaged by the intense discharge of high pressure compressed air
Solution Approach 1:
The discharge ports are arranged in a circular pattern around the periphery of the operating head, utilizing the radial dimension. The suspension lines and umbilical cables are positioned along the central axis or at different radial positions away from the discharge ports. This dimensional separation in the radial direction allows cables to be positioned for ease of operation while avoiding the intense discharge zones, preventing damage.
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
Reduces or eliminates very high frequencies, enhances signal penetration through challenging geological structures, and minimizes damage to marine life and equipment by optimizing frequency content and discharge geometry.
Implementation Method 1
generating seismic energy impulses, i.e., acoustical waves, in a body of water
Implementation Method 2
forming a substantially round output pulse bubble
Implementation Method 3
The shaft has a longitudinal channel having a varying depth... By selecting the length of the sealing surface of the firing seal, a desired mixture of low and moderately high frequencies may be achieved
Implementation Method 4
the highly pressurized gas acts against the operating piston to maintain the shuttle assembly in a closed position until firing
Implementation Method 5
The seismic source is triggered using a solenoid operated valve to release pressurized air into the operating chamber actuating the shuttle assembly to cause an abrupt discharge
Data Source
AI summary
A seismic source for generating seismic waves under water includes an operating head having an operating chamber, a cushion chamber, and discharge ports, a firing chamber attached to the operating head, the firing chamber configured to hold compressed air to be discharged through the discharge ports, and a shuttle assembly having a shaft located within the operating head and configured to prevent the compressed air in the firing chamber to enter the discharge ports when in a close state, and to allow the compressed air in the firing chamber to be discharged through the discharge ports when in an open state. The shaft of the shuttle assembly which extends in both the operating chamber and the cushion chamber, has a channel having a varying depth.