Seismic Source Steering via Virtual Position Control
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Solution Overview
Problem
Existing seismic survey systems face challenges in accurately controlling the position of seismic source arrays and streamers during towing, especially in dynamic water conditions, which affects the precision of 4-D geophysical imaging due to environmental factors and vessel navigation limitations.
Innovation Solution
A method and system that utilize a source steering device to adjust the position of seismic source arrays independently of the vessel's path, by calculating a virtual position and steering the vessel to align it with a pre-plot path, allowing for precise positioning of source arrays and streamers without altering the vessel's trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the vessel's navigation system is used to adjust the positions of the source array and streamers, then the sources can be brought closer to the desired position, but the positions of the streamers and sources are affected by the vessel's position changes, making precise independent control difficult
Solution Approach 1:
The control system is segmented into independent control channels: one for the source array and one for the streamers. Each channel has its own deflector and control mechanism, allowing independent positioning of sources and streamers without coupling them through vessel navigation adjustments.
Solution Approach 2:
Deflectors are introduced as intermediary devices between the vessel and the source array/streamers. These deflectors respond to control signals and adjust the positions of sources and streamers independently, serving as mediators that decouple the positioning control from direct vessel navigation maneuvers.
2Ease of operation
If deflectors are used to maintain streamer separation, then the streamers can be positioned outwardly from the vessel path, but hydrodynamic forces from water currents and environmental factors cause the deflectors to move closer together, affecting source and streamer positions
Solution Approach 1:
The control system incorporates feedback mechanisms that continuously monitor the positions of deflectors, streamers, and sources. Real-time position data is fed back to the control system, which adjusts the control signals to compensates for hydrodynamic forces and environmental variations, maintaining stable streamer separation and source positioning.
Solution Approach 2:
The system uses dynamic control signals that continuously adjust the deflector positions in response to changing hydrodynamic conditions. Rather than relying on static deflector positioning, the system actively adapts to water currents and environmental factors, maintaining optimal streamer separation throughout the survey.
3Adaptability or versatility
If 4-D geophysical imaging is implemented, then changes in geophysical structures can be detected over time, but accurate repetition of sources and streamers at the same locations across different survey times becomes difficult due to environmental factors and navigation limitations
Solution Approach 1:
The system uses pre-programmed survey paths and pre-calculated positioning parameters that are established before each survey. These preliminary plans, combined with real-time feedback control, ensure that sources and streamers return to the exact same positions across multiple survey times, enabling accurate 4-D imaging comparisons.
Solution Approach 2:
The system replaces traditional mechanical navigation-based positioning with an electronic control system that uses sensors, processors, and feedback control. This substitution of mechanical vessel maneuvering with electronic control allows for more precise and repeatable positioning, overcoming the limitations of environmental factors and navigation systems.
Data Source
AI summary
A marine acoustic source system and method for steering a seismic source array in a body of water during a seismic survey. The method includes measuring an actual position of the seismic source array; calculating a virtual position of the seismic source array, wherein the virtual position corresponds to a position of the seismic source array when towed with no adjustment from a source steering device; retrieving a pre-plot path that includes desired positions of the seismic source array for the seismic survey; and steering the vessel based on the virtual position so that the virtual position lies on the pre-plot path.