Vessel Steering for Current-Compensated Streamer Trajectories
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Solution Overview
Problem
Existing marine seismic surveys face challenges in accurately positioning streamers due to difficulties in maintaining a desired trajectory, especially in dynamic water conditions, leading to suboptimal coverage and increased noise, which complicates the acquisition of high-resolution subsurface images.
Innovation Solution
A method for steering a vessel towing streamers that involves determining a desired trajectory, modeling trajectories based on water currents and vessel courses, and applying an inversion process to determine a target course for the vessel, ensuring the streamers follow the desired path by accounting for water currents and streamer dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the vessel steers to follow a predefined preplot line, then the navigation path is simple and straightforward, but the streamer deviates from the desired trajectory due to water currents
Solution Approach 1:
The system performs preliminary action by computing a compensated target course before steering the vessel. The navigation system calculates the water current effect on the streamer and determines a corrected course that anticipates the deviation, allowing the streamer to follow the desired preplot line despite current effects.
Solution Approach 2:
The system implements feedback by continuously monitoring the streamer's actual position relative to the desired trajectory and adjusting the vessel's target course accordingly. The navigation system uses real-time data about streamer deviation and water current to dynamically compute corrected steering commands.
2Measurement precision
If the vessel adjusts course frequently to compensate for water currents, then the streamer positioning accuracy improves, but the navigation complexity and steering dynamics increase
Solution Approach 1:
The system replaces complex manual mechanical steering adjustments with an automated computational system. The navigation system uses computer-based models to calculate water current effects and automatically determines the optimal target course, substituting human judgment and manual control with algorithmic processing.
Solution Approach 2:
The system changes parameters by computing a transformed target course that incorporates water current compensation. Instead of adjusting the desired preplot line, the system modifies the vessel's steering parameters (course angle, speed) to achieve the same positioning goal while accounting for environmental disturbances.
3Measurement precision
If the vessel steers aggressively to correct streamer position, then the streamer trajectory accuracy improves, but the vessel creates excessive noise that degrades seismic data quality
Solution Approach 1:
The system applies partial action by making subtle, precise steering adjustments rather than aggressive corrections. The navigation system calculates minimal course modifications needed to keep the streamer on trajectory, avoiding excessive vessel maneuvers that would generate harmful noise while still achieving positioning accuracy.
4Stability of the object's composition
If the vessel follows the preplot line without compensation, then the vessel path is stable and simple, but the streamer coverage is suboptimal with gaps and overlaps
Solution Approach 1:
The system performs preliminary computation of the compensated target course that accounts for water current effects before the vessel begins steering. This advance calculation ensures the streamer will achieve optimal coverage by predicting and correcting for drift before it occurs.
Solution Approach 2:
The system uses feedback mechanisms to monitor streamer position and adjust the vessel's compensated course in real-time, ensuring continuous optimal coverage. The navigation system compares actual streamer position with desired position and dynamically adjusts steering to maintain proper coverage patterns.
Data Source
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AI summary
A method for steering a vessel (6) towing a streamer (7) or a streamer spread. The method comprises acquiring or determining a desired trajectory (PPL) for at least one point (CS7) of the streamer (7) or of the streamer spread; acquiring or determining water current values; modelling a plurality of trajectories for the streamer (7) or the streamer spread according to a plurality of given courses for the vessel and said water current values; determining a target course (T6) for the vessel (6) in function of said plurality of modelled trajectories for the streamer (7) or the streamer spread, and in function of said desired trajectory (PPL) of said at least one point (CS7) of the streamer (7) or of the streamer spread, so that the position (TCS7) of said at least one point (CS7) of the streamer (7) or of the streamer spread, that results from the determined target course (T6) of the vessel (6), follows said desired trajectory (PPL) or follows a trajectory that is included in a predefined width corridor that contains said desired trajectory (PPL); and steering the vessel (6) according to the determined target course (T6). It is also proposed a related computer program, navigation system and method for seismic data acquisition.