Long-Offset Streamer Depth Configuration for Full Wavefield Inversion
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Solution Overview
Problem
Conventional marine surveying technologies face challenges in acquiring low-frequency, high signal-to-noise ratio data at long offsets, which is crucial for full-waveform inversion (FWI) and hydrocarbon discovery and extraction, due to limitations in equipment capacity and operational costs associated with long streamer cables.
Innovation Solution
The proposed solution involves modifying marine geophysical survey systems by varying streamer depth and group lengths, and utilizing long-offset streamers towed at different depths to acquire low-frequency data with improved signal-to-noise ratios, allowing for increased offsets and reduced equipment in water, thereby enhancing FWI results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If long streamer cables are used to acquire long-offset data, then the offset distance is increased, but the equipment complexity and operational costs increase
Solution Approach 1:
The patent divides the long streamer cable into multiple shorter streamer segments, each towed by separate vessels. This segmentation allows the system to achieve long-offset coverage without requiring a single extremely long cable, thereby reducing equipment complexity while maintaining the ability to acquire long-offset data for FWI applications.
Solution Approach 2:
The patent combines data from multiple shorter streamers towed by different vessels to achieve the equivalent of a single long streamer. By merging the coverage areas and data sets from multiple vessels, the system achieves long-offset capability without the operational complexities of deploying and managing a single extremely long streamer cable.
2Ease of operation
If streamers are towed at standard depths, then ease of operation is maintained, but low-frequency signal quality deteriorates
Solution Approach 1:
The patent applies different towing depths to different streamers based on their specific function and position in the array. Rather than towing all streamers at a uniform standard depth, the system optimizes the depth of each streamer locally to enhance low-frequency signal quality while maintaining operational feasibility. This allows deeper towing for streamers where low-frequency enhancement is critical.
Solution Approach 2:
The patent changes the towing depth parameter of streamers from standard depths to deeper depths for specific streamers in the array. This parameter change is designed to improve the low-frequency response of the seismic signals by reducing surface noise and enhancing the signal-to-noise ratio at depths where low-frequency energy is better preserved.
3Productivity
If multiple vessels are used for simultaneous long-offset acquisition, then productivity is increased, but coordination complexity increases
Solution Approach 1:
The patent employs dynamic positioning and real-time coordination systems that allow multiple vessels to operate simultaneously while maintaining precise spatial relationships. The system dynamically adjusts vessel positions, speeds, and streamer deployments to optimize data acquisition while managing the coordination complexity through automated control systems and real-time communication protocols.
Data Source
AI summary
A method and apparatus includes: towing a first source with a source vessel; towing a second source with a survey vessel, the survey vessel following the source vessel by at least 5 km; towing a streamer spread at a first depth with the survey vessel; and towing a pair of long-offset streamers at a second depth and following the source vessel by at least 5 km, wherein: the first depth is 10 m to 30 m, and the second depth is greater than 30 m. A method and apparatus includes: towing a first source with a source vessel; towing a second source with a survey vessel, the first source and the second source being separated by at least 5 km; towing a streamer spread at a first depth with the survey vessel; towing a pair of long-offset streamers at a second depth, wherein: the first depth is between 10 m and 30 m, and the second depth is greater than 30 m; acquiring long-offset data with long-offset sensors distributed along the long-offset streamers; and constructing a velocity model with the long-offset data. A method and apparatus includes: towing a first plurality of streamers at a first depth of 10 m to 30 m; receiving first signals generated by a first source with the first plurality of streamers; towing a second plurality of streamers at a second depth of greater than 30 m; while receiving the first signals, receiving second signals generated by a second source with the second plurality of streamers; wherein: the first source and the second source are separated by at least 5 km, the second signals represent long-offset data, and a forward-most receiver on each of the second plurality of streamers has a same inline offset from the first source as a forward-most receiver on each of the first plurality of streamers.