Marine Vibrator Sweep Timing for 4D Seismic Position Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Marine seismic surveys using vibrators face challenges in achieving 4D compatibility due to positioning inaccuracies and speed variations of the vessel, making it difficult to match source positions and emit consistent sweeps, especially when transitioning from airgun-based surveys.
Innovation Solution
A method involving real-time monitoring of the vibrator's position and vessel speed, adjusting survey parameters such as sweep length, silent periods, and vessel speed to ensure that a predetermined frequency is emitted at the nominal pre-plot position, thereby aligning the vibrator with the pre-defined grid for accurate 4D data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time monitoring and adjustment of survey parameters is implemented, then 4D compatibility and positioning precision are improved, but device complexity and operational complexity increase
Solution Approach 1:
The system continuously monitors the vibrator's actual position and vessel speed, compares these values against nominal pre-plot positions and target frequencies, and automatically adjusts survey parameters (sweep length, silent periods, vessel speed) to correct positioning deviations and maintain 4D compatibility
Solution Approach 2:
The survey parameters are made dynamic rather than fixed - sweep length, silent period duration, and vessel speed are continuously adjusted in real-time based on actual vibrator position and speed variations to maintain optimal positioning and 4D compatibility
2Measurement precision
If real-time monitoring and adjustment of survey parameters is implemented, then 4D compatibility and positioning precision are improved, but ease of operation deteriorates
Solution Approach 1:
The system automatically performs the monitoring, comparison, and adjustment operations without requiring manual intervention - the vibrator system self-corrects positioning errors and maintains 4D compatibility through automated parameter adjustment based on real-time position and speed data
3Measurement precision
If consistent sweep emission at predetermined frequency is ensured, then 4D compatibility is improved, but productivity and survey speed may be reduced
Solution Approach 1:
The sweep parameters including duration and frequency are dynamically adjusted in real-time to account for vessel speed variations and positioning deviations, ensuring that the vibrator emits consistent sweeps at the predetermined frequency while adapting to changing operational conditions to maintain survey productivity
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
This approach ensures that marine seismic data acquired with vibrators is 4D compatible, allowing for repeat surveys and maintaining consistent energy output while minimizing residual noise and positioning errors, thus enhancing the quality of seismic data for reservoir monitoring.
Implementation Method 1
a vibrator towed by a vessel on a pre-plot grid
Implementation Method 2
driving the vibrator with sweeps so that a predetermined frequency is emitted
Data Source
AI summary
Described herein is a method for acquiring data using a marine vibrator towed by a vessel, the method comprising: obtaining data comprising at least one nominal pre-plot position in a horizontal plane; monitoring a position of the marine vibrator in the and a speed of the vessel; determining an offset between the position of the marine vibrator and the nominal pre-plot position in the towing direction; based on the offset and the vessel speed, adjusting one or more survey parameters and driving the vibrator with a series of one or more sweeps so that a predetermined frequency in the sweep or a subsequent sweep is emitted when the position of the vibrator is within a maximum distance of the nominal pre-plot position.