Seismic Source Clock Synchronization for Continuous Data Acquisition
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Solution Overview
Problem
The existing slip-sweep method for seismic data acquisition is inefficient due to time loss at the end of each shooting salvo, requires a dedicated frequency band for transmission, and limits the number of deployable sources, causing recording to stop upon information transmission issues between vibration sources and recording means.
Innovation Solution
Synchronizing the clocks of seismic sources and recording devices, allowing each source to shoot at predetermined times and continuously record signals, with the option to modify shooting times and use pseudo-random sequences, enabling decentralized source control and minimal radio data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the slip-sweep method is used to increase the number of sweeps per time unit, then productivity is improved, but time loss occurs at the end of each shooting salvo and the number of deployable sources is limited
Solution Approach 1:
The system pre-calculates and stores a table of shooting times for all sources before acquisition begins. Each source independently retrieves its next shooting time from this pre-computed table without waiting for central station authorization, eliminating the time loss that occurs in conventional methods when waiting for transmission permissions.
Solution Approach 2:
The central station's control function is segmented from the sources. Instead of the central station continuously managing each source's shooting timing through radio transmissions, the timing calculation is divided and distributed to each source independently, which autonomously determines when to shoot based on pre-computed schedules.
2Quantity of substance
If multiple vibration sources are deployed simultaneously to increase productivity, then the quantity of sources is improved, but the need for dedicated frequency bands for transmission increases complexity
Solution Approach 1:
The timing control information is extracted from the radio transmission system and embedded directly in the pre-computed shooting time table stored in each source. This removes the need for continuous frequency-band dedicated radio transmissions for timing synchronization, allowing more sources to operate simultaneously without proportionally increasing transmission complexity.
3Ease of operation
If centralized control is used to manage shooting sequences, then coordination is improved, but operational reliability deteriorates due to dependency on radio transmission
Solution Approach 1:
Each vibration source is equipped with an autonomous controller that independently calculates and executes shooting times using pre-computed tables stored locally. The sources self-manage their own timing without requiring continuous authorization or coordination messages from the central station via radio transmission, making the system more reliable as it no longer depends on communication links for basic timing control.
Data Source
AI summary
The invention relates to a method for the acquisition of seismic data that uses sources operable to produce, when they are in a shooting station, seismic vibrations according to a sweep type shooting sequence, of predetermined duration and variable frequency. According to this method, the source and recording device clocks are synchronized, shooting is authorized for each of the sources at a series of predetermined shooting times tk,n, with k being an order number for a given source and n a source order number, between 1 and the number of sources Ns, and carried out on condition that the source is in a state to produce vibrations at such time tk,n, and the signals produced by the receivers are continuously recorded. The invention also relates to a system for seismic acquisition that implements this method.