Downhole Seismic Synchronization via Transit Time Calibration
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Solution Overview
Problem
Coordinating the operation of multiple seismic sensing devices in downhole tools is hindered by variations in their operation, making it challenging to accurately determine event hypocenter locations and moment tensor inversion solutions during micro-seismic surveys.
Innovation Solution
A seismic system that includes a seismic source generating two signals, a downhole sensing device to detect these signals, and a surface acquisition system to determine reference and subsequent transit times, allowing for the identification of synchronization variations by comparing these times and taking corrective measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple seismic sensing devices are deployed in downhole tools, then the capability to conduct micro-seismic surveys is improved, but synchronization variations between devices deteriorate measurement accuracy
Solution Approach 1:
The system performs preliminary synchronization calibration by injecting test signals through the formation and measuring arrival times at multiple sensors before actual micro-seismic surveys. This preliminary action establishes reference transit times and compensates for synchronization variations, ensuring accurate measurements during subsequent survey operations
Solution Approach 2:
The system continuously monitors transit time variations between sensors and uses this feedback to dynamically adjust synchronization parameters. By comparing actual arrival times with expected times based on known source locations, the system identifies and corrects synchronization drift in real-time, maintaining measurement precision across multiple devices
2Reliability
If transit time measurements are taken between multiple downhole tools, then synchronization issues can be detected, but the complexity of the system increases
Solution Approach 1:
The same downhole sensing devices used for micro-seismic detection are also utilized for synchronization measurements. The system injects test signals through the formation and uses the existing sensor array to measure arrival times, eliminating the need for separate synchronization testing equipment and reducing overall system complexity
Solution Approach 2:
The system performs its own synchronization calibration using its internal signal generation and detection capabilities. By injecting test signals and measuring their own response through the formation, the system self-diagnoses and corrects synchronization issues without requiring external calibration equipment or additional operational complexity
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 enables effective synchronization of multiple downhole seismic sensing devices, improving the accuracy of seismic data collection and reducing errors in determining formation characteristics, thereby enhancing the precision of micro-seismic surveys.
Implementation Method 1
a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source
Implementation Method 2
a first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation
Data Source
AI summary
A seismic system that includes a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source. A first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation; and a first surface acquisition system is in communication with the first downhole sensing device. The first surface acquisition system is configured to: determine a first reference transit time based at least in part on detection of the first seismic signal by the first downhole sensing device; a first subsequent transit time based at least in part on detection of the second seismic signal by the first downhole sensing device; andwhether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time.