Borehole Microseismic Sensor Triggering for Data Volume Reduction
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Solution Overview
Problem
Borehole microseismic surveys generate large volumes of data, with only about 1% being pertinent, leading to data rate constraints in telemetry systems, particularly during extended monitoring periods like hydraulic fracturing, where automated event identification is challenging.
Innovation Solution
A system comprising a first sensor for acquiring and transmitting data, a second sensor for detecting microseismic events, and a command module that instructs the first sensor to transmit data corresponding to a predetermined period around the event detection, such as up to five minutes before, during, and after the event, to reduce data transmission volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recording systems are active for extended periods to capture all microseismic events, then event detection completeness is improved, but data volume increases significantly leading to telemetry bottleneck
Solution Approach 1:
The system performs preliminary filtering of acoustic signals at the downhole sensor level before data transmission. By pre-processing and identifying potential events locally, the system can transmit only relevant data portions (before, during, and after detected events) rather than continuous data streams, thus reducing overall data volume while maintaining detection completeness
Solution Approach 2:
The invention extracts and transmits only the relevant portions of acoustic data corresponding to microseismic events and their immediate context, rather than transmitting the entire continuous recording. This selective extraction approach removes unnecessary data while preserving event information, directly addressing the data volume issue
2Speed
If continuous data transmission is used to ensure real-time monitoring, then response time is improved, but data rate constraints are exceeded
Solution Approach 1:
Instead of continuous transmission, the system uses periodic transmission triggered by event detection. The command module activates transmission only when microseismic events are detected, transmitting data for a predetermined period around each event. This periodic approach maintains real-time monitoring capability while dramatically reducing average data rate requirements
3Productivity
If automated event identification is implemented to reduce manual analysis, then productivity is improved, but system complexity increases
Solution Approach 1:
The downhole sensors and command module perform self-service by automatically detecting microseismic events and triggering data transmission without requiring external manual analysis. The system uses local acoustic signal analysis and pressure transient detection to autonomously identify events and manage data transmission, improving productivity while keeping processing complexity localized rather than centralized
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 allows for real-time acquisition of pertinent microseismic data with an unconstrained data acquisition sampling rate and telemetry system, reducing data transmission volume and improving the efficiency of microseismic event detection.
Implementation Method 1
Borehole seismic investigation typically involves generating acoustic waves that travel downwardly into the formation by firing a source placed at the surface of the formation. The acoustic waves are reflected back upwardly toward the surface by subterranean layers of rock.
Implementation Method 2
the second sensor is a high frequency pressure gauge, and the property it detects is a rapid negative pressure transient induced as a fracture opens
Data Source
AI summary
Devices and methods for borehole seismic investigation. The devices can include a first sensor for acquiring data relating to a microseismic event, a second sensor for detecting the start of a microseismic event and a command module for activating the first sensor to transmit data when the second sensor detects the start of the microseismic event. The methods can include activating a first sensor to transmit data relating to a microseismic event when a second sensor detects the start of the microseismic event. The method can also include deactivating the first sensor, or stopping data transmission substantially when the microseismic event ends.