Microseismic Event Grouping for Moment Tensor Inversion
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Solution Overview
Problem
In subterranean exploration and hydraulic fracturing, existing microseismic monitoring technologies face challenges with ill-conditioned receiver coverage, leading to incomplete moment tensor inversion and increased noise, particularly in single-well configurations, which hampers the accurate identification of source mechanisms and fracture analysis.
Innovation Solution
The methodology enhances microseismic monitoring by grouping seismic events with similar source mechanisms using amplitude ratios between P and Sh/Sv phases, improving receiver coverage through multi-event moment tensor inversion, and employing interactive event grouping techniques to refine source mechanism identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-well receiver configuration is used for microseismic monitoring, then device complexity is reduced, but measurement precision and reliability deteriorate due to ill-conditioned receiver coverage
Solution Approach 1:
The patent combines multiple microseismic events into a single multi-event moment tensor inversion framework. By merging information from multiple events with similar source mechanisms, the system achieves better receiver coverage conditioning without requiring additional wells or receivers, thus maintaining simple device configuration while improving measurement precision.
Solution Approach 2:
The patent develops a universal multi-event moment tensor inversion method that can handle various source mechanisms (isotropic, shear, tensile) and different event types within a single framework. This universal approach allows the same receiver configuration to accurately invert different types of microseismic events, improving measurement precision without increasing device complexity.
2Device complexity
If traditional single-event moment tensor inversion is used, then device complexity is low, but reliability and measurement precision worsen due to incomplete inversion and increased noise
Solution Approach 1:
The patent merges multiple events into a unified inversion framework, combining their seismic data to jointly invert for a common source mechanism. This merging approach improves reliability by reducing noise through averaging and providing more robust source mechanism identification compared to individual event inversion.
Solution Approach 2:
The patent performs preliminary clustering of events based on location and timing to identify groups with similar source mechanisms before applying multi-event inversion. This preliminary action ensures that only compatible events are combined, improving the reliability of source mechanism identification by preventing mixing of events with different mechanisms.
3Measurement precision
If multi-event moment tensor inversion is applied, then measurement precision and resolvability improve, but device complexity and computational requirements increase
Solution Approach 1:
The patent segments the overall inversion process into distinct stages: event clustering based on location and timing, grouping events with similar source mechanisms, and then applying multi-event inversion to each group. This segmentation reduces computational complexity by breaking down the large-scale problem into smaller, more manageable sub-problems.
Solution Approach 2:
The patent applies local quality by tailoring the multi-event inversion approach to specific groups of events with similar characteristics. Rather than applying a uniform complex inversion to all events, the method adapts the inversion parameters and grouping strategy to local event characteristics, improving measurement precision while managing computational complexity.
Data Source
AI summary
A technique facilitates enhanced microseismic monitoring. The technique may be applied to source mechanism identification under, for example, ill-conditioned receiver coverage to enhance the resolvability for microseismic monitoring. The microseismic monitoring may be used in hydraulic fracturing monitoring, induced seismicity monitoring, CO2 injection monitoring, other injection monitoring, mining, and/or other techniques which cause microseismic events.