A multi-channel approach for automatic microseismic event association using RANSAC-based arrival time event clustering(RATEC)

TL;DR

This paper introduces RATEC, a robust clustering algorithm that uses RANSAC to eliminate false picks from microseismic data, improving event location accuracy across various array configurations and noise conditions.

Contribution

The paper presents a novel RANSAC-based clustering method for automatic microseismic event association that effectively removes false picks and enhances location estimates.

Findings

RATEC effectively removes false picks in synthetic data.

RATEC improves event location accuracy in 2-D array data.

The method is robust under different noise conditions.

Abstract

In the presence of background noise, arrival times picked from a surface microseismic data set usually include a number of false picks that can lead to uncertainty in location estimation. To eliminate false picks and improve the accuracy of location estimates, we develop an association algorithm termed RANSAC-based Arrival Time Event Clustering (RATEC) that clusters picked arrival times into event groups based on random sampling and fitting moveout curves that approximate hyperbolas. Arrival times far from the fitted hyperbolas are classified as false picks and removed from the data set prior to location estimation. Simulations of synthetic data for a 1-D linear array show that RATEC is robust under different noise conditions and generally applicable to various types of subsurface structures. By generalizing the underlying moveout model, RATEC is extended to the case of a 2-D surface monitoring array. The effectiveness of event location for the 2-D case is demonstrated using a data set collected by the 5200-element dense Long Beach array. The obtained results suggest that RATEC is effective in removing false picks and hence can be used for phase association before location estimates.