Micro-seismic Wave First Arrival Auto Pickup And Source Location Effect Analysis

Microseism is a kind of tiny seism, it is caused by rock burst when underground stratum stress field have changed. Microseismic monitoring is a physical geography technique which is built on acoustic emission theory and seismology theory, it plays an important role in mine, oil field, dam, especially in low permeable oil fields and oil shale exploitation.Under the background of unconventionality oil-gas exploration has developed fast, hydraulic fracturing technique has been more perfect, microseismic monitoring has gradually been the most important method in evaluating hydraulic fracturing effect and mine safety monitoring. In microseismic monitoring technique, first arrival picking up is a fundamental and important link, because of the signal to noise ratio of the microseismic data is low, but its veracity greatly affect the microseism source location result, so accurate and efficient first arrival pickup is the key to the mocroseismic monitoring technique.Based on the above situation, this article has do some researches from several aspects of important links of microseimic data processing.This article firstly introduced the development history and basic theory of microseimic monitoring, and then deeply studied the microseismic first arrival picking up technique, detailedly introduced the advantages and disadvantages of polarization analysis and ratio of energy method, by the means of principle analysis and practical data certification, considered that in polarization analysis the study before widely accepted that the biggest degree of polarization is the first arrival wave trigger point is a kind of approximately picking up principle, and then raised a new first arrival picking up method. It introduced the covariance matrix eigenvalue as the eigenfunction into STA/LTA ratio of energy method to pick up first arrival accurately. Then the author did study on some items of major parameters, just like window length, eigenfunction, self-adaption threshold and some other problems, and raised new viewpoint and method, contrasted with studies before verified the advantages of the method of this article by practical data processing.Traditional artificial microseismic data processing technique wastes time, inefficiency, biggish man-made errors, so this article design a set of microseismic auto location method. At first, preprocessing the microseismic data, use generalized S transform combine with band pass filtering to improve the signal to noise ratio of microseismic data, and then use first arrival auto picking up technique, combined with data reconstruction method based on cross-correlation principle, realized the automatic microseimic source location by the means of P wave time difference method and Newton iteration method, Greatly improve the work efficiency.By the means of Three-dimensional forward numerical simulation and practical data processing, could testify the microseismic auto pick and source auto location method designed by this article is reliable and valid.