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Title: High speed point derivative microseismic detector

Abstract

A high speed microseismic event detector constructed in accordance with the present invention uses a point derivative comb to quickly and accurately detect microseismic events. Compressional and shear waves impinging upon microseismic receiver stations disposed to collect waves are converted into digital data and analyzed using a point derivative comb including assurance of quiet periods prior to declaration of microseismic events. If a sufficient number of quiet periods have passed, the square of a two point derivative of the incoming digital signal is compared to a trip level threshold exceeding the determined noise level to declare a valid trial event. The squaring of the derivative emphasizes the differences between noise and signal, and the valid event is preferably declared when the trip threshold has been exceeded over a temporal comb width to realize a comb over a given time period. Once a trial event has been declared, the event is verified through a spatial comb, which applies the temporal event comb to additional stations. The detector according to the present invention quickly and accurately detects initial compressional waves indicative of a microseismic event which typically exceed the ambient cultural noise level by a small amount, and distinguishes the waves frommore » subsequent larger amplitude shear waves. 9 figs.« less

Inventors:
; ;
Issue Date:
Research Org.:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
672518
Patent Number(s):
5774419
Application Number:
PAN: 8-665,471
Assignee:
Gas Research Inst., Chicago, IL (United States)
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 30 Jun 1998
Country of Publication:
United States
Language:
English
Subject:
44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; SEISMIC DETECTORS; DESIGN; MICROEARTHQUAKES; SEISMIC DETECTION; DATA ANALYSIS; SEISMIC P WAVES; SEISMIC S WAVES

Citation Formats

Uhl, J E, Warpinski, N R, and Whetten, E B. High speed point derivative microseismic detector. United States: N. p., 1998. Web.
Uhl, J E, Warpinski, N R, & Whetten, E B. High speed point derivative microseismic detector. United States.
Uhl, J E, Warpinski, N R, and Whetten, E B. Tue . "High speed point derivative microseismic detector". United States.
@article{osti_672518,
title = {High speed point derivative microseismic detector},
author = {Uhl, J E and Warpinski, N R and Whetten, E B},
abstractNote = {A high speed microseismic event detector constructed in accordance with the present invention uses a point derivative comb to quickly and accurately detect microseismic events. Compressional and shear waves impinging upon microseismic receiver stations disposed to collect waves are converted into digital data and analyzed using a point derivative comb including assurance of quiet periods prior to declaration of microseismic events. If a sufficient number of quiet periods have passed, the square of a two point derivative of the incoming digital signal is compared to a trip level threshold exceeding the determined noise level to declare a valid trial event. The squaring of the derivative emphasizes the differences between noise and signal, and the valid event is preferably declared when the trip threshold has been exceeded over a temporal comb width to realize a comb over a given time period. Once a trial event has been declared, the event is verified through a spatial comb, which applies the temporal event comb to additional stations. The detector according to the present invention quickly and accurately detects initial compressional waves indicative of a microseismic event which typically exceed the ambient cultural noise level by a small amount, and distinguishes the waves from subsequent larger amplitude shear waves. 9 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {6}
}