US 12,761,384 B1Granted

Passive seismic monitoring to detect onset of ground failure hazard

AssigneeMicroseismic, Inc.

InventorsPeter M. Duncan, Michael Thornton

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Abstract

A method for monitoring Earth's subsurface for indication of ground failure includes processing signals detected by seismic sensors disposed proximate the area, by migrating a response of the sensors to each of a plurality of sub volumes. The migrated responses are summed over a first selected time interval. Events having amplitude exceeding an average amplitude over a second selected time interval longer than the first time interval are detected and their amplitudes are summed from within each of a plurality of substantially vertical column of the plurality of sub volumes. A two dimensional smooth surface is calculated based on the summed amplitudes, and a difference between the summed amplitudes and a value of the smoothed surface for each vertical column is calculated. A statistical measure of the difference values is calculated. Statistical measures that exceed a selected threshold are identified as advance indication of ground failure.

Claims16

Dependent claims

A method for monitoring an area of Earth's subsurface for locating subsurface formation failure, comprising:

accepting as input to a computer recorded signals detected as passive seismic signals by a plurality of seismic sensors disposed proximate the area;
in the computer, migrating the recorded signals from each of the plurality of seismic sensors to each of a plurality of predetermined sub volumes within the area;
in the computer, summing the migrated response for each of the plurality of sub volumes over a first selected time interval;
in the computer, detecting, from the summed, migrated response, events having an amplitude exceeding by a predetermined amount an average amplitude over a second selected time interval longer than the first time interval;
in the computer, summing amplitudes of the detected events over a third time interval from within each of a plurality of predetermined substantially vertical columns of the plurality of sub volumes;
in the computer, calculating a smoothed value for the summed amplitudes over the third time interval using the calculated amplitudes for a predetermined number of preceding and succeeding third time intervals and for a predetermined number of grid positions adjacent to each of the plurality of substantially vertical columns;
in the computer, calculating a two dimensional smooth surface based on the smooth values;
in the computer, calculating a difference between the summed amplitudes and a value of the two dimensional smooth surface for each vertical column;
in the computer, calculating a statistical measure of each of the difference values;
identifying those of the statistical measures that exceed a selected threshold as indication of rock formation failure events occurring above a karst in the subsurface formation;
and
using the indication of rock formation failure above the karst to remediate the rock formation failure;
wherein the remediating comprises drilling a relief hole into the karst and inserting a sealing material into the relief hole.

10 more elements

A non-transitory computer readable medium having stored thereon a computer program, the program having logic operable to cause a programmable computer to perform actions, comprising:

accepting as input to a computer recorded signals detected as passive seismic signals by a plurality of seismic sensors disposed proximate an area of Earth's subsurface;
migrating a response of the plurality of seismic sensors to each of a plurality of sub volumes within the area;
summing the migrated response for each of the plurality of sub volumes over a first selected time interval;
detecting, from the summed, migrated response, events having an amplitude exceeding by a predetermined amount an average amplitude over a second selected time interval longer than the first time interval;
summing amplitudes of the detected events over a third time interval from within each of a plurality of predetermined substantially vertical columns of the plurality of sub volumes;
calculating a smoothed value for the summed amplitudes over the third time interval using the calculated amplitudes for a specified number of preceding and succeeding time intervals;
calculating a two dimensional smooth surface based on the summed amplitudes;
calculating a difference between the summed amplitudes and a value of the two dimensional smooth surface for each vertical column;
calculating a statistical measure of each of the difference values;
identifying those of the statistical measures that exceed a selected threshold as indication of rock formation failure events occurring above a karst in the Earth's subsurface, the indication used to remediate the rock formation failure events wherein the remediation comprises drilling a relief hole into the karst and inserting a sealing material into the relief hole.

7 more elements

Dependencies are inferred from the claim text.