reflection methods and results geophysics 492/692
DESCRIPTION
Reflection Methods and Results Geophysics 492/692. L. Josh Michaels, Zach Reynolds, Nick Prina, Molly Hunsaker Survey run by Dr. Lee Liberty of Boise State University . Line 4 Location Map. Lakeside Drive and Manzanita Lane to the north corner of Jasper Lane and Manzanita Lane. Methods. - PowerPoint PPT PresentationTRANSCRIPT
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Reflection Methods and ResultsGeophysics 492/692
Josh Michaels, Zach Reynolds, Nick Prina, Molly HunsakerSurvey run by Dr. Lee Liberty of Boise State University
L
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Line 4 Location MapLakeside Drive and Manzanita Lane to the north corner of Jasper Lane and Manzanita Lane.
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Methods 1 meter geophones and source intervals Usually 3 shots at each source location Seismographs record each shot
individually› Not stacked in the field
Used rollbox to keep the source centered› Excluding the ends of the line
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Processing Data Line 4 = 887 total shot records of 120 traces each Processed using JRG and Viewmat (v. 3.6.3) Selected records examined with a range of bandpass filters
› Designed to maximize reflections and minimize other seismic waves and noise
› 20-100 Hz (10% dip) optimal for reflections in Line 4 Individually examined every record; removed any traces
that failed our criteria› Non-functioning or incorrectly functioning geophone traces› Bad records caused by a misfired trigger on the source, indicated by no
coherent seismic wave pattern › Strong hyperbola patterns caused by movement along the reflection line
during recording
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Record 8064
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Processing Data Line 4 = 887 total shot records of 120 traces each Processed using JRG and Viewmat (v. 3.6.3) Selected records examined with a range of bandpass filters
› Designed to maximize reflections and minimize other seismic waves and noise
› 20-100 Hz (10% dip) optimal for reflections in Line 4 Individually examined every record; removed any traces that
failed our criteria› Non-functioning or incorrectly functioning geophone traces› Bad records caused by a misfired trigger on the source, indicated by
no coherent seismic wave pattern. › Strong hyperbola patterns caused by movement along the reflection
line during recording. Constant velocity stacking
› Ranged from 500 to 3500 m/s (100 m/s intervals)› Stacking reduces random-sourced signals
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Dix Velocity Intervals
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NMO Interpolated velocity
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Dip-filtered CMP stack
Dashed black lines = interpreted faults
Green shapes = artifact errors
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Frequency Analysis
From the unfiltered CMP stack Dominant frequencies at ~30Hz
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Improvement? More controlled acquisition
environment Geophone functionality Removal of 60 Hz electrical noise
› Known to exist, but not dominating signal More thorough velocity model Our results are only preliminary
› Pre-stacked depth migration