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Seismic Reflection: Processing and Interpretation Katie Wooddell UW Madison

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Objectives Develop a velocity model of the Santa Fe River Canyon to aid in structure interpretation Use predictive deconvolution to remove multiple reflections from the data

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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Defining Geometry

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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Killing Traces Vibroseis signal had to be eliminated Channels showing large amounts of noise were deleted

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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Predictive Deconvolution What does it do? Clears seismic data by predicting and eliminating multiple reflections How does it work? A filter is designed that recognizes and eliminates repetitions in the signal

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Deconvolution Equation Robertson 1998

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To Conceptualize... INPUT * FILTER = OUTPUT

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Deconvolution Results Location 109 Time (ms) DECONVOLVEDNO DECONVOLUTION Location 109 Time (ms)

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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Butterworth Filter Bandpass Filter Passes frequencies in the range of the vibroseis sweep (30-300 Hz) Effective in eliminating the noise amplified during predictive deconvolution

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Butterworth Filtering No FilterButterworth Filter Location 109 Time (ms) Location 109 Time (ms)

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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NMO Correction NMO corrects for the delay in first arrival times NMO shifts the arrival times according to a specific stacking velocity This is an important step in the velocity analysis

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Processing Steps Define Geometry Kill Bad Traces CMP Gather NMO Correction / Velocity Analysis Predictive Deconvolution / Butterworth Filter CMP Gather NMO Correction / Velocity Analysis

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A Constant Velocity Analysis was conducted on both deconvolved and non-deconvolved data The following NMO stacking velocities were run for each situation: - 1000 m/s-1200 m/s - 1400 m/s-1600 m/s - 1800 m/s-2000 m/s - 2200 m/s-2400 m/s

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Conclusions Predictive deconvolution is an effective tool for eliminating multiples from seismic data A combination of the 2000 m/s and the 1600 m/s constant velocity models seems to produce a high resolution model This implies a higher average velocity medium on the east side of the fault, giving evidence that the normal La Bajada fault is being imaged

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And a Special Thanks To... The SAGE professors for their knowledge and patience Team 5 for their hard work and some good times Michelle Herrera, my Processing partner Lauren Larkin, who was more enthusiastic about splicing together my seismic sections than I was

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