Seismic Reflection: Processing and Interpretation Katie Wooddell UW Madison

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

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

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

Defining Geometry

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

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

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

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

Deconvolution Equation Robertson 1998

To Conceptualize... INPUT * FILTER = OUTPUT

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

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

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

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

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

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

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

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

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

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

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