seismic reflection processing pre-stack

Basic Seismic ProcessingBasic Seismic ProcessingINPUT

FILTER

CMP Gather

NMO

STACK

MIGRATE

DISPLAY

GEOM

VEL ANAL

STATICS

MUTE

More Seismic ProcessingMore Seismic Processing

INPUT

BP FILTER CMP Gather

NMO

STACK

MIGRATE

DISPLAY

GEOM

VEL ANAL

STATICSDEMUX

VIB CORR

FK FILTER

DECONDMO/

MIGRATE

SAVE

DECON

FK FILTER

MUTE

GAIN RCVR

COHERENCYENHANCE

COHERENCYENHANCE

TIMETO

DEPTH

EDIT

Pre-ProcessingPre-Processing

IN

OUT

DEMULTIPLEXING

VIBROSEIS CORRELATION

Pt

Corr St

Raw St

Pt Raw StX =

Issues: Demultiplex skew

Issues: DeSpike B4 Corr Filtered Pilot

Raw S-tPt *=

Yilmaz, 2001

Vibroseis CorrelationVibroseis Correlation

Yilmaz, 2001

Gain RecoveryGain Recovery

Options:

•Automatic Gain Control (AGC)• Gain info lost•Spherical Divergence (Need Vt)•Exponential Gain Correction•Programmed Gain Control (PGC)•Trace to Trace Gain Balance •Amplitude Statics

Yilmaz, 2001

Gain RecoveryGain Recovery

Original

with Spherical Gain Correction

Yilmaz, 2001

Gain Recovery: AGCGain Recovery: AGC= window length

AGC shadow

Yilmaz, 2001

EditingEditing

Band Pass FilterBand Pass Filter

st

t

s’t

t

Input Output

Sf

f f f

S’fRf

rt

Filter

X =

* =

Time domain

Frequency domain

Bandwidth/Filter LengthBandwidth/Filter Length

Filter length

Bandwidth = f2/f1

50/2535/5

Filter ShapeFilter Shape

Band Pass Filter: ResolutionBand Pass Filter: Resolution

Increasing frequency

Increasing Bandw

idth

model model

Bandpass Filter TestBandpass Filter Test

TVF = Time Varying Filter

FK (2D) FilteringFK (2D) Filtering

t

f

x

k

FK FilteringFK Filtering

Spatial AliasingSpatial Aliasing

FK FilteringFK Filtering

FK FilteringFK Filtering

FK Spectra

before

after

B4

After

Convolutional ModelConvolutional Model

* W t=

DeconvolutionDeconvolution

conv

decon

Poor decon

DeconvolutionDeconvolution

DeconvolutionDeconvolution

Before Decon After Decon