TOPIC:

SEISMIC REFLECTION DATA PROCESSING(idea of some terminology)

DEMULTIPLEXEING.

Sorting.

Editing and Muting.

Gain Recovery.

Static (or datum) Correction.

Deconvolution.

Stacking.

CONTENTS

SeismicReflectionDataProcess

DEMULTIPLEXEING

Demultiplexing is the process of arrangement ofdata from two are more channels in an arrangemanner.

AS : A11A22A12A21A32A23A32A13A33

So By Multiplexing process

A11A12A13 A21A22A23 A31A32A33

We know that seismic recorder store the data inmultiplexed form where first sample of all tracesstores first and followed by the second sample of alltraces and so on.

Sample of all traces data constant time make a timeslice.

So we covert this time slice to trace sequentialorder.TO make the data demultiplexed.

In which all sample of first traces followed by thesecond and so on.

SORTING

After performing some initial processing data needs to besorted out from shot point to the common depth point(CDP) order.

In this process traces from different shot receivercombination that hit the same CDP are grouped togetherthus forming a CDP order data as shown below.

Again it can be seen that this process is simplyarrangement of data from one form to another.

To detect and kill the unwanted traces.

Remove dead traces.

Remove noisy traces.

Cut out pre-arrival nose and ground roll.

EDITING AND MUTING

Muting on actual seismic section

Dead or bad traces

Bad data removed

As seismic waves moves forward it experienced decay inamplitude. This decay in all direction.

Both laterally with off set and vertically with depth.

In processing lose amplitude may b recovered by applyingsome spherical compensation gain and other type of timevariant and trace balancing gains.

Accounting for geometric spreading by multiplying theamplitude with the reciprocal of the geometricspreading factor.

GAIN RECOVERY

Time-shift of traces in order to correct for surface topography

and weathered layer.

Corrections:

where:

Es is the source elevation

Er is the receiver elevation

Ed is the datum elevation

V is the velocity above the datum

t Es Er 2Ed

V ,

STATIC (DATUM)CORRECTION

Static (or datum) CorrectionExample of seismic profile before (top) and after

(bottom) the static correction.

The primary reflection series is random.

The source wavelet is minimum phase and is doesn'tvary though the earth (stationary).

Seismic signal convolve with the earth material highfrequencies are absorbed.

Deconvolution is used to reverse the effect ofconvolution on the recorded data. By reintroducedthe these lost frequencies.

Types: Spicking Deconvolution, Predictive andSurface deconvolution.

DECONVOLUTION

THANKS