Seismic Data ProcessingMain Processing Sequence

Dr Amin KhalilSchool of Physics, USM

Today’s Agenda

• IIR filters

And

• Main Processing Sequences

IIR filters

Properties of an IIR Filter• The general equation of an IIR filter can be

expressed as follows:

M

k

kk

N

k

kk

MM

NN

za

zb

zaza

zbzbbzH

1

0

11

110

1

1

ak and bk are the filter coefficients.

Properties of an IIR Filter• The transfer function can be factorised to

give:

zXzY

pzpzpz

zzzzzzkzH

N

N

21

21

Where: z1, z2, …, zN are the zeros,

p1, p2, …, pN are the poles.

Properties of an IIR Filter• The transfer function can be factorised to

give:

zXzY

pzpzpz

zzzzzzkzH

N

N

21

21

For the implementation of the above equation we need the difference equation:

M

kk

N

kk

k

knyaknxb

knxkhny

10

0

Advantage

Use less memory than FIR filters

Disadvantages

•They are more susceptable to problems of finite-length arithmetic, such as

noise generated by calculations, and limit cycles. (This is a direct

consequence of feedback: when the output isn't computed perfectly and is

fed back, the imperfection can compound.)

•They are harder (slower) to implement using fixed-point arithmetic.

•They don't offer the computational advantages of FIR filters for multirate

(decimation and interpolation) applications.

Types of filters

Matching question.

Main Processing Squence

Basic Processing Sequence:

Basic Processing

Sorting of seismic data This step describe the way we collect and view or seismic data. It consists of the following:

CMP gather

Common shot vs CMP gather

Zero-Offset gather.

This type is applied such that both shots and receivers are at the same location.

Reference for this lecture:

Drijkoningen, G. G. and Verschuur, D.J., 2003. Seismic data processing. TU Delft.

http://geodus1.ta.tudelft.nl/PrivatePages/G.G.Drijkoningen/LectureNotes/SeismicProcessing%28tg001_ta3600%29.pdf

Link

End

Thank you