Download - Seismic data processing 10
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