By Haseeb Ahmed
M.Phil Geophysics
Institute of Geology, University of the Punjab
AVO ANALYSIS

Amplitude
versus
offset
(AVO)
is
primarily
the
variation
in
seismic
reflection
amplitude
with
change
in
distance between shot point and the
receiver
Its another name is AVA (amplitude
variation with angle)
AVO analysis is conducted on CMP data

FIG. SHOWING AVO (A) & (B)

AVO INTRODUCTION
It can physically explain presence
of hydrocarbon in the reservoirs
and
the
thickness,
porosity,
density,
velocity,
lithology
and
fluid content of the reservoir of the
rock can be estimated.

THE
ZOEPPRITZ
EQUATIONS
Zoeppritz
derived
the
amplitudes
of
the
reflected and transmitted waves using the
conservation
of
stress
and
displacement
across the layer boundary
which
gives
four
equations
with
four
unknowns.
Inverting the matrix form of the
Zoeppritz
equations
gives us the exact amplitudes as a
function of angle

THE ZOEPPRITZ EQUATIONS
1
1
1
1
1
2
1
P
1
2
S
2
2
1
P
1
2
P
2
1
1
P
1
S
1
2
2
1
S
1
1
P
2
S
2
1
2
P
2
1
S
1
1
P
2
2
S
2
1
1
S
1
P
1
2
2
1
1
2
2
1
1
S
P
S
P
2
cos
2
sin
cos
sin
2
sin
V
V
2
cos
V
V
2
sin
V
V
2
cos
2
cos
V
V
V
2
cos
V
V
V
V
2
cos
V
V
2
sin
sin
cos
sin
cos
cos
sin
cos
sin
T
T
R
R

THE AKI-RICHARDS EQUATION
The
Aki-Richards equation
is a linearized
approximation to the
Zoeppritz equations
.
The initial form (Richards and Frasier, 1976)
separated the velocity and density terms:
S
S
P
P
V
V
c
b
V
V
a
R
)
(

THE AKI-RICHARDS EQUATION
Where;
,
sin
4
,
sin
2
5
.
0
,
cos
2
1
2
2
2
2
2
P
S
P
S
V
V
c
V
V
b
a
.
2
,
,
2
,
,
2
,
,
2
1
2
1
2
1
2
1
2
1
2
1
2
t
i
S
S
S
S
S
S
P
P
P
P
P
P
and
V
V
V
V
V
V
V
V
V
V
V
V

WIGGINS’ VERSION OF THE
AKI-RICHARDS EQUATION
A more intuitive, but totally equivalent, form was
derived by
Wiggins
.

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- Winter '15
- NAGRAJ
- Impedance matching, Class II railroad, Class III railroad, Rey Mysterio, Jr., AVO