testing the quality of geophone plants for 3-c land acquisition henry c. bland, malcolm b. bertram,...
TRANSCRIPT
Testing the quality of geophone plants for 3-C
land acquisition
Henry C. Bland, Malcolm B. Bertram, Eric V. Gallant
Conventional surface-mount case
Elevated plants cause cases to sway from side-to-side
Resonant frequencies for vertical geophones in different soils
275Houston lawn near garden
110Plowed Houston garden
305EPR grounds
222Friendswood topsoil
432Friendswood clay
400West Texas
Resonant frequency HzLocation
275
110Plowed Houston garden
305EPR grounds
222Friendswood topsoil
432Friendswood clay
400
Resonant frequency HzLocation
C.E. Krohn, 1984, Geophone Ground Coupling: Geophysics
3-C Geophone case styles
Oyo Geospace PC-3D
Oyo Geospace Seismic Nail
I/O Vectorseis
How does geophone plant-depth affect geophone sway?
Experimental apparatus
Glass tube
runway
Sand Box
Geophone
Under test
Retort stand
and support grill
Steel ball 3/16”
Impulsive Ping
Geophone
`
0 0.05 0.1 0.15 0.2 0.25-1
-0.5
0
0.5
1x 10
6 Oyo PC-3D case, crossline, raised 0cm
time (ms)
amp
litu
de
0 0.05 0.1 0.15 0.2 0.25-1
-0.5
0
0.5
1
1.5x 10
6 Oyo PC-3D case, crossline, raised 1cm
time (ms)
amp
litu
de
0 0.05 0.1 0.15 0.2 0.25-2
-1
0
1
2
3x 10
5 Oyo PC-3D case, crossline, raised 2cm
time (ms)
amp
litu
de
On ground
2 cm above ground
1 cm above ground
0 50 100 150 200 250 300 350 400 450 500-100
-80
-60
-40
-20
0
Frequency (Hz)
dB
do
wn
Oyo PC-3D case, crossline component, raised 0cm
0 50 100 150 200 250 300 350 400 450 500-100
-80
-60
-40
-20
0
Frequency (Hz)
dB
do
wn
Oyo PC-3D case, crossline component, raised 1cm
0 50 100 150 200 250 300 350 400 450 500-100
-80
-60
-40
-20
0
Frequency (Hz)
dB
do
wn
Oyo PC-3D case, crossline component, raised 2cm
On ground
2 cm above ground
1 cm above ground
0 50 100 150 200 250 300 350 400 450 500-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Frequency (Hz)
dB
do
wn
Nail, crossline, burried
0 50 100 150 200 250 300 350 400 450 500-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Frequency (Hz)
dB
do
wn
Nail, crossline, raised 2cm
Transmission test
ping
source geophone receiver geophone
))(()(
)()(
fECSCfy
fEfx
RRS
S
.
Geophone coupling transfer function
ping
Sourcegeophone
Receivergeophone
x(f) y(f)
S CRCS
ES ER
))(()(
)( 2 fCSfx
fy
RS
RS
CCC
EE
)(
)(
fx
fykC
0 50 100 150 200 250 30080
90
100
110
120
130
140
Frequency (Hz)
dB
Oyo PC-3D transmission-test source spectrum
0 50 100 150 200 250 30090
100
110
120
130
140
Frequency (Hz)
dB
Oyo PC-3D transmission-test receiver spectrum
0 50 100 150 200 250 300-15
-10
-5
0
5
Frequency (Hz)
dB
Oyo PC-3D transmission-test transfer function spectrum
equals
minus
y(f)
x(f)
Divide by 2
0 50 100 150 200 250 30080
90
100
110
120
130
140
Frequency (Hz)
dB
Nail transmission-test source spectrum
0 50 100 150 200 250 30080
90
100
110
120
130
140
Frequency (Hz)
dB
Nail transmission-test receiver spectrum
0 50 100 150 200 250 300-15
-10
-5
0
5
10
Frequency (Hz)
dB
Nail transfer function spectrum
Conclusions
• Geophones must be completely planted loose soils for 3-C
• Elevated plants resonate in the data band
• Ping technique useful for finding geophone/ground resonances
• Possible method for measuring coupling?
Acknowledgements
• Oyo Geospace Canada
• CREWES Sponsors