Transcript Testing the quality of geophone plants for 3

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
Location
Resonant frequency Hz
West Texas
400
Friendswood clay
432
Friendswood topsoil
222
EPR grounds
305
Plowed Houston garden
110
Houston lawn near garden
275
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 plantdepth affect geophone sway?
Experimental apparatus
Retort stand
and support grill
Steel ball 3/16”
Glass tube
runway
Geophone
Under test
Sand Box
Impulsive Ping
Geophone
`
6
1
Oyo PC-3D case, crossline, raised 0cm
x 10
amplitude
0.5
0
-0.5
On ground
-1
0
0.05
0.1
0.15
0.2
0.25
0.2
0.25
0.2
0.25
time (ms)
6
1.5
Oyo PC-3D case, crossline, raised 1cm
x 10
1 cm above
ground
amplitude
1
0.5
0
-0.5
-1
0
0.05
0.1
0.15
time (ms)
5
3
Oyo PC-3D case, crossline, raised 2cm
x 10
2 cm above
ground
amplitude
2
1
0
-1
-2
0
0.05
0.1
0.15
time (ms)
Oyo PC-3D case, crossline component, raised 0cm
0
dB down
-20
-40
-60
-80
On ground
-100
0
50
100
150
200
250
Frequency (Hz)
300
350
400
450
500
400
450
500
400
450
500
Oyo PC-3D case, crossline component, raised 1cm
0
1 cm above
ground
dB down
-20
-40
-60
-80
-100
0
50
100
150
200
250
Frequency (Hz)
300
350
Oyo PC-3D case, crossline component, raised 2cm
0
2 cm above
ground
dB down
-20
-40
-60
-80
-100
0
50
100
150
200
250
Frequency (Hz)
300
350
Nail, crossline, burried
0
-10
-20
dB down
-30
-40
-50
-60
-70
-80
-90
-100
0
50
100
150
200
250
Frequency (Hz)
300
350
400
450
500
350
400
450
500
Nail, crossline, raised 2cm
0
-10
-20
dB down
-30
-40
-50
-60
-70
-80
-90
-100
0
50
100
150
200
250
Frequency (Hz)
300
Transmission test
source geophone
ping
receiver geophone
Geophone coupling transfer function
Source
geophone
ES
Receiver
geophone
x(f)
y(f)
ER
ping
CS
S
CR
x( f )  ES ( f )
y ( f )  (CS S CR ER )( f )
ES  E R
C  CS  C R
y( f )
2
 ( S C )( f )
x( f )
C k
y( f )
x( f )
Oyo PC-3D transmission-test source spectrum
140
130
y(f)
dB
120
110
100
90
80
0
50
minus
100
150
Frequency (Hz)
200
250
300
250
300
250
300
Oyo PC-3D transmission-test receiver spectrum
140
130
120
dB
x(f)
110
100
90
Divide by 2
0
50
100
150
Frequency (Hz)
200
Oyo PC-3D transmission-test transfer function spectrum
5
equals
dB
0
-5
-10
-15
0
50
100
150
Frequency (Hz)
200
Nail transmission-test source spectrum
140
130
dB
120
110
100
90
80
0
50
100
150
Frequency (Hz)
200
250
300
200
250
300
200
250
300
Nail transmission-test receiver spectrum
140
130
dB
120
110
100
90
80
0
50
100
150
Frequency (Hz)
Nail transfer function spectrum
10
5
dB
0
-5
-10
-15
0
50
100
150
Frequency (Hz)
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