BGK3 – Borehole Geophone
The borehole geophone BGK3 is used to receive P- and S-waves in dry or water filled boreholes. The borehole geophone BGK3 consists of a tri-axial sensor whereas the BGK7 consists of six horizontal sensors, separated by 30° intervals, and one vertical sensor. The geophone is coupled to the borehole wall by a pneumatic clamping system (inflatable bladder). Air is supplied to the BGK3/7 through an electro-pneumatic hybrid cable with a Kevlar tension string. A magnetic compass shows azimuthal deviation to North and can be used to get the orientation of the geophone in the borehole. The cable is terminated by a connector to the seismograph.
Technical Details
| Natural sensor frequency: | 10 Hz (others on request) |
| Sensor arrangement: | Tri-axial (BGK3) or 6 horizontal (30°)/1 vertical (BGK7) |
| Operational depth: | Up to 100 m |
| Receiver length: | 705 mm |
| Receiver diameter: | 50 mm |
| Receiver weight: | 3 kg |
| Cable weight per metre: | 145 g |
| Cable strength: | 2150 N |
| Borehole diameter: | 75 mm (or larger if spacers are used) |
| Clamping system: | Inflatable bladder |
| Orientation: | Magnetic compass (+/-2.5°) |
| Depth indicator: | Cable marking every 2 m |
| Connector: | To any seismograph |
| Storage: | On drum |
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Manufactured by Geotomographie GmbH
Technical Details
Generated wave types: SV
Signal frequencies: Up to 500 Hz (depending on geology and borehole distance)
Operational depth: Up to 100 m
Source length: 1015 mm
Source weight: 6 kg
Cable weight per metre: 377 g
Borehole diameter: 75-100 mm (or larger if spacers are used)
Clamping system: Infatable bladder
Depth indicator: Cable marking every 2 m
Connector: To impulse generator IPG800 or IPG5000
Storage: On drum
Switch box: Switch between two vertical shot directions
