Downhole equipment 

Depths up to 100 m

In general, the standard downhole test is applied for near surface investigations using a simple sledge hammer as surface source together with different kinds of analog borehole geophones designed for maximum depths of around 100 m.


 

Source

Sledge Hammer | Surface Source

The sledge hammer is used to generate seismic waves (P- or S-waves) at the surface. A piezotrigger element is attached to the hammer. The output piezo signal is transformed to a TTL pulse by a small box to provide an exact time break to the seismograph.

It is a suitable source for shallow downhole surveys up to a depth of 100 m.

sledgehammer

Length:

1000 mm

Weight:

5 kg

Receivers

BGK3/7 | 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.

bgk3 7

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

 

BGK5 | Borehole Geophone

The borehole geophone BGK5 is used to receive P- and S-waves in dry or water filled boreholes. The borehole geophone BGK5 consists of four horizontal sensors, separated by 45° 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 BGK5 through an electro-pneumatic hybrid cable with a Kevlar tension string. The cable is terminated by a connector to the seismograph.

bgk5

Natural sensor frequency:

10 Hz (others on request)

Sensor arrangement:

4 horizontal (45°)/1 vertical

Operational depth:

Up to 100 m

Receiver length:

600 mm

Receiver diameter:

51 mm

Receiver weight:

2.8 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

Depth indicator:

Cable marking every 2 m

Connector:

To any seismograph

Storage:

On drum

 

DDS | Dual Downhole System

The Dual Downhole System (DDS) is used to receive P- and S-waves in dry and water filled boreholes in order to determine interval velocities. The DDS consists of two stations each equipped with tri-axial sensors. The stations are mechanically connected to each other to ensure the alignment of all horizontal sensors. Both stations are coupled to the borehole wall by a pneumatic clamping system (inflatable bladder). Air is supplied to the DDS 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 DDS in the borehole. The cable is terminated by a connector to the seismograph.

dds

Natural sensor frequency:

28 Hz (others on request)

Sensor arrangement:

Tri-axial

Operational depth:

100 m

Number of stations:

2

Station interval:

2 m

Station length:

620 mm

Station diameter:

65 mm

Station weight:

2.5 kg

Cable weight per metre:

145 g

Cable strength:

2150 N

Borehole diameter:

75 mm

Clamping system:

Inflatable bladder

Orientation:

Magnetic compass (+/-2.5°)

Depth indicator:

Cable marking every 2 m

Connector:

To any seismograph

Storage:

On drum

Depths up to 2000 m

In case of deeper underground investigations (e.g. for nuclear end storage investigations or mining purposes) large weighted vibrator surface sources are required together with a digital borehole geophone whose technology fulfills the requirements for downhole measurements in depths up to 2000 m.


 

Receiver

BGK1000 | Borehole Geophone

The BGK1000 is a digital borehole geophone used to receive P- and S-waves in dry and water filled boreholes. It is manufactured by Hinz Messtechnik GmbH and exclusively distributed by Geotomographie. The borehole geophone BGK1000 consists of a downhole probe with a tri-axial geophone sensor and a surface communication unit connected to the USB port of a laptop. Optionally, a hydrophone sensor can be added. An auxiliary channel can be connected to the surface unit to record an external seismic signal, i.e. a pilot vibrator sweep. Triggering is made via the surface unit allowing TTL pulse, geophone or contact triggering. The borehole geophone is designed to run on a winch equipped with a 4-conductor cable and a Gearhart Owen cable head. The geophone is coupled to the borehole wall by a mechanical clamping system (motor-driven arm). A magnetic compass is used to get the sensor orientation in the borehole. Seismic data are stored in SEG2 format by the acquisition software. A seismograph is not required.

BGK1000

Natural geophone sensor frequency:

15 Hz (others on request)

Sensor arrangement:

Tri-axial

Power supply:

12 V input 72 V output

Operational depth:

Up to 2000 m

Max. pressure:

200 bar

Temperature range:

0 - 70 °C

Receiver length:

800 mm

Receiver diameter:

60 mm

Receiver weight:

8 kg

Borehole diameter:

75 - 200 mm

Clamping system:

Motor-driven clamping arm

Orientation:

Magnetic compass (+/- 2.5°)

Communication:

2 wire RS-485

Downhole electronics:

DSP = Blackfin 548, 64 MB SDRAM

Cable head:

GO-4

Digitization

Design:

Hinz Messtechnik GmbH

A/D conversion:

24 bit

Sampling frequencies:

250, 500, 1000, 2000, 4000, 8000, 16000, 48000 Hz

Trace length:

Max. 21 s

Trigger:

TTL, geophone, contact

Software:

SmartRec (Geotomographie)