Introducing DJB Instruments Down Hole Seismic Sonde for all your vibration measurements

The DJB Instruments Down Hole Seismic Sonde harnesses the advantages of piezoelectric technology over other technologies for the measurement of vibration. It has a large bandwidth compared to other seismic sensors such as geophones or seismometers. There are no spurious (invalid) responses within the bandwidth of interest. The use of down hole amplifiers can improve the signal to noise ratio.

The instruments themselves can be operated off a simple 12v battery, and their low power consumption results in long battery life.

Large accelerometers and low noise amplifiers

• The instrument contains three A/1800 voltage accelerometers each containing integral electronics, with an operating temperature of 125°C.
• The sensors are configured on three orthogonal axis.

Features

• Give a very high output
• ABle to detect small signals
• Provide a high quality signal that does not degrade over time

Advantages of Seismic Sondes over other Seismic Monitoring Instruments

• Slimline diameter of 76mm means the instrument can be deployed in small bore holes.
• Can be deployed at a depth of up to 400m
• Does not require a clamping mechanism as it rests at the bottom of the hole.
• No moving parts, thus, more reliable.
• Large accelerometes and low noise amplifiers give a high output which is very sensitive to even the smallest of signals.
• No deterioration of signal over time.
• Easily removable for redeployment.
• The internal accelerometers have a large bandwidth compared to other geophones or seismometers, this faciliates additional analytic treatment.
• No spurious responses within the bandwidth of interest.
• Down-hole amplifiers to improve signal to noise ratio.
• Can be operated off 12v batteries.
• Low power consumption provides a long battery life, even on small batteries in remote areas.

Applications

Geothermal Energy

“We’re using an array of DJB’s highly sensitive accelerometer-based seismic sondes at the Eden Project. They monitor any seismic activity, whether natural or induced, while injecting water to open the natural fractures in the rock. DJB Instruments has developed a unique product which is being adopted worldwide and EGS Energy are proud to use them at the proposed
EGS site at the Eden Project.”

Roy Baria, Technical Director, EGS Energy.

One of many renewable energies being developed allows for the extraction of heat from the upper crust of the earth to produce electrical power. This is called Engineered Geothermal Systems (EGS) and is currently being taken up commercially.

Initially, a borehole is drilled to a depth to reach a defined temperature (in Western Europe around 5000m will produce a temperature of 200°C) and water is injected in order to open up natural fractures, which generate seimic sound. The opening up of fractures is monitored by an array of seismic sondes. The seismic sounds are triangulated to find out exactly where and when natural fractures are opened.

This gives an insight into what is happening at great depth and an image is produced to show the area where water has migrated. A second borehole is drilled about 600m away based on the image produced by the seismic sounds. Cold water is then pumped first into the well which flows through the opened fractures and is returned to the surface as steam. This is then converted into electrical power.

Current Installations of the DJB Seismic Sonde

Landau, Germany

In 2007, the first geothermal power plant with focus on commercial electricity production was put into operation in Germany using the DJB Seismic Sonde.

The Geysers, California

In 2009, a pilot project was started, drilling in California, with DJB Seismic Sondes rolled out accross the project.

To view the complete DJB Instruments product range, click on the link

For a further discussion contact our Melbourne office by email or phone: +61 3 9874 5777