Wall lock borehole geophone

The cable has 4 or 6-conductors with Kevlar® braid strength member and polyurethane jacket, specially manufactured for Geostuff. The cable can be easily disconnected from the geophone for ease of handling. Popular lengths are normally available from stock, and custom lengths are available on special order.

Model BHG-2 (above left) contains a 3-component geophone in an X-Y-Z orientation.

The BHG-3 (center) includes three geophone elelments, plus a fluxgate compass and a servo mechanism which automatically rotates the horizontal geophones to the azimuth of your choice so that you can align the horizontal sensors with the energy source.

The BHGC-5 controller operates that tool and routes the digital signals directly to your laptop, eliminating the need for a conventional seismograph. That system is powered by a separate 12-volt battery.

Geostuff offers a selection of wall-lock borehole geophones.

Each geophone features a wall-lock clamping mechanism with a robust, steel spring, expanded by a DC electric motor.

There are no rubber bladders to break or tubes to leak, and operation is relatively independent of depth. The standard geophone elements are an X-Y-Z array, high-output, 15-Hz natural frequency that can operate with the tool vertical or horizontal. The standard clamp mechanism works for holes between 2 and 6 inches (48-150 mm), but for larger holes extenders are available. The outside diameter is 1.85 inches (47 mm), small enough to fit inside a schedule-40, 2-inch plastic pipe.

Controllers operate the clamp and route the signals to a conventional seismograph. Output adapter cables are available for any analog seismograph. The BHGC-1 operates a single 3-component geophone, and the BHGC-4 can operate up to four geophones.

The controllers contain an internal, 24-volt rechargable battery, sufficient for several weeks of surveys.

The BHGC-5 controller operates the tools and routes the digital signals directly to your laptop, eliminating the need for a conventional seismograph. One controller can operate an array with up to 24-geophones. Additional controllers can be daisy-chained to operate additional strings of geophones. That system is powered by a separate 12-volt battery.

Geostuff has published a tutorial paper describing the field methods for conducting borehole shear wave surveys. To read or download a copy, click Downhole Shearwaves

An internal 32-bit A/D converter digitizes the signals from the three sensors in the tool. The data is sent to the surface, free of any analog noise from the cables. More significant, additional tools can be strung together to form a downhole array with up to 24 geophones. A digital compass provides the azimuthal orientation of each tool, included with the seismic data. The BHG-5 connects directly to your laptop computer through a controller for display, analysis and data storage, eliminating the need for a separate seismograph, reducing overall cost. Download a BHG-5 Data Sheet