Ever wanted accurate compressional and shear wave arrival times in uncompacted near surface sediments? The borehole P-S seismic suspension logging probe has been designed for this purpose and can provide these measurements from inside PVC casing.
By themselves, the compressional and shear wave arrivals time may not seem important properties but together and with density measurements, elastic rock properties such as Poisson’s Ratio, Shear Modulus, Bulk Modulus and Bulk Compressibility can be calculated.
Previously, these parameters could be calculated using the fullwave sonic probe but in uncompacted, near surface sediments the shear wave was very difficult to pick. Also, the fullwave sonic needs openhole conditions in the borehole.
The suspension logging probe consists of:
- A single dipole transmitter which means the energy source can provide outputs in more than one direction allowing normal and complimentary shear waves to be recorded.
- Two receivers where the isolation section can be changed to provide a different transmitter to receiver configuration.
The suspension logging probe is in common use in European geotechnical investigations, particularly offshore windfarms. Additionally the probe is used in earthquake prone areas such as Japan – you want to know your building and rad structures are earthquake proof!!
Requirements are:
- Openhole or PVC cased borehole 50mm or greater.
- Fluid filled conditions