The P-S suspension logging is one of the available technologies to determine the compressional [P] and shear [S] wave downhole velocities. Developed in the mid-1970s to measure seismic shear wave velocity in deep boreholes and mainly was used by researchers the OYO Corporation of Japan. In the early 1990s its acceptance gained in the US among earthquake researchers. Measurements are made in a single borehole filled with fluid. The technology allows high resolution P & S wave survey to the depth of the borehole.

       Enerson Engineering uses a 7m long probe (with 2m filter system), low frequency acoustic probe that uses a downhole pressure wave energy [hammer] with a two receivers (geophones) spaced 1 meter apart. Armored 4 conductor cable is used to lower the tool into borehole and convey data between the recording systems on the surface and the downhole receivers. The high-energy hammer generates the wave in the borehole fluid. Seismic waves [P & S] transmit along the borehole wall and at each geophone locations, the P and S waves are picked up as pressure waves which then send the data to the recorder on the surface.
Advantages P-S suspension log over other conventional procedures:
It provides a specific measurement at any chosen depth in the borehole rather than interpretation from surface methods using integration through stratigraphy.

Its fast, actionable and affordable technique which brings detailed geotechnical information of the stratigraphy.

The high energy wave source has higher power than conventional sonic probes.

The low frequency acquisition technic has more representation to engineering.

Possible of Realtime visualization of small wave and storage of many test data either moving bottom-up or top-down.

Measurements can be repeated at a single station to minimize noise interference until a cleaner wave is acquired.
Acquisition intervals can be stationed at the client’s essential of details like every 10cm, 25cm, 50cm…. etc..

The probe can be deployed in a freshly drilled, uncased fluid-filled hole, though PVC cased boreholes can also be used (results are better in uncased).

All measured and processed data can be exported as “.las file” to be imported in different engineering programs.

 

Applications:

  • Foundation studies of bridges, buildings, abutments … etc
  • Measurement of soil properties (Vs, Vp, Shear-Young-Bulk moduli, Poisson’s ratio)
  • Seismic site response studies, dam safety exploration, characterization of subsurface motion and many other engineering research and investigation works
PS Suspension Logging
PS Suspension Logging