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Geoquip Marine • DPS – Downhole P&S Logging Sonde

Product Type
Wireline Logging Tool
Product Snapshot
Product Name
DPS – Downhole P&S Sonde
Product Type
Wireline Logging Tool
Manufacturer
GeoVista
Procurement
Equipment & Operator
Overview
Geoquip Marine own and operate a Geovista DPS Downhole P&S sonde which allows simultaneous measurement of P & S wave velocities within the borehole environment. It comes with one transmitter and two receiver modules. The energy source of the transmitter operates as a dipole source. Each receiver contains two transducers, one for the detection of the compression waves (P) and the other for the detection of the shear waves (S). Each transducer responds to different frequencies. The sonde is stopped at selected depths where acoustic data is acquired in different modes that allow the determination of these P and S velocities. This is done without the need for clamping and this method gives better accuracy and resolution than other seismic methods.

The performance of the system is engineered to give good results in the slower formations encountered at shallow depths while also performing well in deeper formations with higher velocities. The data acquired by the system is recorded in the industry standard SEG2 file format, allowing many commercially available packages to read the data.
 
Features & Applications
Key Features
  • Compatible with Geoquip Marine's geotechnical drilling rigs and geotechnical vessels
 
Applications
  • Geotechnical site investigation - foundation studies, wind farms, offshore structures, dam safety
  • Physical properties of soil/rock - shear modulus, bulk modulus, compressibility and Poission's ratio
  • Earthquake engineering - characterisation of strong motion sites
  • Velocity control for seismic reflection surveys
  • Engineering
 
Operating Conditions
Borehole Type
Open-hole, water-filled
Logging Speed
Static measurements
Probe Specifications
Diameter
50 mm
Length (Assembled)
4.85m or 5.85m (depending on which isolator section is used)
Weight (Assembled)
14kg (excluding extra isolator sections)
Pressure (Max)
5MPa
Receiver Type
Geophones (s) ● Piezoelectric P wave transducer
Receiver Spacing
Adjustable
Waveform Acquisition Period
5mS - 80mS
Sampling
2.5, 5, 10, 20, or 40 µs (independently selectable)
Downhole Gain
Adjustable between 0dB - 24 dB per channel
Launch & Recovery
Winch ● Geotechnical Drilling Rig
Related Products
Geoquip Marine operates a Robertson Geo PS Logger Probe – a low-frequency acoustic sonde designed to measure compressional (P) and shear-wave (S) velocities in soils and soft rock formations. It operates using indirect excitation rather than mode conversion as in a conventional sonic. It is capable of acquiring high resolution P and S wave data in ... Moreborehole depths of up to 600m in water.

The PS Logger probe contains a unique design of powerful hammer source and two receivers, separated by acoustic damping tubes. To acquire data, the probe is stopped at the required depth and the source is fired under surface command. Firing causes a solenoid-operated shuttle aligned across the borehole axis to strike plates on opposite sides of the probe in turn, setting up a pressure doublet in the surrounding fluid. The resultant fluid motion produces a tube wave at the borehole wall with velocity close to the shear velocity of the formation together with a compressional wave.

As the waves propagate parallel to the borehole axis, they set up corresponding fluid movements that are detected by the two neutral buoyancy 3D hydrophone receivers and geophones, allowing the wave velocity to be determined. The facility to stack multiple shots and filter the data as in normal seismic data acquisition is included in the operating software.
Contact Us
Phone
+41 71 227 40 00