Schlumberger

Phase Velocity Sonde

Marker measurement of up- and downflow velocity of oil and water phases

The Phase Velocity Sonde (PVS) is a production logging tool used in conjunction with the RSTPro reservoir saturation tool to measure the velocity of two separate phases (water and oil) in a flowing horizontal or highly deviated well. A chemical marker with a high thermal neutron absorption cross section (sigma) that is miscible only with the phase of interest is injected into the borehole. The passage of the marker downstream is detected by the borehole sigma measurement of the RSTPro tool.

Determining the downhole flow profile

The PVS measures upflow or downflow depending on where it is placed in the toolstring with respect to the RSTPro tool. The fluid velocity is determined from the ejection-to-detector distance and travel time. These data are essential for accurately calculating the volume of water, oil, or both fluids flowing in the wellbore. This provides a reliable basis for determining the flowing profile of the well at downhole conditions in comparison with individual-fluid production at surface conditions.

For extended operaions, the PVS main module can be combined with an auxiliary module to provide an additional chemical marker reservoir.

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