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two-pass method

1. n. [Production Logging]

A technique for interpreting the results from a spinner flowmeter using two logging runs over the zone of interest, one up and one down. If the two passes are run at the same cable speed, they will overlay below the perforations, where there is no flow. If they were not run at the same speed, the curves are shifted to overlay. Elsewhere, the separation between the curves gives the relative contribution of each zone. Viscosity changes should have a small effect, since they will have the same influence on both passes. The technique is applicable when the flow is single-phase, or else multiphase with a sufficiently homogeneous-flow regime, such as with emulsion or dispersed bubble flow.

See: effective velocityflow profileflow regimemultipass methodsingle-pass methodspinner flowmeterspinner reversalthreshold velocityvelocity correction factor