(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 sufficientlyhomogeneous-flow regime, such as withemulsion or dispersed bubble flow. See: Effective Velocity, Flow Profile, Flow Regime, Multipass Method, Single-Pass Method, Spinner Flowmeter, Spinner Reversal, Threshold Velocity, Velocity-Correction Factor