Flowshot technique

摘要

A pulsed neutron source irradiates an earth formation. The irradiation produces N¹⁶ from O¹⁶ in a fluid in the borehole, and the gamma rays produced by the subsequent decay of N¹⁶ are detected by a plurality of spaced apart detectors. The count rates of the detectors are accumulated over a time sampling interval to produce temporal signals. Processing of the temporal signals using correlation, differentiation and/or semblance techniques is used for determination of the flow velocity of one or more fluids in the borehole.