什么是 Wireline logs？

A wireline log is a continuous record of a physical property of the rocks against depth, measured by a probe lowered on a cable into a borehole. The gamma-ray log records the natural gamma radiation of the rock, in API units: high in shale, whose clays hold potassium, thorium and uranium, low in clean quartz sand and in limestone. The density log records the bulk density from the scattering of gamma rays emitted by a source on the probe. The sonic log records the interval transit time of a compressional wave, in microseconds per foot. The neutron log records the slowing of neutrons by hydrogen, and hence the water held in the pores and in clays.