Method and apparatus for reducing statistical variations in nuclear well logs

This patent describes an apparatus for reducing statistical variations in nuclear borehole logs while maintaining responsiveness to formation changes. The method comprises: a narrow filter for deriving a narrow digital moving average of the log data using a first relatively narrow interval, thereby yielding relatively good formation bed resolution; a wide filter for deriving a wide digital moving average of the log data using a second interval wider than the first, to produce a smaller statistical variation in the log data than produced by the narrow filter; and digital statistical dampener means for deriving an index of the difference between the narrow and the wide derived averages