Abstract: A method of determining a depth correction for a logging tool that is moved, while suspended from a cable, along a well, the method being of the type in which a measurement of tool depth is performed at the surface at successive instants, the tool comprising at least two sensors suitable for measuring a characteristic of the well at each instant said two sensors being offset longitudinally in the displacement direction of the tool. The method comprises, at each of said instants:determining a first value for tool velocity by intrinsic measurement;determining a second value of the velocity by correlation between information received from the two sensors; andcombining the first and second velocity values to determine a depth correction to be applied to the surface depth measurement.