Well logging system

Abstract

A well logging system includes a logging tool adapted to be passed through a borehole traversing an earth formation. The logging tool contains a sensor sensing a condition of the earth formation and providing electrical pulses corresponding in number and peak amplitude to the sensed condition. A first electrical pulse from the sensor occurring during each predetermined time period of a plurality of predetermined time periods, is stretched and then converted to parallel digital signals. A register receives the parallel digital signals and provides a serial digital signal in response to the shift pulses. A network provides an electrical synchronization pulse each time period prior to the occurrence of the shift pulses. A light emitting diode converts the synchronization pulses and the serial digital signals to corresponding light pulses. A cable including a fiber optic conductor transmits the light pulses uphole to the surface. Surface electronics includes a light-to-electrical converter for providing corresponding electrical pulses in accordance with the light pulses, so that the light-to-electrical converter provides a synchronization pulse followed by a serial digital signal each time period. Another circuit provides a set of shift pulses in response to the synchronizing pulse from the light-to-electrical converter, and an output circuit provides parallel output digital signals corresponding to the sensed condition in accordance with the shift pulses and the serial digital signals from the light-to-electrical converter.