| 摘要 |
1,163,535. Radio-active borehole logging. BRITISH PETROLEUM CO. Ltd. Dec. 15, 1966 [Dec.16, 1965], No.53451/65. Heading G1A. A borehole is logged by transmitting pulses of radiation into the formations surrounding a logging sonde, measuring the intensity of induced gamma activity at a number of instants at varying times after the exciting pulse and transmitting the measurements to the surface as pulse position modulated time multiplexed signals. A scintillation detector D is synchronized with a pulsed neutron source NS to detect induced radiation from the formations in the intervals when the source is not emitting. AND gates E1-E23 are opened in sequence so that the output of detector D passes into 23 channels corresponding to different times after the exciting pulse. The pulses are standardized by monostable circuits M1-M23 and integrated by integrators I1-I23 to produce signals representative of the number of pulses received in each channel. The outputs of integrators I1-I23 are fed in turn through sequentially operated AND gates A1-A23 to a multiplex transmitter TT. In TT the analogue signals from the integrators are converted into pulse position modulated signals and transmitted up the logging cable to a multiplex receiver TR which distributes the position modulated pulses through 23 AND gates B1-B23, to stores ST1-ST23. The contents of the stores may be displayed on a C.R.T. in the form of the decay curve of induced radiation in the formations, and the contents of selected combinations of stores may be displayed on indicators IND1-IND5 by suitable closure of switches SS1-SS115. The ratio of selected channels may be displayed on a ratio meter RM. The synchronizing pulses for the neutron source NS and detector D and the various gates are provided by a multi cathode discharge tube as described in Specification 1,095,630. The pulses passing a selected one of gates E1-E23 into a corresponding channel may be applied to a pulse height analyzer and the results of the analysis transmitted up the logging cable as pulse position modulated time division multiplexed signals as described in Specification 1,095,630. |
