| 摘要 |
A radioactive logging source carried by a logging tool injects gamma rays into the formation. A detector generates a pulse for each gamma ray incident upon the detector having an amplitude proportional to the gamma ray energy. Electrical signals corresponding to each such amplitude are delivered to the surface. These incident gamma rays originate from the formation as well as from a monitor source of gamma rays of known energy adjacent the detector. An energy peak from the gamma ray energy spectra transmitted to the surface corresponding to gamma rays of known energy from the monitor source is accurately identified. At the surface, the peak is tracked during the logging procedure and a control signal functionally related to observed monitor peak shifts generated and delivered to the logging tool. A control circuit alters magnitude of the high voltage supply providing power to the detector in response to the control signal.
|
