Method and apparatus for gamma ray well logging Patent #: 4628202
ApplicationNo. 07/067579 filed on 06/29/1987
US Classes:250/269.3, Having gamma source and gamma detector250/266With spacing or direction of detectors
ExaminersPrimary: Fields, Carolyn E.
Attorney, Agent or Firm
International ClassesG01V 5/00 (20060101)
G01V 5/12 (20060101)
AbstractA technique for measuring the density and a lithology-dependent factor, compensated for borehole effects, with a gamma ray logging source and one or more gamma ray detectors has been disclosed. Other borehole variables are also measured and used as quality indicators. The technique uses the spectral information from the detected gamma rays to calculate all of the unspecified variables relevant to the measurement. This technique also allows a lithology-dependent parameter based on the short-spaced detector to be compensated for borehole effects without contaminating the measurement with lesser-quality data from a detector spaced further from the source. Furthermore, it allows multiple measurements of a lithology-dependent factor made with multiple detectors to be compensated separately. The multiple compensated measurements can then be combined to form a quantity which indicates the quality of the measurement. This technique also allows the measurement of a compensated density whose vertical resolution is that of the short-spaced detector.