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PICO Compensated Spectral Density Logging Tool (CSDL)

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Compensated Spectral Density logging tools determine formation bulk density (ρb) and borehole compensated photoelectric factor (Pe) by using a chemical source of gamma radiation along with gamma detectors. Materials in the path attenuate gamma rays as they travel from the source to the detectors. Analysis of the energy spectrum of the detected gamma rays yields ρb and Pe. The density measurements indicate formation porosity when formation lithology is known. The Pe value serves as the lithology indicator in single mineral formations. When combined with Neutron data, multiple mineral formation porosity and lithology can be determined. Spectral Density tools can be run in any type of borehole fluid.


  • Determine porosity
  • Identify lithology
  • Delineate thin beds
  • Indicate formation gas
  • Calculate shale volume


  • Combinable with most other logging tools
  • Can be run in open and cased holes