Density and lithodensity logging aimed to measure formation’s bulk density along the length of a borehole. Density logging tool sends gamma rays into a formation and detects those that are scattered back. Typical logging source emits gamma rays at a high energy level. Emitted gamma rays undergo Compton scattering and lose energy. Thus, the gamma count rate depends upon the electron number density, which is directly related to the bulk density of a formation.

Meanwhile, lithodensity logging tool (LDT) detectors can distinguish “hard” and “soft” gamma rays. High energy waves are the result of Compton scattering, while the low energy waves resulted from the photoelectric absorption effect, Pe. So, we can use the count rates measured in the higher energy shaded window (for hard gamma rays) as a measure of the bulk density.

Photoelectric absorption effect is strongly related to the nature of the formation matrix. The formation porosity and the nature of fluid in the pores have little effect on Pe, so in simple lithology, the measurement is a good matrix indicator all by itself. The only restriction for this method is the usage of barite and hematite in mud fluid system, as their high photoelectric absorption will deteriorate the recorded values in well and will not reflect the real formation composition.

Density and lithodensity logging solve the following tasks:

- bulk density estimation;

- measuring Pe;

- detailed lithology differentiation;

- calculation of reservoir properties;

- identification of mineral components;

- uses for lithology modeling accompanied by elemental capture spectrometry.

Operational P-T conditions: 

	MAX			MAX
	150; 175 °C			120 MPa