Saturation, lithology, and porosity through casing

The RSTPro reservoir saturation tool incorporates a pulsed neutron generator and a dual-detector spectrometry system to measure elemental concentrations, including carbon and oxygen, and the formation neutron-capture cross section (sigma) during a single trip in the well.

Oil volume is computed from the carbon/oxygen (C/O) ratio determined through full spectral analysis to eliminate any environmental bias and also from a windows-based C/O ratio. Proprietary alpha processing combines the two volume determinations to deliver a saturation answer that is both highly accurate and can be acquired at faster logging speeds. The accuracy of the resulting reserves estimates is comparable to that from core analysis.

The sigma measurement is used to determine porosity and differentiates between saline water and oil to calculate formation oil saturation. Where formation water is fresh or of unknown salinity, saturation is determined from the C/O ratio measurement, which is salinity independent.

A quantitative, mineral-based lithology interpretation is produced by inputting the elemental yields measured by the RSTPro tool to SpectroLith spectroscopy lithology processing.