DETERMINING THE DENSITY OF MULTIPLE LAYERS USING GAMMA SPECTROSCOPY

Due to the volumetric nature of the physics and the measurement, traditional gamma-gamma density tools measure an average bulk density of the formation. However, a bulk measurement is not adequate for certain applications where a more detailed resolution of a radial density profile is necessary. In this paper, a new approach of gamma spectral analysis is introduced focusing on the main Compton scattering angles. Several energy windows are linked to the unique radial layers based on scattering angles and location of interaction. As a result, the density of multiple layers can be calculated. The paper first outlines the main principles and analytical structures to formulate two methods to measure layer densities. Then computer simulation tools are used to simulate realistic tool configuration and measurement response to validate and benchmark efficacies of the outlined methods. Finally, a case study is presented to demonstrate the applicability of these methods using laboratory data. The paper is concluded with a list of other possible applications such as open-hole density and behind-pipe evaluation where layer density can provide more details for the analysis.