Numerical Simulation of the Litho-Density Tool Lithology Response

Abstract

ABSTRACT The numerical simulation of gamma ray logging in the context of the measurement of a formation's average photoelectric absorption properties by the LITHO-DENSITY Tool (LDT) is discussed. The accuracy of a model of the LDT's response, which has been developed using the MCNP transport code, is exhibited through comparison to experimental data. This model is then used to examine in detail the connection between the tool's response and formation properties by means of spectral studies of the spatial, angular and energy distribution of the photons which contribute to this response. Further model calculations of the collision density distributions of detected gamma rays are used to explore bow the LDT's measurements spatially sample the formation.