A comparison of theoretical solutions of the three-layer coaxial diffusion approximation of the borehole with measurements at the Zielona Góra calibration facility

Czubek has obtained a practically successful solution of a two-layer borehole geometry using the neutron diffusion approximation. Czubek and Woznicka solved the more realistic three-layer borehole model, which includes a middle layer consisting of mud-cake or steel tubing, in this approximation. The comparison with experimental data for 15-mm thick steel tubes shows some discrepancies. By using an exact Monte Carlo solution of the Boltzmann equation for calculating the migration length, measurements agree more closely with the “general calibration curve”. This opens opportunities for cased borehole logging.