In this section of the website, the origins of micro geophysical modeling are touched upon and four LVFPM OUTPUTS - fast neutron slowing down length (Ls), thermal neutron diffusion coefficient (D), thermal neutron diffusion length (L), and thermal neutron capture cross section (SIGMA) - are seen in their native habitat.
Figure 1, taken from US Patent 3,906,224 and a full copy, are provided below.This Figure forms the starting point for a discussion of the effects that different neutron sources and their energiesand modes of operation have on nuclear well logging tools.
Figure 2 was generated by LVFPM: it forms the basis for a novel way to measure neutron porosity with a neutron generator-based logging tool that has both good porosity measurement sensitivity and good count rates.The genesis of this method is US Patent 3,818,225 and a copy is also provided below.The main idea is to directly measure the thermal neutron diffusion coefficient and then use the relationships shown in Figure 2 to obtain neutron porosity.