PORE SIZE, ORIENTATION AND SHAPE; LAMINAE; AND FRACTAL DIMENSION EFFECTS ON THE RESPONSE OF SEVERAL NUCLEAR LOGGING TOOLS

摘要

The origin and use of nuclear forward models likeSNUPAR and MSTAR are traced. Significantimprovements to these initial efforts are proposed.The Transmission Probability Method is applied to avuggy formation and thereby to derive Zakharchenko'sequation. It is thereby demonstrated that the classiclinear mixing rule for the macroscopic thermal neutronabsorption cross section implies an infinitesimal poresize. Impact of this result on other parameters outputby forward models is presented.Pore size, shape, and orientation are examined forvuggy and laminated formations. Impact of poresystem fractal dimension is presented and new detailsgiven as to how such calculations are performed.Finally, impact on cased hole bulk density and casedhole neutron porosity are presented for two and threedetector pulsed neutron logging tools.Results are presented in terms of changes to gamma rayoutput parameters selected from: gamma hydrogenindex, bulk density, electron density index, apparentbulk density, photoelectric factor, effective atomicnumber, linear absorption coefficients, density porosity,and cased hole bulk density.Results are also presented in terms of changes toneutron output parameters selected from: capture crosssection, diffusion length, diffusion coefficient, transportcross section, slowing down length, migration length,neutron porosity, neutron hydrogen index, and casedhole pulsed neutron porosity.