Monte Carlo simulation to key parameters of a compensated neutron logger

A compensated neutron logger （CNL） is designed by using Monte-Carlo simulation for lead shield thickness, near-to-far detector spacing range, source-to-detector spacing range, and detector＇s effective length. The calculated results indicate that the optimum conditions for CNL are 80-ram thick lead plus 1-cm thick LiOH shield in front of the near detector, 250 mm for the near-to-far detector distance （Ar）, and the source-to-detector distance （r） of 90mm. Simultaneously, some conclusion also obtained here, near/far detector counting response ratio （R） increases with the effective length of detector, R increases with the porosity for oil and water sandstones, and the oil sandstone is a bit greater than water sandstone.