基于高能中子自补偿校正的D-T源确定中子孔隙度改进方法OA

D-T source neutron porosity logging exhibits low sensitivity in high-porosity formations,and its response character-istics differ from those of conventional compensated neutron logging across various lithologies and in shaly formations.This study proposes a novel method that utilizes thermal neutron counts within a pulsed time window to characterize a self-compen-sated correction factor for high-energy neutrons,combined with a thermal neutron count ratio to determine porosity.Monte Carlo simulations were conducted to construct wellbore-formation models,simulating the distributions of fast and thermal neu-trons under varying porosity and shale content for both D-T and Am-Be sources.The self-compensated correction factor for high-energy neutrons and neutron porosity logging responses were systematically analyzed and validated using field logging da-ta.The results show that the thermal neutron count ratio increases with porosity.After applying the fast neutron self-compen-sated correction,the relative sensitivity improves by a factor of 1.85 to 2.69(for limestone formations with porosity ranging from 20%to 40%),and the porosity deviation is reduced to 49%-52%of the original value.In particular,the porosity ac-curacy decreases from 1.55%to 0.80%in limestone formations with 30%porosity.In sandy shale formations with 13%-22%porosity,the absolute error of the calculated porosity is reduced to within 2%compared with conventional compensated neutron logging.This method effectively addresses the low sensitivity of D-T neutron sources in high-porosity formations and provides a promising approach for neutron porosity evaluation in cased-hole wells.