Simulation of epithermal neutron migration in fractured sandstone-hosted uranium deposits with variable porosities and dip angles

Uranium ores, as a significant clean energy source, have been highly anticipated in the field of geological exploration. However, fractured sandstone-hosted uranium deposits (pore-fissure type uranium deposits) face challenges in exploration because of their complex structures. Therefore, to quantify such uranium deposits, it is necessary to investigate the response relationships between the occurrence state and content of uranium and the parameters of geological structures (pores and fissures). This study simulated the neutron migration in the pore-fissure type sandstone-hosted uranium deposits using the prompt neutron log technology and the directive probability simulation algorithm. Through an ideal model, this study focused on the effects of fracture structures on neutron logs. The results are as follows: (1) The effects of fissure porosity on epithermal neutron migration intensified significantly with an increase in porosity, accompanied by substantially enhanced log response sensitivity; (2) The epithermal neutron accumulation peaks exhibit a multi-point distribution in a nearly vertical fissure environment; (3) The fracture environment with high dip angles manifested the most significant attenuation effect on the neutron energy and time spectrum peaks, and the neutron time spectrum peaks tended to move to the low-dip-angle interval with an increase in porosity; (4) In the fracture environment with variable dip angles, there was a linear relationship between the porosity and the epithermal neutron count ratio, which can assist in correcting the uranium content range in fracture environments at specific angles. The above results can provide a theoretical reference for the exploration of fractured sandstone-hosted uranium deposits and other uranium deposits in a complex environment and improve the quantitative accuracy of uranium deposits.