Simulation of epithermal neutron migration in fractured sandstone-hosted uranium deposits with variable porosities and dip angles
ZHANG Xue-Ang1(), YANG Zhi-Chao2, LI Xiao-Yan1, DONG Li-Yuan1
1. School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, China 2. School of Geophysics and Measurement-control Technology, East China University of Technology, Nanchang 330013, China
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.
Li P J, Li Y Y, Xu M H, et al. A study of automatic correction method for the influence of formation water salinity on compensating neutron logging[J]. Geophysical and Geochemical Exploration, 2019, 43(4):815-821.
[2]
Wood D A. Gamma-ray log derivative and volatility attributes assist facies characterization in clastic sedimentary sequences for formulaic and machine learning analysis[J]. Advances in Geo-Energy Research, 2022, 6(1):69-85.
doi: 10.46690/ager
Zhang X A, Yang Z C, Wei X. Water layer neutron logging in multi-angle crack environment[J]. Geophysical and Geochemical Exploration, 2018, 42(6):1221-1227.
[4]
Sun Q F, Li N, Duan Y X, et al. Logging-while-drilling formation dip interpretation based on long short-term memory[J]. Petroleum Exploration and Development, 2021, 48(4):978-986.
doi: 10.1016/S1876-3804(21)60082-4
[5]
Gama J, Schwark L. Lithofacies of early Jurassic successions derived from spectral gamma ray logging in the Mandawa Basin, SE Tanzania[J]. Arabian Journal of Geosciences, 2022, 15(16):1373.
doi: 10.1007/s12517-022-10622-4
[6]
Han R Y, Wang Z W. Monte Carlo simulation of scintillation crystal detector for formation element logging[J]. Global Geology, 2019, 22(2):128-132.
Zhang X A, Yang Z C, Wei X. Numerical simulation of neutron logging in fracture uranium environment[J]. Journal of East China University of Technology:Natural Science, 2019, 42(1):68-73.
[8]
Kang D J, Xie Y F, Lu J G, et al. Assessment of natural gas hydrate reservoirs at Site GMGS3-W19 in the Shenhu area, South China Sea based on various well logs[J]. China Geology, 2022, 5(3):383-392.
Song F, Liu Z F, Luo J B, et al. Casing influences in uranium fission prompt neutron logging based on MC simulation correction[J]. Nuclear Electronics and Detection Technology, 2020, 40(6):927-931.
Lai Y H, Wang H T, Chen R. Real-time correction method of uranium mine caliper based on prompt neutron well logging[J]. Nuclear Techniques, 2021, 44(6):55-59.
[11]
Zhang L, Yu H W, Li Y, et al. Improved formation density measurement using controllable D-D neutron source and its lithological correction for porosity prediction[J]. Nuclear Science and Techniques, 2022, 33(1):26-36.
doi: 10.1007/s41365-022-01011-3
[12]
Zhang F, Chen S Q, Liu T, et al. A quantitative calculation method for fracture density using the neutron self-shielding modification and neutron-induced gamma logging[J]. Geophysics:Journal of the Society of Exploration Geophysicists, 2022, 87(3):D91-D100.
Xiao C J, Zhang G Y, Yuan G J, et al. Study on standard decay curve method in uranium determination by delayed neutron counting[J]. Nuclear Techniques, 2015, 38(12):24-28.
[14]
Darmovzalova J, Boghi A, Otten W, et al. Uranium diffusion and time-dependent adsorption-desorption in soil: A model and experimental testing of the model[J]. European Journal of Soil Science, 2020, 71(2):215-225.
doi: 10.1111/ejss.v71.2
Li P, Yang L Z, Zhao L X, et al. Study on casing stability under non-uniform ground stress for in-situ leaching well of a uranium deposit in Xinjiang[J]. Uranium Mining and Metallurgy, 2022, 41(4):368-376.
[16]
Malik P P, Maity J. Synthesis and leaching behaviour of borosilicate glasses containing uranium as radioactive waste[J]. Journal of the Indian Chemical Society, 2020, 97(12c):2909-2913.
[17]
Buckner M Q, Wu C Y, Henderson R A, et al. Measurement of the 242mAm neutron-induced reaction cross sections[J]. Physical Review C, 2017, 95(2):024610.
doi: 10.1103/PhysRevC.95.024610
[18]
Zhang S X, Zou C C, Peng C, et al. Abnormally high natural radioactivity zones in the main borehole of the continental scientific drilling project of cretaceous songliao basin:Geophysical log responses and genesis analysis[J]. Chinese Journal of Geophysics, 2018, 61(11):4712-4728.
Liang Y S, Guang S B, Feng L L I. Comparisons of prompt fission neutron logging and gamma logging applied in sandstone-type uranium ore drill holes[J]. Journal of Astronautic Metrology and Measurement, 2016, 36(3):68-73.
Xie X Y, Xu W J, He C H. Study of the effect of water layer thickness in transient fission neutron logging[J]. West China Exploration Engineering, 2019, 31(4):121-122.
[21]
Wang D, Zhang C F, Li B J, et al. Simulation of suppression of gamma sensitivity of fission electron-collection' neutron detector[J]. Chinese Physics Letters, 2016, 33(5):30-33.
Zhang L, Chen Z Y, Li S R, et al. Characteristics of uranium minerals in wall-rock alteration zones of the Mianhuakeng (No.302) uranium deposit, northern Guangdong, South China[J]. Acta Petrologica Sinica, 2018, 34(9):2657-2670.
Li Y B, Li Y, Wei B, et al. Application of CSAMT and shallow seismic reflection to uranium exploration in south western Songliao Basin[J]. Geology and Exploration, 2019, 55(6):1442-1451.
Zheng X, Wang Y H. The relationship study between oil and gas reservoirs and sandstone-type uranium deposits in the same sedimentary basin in China[J]. Ground Water, 2019, 41(5):107-109,176.
Yu X, Wang S, Hu Y C, et al. Study on electrical structure and uranium metallogenic environment of basalt-covered area in the northern Erlian Basin[J]. Geophysical and Geochemical Exploration, 2022, 46(5):1157-1166.
[26]
Zhang X A, Yang Z C, Tang B, et al. Distinguishing oil and water layers in a cracked porous medium using pulsed neutron logging data based on Hudson's crack theory[J]. Geophysical Journal International, 2018, 213(3):1345-1359.
doi: 10.1093/gji/ggy065
[27]
Zhang X A, Yang Z C, Li X Y. Simulation of multi-angle fractured uranium deposits by neutron logging[J]. Geophysical Journal International, 2020, 223(3):2027-2037.
doi: 10.1093/gji/ggaa436
