摘要
根据D-D反应中子的能谱和角分布数据,建立了中子源模型;根据石灰岩地层标准刻度井群数据,建立了井模型。采用MCNP程序模拟了井中中子和γ射线的输运,得到了不同地层密度和不同源距处NaI探测器中的混合γ射线能谱和非弹γ射线能谱。在混合γ射线能谱2.5～5.0 MeV能区开窗,研究了开窗区混合γ射线相对计数随源距的变化关系,确定源距应选择在30～80 cm范围,给出了密度与混合γ射线计数之间的非线性关系。研究表明,可以利用D-D中子源的混合γ射线能谱来实现n-γ密度测井。
A D-D neutron source model was developed according to the neutron spectrum and the neutron angular distribution of D-D reaction. A standard calibration well model was built. The transports of the D-D neutrons and γ-rays in the well were simulated using MCNP code. The mixed γ-spectra and inelastic γ-spectra in the NaI detector were obtained for both different distances from a neutron source and different densities. Mixed γcount in the energy range of 2.5 to 5.0 MeV as a function of distance shows that the NaI detector should be located at a distance of 30-80 cm from the neutron source. The nonlinear relationships between the density and the mixed γ count were presented in this paper. It was demonstrated that the energy spectrum of mixed γ rays can realize the n-γ density logging.
出处
《原子核物理评论》
CAS
CSCD
北大核心
2013年第2期151-155,共5页
Nuclear Physics Review
基金
中国石油集团公司十一五计划基础研究资助项目~~
关键词
密度测井
D-D中子源
蒙特卡罗模拟
石灰岩
density logging
D-D neutron generator
monte-carlo simulation
limestone
