复杂环境下脉冲中子测井时间谱变化规律及铀定量算法研究

In the field of uranium exploration, the “direct uranium determination” key technology of the pulsed neutron logging is blocked by foreign countries, and it is developing at the initial stage in China. Considering the difficulties of the.current uranium quantification technologies such as the slow speed, the low efficiency and the nonideal reliability, the main objective of this project is to reveal the change law of neutron decay time spectrum of pulsed neutron logging under the complicated environment. Based on the physical mechanism of the interaction between the neutron and the stratum, and the formation of uranium fission, this project is planning to propose the “Trinity” research program on the basis of the numerical simulation, the standard model test and the field parameter bore-holes experiment, study the influence mechanism and variation characteristics of the neutron decay time spectrum under the complicated environment including the ore beds with different radioactive materials and the bore-holes with different diameter and liquid, optimize the pulsed neutron logging uranium content interpretation method under the complicated formation environment and borehole condition, and finally construct the numerical analytical method of the pulsed neutron logging uranium content under the complicated formation environment. This project will make the important contribution to improving the basic theory of the uranium pulsed neutron logging.

在铀矿勘查领域，直接测铀的铀裂变瞬发中子测井（即脉冲中子测井）技术被国外封锁，我国正处于发展初期。针对现有技术的铀定量速度慢、效率低和可靠性不强等难题，本项目以揭示复杂环境下脉冲中子测井中子衰减时间谱变化规律为主要目标，以中子与地层核素相互作用以及地层铀裂变的物理机理为基础，拟构建常见含铀地层(砂岩地层)和不同钻孔环境的数值模型，借助标准模型井和野外参数井，研究复杂环境（含不同放射性物质的矿层及不同孔径和不同孔液的钻孔）对中子衰减时间谱的影响机制和变化特征，优化复杂地层环境和钻孔条件的脉冲中子测井铀含量解释方法，最终形成复杂地层环境下脉冲中子测井铀含量的数值解析方法。本项目将为完善脉冲中子测井的基础理论做出重要贡献。

在铀矿勘查领域，直接测铀的铀裂变瞬发中子测井（即脉冲中子测井）技术被国外封锁，我国正处于发展初期。本项目以揭示复杂环境下脉冲中子测井中子衰减时间谱变化规律为主要目标，以中子与地层核素相互作用以及地层铀裂变的物理机理为基础，构建了常见含铀地层(砂岩地层)和不同钻孔环境的数值模型，利用仿真模拟研究了地层泥浆密度和不同钻孔套管厚度中子衰减时间谱的变化特征，并形成了相关的修正方法；修正方法在标准模型井进行了验证，主要在铀模型和钍模型上开展了初步实验；将项目研究所得的修正方法应用到E/T铀含量解释方法中，在野外进行了初步应用实验，实验结果表明，数值模拟所得到的规律与实际工作一致，为后续脉冲中子测井野外推广应用提供了理论研究基础。