铀矿γ能谱测井铀等多元素含量分层解释法

与石油γ能谱测井用于追踪生油层等目的不同,铀矿γ能谱测井是为了直接获得铀含量的分布或找出非矿夹层,同时还能获得其他主要放射性元素的含量分布。这需要对γ测井资料进行分层解释。首先引入能谱型地质脉冲函数,对饱和矿体建立反映沿井轴方向各测点γ仪器谱与放射性元素含量分布之间函数关系的能谱型γ场正演方程。再引入分层解释思想,采用近似地质脉冲函数简化该方程,并进行三点式反褶积以获得薄层目标元素的含量等效窗计数率,进而得到对应的解释含量。实例计算表明,解释结果较好反映了铀等目标元素含量的实际分布;主要目标元素在矿体中间部位各层的平均解释含量相对误差低于6.5%。

Subdivision interpretation to measure the contents of uranium and other radio-elements based on a gamma-ray spectra-log during uranium exploration

Gamma-ray spectra-log measurements are used in uranium exploration to determine the uranium distribution in the bed and to identify intercalated beds containing little uranium.The measurements also determine the distributions of other radio-elements.The gamma-logging data analysis then uses subdivision interpretation.This paper describes the spectral geological pulse function and the spectral gamma-ray field forward calculation used to relate the gamma-ray spectra measured at a point along the well-axis and the radio-element distribution in the saturated ore.Subdivision interpretation and an approximate geological pulse function are used to simplify the equation.The energy window count rate equivalent content of radio-elements in a unit-layer is calculated using three-point de-convolution to get the radio element contents.A practical example shows that the results accurately reflect the real distributions of uranium and other target radio-elements.The relative error of the average concentrations in central layers in the ore is less than 6.5%.