Abstract: This paper briefs about research and design of formation element and mineralogy (FEM) logging tool. BGO crystal prober is used to significantly improve the detection efficiency of gamma rays as compared to the traditional NaI (TI) prober. The boron sleeve with a certain thickness is wrapped on the outside of the tool in order to eliminate the background gamma caused by the tool itself. The analysis is made of the design and procedure of control circuit for acquisition, element standard spectra obtained by Monte Carlo modeling, the method of spectral processing, and oxides closure model. FEM logging tool is tested for simulated well and on-the-site logging. The results confirm that FEM logging curves can desirably reflect lithological characters of strata in different regions.

摘要： FEM 地层元素测井仪采用BGO 晶体探测器, 相较于传统的NaI (Tl) 探测器, 大幅提高了对伽马射线的 探测效率。为了消除仪器自身材料产生的俘获伽马本底, 在仪器外表面加了一定厚度的硼套。文章介绍了采集控制电 路的设计和流程, 元素标准谱的制作方法、解谱方法和氧化物闭合模型。对FEM 地层元素测井仪进行了模型井和现场 测井试验, 结果证实在不同岩性地区FEM 地层元素测井曲线均能较好地反映地层岩性特征。

关键词: 地层元素测井, 辐射俘获核反应, 元素标准谱, 解谱, 氧化物闭合模型