基于新型CeBr3探测器井下γ能谱测量238U关键技术研究

Research on Key Technology of Downhole γ Spectrum Logging 238U Content Based on New CeBr3 Detector

  • 摘要: 为实现铀资源勘查中无需铀镭平衡修正、镭氡平衡修正,通过现场测井技术便可直接获取地层铀含量,研究了基于新型溴化铈(CeBr3)探测器的井下γ能谱测铀技术。针对井下地层铀矿体高强度γ射线的采集需求,设计了基于FPGA的快速数字化信号采集处理系统,实测获取了标准饱和模型井的γ射线谱,并分析了来自镭系214Bi的934 keV及1 120 keV对于1 001 keV能峰的剥谱影响,构建了1 001 keV能峰处铀镭比例系数,最后利用1 001 keV能峰剥谱后的净面积计算了238U含量,并在国家标准饱和模型井实测验证。结果表明,利用1 001 keV能峰在各标准饱和模型井的238U测量值与标称值相对偏差均在±10%以内。

     

    Abstract: In order to detect the uranium content of the formation directly through on-site logging technology without uranium radium balance correction and radium radon balance correction in uranium resource exploration, a new type downhole γ spectrum uranium measurement technology based on cerium bromide (CeBr3) detector was studied. Aiming at the high-intensity γ-ray acquisition requirement of underground uranium ore bodies, a fast digital signal acquisition and processing system based on FPGA was designed, and the γ-ray spectrum data of the standard saturation model well were obtained through actrual measurement. And the effects on the stripping spectrum of 1 001 keV energy peak were compared and analyzed from the 934 keV and 1 120 keV energy peaks of radium series 214Bi. And then, the proportional coefficient relationship between 238U and 226Ra at the 1 001 keV energy peak was constructed. Finally, the net area of the 1 001 keV energy peak after stripping was used to calculate the 238U content, which was verified by the national standard saturation model well. The results show that the relative deviation between the 238U content of each standard saturation model well measured by the 1 001 keV energy peak and the nominal value is within ±10%.

     

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