Abstract：The quality of carbon - oxygen ratio spectral logging curves not only depends on the characters and technical level of logging instrumentation itself,but also depends on the element contents of borehole and stratum as well as the impact of such factors as logging environment,logging speed and sample interval et al.Using the time series analysis method presented by Mr. Kerford and Georgi,the indexes ( repeatability,S/N ratio and vertical resolution ) of each ratio curve of real-tested carbon - oxygen ratio spectral log can be estimated quantitatively by using coherent technique.The practical application showed that carbon - oxygen ratio,silicon - calcium ratio,porosity indicator ratio,iron indicator ratio and salinity indicator ratio of carbon - oxygen ratio spectral log measured by single detector have good quality and can be used for practical interpretation,but lithology indicator ratio and calcium - silicon have bad repeatability and can't be used for practical interpretation;carbon - oxygen ratio,silicon - calcium ratio,porosity indicator ratio and salinity indicator ratio measured by double detector have better quality than that by single detector,among which the quality of carbon - oxygen ratio spectral logging curves measured by far detector is better than that by near detector,the quality of capture curves is better than that of non-elastic dispesive curves.
