基于CATO方法的碳氧比能谱测井资料解释

Interpretation of C/O spectral logging data based on CATO

根据碳氧比能谱测井的原始谱线资料,采用了一种新的方法,即CATO方法来计算剩余油饱和度。CATO是碳氧比能谱测井中,非弹性散射谱线中消除了氧计数影响的非弹性散射计数率与氧的计数率的比值,该值对油和水的响应与常规碳氧比值相似;但相对常规碳氧比值,它具有统计涨落小、受岩性变化影响小、对油水的响应增加等优点。通过实际资料验证,该方法对水淹层的剩余油有很好的判断作用,具有良好的应用前景。

The C/O spectral logging is one of the effective methods to distinguish the oil and water layer, to determine the water saturation and to identify lithologies in a cased hole. This paper introduces a new method, that is, cation/oxygen ratio (CATO), a carbon/oxygen type measurement, to calculate the residual oil saturation based on the raw spectral logging data. CATO is the ratio of all inelastic gamma rays except those from oxygen, to the oxygen inelastic gamma rays. Relative to the conventional C/O method, CATO has such advantages as follows: less statistic variation, less influences on the variation of lithology types and more sensitive to the differences on oil and water. The results show that this method can cope with the conventional interpretation method very well and has a very good perspective in the oil development phase.