巴西桑托斯盆地盐下白垩系储层埋深4000～6000 m,流体性质极为复杂,流体类型识别困难.基于CO2不含氢元素及其超临界状态下与油密度相当的物理特性,选取反映流体含氢指数的中子测井、随钻核磁共振测井与电缆核磁共振测井及密度测井,在有随钻核磁共振测井情况下通过密度孔隙度-电缆核磁共振总孔隙度与随钻核磁共振总孔隙度之间的差值交会,在无随钻核磁共振测井情况下通过密度孔隙度-中子孔隙度交会,并结合地层测试、试油结果实现超临界状态CO2半定量评价和流体识别.研究结果表明,参加检验的储层流体类型综合识别符合率达86.6，,证明该流体识别方法在巴西桑托斯盆地盐下应用效果较好,是解决含超临界CO2复杂流体识别的有效技术手段.

The fluid properties of the pre-salt reservoir in Santos Basin, Brazil are extremely complex. In addition to conventional oil and gas, there are also non-hydrocarbon gas layers dominated by supercritical CO2, condensate gas layers containing supercritical CO2 and volatile oil layers. In the formation at depth of 4 000-6 000 m, the density of supercritical CO2 is similar to that of oil, and the difference in response characteristics of conventional logging is small, so it is extremely difficult to identify the fluid type. There are few studies on this in the world, and there is a lack of effective technical means. In this paper, based on the physical property that CO2 does not contain hydrogen and its supercritical condition is equivalent to the oil density, neutron logging, NMR logging while drilling and NMR logging and density logging reflecting the hydrogen content index of the fluid are selected. By crossing of density porosity-neutron porosity and density porosity-total porosity difference of NMR logging while drilling and NMR logging, the semi-quantitative evaluation of supercritical CO2 and identification of fluid were realized by combining with formation test and oil test results. The results show that the coincidence rate of the comprehensive identification of reservoir fluid types is up to 86.6，, which proves that the identification method has a good application effect in Santos Basin, Brazil. This technique is an effective method to identify complex fluid containing supercritical CO2 and is of great significance to well logging interpretation and evaluation.