The subsalt lacustrine carbonate rock in the Santos Basin is a hot spot in global oil and gas exploration. The water depth of the area exceeds 2000 m. It is difficult to accurately identify the fluid properties in discovered subsalt oil reservoirs because of varying degrees supercritical CO2, presence of Oil zone and low resistivity oil zone and oil-based mud drilling, and brought difficul-ties and challenges in oil and gas exploration, development and production. Based on free hydrogen of CO2 physical characteristics and the density close to oil density in supercritical condition, establish a logging variance re-sponse relationship under different CO2 volume of oil and gas zones and quantize the difference to accurately calculate the volume of CO2. Accord-ing to the analysis of logging and mud logging response characteristics in low resistivity oil zone, combine different evaluation method such as cross plot method, mud logging method, the two-dimensional nuclear magnetic technology and MDT pressure data to effectively identify low resistivity oil zone. The quantitative calculation of the CO2 volume has high accuracy, and the comprehensive identification method of the fluid property is valid. The re-sults were verified by testing and coincidence rater was more than 95%. This technical method has an important guidance and reference value in oil and gas exploration in the Pre-Salt of Brazil.