Abstract: Many gas wells were discovered in Z blocks, and the number of gas layer is larger in single well and the total gas is thick. In the seismic profile, the gas-bearing event features in higher thickness, dropping down and low frequency. There are many reasons for òbright spotó in this area, and the gas and gas-water layer of different saturation is strong in amplitude. Studies suggest that it is not difficult to identify the distinction between the water and gas, but the quantitative prediction of gas saturation. In this paper, based on pre-stack inversion and rock physics analysis, perturbation experiments were conducted to identify the sensitive parameter for saturation and obtained the sensitive parameter and the relationship between the density and saturation. Finally the relationship was used to examine the application effect in overseas oil and gas basins.

Key words: pre-stack inversion, rock physical analysis, sensitivity parameter perturbation experiment, density and saturation prediction