Study on gas identification factor of tight sandstone reservoirs in Lower Shihezi formation from Daniudi Gasfield, Ordos Basin

The tight sandstone reservoirs in lower Shihezi formation from Daniudi Gasfield of Ordos Basin is characterized by low-porosity,and the variation of geophysical characteristics followed by oil saturation and gas saturation is weak relatively, therefore the identification of reservoir fluid is difficult in the area. In order to solve the problem, we optimized gas-bearing sensitive elastic parameters based on rock physical parameters testing. By using the relationship in parameters, we derived computation formula for fluid sensitive elastic parameters and constructed a new gas-bearing identification factor. By utilizing the P-wave and S-wave impedance simultaneous inversion result of prestack seismic data, the data volume of new gas-bearing identification factor was computed and applied to the reservoir fluid detection in Daniudi Gasfield. The application results indicate that the new gas-bearing identification factor can effectively highlight the impact of fluid changes and is sensitive to the gas-bearing tight sandstone reservoirs with good anti-noise capability.