A study on the identification technique of high- amplitude "bright spots" in the Huagang Formation of the X gas field in the Xihu Depression

Abstract Due to the small number of exploration wells and similar AVO (Amplitude Versus Offset) types of different fluids in the study area, the use of conventional P (fitting intercept), G (fitting gradient), P×G, P + G and other hydrocarbon detection attributes can no longer effectively identify the fluid properties of the study area, and it is urgent to find a hydrocarbon detection method suitable for the effective reservoirs in the area. Through the analysis and statistics of single-point pre-stack AVO of the drilled wells, the intercept and gradient intersection template for fluid identification are established. The gas-bearing sandstones show obvious AVO characteristics of class II ~ III, and different fluid types are basically distinguishable in the intersection template. We propose the scalar Poisson ratio attribute by borrowing the idea of the study of Poisson impedance, which can enhance the sensitivity of the identification of gas-bearing in the study area, and it can be used in the gas-bearing in the Xihu Depression. Good application results have been achieved in the hydrocarbon detection in the middle and deep layers, and progress has been made to improve the reliability of hydrocarbon detection in the reservoirs in the less well area.