Rock physical modeling and sweet spot characteristics of tight reservoir constrained by high-temperature and high-pressure experimental data——A case study of Huagang Formation in Xihu Depression

Rock physics models serve as a bridge connecting reservoir physical property parameters and elastic parameters. However, traditional rock physics modeling is usually carried out under normal temperature and pressure conditions, ignoring the influence of formation temperature and pressure on rock physical properties. Studying the relationship between physical parameters such as porosity and water saturation and seismic parameters under reservoir conditions (high temperature and high pressure) is of great significance for the accurate identification and quantitative interpretation of reservoir sweet spots. Taking the tight sandstone reservoir of the Huagang Formation in the Xihu Depression as the research object, based on high-temperature and high-pressure rock physics experiments, this paper fits the response relationships among the elastic parameters of rock matrix, dry rock skeleton and saturated rock, then establishes a rock physics modeling method based on the KT model and WPH model, finally clarifies the rock physics response characteristics of the tight sandstone reservoir sweet spots of the Huagang Formation, compiles rock physics templates and identifies the sweet spot-sensitive elastic parameters. The results show that the rock physics model based on the KT model and WPH model has high simulation accuracy for the tight sandstone reservoir of the Huagang Formation in the Xihu Sag, with the velocity curve reconstruction error less than 5%; the sweet spot-sensitive parameter is the P-wave to S-wave velocity ratio, and the ratio less than 1.65 can effectively indicate sweet spots.