Elastic Characteristics And Petrophysical Modeling Of The Jurassic Tight Sandstone In Sichuan Basin

In recent years, a breakthrough has been made in the hydrocarbon exploration of the Jurassic continental tight sandstone in Sichuan Basin. It has clarified that the transition zone between central and Western Sichuan has the geological conditions to form large-scale gas fields. However, there are few studies on the elastic properties of this set of tight sandstone, resulting in the low accuracy of "sweet spot" reservoir prediction using seismic methods. To solve this problem, this study uses 32 samples from the Jurassic Shaximiao Formation in the Sichuan Basin to conduct a systematic acoustic measurement, based on which the change pattern of seismic elastic properties of the samples are analyzed. The effects of different diagenesis on rock reservoir performance are determined by integrating X ray diffraction mineral composition analysis, scanning electron microscopy, and thin section characteristics of castings and rocks. Results show that the tight sandstone reservoirs in the study area behave like a porous type, and is affected by differential diagenesis. The differences in clay, calcium and silica contents as well as their different distribution characteristics have a great impact on the elastic properties of rocks. The early calcitic cementation as well as the compaction and dissolution with intense plastic elastic particles has significant impact on the rock porosities and seismic elastic properties in the study area. Therefore, the petrophysial model of the tight sandstone in the study area is established by using a contact-cementation model, differential equivalent modulus model and the Hashin-Shtrikman upper bounds for critical porosity correction, respectively.