Rock Physics Model for Tight Sandstone with Complex Pore Geometry

Tight sandstone gas with abundant reserve and wide distribution will be the key field in seismic prospecting. We introduce the digital characterization for the micro pore structures in tight sandstone based on high-resolution CT scanning technology, and then build a pore geometry model with several types of pore shapes and two types of pore connectivity. When elastic wave propagates in this kind of porous medium, fluid in pores with different shapes and connectivity will respond differently, which affect the elastic properties of tight sandstones. Therefore, we apply Biot-Gassmann equation and Mori-Tanaka model to analyze the connected and isolated pores respectively, and then formulate a new rock physics model. By comparison with experimental data, this model can give more reasonable explanation.