Dual porosity rock physics model for organic-rich shale

Kerogen is not only regarded as a significant indicator for gas source potential, but also seen as an important composition embedded in shale matrix or filled in pore space. Meanwhile, there are also some microcracks existing in kerogen according to SEM observations published previously which are usually ignored. Aimed at multiple pore types developed in Jiannan area, this paper proposes a dual rock physics model with complicated pore types for organic-rich shale. Pore space is divided into two parts - matrix porosity and kerogen porosity. Kerogen pore space is full filled with oil or gas. In addition, matrix pore space is also split into moldic pores, inter-particle pores and cracks. Based on the above analysis, wide discussion about the effects of kerogen on elastic properties of shale is made to provide a guidance for the optimization of interval for fractured. Application on two shale wells from Southern China agrees well with gas detection and practical production, which proves its feasibility and effectiveness.