Permeability characteristics of sandstone based on NMR-coupled real-time seepage

Aiming at the problem that the traditional macro-relationship between porosity and permeability is difficult to accurately predict the permeability characteristics of reservoir sandstone, the nuclear magnetic resonance-coupled real-time seepage system is used to explain the variation of micro-pore-structure for sandstones in the process of penetration. The effects of the multi-scale pore compression coefficient on the permeability characteristics are quantitatively analyzed. Then, a formula for calculating the permeability of sandstone considering the pore compression sensitivity at multiple scales is proposed. The results show that: (1) The deformation mechanism of multi-scale pores is different under different stress conditions. The increase of the confining pressure leads to the obvious closure of large pores, while the increase of osmosis pressure promotes the development and expansion of small pores. (2) The proposed method for the permeability considering pore compression sensitivity at multiple scales has a good consistency with the experimental results.