基于NMR耦合实时渗流的砂岩渗透特性研究

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

针对传统宏观孔渗关系难以准确预测储层砂岩渗透特性的问题,采用核磁共振耦合实时渗流系统,从细观角度阐述了渗透过程中砂岩孔隙结构变化规律,定量分析了多尺度孔隙压缩系数对渗透特性的影响,进而提出了一种考虑多尺度孔隙压缩系数的砂岩渗透率计算方法。结果表明:(1)不同应力条件对多尺度孔隙作用机制不同,围压增大导致大孔隙明显闭合,而渗压增大促使小孔隙发育扩展;(2)考虑多尺度孔隙压缩系数的砂岩渗透率计算方法与试验结果拟合更好。

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.