流体敏感性损害对页岩纳米孔的影响

通过页岩流体敏感性损害试验和液氮吸附试验研究龙马溪组黑色页岩在流体矿化度和pH值变化时岩石渗透率和纳米孔隙结构的变化。结果表明:龙马溪组页岩经流体损害后,速敏、盐敏和碱敏损害程度表现为中等偏强到强;页岩微孔和中孔分布并不均匀连续,孔径为1~30 nm,以0.3和3.8 nm分别为峰值的双峰分布;盐敏损害对岩石纳米孔的影响较小,碱敏损害使页岩孔喉直径减少13.20%,比表面积增加32.85%,同时产生大量1 nm孔隙,孔径分布由损害前的双峰状改变为三峰状分布;流体对岩石的溶蚀作用及新矿相的生成是页岩产生盲端微孔和连通微孔阻塞的原因。

Influence of fluid sensitivity damage on nano-pores of shale reservoir

The shale permeability and nano-pore structure variation of the black shale in Longmaxi group were studied subjecting different fluid salinities and pH via a fluid sensitivity damage method and nitrogen adsorption experiment. The results show that the degrees of the sensitivities of the shale rock sample to flow, salt and alkali damages can be ranked as medium to strong. The distributions of micropores and medium pores in shale are not uniformity. The pore diameter varies from 1to 30nm, with a bimodal distribution peaks at 0.3nm and 3.8nm. Salt sensitivity damage has little impact on the nano-pores, while alkali sensitivity damage can make shale pore diameter reduce by 13.20%, and the specific surface areas increase by 32.85%. Alkali sensitivity damage can generate a large number of micropores around 1nm in diameter, which makes the original bimodal distribution of pore sizes into tri-modal peaks. The fluid dissolution and new ore generated are the reasons that might produce many blind-end micropores and may also block some connected micropores.