页岩在不同活度溶液中的膨胀

Swelling of shale in different activity solutions

用较高活度的页岩样品置于不同低活度的盐溶液上方,测定其吸附等温线,发现溶液活度越低页岩脱水越甚。测定页岩在不同溶液中的线膨胀量。当溶液活度降低到一定值时,页岩开始发生收缩,一段时间后收缩页岩重新膨胀,收缩量随溶液活度降低而增大。证实了活度平衡理论在水基流体中成立,但渗透压是一种动力学现象,具有瞬时特征。最后讨论了毛细管效应不是导致页岩膨胀的主要因素。

Shale swelling experiments were carried out to investigate osmotic hydration. The instruments used in the swelling experiments were digital swelling indicators, with a resolution of 1μm. The linear swelling of three types of shales was measured in vari-ous solutions with different activities. It was again confirmed that ' balanced activity theory' holds true in water-based fluids as in water-in-oil emulsions. It was further concluded that the osmotic pressure in water-based systems is kinetic phenomenon with transient characteristics; there would be no remaining osmotic potential when true thertested were measured and capillary effects investigated. It was shown that the capillary effect is not the only mechanism involved in shale swelling. The aforementioned conclusions are initial and at the frontier of the international research. In addition, this project made some contributions to the existing theory concerning shale swelling. For instance, the unique inhibition mechanism of potassium ions was confirmed from a completely new perspective.