无机盐对气藏砂岩表面动态润湿性的影响研究

Study on effect of inorganic salts on dynamic wettability of sandstone surface in gas reservoir

为了研究低矿化度水水驱过程中盐离子及矿化度与岩石润湿性的关系,用接触角测定仪测定了盐水在砂岩表面的接触角随时间的变化,并对变化机理进行了探讨。结果表明:液固之间的接触角随时间的增加而减小,初期减小速度较大,后期较小;水相中盐离子增加了砂岩表面的疏水性,降低了水在砂岩表面的润湿速率,润湿速率随矿化度的增加先增加后降低;Ca2+、Mg2+对润湿性的影响大于Na+。

The varying process of the contact angle of salt water on the sandstone surface with time is tested using contact angle tester,and the varying mechanism is discussed. The result shows that the contact angle is always decreasing with the increase of time,and the decreasing rate of the contact angle at beginning is greater than that in later period; the salt ions in water increase the hydrophobicity of sandstone surface and reduce the wetting rate of the sandstone surface,while the wetting rate increases firstly and then decrease with the increase of the salinity of salt water; the effect of Ca2 +or Mg2 +on the wettability of sandstone surface is greater than that of Na+. The study result proves that the low salinity water flooding has important influence on oil and gas exploitation.