不同温度、羧酸溶液中长石溶解模拟实验

报道了在100℃、140℃下微斜长石在不同羧酸溶液中的溶解实验数据。通过实验表明1)反应温度增高,可增强溶液中阳离子的活性和迁移性,加快长石溶解的反应速率,促进长石的溶解。2)在强酸性条件下,pH值的变化可影响长石的溶解。但在中等酸性条件下,pH值对长石的溶解影响很小。3)羧酸(乙二酸)可不同程度地促进长石溶解,可通过形成乙二酸络合物的形式,增加离子在溶液中的溶解度。但乙酸络合物的作用不明显。长石溶蚀导致岩石孔隙度变大,并且改善孔喉性质。同时,由于乙二酸络合物的存在,增加了Si在溶液中的溶解度,阻止了石英加大和其它成因SiO₂的生成,有利于次生孔隙和原生孔隙的保存。4)长石溶解使溶液中Al的浓度较高,但由于铝-羧酸络合物的亲油性比亲水性强,故有一部分Al被分配到油相中,这也是目前大多数油田水中Al浓度偏低的主要原因。

Dissolution of Microcline by Carboxylic Acids at Different Temperatures and Complexing Reaction of Al Anion with Carboxylic Acid in Aqueous Solution

Experiments were performed to investigate the effects of mono functional and bi functional carboxylic acids on microcline at different temperatures. The experimental results are as follows: As temperatures arises, the concentrations and mobility of Al, SiO 2 and other components are enhanced to allow rapid dissolution of microclines. At low pH, dissolution of microclines control with pH. However, pH is probably not significant under moderately acidic conditions. Date from these experiments indicate that oxalic and acetic acids reacting with microclines at different temperatures can enhance the solubility of Al and other cat ions and create secondary porosity, although oxalate has a much greater effect than acetate. Although organic acids can enhance substantially the solubility of Al, organic anion aluminum complexes prefer oil to water. So the concentrations of Al in the oilfield waters are low.