资源环境科技发展态势分析平台

It is widely accepted that the zeta potential in natural sandstones is negative in the brine pH and compositions found in the subsurface. The zeta potential is a measure of the electrical potential at a mineral surface. We report new measurements of the zeta potential using a saline natural brine rich in divalent ions. The sandstones samples were quartz-dominated but some also contained dolomite, siderite and clay minerals. The quartz-dominated sandstones showed behaviour consistent with earlier studies, but the dolomite- and siderite-bearing samples returned positive zeta potentials. We suggest that this is caused by a positive zeta potential on dolomite and siderite mineral surfaces, adsorption of divalent ions onto quartz mineral surfaces and/or ion exchange with clay minerals. The results have broad implications for the zeta potential of natural sandstones, because the magnitude and polarity of the zeta potential impact geophysical monitoring and the transport of the charged contaminants.