Point of zero charge for sandstone and carbonate rocks by streaming potential

Abstract

Point of zero charge (PZC) is defined as the PH at which a solid surface submerged in an electrolyte, exhibits zero net charge. Previous studies have reported different values of PZC for carbonate and sandstone rocks, mostly utilizing the electrophoresis technique. The aim of this study is to investigate and verify the PZC of carbonate and sandstone rocks. The PZC measurements were conducted in various brine salinities. Voltage measurements were recorded at a sampling rate of 1 Hertz by the National Instrument Data Acquisition System, using LabVIEW software. The PZC for both carbonate and sandstone rocks has been observed in the range of 9.40 to 9.70 and 2.2 to 2.9 respectively. As streaming potential measurement has been proposed to monitor water encroachment, having the understanding of PZC value will enable the signal to be interpreted more accurately. As a result, water encroachment issue will be overcome efficiently.