Simultaneous measurement of hysteresis in capillary pressure and electric permittivity for multiphase flow through porous media

Abstract

Abstract We present a tool that simultaneously measures the complex permittivity and the capillary pressure characteristics for multiphase flow. The sample holder is a parallel plate capacitor. A precision component analyzer is used to measure the impedance amplitude and phase angle as a function of frequency (1kHz to 3MHz). The complex impedance of the (partially) saturated sample is directly related to the effective complex permittivity. We have conducted main drainage and main imbibition cycles for unconsolidated sand-water-gas (CO2∕N2) systems at 8-bar pressure and at temperatures between 27°C and 28°C. Hysteresis in capillary pressure and electric permittivity, as a result of phase distribution, is found between drainage and imbibition for f=3MHz and becomes more pronounced at higher water saturations. Good agreement of the measured electric permittivity with the complex refractive index model indicates that induced polarization is not observed for 3MHz and the water saturation is reasonably predicted. The experiments have been performed to study the capillary pressure behavior during CO2 sequestration.