Experimental Research of Shale Gas Electrical Properties Based on Fluid Distribution

This paper presents an experimental method by establishing the relationship between RI-Sw and T2 distribution to research electrical properties of shale gas. A full range of water saturation is established based on an appropriate combination of spontaneous imbibition and semi-permeable plate drainage. NMR is used to identify water saturation and T2 distribution of water saturated pores which contribute to the conductivity. The RI-Sw curve shows a nonlinear relationship, and it can be divided into three parts with different behaviors. Experimental researches indicate that, free water, and water trapped by capillarity in the non-clay matrix, differ in terms of electrical conductivity from water absorbed in clay. In shale gas, the conductivity contribution of free water shows power law behavior on a double logarithmic scale. While clay bound water shows an exponential law characteristic on the double logarithmic scale. The new experiments prove the applicability of imbibition, drainage and NMR in investigating electrical properties of shale gas and distinguishing fluid distribution which makes contribution to conductivity.