Study of the properties of non-gas dielectric capacitors in porous media

Abstract

The size of pores and throats is at the nanometer scale in tight oil and shale gas zones, and the resistivity of these reservoirs is very high, so the reservoirs show more dielectric properties than conductivity properties. The conductive and dielectric characteristics of a parallel plate capacitor full of fresh water, NaCl solutions, and solid dielectrics, for example, sands are investigated in this paper, and the capacitance data of the non-gas capacitor are measured at different salinities and frequencies by a spectrum analyzer. The experimental results illustrate that the capacitance of this kind of capacitor is directly proportional to the salinity of the solutions and inversely proportional to the measuring frequency, the same as a vacuum parallel plate capacitor. The remarkable phenomenon, however, is that the capacitance is inversely proportional to the square of the distance between two plates. The specific characteristic of this capacitor is different from the conventional parallel plate capacitor. In order to explain this phenomenon, the paper proposed a new concept, named ''single micro ion capacitor'', and established a novel model to describe the characteristics of this particular capacitor. Based on this new model, the theoretical capacitance value of the single micro ion capacitor is calculated, and its polarization and relaxation mechanisms are analyzed.

Research into the inversion of the induced polarization relaxation time spectrum based on the uniform amplitude sampling method

“…2 The IP RTS and uniform amplitude sampling 2.1 IP discrete equations description and the RTS We assume that the porous medium has the same pore diameter, then the measured IP decay potential will satisfy a single exponential decay law (Tong and Tao 2007;Liu et al 2015). The corresponding relationship between the relaxation time constant and the pore diameter is as follows:…”