Virtualized Broadband Measurement Method For Rock Electrical Properties

Electrical properties of reservoir rock are important factors to evaluate oil and water layers, underground oil and gas reservoir distribution. Accurately describing the dielectric behaviors of rock is of great significance to the electrical logging application. In this paper, a new virtualized broadband measurement method for rock electrical characteristics based on the principle of parallel-plate capacitor is proposed, and the validity and accuracy of this method are verified.Based on a thorough investigation of the parallel-plate capacitor method for electrical parameters measurement, a numerica l parallel-plate capacitor device is precisely modeled by the electromagnetic simulation software HFSS. Virtualized measurement for electrical properties of several virtualized tested samples is conducted by numerical simulation in a frequency range of 100K-1GHz. The simulated results, theoretical reference value and the experimental measurement results agree well, which validates the feasibility of virtual measurement. However, the measured value is not stable at high frequency band and deviated from the theoretical reference value above 700 MHz. Optimization is carried out to improve the impedance transformation of the virtual measuring system based on the in-depth analysis of the structure and electrical field distribution. And a set of experimental measurement fixture which optimizes the high frequency measurement is realized. The experimental measurement results obtained by the optimized measurement system are more stable and accurate in a frequency range of 100K-1GHz, which realizes wideband measurement for the rock electrical properties. In a frequency range of 100K-1GHz, virtualized measurement and analysis for numerical model of several classical rock composite materials with different crystal structure is conducted by the optimized parallel-plate capacitor model. The virtualized measurement results agree well with the theoretical results, which further verify the validity and accuracy of the virtual measurement method. This work can provide an effective basis for the analysis of the electrical properties of composite materials with arbitrary microstructure and the research of digital core.