Dielectric Dispersion of Hydrate-Bearing Artificial Sediment—Detection Method and Experimental Observations

In this article, we reported a critical improvement on the measurement method for the dielectric dispersion characteristics of hydrate-bearing sediment in a frequency range between 1 MHz and 3 GHz, and, with the use of the method, a systematic evaluation of the microwave dielectric dispersion of the hydrate-bearing artificial sediment and influence factors. First, the optimized and verified procedure of the dielectric detection method was introduced, followed with the results of complex permittivity (CP) measurements obtained by carrying out a series of experiments with different dielectric configurations. To balance the frequency coverage of the dispersion characteristic of both hydrate and solution among the dielectric measurement, the inversion means of the open-ended coaxial (OEC) probe was improved so that the lower frequency limit of the method has been extended as low as 1.0 MHz. Furthermore, error analysis based on the experimental results among the overlapping frequency range with cylindrical capacitance verified the detecting accuracy of the OEC probes below 10 MHz. The microwave dielectric dispersion of hydrate-bearing artificial sediment as a function of sediment particle size, temperature, and clay content was determined. It was found that the dielectric spectrum is not only routinely dependent on the porosity and temperature, but more importantly, the introduction of clay content has a distinct dynamic influence on the dielectric spectrum and the formation and dissociation process.