Fabrication of High-Stability Solid-State Receiver Electrodes in Exploration System for Detecting High-Resistive Gas Hydrates

Tuesday, 3 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
C. S. Kuo, H. T. Peng, and J. Y. Lin (Department of Chemical Engineering, Tatung University)
Generally, gas hydrate is nearly a prefect isolator with electrical resistivity of ca. 20,000 Ω·m. Therefore, the resistivity of seafloor sediments with brine-filled pores typically ranges from 0.5 – 1.0 Ω·m, whereas sediments containing hydrate within the pores can have resistivity of ca. 10 Ω·m. As for massive blocks of hydrate, it can have resistivity of 100 Ω·m or more. Up to date, electromagnetic (EM) and direct current resistivity (DCR) techniques are generally employed to explore gas hydrate by measuring electrical resistivity. Nevertheless, both of methods still require high-stability receiver electrodes for monitoring the variance of potential difference. 

In this study, the solid-state silver/silver chloride (Ag/AgCl) electrodes were successfully developed for using at high-pressure environment of deep sea. To evaluate the potential of solid-state Ag/AgCl electrodes as the receiver electrodes in EM and DCR systems, the effects of temperature, composition and flowing velocity of simulated seawater solution on the stability of the solid-state Ag/AgCl electrodes were investigated systemically. The solid state electrodes showed potential variance of ± 0.35mV at environment of room temperature or 5 . Moreover, it revealed that the potential variance within ± 0.4mV when the simulated seawater solution containing 0.009 wt% bromide or 0.5wt% sulfate ion. Furthermore, it presented the potential variance within ± 0.45mV at flow rate of water in 1.5 m/s or vibration frequency at 100 Hz. Therefore, the fabricated solid-state Ag/AgCl electrode could be a promising receiver electrode candidate in EM or DCR exploration system for detecting the high resistive target, gas hydrate, under the shallow sea bead.