Characterizing spatial distribution of ice and methane hydrates in sediments using cross-hole electrical resistivity tomography

Electrical resistivity is an essential parameter for assessing the abundance of gas hydrates and predicting their location. However, imaging techniques are poorly developed for detecting the electrical resistivity distribution of hydrate-bearing sediments. In this study, a cross-hole electrical resistivity tomography (CHERT) array was established in the large-scale simulator for characterizing the spatial distribution of the sedimentary system. Iceand methane hydrate-bearing sediments were investigated respectively using CHERT. The results show that CHERT effectively observed the significant influence of methane hydrate/ice formation and salt drainage on the variations in electrical parameters. Their formation leads to a sustained increase in average resistivity, while salt ion exclusion leads to an increase in pore water salinity, resulting in a decrease in local resistivity. Moreover, CHERT observed a range of resistivities from a few Omega & sdot;m to several thousand Omega & sdot;m for ice- and methane hydratebearing sediments, which is consistent with the resistivity response of hydrate reservoirs in the field. It is suggested that CHERT can be used for hydrate reservoir detection and combined with acoustic imaging to more accurately characterize the spatial distribution of hydrates. These results contribute to advancing the potential application of CHERT technology in multi-method and multi-scale gas hydrate monitoring initiatives.