Resistivity Response of Hydrate-Bearing Silty-Clayey Sediments under Temperature-Electricity-Mechanical Coupling Properties

Studying the resistivity response of hydrate-bearing silty-clayey sediments under an undrained state is vital for exploring and monitoring natural gas hydrates. To this end, samples with varying hydrate saturations and effective confining pressures were synthesized by using a triaxial apparatus with an integrated resistivity measurement system. The resistivity response characteristics were systematically investigated throughout the entire experimental process. The experimental results demonstrate the following: (1) Temperature and initial water saturation significantly affect sediment resistivity, and cooling can increase sediment resistivity by up to 50%. (2) Hydrate formation causes a sharp rise in sediment resistivity, while preformation conditions (including stress history, initial water saturation, and hydrate saturation) exhibit a notable influence on postformation resistivity. (3) Water saturation leads to substantial resistivity reduction, whereas consolidation shows relatively minor effects. (4) Shearing behavior gradually decreases resistivity, with drainage conditions critically impacting pore structure evolution. Under 1 MPa effective confining pressure, undrained conditions yield over 200% greater resistivity reduction than drained conditions. The research conclusions are expected to provide theoretical support for the exploration and exploitation monitoring of natural gas hydrates in silty-clayey reservoirs in the South China Sea.