Experimental Study of the Effect of Clay Minerals on the Electrical Characteristics of Clayey Silt Hydrate-Bearing Sediments

Abstract

The mineral composition and content vary greatly in different layers of the clayey silt hydrate-bearing reservoirs in the South China Sea, and the changes in mineral composition and content directly affect the formation and dissociation characteristics of gas hydrates, resulting in differences in electrical characteristics, especially the changes in clay mineral type and content, which have a more significant impact on the hydrate-bearing sediments. In this investigation, the effects of clay mineral types and contents on the synthesis and electrical characteristics of clayey silt hydrate-bearing sediments were studied by simulating the formation and dissociation of gas hydrates. Besides, the microscopic characteristics of gas hydrates were analyzed by high-precision X-ray computed tomography (CT) scanning technology, and the macroscopic electrical behavior mechanism of clayey silt hydrate-bearing sediments containing different clay minerals was revealed. The results show that the formation rate and dissociation rate of montmorillonite silt hydrate-bearing sediments are lower than those of illite silt hydrate-bearing sediments under the same formation and dissociation conditions. Besides, the resistivity of illite silt hydrate-bearing sediments is more significantly affected by gas hydrates. During the process of formation and dissociation, the resistivity of illite silt hydrate-bearing sediments with the same gas hydrate saturation is higher than that of montmorillonite samples.