Numerical simulation of AVO response characteristics from pore-filling gas hydrate in Qilian mountain permafrost, China

Abstract

The seismic reflection wave amplitude variation with offset (AVO) technique can effectively extract the lithology and fluid parameters that are hidden in the seismic record, and thus can be applied to gas hydrate prospecting and assessments in the permafrost region. Based on the geological conditions of pore-filling gas hydrate reservoir in Qilian mountain permafrost, the forward simulation velocity model of gas hydrate, by the rock physics model of the equivalent medium theory, was established. The AVO response characteristics of the gas hydrate reservoir with different properties by the forward modeling velocity model and the ray tracing theory were studied. The sensitivity of elastic parameters, for gas hydrate reservoir identification and formation lithology, was also studied. The AVO attribute partition changing with the porosity is quite well; the AVO attribute partition changing with the saturation presents continuous transition and could not be distinguished easily, and the AVO attribute partition changing with the thickness of the gas hydrate reservoir is linear. The μ and E are the most sensitive parameters to the properties of the gas hydrate reservoir, the crossplot of μ and E can effectively identify the gas hydrate reservoir, and the crossplot of μ and λ/μ could identify the lithology of the gas hydrate reservoir.