Hoda Yari - Department of Earth Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
Majid Nabi-Bidhendi - Institutes of Geophysics, University of Tehran, Iran
Naser Keshavarz - Geoscience Faculty, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
Reza Heidari - Department of Earth Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran

Due to the substantial effect of the gas hydrate distribution model (cement, un-cement, or hybrid of both models) on the elastic properties (such as shear modulus, bulk modulus, Poisson’s ratio, etc.), determining the distribution model in the hydrate-bearing sediments is a requirement for decreasing uncertainty in quantitative studies based on seismic velocities. Many different empirical and theoretical rock physics theories cover different ranges of rock properties. Among them, the Effective Medium Theory (EMT) is the most appropriate in quantitative studies of gas hydrate resources. Four types of hydrate distributions have been considered and divided into two cemented and un-cemented categories. EMT is one of the advanced rock physics modeling tools. This theory has been modified by introducing hybrid distribution models of gas hydrate instead of having assumptions about single models of hydrate distribution. Moreover, when a scientific manuscript is written, using dangling and misplaced modifiers are not suggested. On the other hand, one method to determine the gas hydrate distribution model can be performed by identifying AVO’s class on the bottom simulating reflector (BSR); caused by the contrast between an overlying gas hydrate and underlying free gas sediments. This reflector mimics seafloor topography, cross-cuts stratigraphic reflections, and is controlled by thermodynamic conditions. The results of this study on conceptual models showed that in hybrid approach for hydrate distribution, AVO’s class on BSR shows sensitivity to (۱) the combination type of gas hydrate distributions models, (۲) the total saturation of the gas hydrate and free-gas across the BSR.

Gas hydrate distribution, Effective Medium Theory (EMT), hybrid models, Amplitude Variation vs Offset (AVO)