Numerical Modeling Of Seismic Wave Field And Property Research For The Gas Hydrate

This paper relies on my tutor's Natural Science Fund Project: the nature gas and hydrateresearch on the basic of the composition elastic porous media (No: 40474043). On the base ofthe research for the composition elastic porous media theory, combine it with the seismicwave modeling to study the seismic wave field trait. Correlative achievements can be apotential theory and method basis for the seismic exploration and of the gas hydrates.The research content includes:In this paper, describes the developed history and research present situation about thetheory of the porous media from both the rock physics and the wave physics, and detaileddescribes the composition elastic porous media model. The results from these methods arecompared and analyzed, and the composition elastic porous media model is reasonable.The paper adopts the staggered-grid high-order difference method of one-order elasticwave equation, and uses the C programming language to achieve the wave field numericalsimulation. We adopt the equivalent method for the porous media. The paper adopt the threetypical geology models, detailed describe the transmission trait on the time and space of thesource, and the reflected wave, transmission wave, refracted wave and the diffracted wave ofthe elastic interface.Based on the above research, analyzes the applicability of AVO in hydrate research:When the hydrate saturation is less than the critical saturation, the AVO curve can indicatewhether there exists any gas below the BSR, and it doesn't work when the hydrate saturationis more than the critical saturation. The paper also combines the AVO to analyze the possiblecause of the BSR: (1) It has free gas below the BSR;(2) the hydrate saturation is very highwhen there isn't any free gas below the BSR. The research on blanking zone combines theCGHC and VGHC models. It shows the reason is hydrate saturation changing with porosity.But in reality, the sedimentary deposit is more complex, so it must integrated different datasuch as geochemistry and geology to improve the research accuracy.This paper also discusses the effect to the seismic parameters when the difference of theporosity or the hydrate saturation. It indicates the former effect is larger than the latter.In the end, the paper researches the NIU2 equation, and compares the results from otherequations, the Poisson's ration computed by the NIU2 equation is reasonable.