The Seismic Response Calculating for Marine Gas Hydrate Based on the Theory of Forward Modeling

摘要

Marine gas hydrate occurs in the top few hundred meters of sediments on the continental slope, it is the important method by using seismic response forward calculating. But the conventional seismic modeling method can't model the characters of the seismic wave propagation. Using the seismic elastic wave theory (Xu 1997), it is more suitable to emulate the seismic response of BSRs. Simulation shows that BSRs are still one of the best indicators of presence of gas hydrate-bearing sediments. If BSRs are found, gas hydrates can be considered to exist. BSRs are primarily caused by free gas beneath the base of gas hydrate stability zone (BGHS). BSRs are approximately corresponding to the BGHS. The relationships between gas hydrate gas system and BSRs should be studied from view points of dynamic evolution. The seismic response of BSRs is the strong reflections, but when the angles of incidence exceed 30 degree, the BSR amplitudes increase fast. In the AVO inversion of real seismic data related to gas hydrate, the Shuey formula (trinomial) is more precise.