Abstract:

Bottom simulating reflector (BSR) is the main indicator of gas hydrates. However, there are still two problems which are not successfully solved up to now in identification of gas hydrate: one is how to identify hydrate sediments when BSR is not clear or not in existence on seismic sections, and the other is how to recognize the top of the hydrate layer and the bottom of the free gas layer. In this paper, the seismic data of line USGS95-1 in Blake Ridge are studied through wavelet multi-scale method to show that wavelet scales of seismic data from hydrate sediments are larger than the ones of the data from free gas layer.Moreover, the gas hydrate layer on optimal-scale section shows a high scale zone of paralleling bottom in the low scale background. This difference in wavelet scales of seismic data between gas hydrate sediments and free gas area can be used not only to recognize gas hydrates, but also to distinguish the top of the hydrate layer and the bottom of the free gas layer.

Key words: gas hydrate, wavelet transform, bottom simulating reflector, optimal scale, free gas, Blake Ridge