HIGH RESOLUTION SEISMIC METHOD FOR SHALLOW GAS HYDRATES EXPLORATION

The shallow gas hydrate is a very important exploration target of gas hydrate resources. It is also very important for prediction and evaluation of deep-water geo-disasters and their climatic consequences. Seismic exploration is a basic mean for gas hydrate exploration. However, the shallow gas hydrate occurs in the sediments near the seafloor, of which the buried depth is generally less than 60 m, and dominated by high frequency signals. Therefore, it requires a high shallow seismic resolution. Conventional seismic exploration methods are not able to meet the needs in the shallow gas hydrate exploration. According to the characteristics of shallow gas hydrates, we proposed in this paper a high-resolution seismic exploration method, which fully uses the advantages of small-scale high-resolution multichannel seismic technology, combined with the parametric array sub-bottom profile. This method has much improved the seismic resolution for the shallow deposits, and good enough to meet the requirements of data resolution for the shallow gas hydrate exploration. The bottom simulating reflector (BSR) of the shallow gas hydrate is usually not so obvious, and closely related to methane leakage. Therefore, the geomorphic features related to gas leakage in the seafloor, gas migration pathways, velocity anomalies and amplitude anomalies are important indicators for recognition of shallow gas hydrates.