SEISMIC WAVE FIELD SIMULATION AND CHARACTERISTIC ANALYSIS OF SUBMARINE SHALLOW GAS

With the consideration of the viscosity of the seabed medium, we discussed the two-dimensional viscoelastic wave equation in this paper and established upon it the seabed shallow gas model which includes the physical parameters of density, quality factor and so on, in order to accurately describe the target of interest. Then, using the numerical simulation method, we calculated the seismic responses for four kinds of seabed shallow gas model, i.e. the group (block) shallow gas, high-pressure gasbag, concave airway, and gas diapir. In order to effectively suppress the numerical dispersion caused by difference calculation of the coarse grid, the transmission of flux correction (FCT) algorithm is applied to the solution of wave equation, to enhance the precision of seismic wave field simulation and computation efficiency. Through the calculation, we obtained the seabed seismic profile characteristics of shallow gas under the condition of different gas reservoir, and the identification marks of typical acoustic profiles. The results may provide an effective mean for scientific research of marine geohazard survey.