海底浅层气的地震波场模拟与特征

    SEISMIC WAVE FIELD SIMULATION AND CHARACTERISTIC ANALYSIS OF SUBMARINE SHALLOW GAS

    • 摘要: 考虑海底介质的黏滞性,讨论了二维黏弹性波动方程,建立了包含密度、品质因子等物性参数的海底浅层气模型来精确描述目标,采用数值模拟的手段,正演计算了地震波在团(块)状浅层气、高压气囊、下凹气道、气底辟等4种不同海底浅层气模型中的传播响应。为了有效地压制在粗网格下差分计算产生的数值频散,将通量校正传输(FCT)算法应用于波动方程的求解中,提高了地震波场模拟的精度和运算效率。通过计算获得了不同储存层条件下海底浅层气的地震波剖面特征,得到了典型声学剖面识别标志,为海洋地质灾害勘察提供了一种有效的科学研究手段。

       

      Abstract: 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.

       

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