气枪激发信号传播的谱元法数值模拟研究

Study on SEM numerical simulation of airgun signal transition

为了研究气枪激发信号的波场,本文利用谱元法对双相介质中波的传播做了数值模拟,分析了波的传播特征.本文主要做了以下工作:(1)研究了使用谱元法(SEM)模拟孔隙弹性介质中波的传播,模拟结果表明,采用谱元法能有效解决双相介质的波场传播模拟问题.(2)验证了Biot理论中慢纵波的存在.双相介质中存在明显的慢纵波,流相波场的慢纵波比固相波场的明显,慢纵波具有很强的散射性质.(3)研究了地震波在孔隙度变化的沉积层中传播规律,验证了孔隙度对于相速度的影响.(4)针对有限的水库底部情况,研究了起伏界面对波传播的影响.

In order to study the wave field excited by signal gun, we deduce the seismic wave equation from the theory of porous media based on averaged method. We do the numerical simulation of seismic wave propagation by the spectral element method. We mainly do the following work： （1） We present a numerical implementation of the Biot equations for 2-D problems based upon the spectral element method （SEM）,the simulation result shows that SEM can simulate wave propagation effectively. （2） Validate the existence of the Blot＇s slow compressional wave. We study wave propagation at acoustic-poroelastic discontinuities. （3） study wave propagation in compacted sediments with gradients in porosity, influence of porosity on phase velocity. （4） As the reservoir bottom is limited, influence of fluctuant interface on wave propagation. demonstrate We the we investigate the