The Research Of Seismic Forward Modeling Based On Frequency-dependent Rock Physical Model

When the seismic wave propagates in a complex underground medium,for example,the medium includes multiple fluid types or existence of cracks or complex rock skeleton features,the seismic waves will disperse and decay during propagation.Based on the different factors that cause the dispersion and attenuation of seismic waves,a layered media model filled with multiphase fluid is constructed to analyze the dispersion and attenuation of seismic wave propagating in this medium when a large number of fluids are contained underground features,provides a new idea for the practical application of reservoir prediction and fluid identification.Based on the consideration of fluid containing fluid in porous media,a three-phase periodically stratified patchy saturation model is constructed and the three-phase periodic stratified model under the Biot's theoretical framework is deduced,the seismic wave velocity dispersion and attenuation expression is showed.In this paper,we consider the various types of fluids,the heterogeneity of skeletons and the mineral composition in the background medium,and analyze the factors which may cause the dispersion and attenuation of seismic waves.The three-phase periodic layered patches are saturated rock physical model and found that when the three fluids were filled in different order,the attenuation and dispersion characteristic were also different.Then it was found that the frequency dispersion attenuation curves of seismic wave show different characteristics when different saturations exist in porous media,the attenuation characteristics become more complicated.Using the characteristics of seismic attenuation and dispersion to analyze waveform characteristics,we can observe the change of waveform polarity and the change velocity of waveform polarity.Based on the White periodic model,this paper constructs physical property parameters models with different saturation and permeability,analyzes the relations between seismic attenuation and velocity dispersion and different physical parameters,and then constructs the petrophysical model,and uses the actual logging data The shear wave prediction,and compared with the actual speed,and achieved good results.Based on the characteristics of dispersion and attenuation of seismic waves on a periodic layered model,this paper further characterized seismic wave dispersion and attenuation characteristics in the presence of various fluids in the local medium based on seismic wave forward modeling.The two-dimensional Biot biphasic theory was solved using the Masson's discrete method.The equations are forward simulated,and the differences in frequency dispersion and attenuation caused by different fluid filling sequences are analyzed according to the snapshot of the wave field.