Research On Anisotropic Velocity Analysis Based On Rock Physical Simulation

Rockphysics is the bridge of log data,seismic processing and reservoir parameters.Whenthe reservoir properties or fluid in the pore change,will resulting in corresponding changes ofseismic response characteristics.The direct impact of the change of the rockphysicalparameters on seismic response is the change of velocity.Velocity analysis is the key step of seismic processing,accurate velocity field is thefoundation for the next work.This paper discussed several accuracy criterion of theconventional velocity analysis,above this foundation, some factors which affecting theresolution and accuracy of velocity analysis,such as spread length, velocity sampling interval,width of time window, noise,frequency band and so on was analyzed.Conventional velocity method which is based on the assumption of isotropy conditions,can also get good results in a short spread,while because of the nonhomogeneity andanisotropy of the medium and the complexity of the reflector,reflection traveltime curvebecome non-hyperbolic,the influence of anisotropy on traveltime is particularly evident,especially in the large spread and long offset, phenomenon of NMO uneven often occur,remval was applied in conventional processing,this is a waste of long spread information,which reduces the accuracy of seismic data processing.Based on conventional velocity analysis,this paper derived several anisotropicnon-hyperbolic moveout formula,and compared with conventional hyperbolic moveoutformula and exact travetime.The error generated by the hyperbolic moveout becomes largeras the offset increases,while the anisotropic non-hyperbolic moveout generate samllererror,and Alkhalifah method still has higher accuracy in the large offset.Anisotroy velocity analysis,which taking into account the anisotropy factors ontravetime,solved the problem of NMO uneven in the long offset.So the long offsetinformation was applied,and the entire spread was involved in the stacking,and avoiding theshotcomings of NMO uneven and weak stacking energy in the far offset.On the stacked section,the continuity and the resolution of the event was improved,and the energy wasenhanced.In the last,I develop anisotropic velocity analysis and NMO correction software,which achieves good results both in the model test and real data processing.