The application of forward modeling technique in seismic acquisition design

With the further development of seismic exploration and exploitation,the main field of seismic exploration is gradually turned to the complex regions,which not only refer to the areas with complex surface conditions,such as mountainous region,hill,Gobi,desert,loess covered terrains and so on;but also refer to the areas with complex subsurface geological structure and complex formation conditions,such as complex fault block areas in the east China,overthrust zones in western China and coal bed blind zones in Ili basin etc.New challenges and higher requirements are made on seismic exploration by all these.Aiming at difficulties which face in seismic exploration,seismic forward modeling is an important means and methods to perform the study of such problems.For time being the software in the worldwide market which has the function of seismic forward modeling mostly uses the method of ray-tracing to complete forward modeling based on the ray theory,which cannot reflect well dynamics characteristic of seismic wave,therefore correct results can't be obtained in the complex area.Although forward modeling module was used based on sonic wave equation for some kinds of software,second-order finite difference was used,the speed is therefore slow,and the precision is also low,it's difficult to be widely applied in real production.In this paper,by using high-order finite-difference,the dispersion problem of solving wave equation is effectively overcome compared with conventional finite-difference algorithm,and efficient OpenMP parallel computational model is used for parallel optimization,the speed and accuracy of forward calculation is improved to a large extent;meanwhile second-order Higdon boundary condition is realized and the effect of boundary absorption is improved to increase the computational speed to some extent too.The buried depth of main target layer in Tazhong region is very deep,reverse faults are developed in this region,the characteristics of seismic reflection are also complex,which increase the difficulty of seismic exploration in this region.Forward modeling is an important technology to carry out seismic method study in this area.In this paper based on the geological model in this region,geometry system of seismic acquisition is verified by using wave equation forward modeling technique,and a scientific basis is provided for seismic acquisition geometry design in this region.