The Research Of3-D Erosswell Seismic Gaussian Beam

With the improvement of seismic prospecting accuracy the conventional method ofsurface seismic has become difficult to obtain the high resolution seismic profile. The seismicwaves stimulated on the surface are easily disturbed by the ground industry as well as theseismic high frequency signal, which are strongly absorbed by shallow layer, leading to thelow resolution of seismic profile and weak effective wave. Crosswell seismic can solve thisproblem effectively because of its special geometry system. The high frequency effectivesignals avoid the absorption of aerated layer effectively and can be easily achieved becausethe source and the receiver are put in the adjacent wells at the same time. This methodcontains rich information of subsurface wave fields. It not only receives up going reflectionwave, but also accepts down going reflection wave.Crosswell seismic wave field forward can effectively distinguish the characteristic ofvarious wave fields, The core of forward methods is ray tracing, but the conventionalmethods of ray tracing can only reflect the kinematic characteristics of waves, they can notdisplay the dynamic characteristics of waves. In order to make up the shortages, this paperuses gaussian beam forward method. This way not only considers the kinematiccharacteristics, but also shows the attenuation of seismic wave energy, and also takes theabsorption into account at the same time when seismic wave transmitted in the subsurfacestratum. Gaussian beam is the high frequency approximation value that wave equation focuson rays, it represents a high frequency energy tube which use ray as its center. The seismicwaves in all directions come from the source, next, the trace of the central ray is acquired bythe kinematic ray tracing, then using dynamic ray tracing, calculating the dynamiccharacteristics of every rays, Finally, the ultimate synthetic records are formed according tothe Gaussian wave packet which stack together the effective rays.Based on the above ideas, This paper writes the procedure of crosswell seismic gaussianbeam forward procedure using C++language in the environment of Microsoft Visual Studio6.0, and designs the user interface combining with Qt development tool, forms a commercialsoftware of crosswell seismic gaussian beam finally.