Studies Of2-D Modeling And Inversion With Seismic Reflection Travel-time

Under complicated conditions, collection of data information of seismicexploration is severely influenced and the original seismic record finds it difficult toreach a rather high signal to noise ratio, which thus will lead to a huge difficulty inprocessing seismic data. Therefore, the precondition of solving the problems such asstatics correction, excitation and reception, skewing and amplitude recovery is tomake clear underground velocity structure of complicated regions of terrain. Imagingtechnique was firstly applied in the field of medical science. Since its introduction ingeosciences in the70s to80s, imaging technique has developed into a maturetechnology which is widely applied in the field of geophysical exploration.Tomography obtains data through observing external of objects, inverts andconstructs the internal structure images of objects. As travel time of seismic wavesreaching receiving stations is related to wave velocity of underground mediums thatseismic waves pass through, analyzing data of travel time of seismic waves throughinversion can figure out velocity structure of underground mediums. Seismic traveltime tomography method based on ray tracing theory can clearly observe the traveltime due to rather high signal to noise ratio of the travel time. The method mainlystudies kinematic characteristics of seismic waves. As a result, the method possessesfast computation speed, develops relatively early and owns rather mature technicalmethods as the main method of seismic tomography at present.The paper reviews the development history of seismic tomography and expoundsdomestic and foreign development situation of forward modeling method and inversemethod of ray tracing. The paper constructs abnormal body model of homogeneoushalf space which is used for forward and inverse calculation. Forward modelingmethod of ray tracing adopts pseudo bending method which constantly disturbs theinitial ray path and minimizes the travel time of path segments along rays instead ofdirectly solving ray equations. Inverse method adopts damped least square methodand adds regularization smooth matrix in objective functions of inversion throughregularization of the method. Comparing the results before and after regularization, it shows that adding regularization smooth matrix exerts a positive influence onimproving inversion results.