The P-wave And PS-wave Velocity Inversion Of OBS Data And The Development Of Software

The data of the OBS(Ocean Bottom Seismometer) has plentiful wide angle reflection and transverse wave information. It is important to take the OBS exploration in gas-hydrate investigation. According to the character of P-velocity and PS-velocity in gas-hydrate, the studying of velocity inversion of OBS data would provide evidence of gas-hydrate's existence.In this thesis, the data we get is a common receiver gather because we usually only have several OBS when we shot on the ocean surface and receive data on the ocean bottom. Sometimes the travel time in the water is longer than one second. So the OBS data is different from the data of ordinary seismic exploration and the velocity inversion needs a special method and a new procedure. Nowadays, the commercial OBS data processing and inversion software is still not on the market. It is a challenge and an opportunity to develop the OBS inversion software.In the procedure of OBS velocity inversion software programming, we solved the problem of large data's quickly reading using memory mapping, the problem of flickering graphic drawing using double buffer , the problem of 2D and 3D visualization using open-inventor technology.We improved the method of coherence inversion on the base of studying sorts of method in OBS data's velocity inversion. Thus, we can get P-velocity and PS-velocity more precisely through earth modeling, ray tracing, coherence calculating, velocity scanning and layer by layer inversion.This software has been applied in the P-velocity and PS-velocity of OBS data in South China Sea and the results are proved to be good.