A Study On Pivotal Data Processing Procedure Of Ocean Bottom Seismograph

In recent years, the prospecting technology of the OBS(Ocean Bottom Seismograph) has quickly developed. OBS in detecting gas-hydrate is more effective than other multi-components seismic methods. Because the OBS is planted on the ocean's bottom, the converted S wave could be stored in the recording device, which made the method obtain more information of the earth. After data processing, velocity curves of the P wave and the converted S wave can be gained. Contrasting the velocity curves can help us to know whether the earth has the gas-hydrate.The OBS location on the oceanic bottom will be drifted because of the oceanic current, so OBS exact location must be known. OBS has four components: one vertical component, two horizontal components (all above three components are Perpendicular to each other) and a hydrophone. Because the OBS is stationary and the air-gun is stimulated along the shot line. OBS data is common receiver gather. So amplitude and polar direction of traces in the same shot line is inconsistent, which makes the amplitude energy is instability. Rotation of horizontal components can resolve this instability. The vertical component is not single P wave data, and two horizontal components is not single S wave data, and mostly contain P wave and S wave, which mainly because the reflected wave is not perpendicular to the surface(or the reflection angle is not zero). Decomposition of the vertical and horizontal components must be done for gaining the pure P wave data and S wave data. The rotation and decomposition are the data foundation for getting the exact velocity curves of P wave and PS wave.OBS geometry, data acquisition, data processing and theory of prospecting gas-hydrate will be instructed in the paper. The OBS data processing method will be proposed by researching the multi-wave data processing methods. The OBS bottom locating, rotation of horizontal components and decomposition of vertical and horizontal components will be seriously studied, and testified by model simulation and real OBS data. The result of above data processing parts are very good, and achieve the processing purpose well.