荔湾深水速度分析方法研究

Study on velocity analysis method on deep water in Liwan area

荔湾深水地震资料采用长电缆大排列采集,且地下各向异性问题严重,严重影响了速度分析的精度。常规双曲线及各向异性时距曲线仿真结果表明:时差误差受电缆长度(X/D)、各向异性(Eta)两个因素影响;电缆越长、各向异性越强,用常规速度解释造成的时差误差越大;优选出了基于各向异性介质的速度分析方法,道集大偏移距部分得到了有效拉平,地震高陡倾角的成像精度有很大提高,较好地解决了荔湾深水区长电缆地震资料的速度场和各向异性的问题,为深水长电缆地震资料处理提供了较好的技术手段。

Liwan seismic data collected by long cables is anisotropical which influences the accuracy of velocity analysis. The conventional hyperbolic and anisotropic time-distance curve simulation results show that the time error is controlled by the cable length （X/D） and anisotropic （Eta）, the longer the cable, the bigger the time error will be found if it is explained by conventional velocity; the velocity analysis method based on anisotropic medium is optimized and the offset is flattened effectively; the seismic imaging accuracy of high steep dip angle is improved greatly which solve the problem of the long cable seismic data velocity field and anisotropic in Liwan deep-water. It provides a good technical means for the processing of long cable seismic data in deep water.