TTI各向异性叠前深度偏移技术在库车复杂山地的应用

Application of TTI Anisotropic Prestack Depth Migration Technology in Complex Mountain Areas of Kuqa Depression

库车坳陷复杂山地地表地下双重复杂、地表高差大、山体发育、沟壑纵横,古近系膏盐岩挤压变形严重,厚度变化大,盐上浅层高陡,盐下目的层逆冲叠瓦断块发育,导致地震资料信噪比低,成像效果较差。通过多年复杂山地地震资料处理研究,形成了起伏地表TTI各向异性叠前深度偏移技术。叠前深度偏移速度建模中,采用了小平滑基准面,通过微测井约束层析反演计算静校正厚度、时间和速度,建立较高精度的浅表层速度模型;综合应用地表露头、重磁电、地质和钻测井资料约束建立了合理的中深层速度模型;采用井控TTI各向异性参数提取及网格层析成像技术提高了速度模型和成像的精度。通过TTI各向异性叠前深度偏移处理,库车坳陷复杂山地地震资料信噪比和成像质量明显提高,为区带研究及圈闭落实奠定了基础。

The complex mountain areas in Kuqa depression are characterized by complicated surface and underground conditions,large el?evation difference,developed mountains and many gullies.The Paleogene gypsum salt rock suffered from serious deformation with large variations in thickness.The post?salt layer is high and steep and thrust imbricated faults are developed in the pre?salt target zone,resulting in low signal?to?noise ratio and poor image effect of seismic data.Over many years of research on seismic data processing in complex moun?tain areas,TTI anisotropic prestack depth migration technology has been developed for relief surfaces.The small smooth datum is used in prestack depth migration modeling.Thickness,time and velocity for static correction are calculated through microlog constrained tomogra?phy inversion and high?precision velocity model for shallow layers is established.A reasonable model is established for mid?deep layers by comprehensively using the data of surface outcrop,gravity?magnetic?electronic method,geology and drilling.The qualities and accuracies of the velocity models are improved by using TTI anisotropic parameter extraction and grid tomogrqaphic imaging technology.Based on the TTI anisotropic prestack depth migration processing in the complex mountain areas of Kuqa depression,the signal?to?noise ratio and imag?ing quality are significantly improved,which lays a foundation for regional geological study and trap identification.