高阶旅行时校正技术在非均质中的应用

Application of Higher-Order Traveltime Correction to Anisotropic Media

塔里木盆地低幅度构造和碳酸盐岩裂缝中普遍存在着速度各向异性。常规正常时差(NMO)校正和含高次项的NMO校正技术都难以消除由于各向异性引起的非双曲线走时,从而影响后续的叠加成像和储集层研究。基于各向异性的高阶旅行时校正技术理论相比NMO各向同性的理论假设,更接近于真实地层介质。研究提出了应用高阶旅行时校正技术在各向异性介质中进行速度分析的方法,给出了求取各向异性参数η的流程。研究实例表明,高阶旅行时校正技术和NMO校正结合应用,能有效地解决各向异性问题,满足低幅度构造精确成像的需要。

Velocity anisotropy can be widely seen in low-relief structures and carbonate fractures of Tarim basra. It is difficult tor both conventional normal moveout （NMO） and multi-term Taylor series expansion to eliminate nonhyperbolic traveltime caused by anisotropy, which will affect following stack imaging and research of reservoir rocks. Compared with NMO based on assumption of isotropy, the technique of higher-order traveltime correction based on theory of anisotropy is more approximate to the real formation media. By using this technique, a methos for velocity analysis in anisotropic media is proposed, and a typical seismic procession flow for anisotropic parameter η is given. The study shows that the technique of higher-order traveltime correction combined with NMO can solve efficiently the problem of velocity anisotropy and meet the need of accurate imaging in low-relief structures.