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过去几年,海上技术有了几项重大发展,产生了在近海环境下适于方位各向异性分析的采集技术。事实上,这些发展和用P-P波P-S波振幅随方向变化(AVD)进行地震各向异性估算的理论的进展是同步的。实际上,这种AVD方法对宽方位覆盖的要求只有在最近才能得到满足。为了指导今后的工作,使用相交拖缆测线的资料评价了AVD方法。本文给出了运用该方法证实北海中部白垩地层内含烃裂缝走向的例子,研究结果证明该方法对裂缝非常敏感,有助于指导进一步的油气分析。新一代的垂直电缆、海底地震传感器、变井源距VSP以及3-D VSP等方法将最终导致海上环境中应用此方法进行高分辨率方位各向异性的估算。
Over the past few years, there have been several major developments in offshore technology that have resulted in acquisition techniques suitable for azimuthal anisotropy analysis in offshore environments. In fact, these developments are in synchronic with the progress made in the theory of seismic anisotropy estimation of P-P wave P-S wave amplitude with direction change (AVD). In fact, the requirements of this AVD approach for wide azimuth coverage have only recently been satisfied. To guide future work, the AVD method was evaluated using data from intersecting towline surveys. This paper presents an example of using this method to confirm the hydrocarbon fractures in the chalk sediments in the central North Sea. The results show that this method is very sensitive to fractures and helps to guide further oil and gas analysis. A new generation of vertical cables, undersea seismic sensors, variable source spacing VSPs and 3-D VSPs will eventually lead to high-resolution azimuthal anisotropy estimates using this method in offshore environments.