东营凹陷砂砾岩体OVT域宽方位地震正演模拟

OVT-Domain Wide-Azimuth Seismic Forward Modeling of Glutenites in Dongying Sag

针对东营凹陷近物源砂砾岩体相带及岩性变化快的特点,建立砂砾岩体三维地质模型,开展宽方位地震正演模拟。利用模拟数据体,通过OVT域道集分方位叠加,分析方位角变化对地震波走时、振幅等参数的影响,建立方位角及振幅与有利储集层的匹配关系。研究表明:砂砾岩体沉积方向的变化导致地震波传播产生方位差异,地震波反射存在方位各向异性,选择垂直于沉积边界的方位角进行分方位叠加,得到的叠加数据体对砂砾岩体顶界面及内部界面响应较为敏感,振幅较强,可更有效地揭示不同期次砂砾岩体的接触关系,准确识别砂砾岩体,精细预测有利储集层的分布范围。宽方位OVT域地震数据能有效进行砂砾岩体预测,在东营凹陷北部陡坡带砂砾岩体储集层预测中取得较好的应用效果,储集层预测结果与实钻较吻合。

Considering the varying lithofacies and lithology of the proximal glutenites in the Dongying sag,a three⁃dimensional geological model of the glutenites was established for wide⁃azimuth seismic forward modeling.Using the simulated data cube,and through azimuthal stacking of gathers in OVT⁃domain,the effects of azimuth variation on parameters such as seismic travel time and amplitude were analyzed,and the relationships between azimuth/amplitude and favorable reservoirs were established.The results show that the variation in the sedimentary direction of the glutenites causes azimuth differences in seismic wave propagation,leading to azimuthal anisotropy in seismic reflections.The data cube obtained from azimuthal stacking at the azimuth perpendicular to the sedimentary boundaries is more sensitive to the responses of the top and internal boundaries of the glutenite,with stronger amplitudes.It more effectively reveals the contacts between glutenites of different periods,thereby facilitating the accurate identification of glutenite and fine prediction of favorable reservoir distribution.Wide⁃azimuth OVT⁃domain seismic data are proved effective in glutenite prediction,and have been successfully applied in predicting glutenite reservoirs in the steep slope zone of the northern Dongying sag,with the prediction results in good agreement with actual drilling results.