论文详情
山前带地区地表起伏剧烈、地下构造复杂。当地表速度横向变化剧烈或地表高程变化很大时,基于高程静校正的常规偏移成像方法难以消除起伏地形对偏移的影响。针对山前带高陡构造的成像,提出了一种曲坐标系下起伏地表棱柱波逆时偏移成像方法。将棱柱波逆时偏移成像方法引入曲坐标系下的声波方程中,推导出曲坐标系棱柱波逆时偏移方程,利用棱柱波提高山前带高陡构造的成像精度,并采用贴体网格剖分技术及坐标变换技术,在曲坐标系下进行偏移计算。简单起伏地表凹陷模型和起伏地表火山岩模型试算结果表明,坐标变换后的起伏地表被映射为水平地表,曲坐标系下起伏地表棱柱波逆时偏移成像方法克服了起伏地表对成像的影响,得到了准确的山前带高陡构造成像结果。
The surface topography of a piedmont zone fluctuates violently,and its underground structure is complex. When the near-surface lateral velocity or elevation changes drastically,the conventional migration imaging methods based on static correction cannot overcome the influence of undulating surface topography on the migration imaging. To overcome the imaging problem of steeply dipping structures in piedmont areas,a prismatic wave reverse-time migration method based on body-fitted grids is proposed in the curved coordinate system,which makes complete use of prismatic waves to improve the imaging accuracy of steeply dipping structures in the foothill areas. The method was implemented in the curved coordinate system using body-fitted grids and coordinate transformation technology. Numerical examples on simple topographic sag and topographic volcanic rock models demonstrated that the irregular surface was transformed to a horizontal one by coordinate transformation. The proposed prismatic wave reverse-time migration method was able to produce accurate and steeply dipping structural images of the foothill areas and overcome the influence of undulating surface topography.
国家自然科学基金项目(42174138,42074133)、中国石化地球物理重点实验室开放基金项目(wtyjy-wx2017-01-04)、中石油重大科技专项(ZD2019-183-003)、中央高校基础研究基金项目(19CX02010A)和学校人才引进费项目(20180041)共同资助。