起伏地表直接成像技术研究进展

常用的高程静校正方法需要满足地表一致性假设的基本条件,但在我国西部与南方山前带油气勘探区内,地表起伏剧烈,横向变速明显,地表一致性假设不再成立。为了对复杂山前带进行准确的成像,起伏地表直接成像方法得到了广泛研究与快速发展。对起伏地表直接成像技术的研究进展进行了综述,包括基于射线理论的起伏地表偏移,基于单程波方程的起伏地表偏移及基于双程波方程的起伏地表变网格、曲网格、三角网格逆时偏移,起伏地表粘声逆时偏移,起伏地表各向异性逆时偏移,起伏地表最小二乘偏移等,并对起伏地表速度反演方法进行了总结。从简单的起伏地表构造成像到同时存在剧烈起伏地表及复杂地下结构的双复杂构造直接成像回顾了起伏地表成像的总体发展趋势,指出基于双程波方程的起伏地表直接成像方法是未来的主要研究方向,该方法在理论上可以对任意复杂构造进行精确成像,对速度的依赖性强和计算量庞大是其主要的发展瓶颈。

The assumption of surface regularity is the basis for the commonly used elevation static correction method.In some areas such as piedmont area of western and southern China,the assumption is hardly satisfied if severe surface undulations are present,or evident lateral variations of nearsurface velocity exist.Several methods for topographic images were developed in recent years,with the aim of imaging piedmont areas accurately.In this study,various topographic prestack depth migration methods have been reviewed.These methods,by which the imaging is performed on the rugged surface directly,include the topographic prestack depth migration based on ray theory,the oneway wave equation,and the twoway wave equation (reverse time migration,RTM).The RTM can be implemented on the basis of dualvariable grids,curvilinear grids,or triangular grids.In addition to these methods,the viscoacoustic RTM,anisotropic RTM,and leastsquares RTM (LSRTM) for rugged topography have been reviewed,and the methods for topographic velocity inversion also have been summarized.The general trend in the technologies for imaging undulated surfaces shows a transition from the direct imaging of undulated surfaces to the direct imaging of dualcomplexity structures,featuring both undulated surfaces and complex subsurface structures.Methods for topographic imaging based on the twoway wave equation represent the main focus of future research,for which the main challenges are the heavy dependence on highprecision velocity measurements and the large computational costs.

国家自然科学基金(41774133,41904101)、国家科技重大专项(2016ZX05024-003-011,2016ZX05006-002-003,2016ZX05002-005-007HZ,2016ZX05014-001008HZ,2016ZX05026-002-002)、国家重点研发计划(2016YFC060110501)、中央高校基本科研业务费专项资金(19CX2010A)、中国石化地球物理重点实验室开放基金(wtyjy-wx2017-01-04,wtyjy-wx2018-01-06)、山东自然科学基金(ZR2019QD004)、中国石油大学(华东)人才引进费(20180041)共同资助。