摘要
基于双程波动方程的逆时偏移是一种高精度偏移成像方法,适用于复杂构造的成像,但是该方法对偏移速度模型较敏感。因此,提出了一种新的倾角约束逆时偏移,将正传和反传波场分解为不同角度分量,进而利用倾角约束成像条件,显著提升了逆时偏移在速度不准确情形下的成像质量。同时,即使在速度准确情形下,由于其他非一次反射波能量的存在,可能会导致成像假象,而提出的倾角约束逆时偏移可以利用菲涅尔带内的反射信息明显压制此假象。此外,为了提高效率,进行震源正传波场的分解时,可以利用对高频波场成分计算入射角来实现。复杂模型数值测试结果验证了该方法在存在速度误差的情况下,改善了成像质量,并且在速度正确的情况下,压制非一次反射波导致的假象。
Reverse time migration(RTM)based on the two-way wave equation may yield high-precision images of complex subsurface structures.However,RTM is sensitive to the velocity model.This paper proposes a new dip-constrained RTM method.The forward propagating wavefield from the source and backward propagating wavefield from the receiver are decomposed into different directional components,and then an automatic dip-constrained imaging condition is utilized to improve imaging quality in the presence of velocity errors.Meanwhile,our method may mitigate the artifacts caused by non-primary reflections,even when the velocity model is correct,by using the reflection signals within the Fresnel zone.To increase efficiency,we introduce the frequency-domain snapshot to compute the incident angle for source wavefield decomposition.Numerical tests on a complex velocity model show improved imaging in the case of inaccurate velocities and mitigated artifacts caused by multiple reflection waves in the case of the accurate model.
作者
范旭
马军茂
王晨
马凯
李亦航
FAN Xu;MA Junmao;WANG Chen;MA Kai;LI Yihang(Institute of Geophysics,Research Institute of Exploration and Development,Xinjiang Oilfield Company,PetroChina,Urumqi 830013,China;College of Geophysics,China University of Petroleum(Beijing),Beijing 102249,China)
出处
《石油物探》
北大核心
2025年第2期257-263,共7页
Geophysical Prospecting For Petroleum
基金
国家科技重大专项课题(2017ZX05008-007)资助。
关键词
逆时偏移
倾角约束成像条件
速度误差
倾角道集
reverse time migration
dip-constrained imaging condition
velocity error
dip-angle gather
