宽方位层析建模技术及其在YA高密度三维的应用研究

苏北盆地宽方位地震资料存在主测线方向覆盖次数明显高于联络线方向覆盖次数的问题,导致OVT域共成像点道集(OVG)上剩余曲率拾取的密度和质量在不同方位存在较大差异,影响了宽方位层析反演的精度。提出了一套基于OVT域方位角分组的宽方位层析速度建模技术流程,首先根据苏北盆地地震数据中方位角分布特点,将OVG按照方位角范围划分为不同的方位角组,然后对每个方位角组分别进行射线追踪和建立线性方程组,利用线性方程组及其对应的方位角进行宽方位网格层析反演,得到一个速度更新量,依据此更新量形成一个新的速度模型。最后利用新的速度模型进行OVT域深度偏移成像。将其应用于苏北盆地宽方位地震数据的结果表明:与常规层析建模技术相比,宽方位层析建模技术提高了速度模型精度,速度细节更加丰富,为提高苏北盆地宽方位地震资料复杂小断块成像精度提供了有效的技术支持。

Wide-azimuth seismic data in the Subei Basin exhibit a significantly higher fold number in the inline direction than in the crossline direction.This is undesirable as it leads to a difference in the density and quality of the selected residual curvature on the offset vector gather (OVG) in different directions,thereby affecting the accuracy of the wide-azimuth tomographic inversion.In this paper,a wide-azimuth tomographic velocity modeling algorithm is proposed based on azimuth grouping in the offset vector tile (OVT) domain.First,according to the spatial pattern of the azimuth of the seismic data in the Subei Basin,the OVG is classified according to different azimuth ranges.Then,ray tracing is performed and linear equations are formulated for each azimuth group.By performing a wide-azimuth grid tomographic inversion using linear equations and their corresponding azimuth,a velocity update is quantified.A new velocity model is then established according to this update.Finally,the new velocity model is used for depth migration imaging in the OVT domain.Results of the application of this algorithm in the Subei Basin show that,compared with conventional tomography modeling,the proposed approach offers better accuracy in the velocity model,with richer velocity details,thereby providing effective technical support for improving the imaging accuracy of complex fault blocks using wide-azimuth seismic data in the Subei Basin.

中国石化科技部项目(PE19003-2)资助。