基于井控地质约束的陵水宝岛凹陷各向异性参数反演与分析

Inversion and analysis of anisotropic parameters in Lingshui Baodao sag based on well control geological constraints

琼东南盆地深水区地质条件复杂,不仅地层速度的横、纵向快速变化,而且地震反射的波场复杂,常规地震速度反演和偏移归位难以满足复杂构造成像的要求,因此造成中深层地震资料信噪比低和偏移归位不准等问题。为解决上述偏移成像问题,不仅需要发展适应速度建模技术,还要充分利用井的信息提高各项异性参数反演的准确性,统计分析其各向异性规律,利用TTI各向异性偏移提高偏移归位精度,从而实现高精度的地震偏移成像。这里采用基于井控地质约束的各向异性参数反演技术,准确估计各向异性参数,以统计分析琼东南盆地深水区各向异性规律。从各向异性的纵向结构来看,乐东组各向异性小,黄流组、梅山组各向异性大,到陵水组逐渐过渡为稳定各向异性。从各向异性与水深的变化相关性上分析,在陵水凹陷,同一套层系浅水区各向异性小,深水区各向异性大;在宝岛凹陷,乐东组和莺歌海组浅水区各向异性小,深水区各向异性大,黄流组和梅山组浅水区各向异性大,深水区各向异性小。上述各向异性的规律分析,为深水区无井少井下速度建模和构造落实提供借鉴。

The deep water area of Qiongdongnan basin has complex geological conditions,not only the formational velocity variation horizontally and vertically,but also the complex of the wave field of seismic reflection.It is difficult for meeting the requirements of complex structural imaging to use the conventional seismic velocity inversion and migration homing are difficult to meet the resulting in low signal-to-noise ratio and inaccurate migration homing of seismic data in middle and deep layers.In order to solve the above migration imaging problems,it is necessary not only to develop adaptive velocity modeling technology,but also to make full use of well information to improve the accuracy of inversion of various anisotropic parameters,to statistically analyze the anisotropy law,and to improve the migration homing accuracy by using TTI anisotropic migration,and so as to realize high-precision seismic migration imaging.In this paper,the anisotropic parameters inversion technology based on well control geological constraints is used to accurately estimate the anisotropic parameters,so as to statistically analyze the anisotropy law in the deep water area of Qiongdongnan basin.From the longitudinal structure of anisotropy,Ledong formation has small anisotropy,Huangliu formation and Meishan formation have higher anisotropy,and gradually transit to stable anisotropy from Lingshui formation.According to the analysis of the correlation between anisotropy and water depth,in Lingshui sag,the anisotropy in shallow water is small,but that in deep water is large;in Baodao sag,the anisotropy in shallow water of Ledong formation and Yinggehai formation is small,and that in deep water area is large;in Huangliu formation and Meishan formation,anisotropy is large in shallow water area and small in deep water area.The analysis of the above anisotropy law can provide more accurate guidance for the modeling and structural implementation of no well and less downhole velocity in deep water area.