高精度结构曲率提取方法在潜江凹陷构造解释中的应用

广泛用于描述地质体几何形态变化的结构曲率属性可通过求取地层视倾角的偏导数获得,因此地层视倾角估计的精度直接影响结构曲率估计的精度。江汉潜江凹陷工区目的层断层发育、高陡构造较多、地震资料信噪比低,常规结构曲率提取方法无法有效提取目的层的结构曲率并用于断层及高陡构造等复杂构造带的解释。为此,采用了一种高精度结构曲率提取方法来提取研究区实际资料的结构曲率。该方法首先利用三维数据的瞬时相位构建梯度结构张量,并在此基础上估计地层视倾角;然后采用多窗估计技术来提高地层视倾角的估计精度;最后以高精度地层视倾角为基础进行地层结构曲率估计(包含最大正曲率和最大负曲率)。将高精度结构曲率提取方法及商业软件曲率模块用于江汉潜江凹陷的实际资料处理,结果表明:高精度结构曲率提取方法所提取的地层结构曲率在抗噪性以及断层结构等的刻画精度方面明显优于商业软件曲率模块所提取的地层结构曲率,同时对高陡倾角构造及大断层等构造复杂带的刻画精度更高,更有利于构造解释。该方法可应用于其它类似地区。

Structural curvature is widely used to characterize geometric changes of the geological target.Usually,the curvature can be obtained by computing the partial derivatives of the apparent seismic dips.Therefore,the precision of apparent dip estimation affects the accuracy of structural curvature extraction.The Jianghan-Qianjiang depression exhibits well-developed faults and steep structures.Additionally,the signal-to-noise ratio of one 3D post-stack dataset in the Jianghan-Qianjiang depression is very low.However,the commonly-used structural curvature extracting method cannot effectively extract the curvature of target horizon,and therefore another method based on high-precision dip estimation was proposed to extract some structural curvature attributes in the Jianghan-Qianjiang depression.First,instantaneous phase was used as the fundamental dataset to reduce the influence of the lateral variation in amplitude.Then,this phase was used to construct a gradient structure tensor (GST) matrix with three non-negative eigenvalues.After that,the seismic volumetric dip was calculated from the dominant eigenvector,and a similarity measure was constructed based on these three eigenvalues.Based on the similarity measure,the dip estimation was improved using multi-window technology.Finally,the structural curvatures were extracted by computing the partial derivatives of the seismic volumetric dip.This method was applied to one 3D post-stack dataset in the Jianghan-Qianjiang depression.The results showed that the extracted structural curvatures had better anti-noise performance and fault characterization than other commercial software.Moreover,the extracted structural curvatures characterized some complex structures such as certain large faults and steep structures,unlike other methods.The results show that the proposed curvature extracting method provides a strong basis in the structural interpretation of the Jianghan-Qianjiang depression and can be extended to other regions with similar structures.

基金项目：国家科技重大专项(2017ZX05049002-004)和国家自然科学基金(41504092,41774135)共同资助。