基于WVD-MEM的高分辨河道识别方法

High-resolution channel identification method based on WVD-MEM

作为重要的油气储集体,河道砂体一直是油气勘探开发领域的热点研究目标。近年来,随着油气勘探开发程度的不断加深,埋藏更深、宽度更窄、厚度更薄的河道逐渐成为关注重点。然而,受河道埋深、纵横向分布特点和地震资料主频、频带、空间分辨率等因素的制约,运用传统的地震属性解释和时频分析方法进行高精度河道识别难度较大,识别效果往往欠佳。为此,采用Wigner-Ville分布(WVD)与最大熵方法(Maximum Entropy Method,MEM)相结合的非平稳信号分析方法(简称WVD-MEM),研究通过MEM扩展WVD的核函数项,有效消除WVD信号分析中存在的交叉项干扰,同时保持较高的时频聚焦性和分辨率,进而计算WVD的最大熵功率谱、瞬时振幅等地震属性,从提升瞬时振幅、功率谱等分辨率的角度,突出地震数据的河道响应特征,提高分辨能力。该方法在川西地区地震资料河道识别的实际应用中取得了良好效果。

As important oil and gas reservoirs,channel sandbody sedimentary has long been a hot research object in the field of oil and gas exploration and development.In recent years,as oil and gas exploration and development continue,channels at greater buried depth with smaller width and lesser thickness have gradually been brought into the focus of attention.However,restrained by factors such as buried depth,complex vertical and horizontal distribution,and low dominant frequency,narrow frequency band,and low spatial resolution of seismic data,it is difficult to identify the channels with high precision.Traditional identification methods including seismic attribute interpretation and time-frequency analysis are often not effective.In this paper,the non-stationary signal analysis method which combine the Wigner-Ville distribution(WVD)and the maximum entropy method(MEM)together(WVD-MEM method for short)was studied.The kernel function of the WVD was extended by the MEM,which not only eliminated the cross terms in WVD signal analysis but also delivered high time-frequency concentration and a high resolution.Furthermore,the maximum entropy power spectrum,instantaneous amplitude,and other seismic attributes of WVD were calculated,which was aimed at highlighting the channel response characteristics and resolution of seismic data from the perspective of improving the resolution of instantaneous amplitudes and power spectra.This method has achieved good results in the application of seismic data channel identification in western Sichuan area.