瞬时频域衰减属性及其在碳酸盐岩裂缝检测中的应用

基于AVO梯度、走时及速度的纵波方位角裂缝检测已有较多研究和应用.由于裂缝及所含流体的综合作用，碳酸岩裂缝性储层的地震响应具有高频衰减、频带低移及方位各向异性的特点,因此应用衰减属性进行裂缝预测具有重要价值.基于小波变换计算的瞬时频域振幅谱及以此为基础提取的衰减属性，由于在时域和频域都有较好的分辨率能力，能够准确地刻画出碳酸岩裂缝性储层的非均质性.结合三维地震纵波数据的分方位角处理和分析技术，可以由方位衰减属性估算裂缝相对密度.对Z区下古生界潜山碳酸岩储层进行的裂缝预测表明，由衰减梯度和85%能量比频率两种属性导出的裂缝发育密度具有很好的相关性，且与实际情况符合.

P-wave azimuthal attenuation attributes in wavelet-scale domain and its application to fracture detection in carbonate

Subsurface fracture detection using P-wave azimuthal attributes such as AVO、travel time and phase velocity has been common in recent years. For carbonate reservoir, significant attenuation of high frequencies is observed due to the fractures and fluid in content, and the spectral is shifted toward lower range. Thus, seismic attenuation attributes can be used for fracture analysis. The wavelet-scale spectra are calculated with wavelet transform for its high resolution in both time and frequency domains. Special azimuthal attenuation attributes can be then derived and used to estimate the fracture density with the support of azimuthal pre-stack seismic data processing techniques. Application to the Eopalaeozoic buried hill in the Z oilfield shows that the two types of azimuthal attributes, attenuation gradient and frequency at 85% energy ratio, are closely related to fracture characteristics of carbonate reservoir.