Gabor-Morlet小波变换分频技术及其在碳酸盐岩储层预测中的应用

Spectral decomposition technique based on Gabor-Morlet wavelet transform and its application to carbonate reservoir prediction

(1.中国石油大学(北京)资源与信息学院地质地球物理综合研究中心,北京102249;2.油气资源与探测国家重点实验室,北京102249)

Lab for Integration of Geology and Geophysics,Faculty of Natural Resource and Information,China University of Petroleum,Beijing,102249,China

地震分频技术可以刻画碳酸盐岩储层中由缝洞引起的地震反射频率特征。常规小波变换频谱分解技术使用的是尺度参数,难以与频率参数直接对应,其结果的地质含义不够明确。Gabor-Morlet小波变换直接使用频率参数,能更有效地突出信号的局部特征。塔中地区奥陶系碳酸盐岩有效储集空间以次生孔、洞和裂缝为主,基质孔隙度低、渗透性较差,储层的非均质性极强,用常规地震属性方法不能有效地描述储层的分布特征。为此,分别利用常规小波变换和Gabor-Morlet小波变换谱分解技术对塔中地区奥陶系良里塔格组碳酸盐岩储层进行了预测,并将两种方法的预测结果与钻井数据进行了对比分析,结果表明,基于Gabor-Morlet小波变换的频谱分解技术储层预测结果与实际钻井数据的吻合率在90%以上。

Seismic spectral decomposition technique can describe the characteristics of seismic reflection frequency caused by fractures and caves in carbonate reservoirs.Conventional wavelet transform spectral decomposition methods use scale parameters,which is difficult to directly correspond with frequency parameters,and cannot give clear geological significance.On the other hand,Gabor-Morlet wavelet transform directly utilizes frequency parameters,so the local characteristics of signal can be more effectively protruded.The effective reservoir space of Ordovician carbonate reservoir in central Tarim Basin is mainly of secondary pores,caves and fractures,the matrix has low porosity and relatively poor permeability,and the reservoirs has strong heterogeneity.Therefore,conventional seismic attribute methods cannot effectively describe the distribution characteristics of reservoirs.So we applied conventional wavelet transform and Gabor-Morlet wavelet transform spectral decomposition technique to predict the Ordovician Lianglitage carbonate reservoir in central Tarim Basin.Then,the results of the two methods were compared to drilling data,which indicates that the coincide ratio between the reservoir prediction results by the spectral decomposition technique based on Gabor-Morlet wavelet transform and actual drilling data reaches above 90%.