谱反演方法在致密薄层砂体预测中的应用研究

在以致密砂岩为储层的非常规致密油勘探开发中,由于靶区选择和水平井部署的需要,落实致密砂体的横向展布至关重要。松辽盆地北部白垩系扶余油层致密砂体整体薄层发育,特别是T₂强反射界面屏蔽问题的存在,一直制约着致密薄层砂体的识别精度。为此,开展了针对大庆长垣扶余油层致密薄砂体预测的谱反演方法应用研究。在简介谱反演方法原理的基础上,为了保证反演算法的计算精度,利用复数域快速匹配追踪算法提高时频转换的精度;通过提取时变子波提高反射系数时频谱的准确性。应用研究结果表明,将谱反演得到的地震反射系数体与宽频零相位子波进行褶积运算,获得的研究区宽频保幅地震数据有效削弱了T₂的屏蔽效应,改善了复合波的叠置问题,清晰地反映出了薄层砂体顶、底界面,并很好地保持了振幅与砂体的对应关系。

Due to the need of selecting target areas and deploying horizontal wells,it is very important to understand the lateral distribution of tight sand bodies in unconventional tight sandstone reservoir exploration and development.The tight sandstone is characterized by the development of Cretaceous thin-beds for Fuyu reservoir in the north of Songliao Basin.And the identification accuracy of the thin-bed sand bodies is restricted by the shielding effect from the strong reflection interface T₂.Therefore,we study spectral inversion technique for the prediction of the tight thin-bed sand bodies in Fuyu formation,Daqing Placanticline.In order to ensure the accuracy of spectral inversion,fast matching pursuit algorithm in complex domain is used to improve the precision of the time-frequency conversion and the accuracy of time-frequency spectrum of reflection coefficient is increased by the time-varying wavelet extraction.The results of spectral inversion show that:the seismic reflection coefficient volumes from spectral inversion are convoluted with the broadband zero-phase wavelet,thus obtained broadband preserved amplitude seismic data effectively suppress the shielding effect from T₂ in target area.The results also indicate the improvements of composite reflections overlay,the top and the bottom interface of the thin-bed sandstone detected clearly,and the favorable correspondence between amplitude attributes and sand bodies.

国家重点基础研究发展计划(973计划)(2013CB429805,2009CB219301)、国家自然科学基金(41174080,41340039)和公益性行业科研专项(201011078)共同资助。