利用时频分析技术预测依拉克构造有利砂体分布

Favorable sand body prediction based on the time-frequency analysis in Iraqi Structure

依拉克构造白垩系舒善河组属多物源的扇三角洲沉积体系,其砂体变化快、储层非均质性强,有利砂体难以预测。本文采用时频分析法,即首先通过S变换将时间域地震信号转换到频率域,并基于精细时深标定,优选能识别出目标层段分流河道砂体的优势频率体;再依托优势频率(40Hz)数据体,综合应用相干、瞬时振幅等多属性分析技术,预测有利相带的分布;在该有利相带约束下,利用三维砂体雕刻技术识别出(6个)有利砂体,清晰刻画了砂体的规模和展布特征。根据预测结果,选择在2号砂体上布设探井,实钻后获得高产油气流,表明预测结果与实钻结果很好吻合。

Shushanhe Formation of Early Cretaceous in Iraqi Structure is a fan delta sedimentary system governed by multiple sources.Due to quick sand body changes and strong reservoir heterogeneities it is difficult to predict favorable sand bodies.In this study,the time-frequency analysis is used to solve the difficulty.Firstly,time-domain seismic data is transformed into frequency-domain seismic data with S transform.Then according to the timefrequency analysis of cross-well seismic data and well-to-seismic accurate calibration,the optimum frequency volume is determined,on which channel sand bodies in the target can be easily identified.After that,the favorable sedimentary facies distributions are identified based on the optimum frequency(40Hz)volume and multi-attribute analysis(coherence and instantaneous amplitude).With the constraint of this favorable sedimentary facies,six channel sand bodies are accurately interpreted and described by 3D sculpture.An exploration well in Sand body 2 proposed based on our prediction obtains high-yield oil and gas flow after drilling,which demonstrates a very good match with our prediction.