基于地震多属性融合的断层识别与评价——以塔里木盆地SHB地区碳酸盐岩缝洞型储层为例

Fault Detection and Evaluation Based on Fusion of Multiple Seismic Attributes——An Example of Fractured and Vuggy Carbonate Formation in SHB Area,Tarimu Basin

塔里木盆地SHB地区的深部碳酸盐岩缝洞型储层主要发育于断裂破碎带,大多表现为断裂破碎形成的裂缝和后期溶蚀形成相互连通的断溶体。因此,断层的识别与精细评价成为该区缝洞型储层识别评价的基础。考虑到研究区处于沙漠腹部,深部地层的地震反射能量相对较弱,用单一地震属性难以实现断裂带的识别。本文针对研究区地震资料的地质-地球物理特征,提出融合多种地震属性的断层识别与评价方法。①利用地震剖面上"断裂+杂乱反射"特征,识别可能存在的断裂或裂缝带;②运用谱白化和倾角导向滤波方法,拓频并压制地震数据的随机噪声;③用去噪和拓频后的地震数据计算相干体、蚂蚁体等多种地震属性;④融合多种地震属性来识别和评价断层,并用剖面形态和平面切片的组合分析不同断裂系统的形成次序;⑤利用多种地震属性与稀疏脉冲反演结果综合进行缝洞体预测,与实钻结果对比具有良好的一致性。

The fractured and vuggy reservoirs in deeply buried carbonate formation at SHB area Tarim basin are mainly deposited in fault systems ruptured by regional structural stress,the storage space consists of fractures caused by fissured faults and Karst vugs because of subsurface dissolution.Therefore,identification and evaluation of faults becomes the key step of the reservoir assessment.Considering the weakness of the seismic energy reflected from the deeply buried formation and the strong attenuation of the unconsolidated sand over the surface in the center of the deserts,the identification of faults confronts challenges with any one kind of seismic attribute.In this study,we developed a processing procedure for identification and characterization of faults with fusion of optimal seismic attributes’data set through understanding of the geological and geophysical characteristics in the target area.First,the fault caused diffusions in the seismic profiles have been identified as the suspected proofs of the existence of the faults or fractures.Secondly,methods of spectral whitening and dip angle directed filtering have been implemented for noise attenuation and frequency band extension.Next,the seismic data set after noise attenuation and frequency extension has been input into processing procedures of multiple seismic attributes calculation,such as coherence,ant tracking,and curvature.Moreover,identification and evaluation of faults in subsurface formation have been fulfilled with the fusion of multiple seismic attributes,and also the probable time window of the formation of the faults has been analyzed with the combination of the seismic profiles and attributes’slices.Finally,the sparse pulse inversion results constrained with the optimal seismic attributes and structural vectors have been applied to prediction of spatial distribution of fractures and vugs,and well consistency with the drilled results has been achieved.