AVO/AVA反演对非均质储层横向分辨率影响

 塔里木盆地碳酸盐岩储层以次生溶蚀孔洞为主要储集空间,表现为强非均质性的特点。孔洞体积的准确计算对油田开发方案制定意义重大。受地表沙漠化和储层深埋藏的影响,塔中地区地震资料具有低信噪比和分辨率的特点。适合于对该地区储层描述以及孔隙流体探测的叠前地震反演方法通常为角道集部分叠加的AVA反演。与单道AVO反演相比,AVA反演基于角道集的叠加,在提高信噪比的同时将影响反演结果的横向分辨率。本文通过物理模拟的办法,建立了不同大小、低速介质充填的孔洞物理模型。在采集的地震资料基础上,量化分析了AVO反演与AVA反演两种不同叠前地震反演方法对同一孔洞的反演结果在非均质储层横向分辨率上的差异,并且与孔洞实际尺寸进行了对比。结果表明,地震道集的叠加在提高信噪比的同时降低了横向分辨率,地震道集叠加后一道所代表的范围越大,横向分辨率降低越明显。

The Impact of AVO/AVA Inversion on the Lateral Resolution of Heterogeneity

Carbonate reservoir is widely developed in the Tarim Basin of China, where a large number of oil fields are discovered. The reservoir storage spaces in the area are mostly secondary dissolution caves and are characterized as strong heterogeneity. One of the key technical problems is how to accurately calculate the volume of these caves. Influenced by desertification surface and deeply buried reservoir, the seismic data collected from the area has the obvious characters of low signal-to-noise ratio and low resolution. The pre-stack seismic inversion often used in here is AVA inversion using partially stacked data to characterize the carbonate reservoir. Comparing with AVO inversion using single trace, AVA inversion suffers from the loss of lateral resolution when characterizing heterogeneity. Considering the question mentioned above, a physical model is used to analyze the influence of AVO/AVA inversion on heterogeneity. On the one hand, the differences in the lateral resolution of AVO/AVA inversion are quantitatively studied. On the other hand, the results of seismic inversion are compared with the actual size of caves in the physical model. The results demonstrate that the signal-to-noise ratio is able to be improved by AVA inversion while the lateral resolution is subsequently reduced. For the AVA inversion, seismic incident angle gather is divided into three parts, using for pre-stack inversion, the reservoir heterogeneity resolution is able to be reduced up to 33%.