镇泾地区长8段三维地震强振幅异常带成因探讨

发布时间：2018-06-20 13:31

本文选题：镇泾地区 + 张家滩页岩　；参考：《石油地球物理勘探》2017年02期

【摘要】：在鄂尔多斯盆地西南部镇泾地区约2000km2三维地震区的长8段沿层振幅平面图上,存在多条北西向带状强振幅异常,它们与多年来地质上所勾绘的长8段河道砂岩北东向延伸方向近于垂直,北西向的振幅异常延伸对属性和反演等方法预测长8段砂岩厚度和展布造成较大的影响。本文从700km2代家坪三维地震和区内60余口钻井资料入手,经过综合分析可知,长8段北西向振幅异常与长7段的沿层振幅趋势完全一致,而与黄土塬地表地貌无关,与浅层白垩系、侏罗系、延长组长6段和长9段沿层切片上振幅异常的延伸趋势不同。长8段振幅切片上不同振幅区钻井合成道振幅大小与振幅切片上井点实际振幅大小一致,其振幅增强与长7段张家滩页岩厚度增大和波阻抗减小相关。页岩厚度变化可能与垂直于湖岸线的长72重力流水道对下伏长73侵蚀有关。延安组低速煤层强反射对下伏地层的不均衡屏蔽与长8带状振幅异常无明显关系;某些北西向断裂带的振幅减弱对带状振幅异常的形成也有一定的强化作用。这些振幅变化对长8砂岩三维地震储层识别造成了较大影响,是该区地震勘探需要解决的重要问题之一。
[Abstract]:There are many strong amplitude anomalies along the layer of Chang 8 formation in Zhenjing area of southwestern Ordos Basin, which is about 2000km2, and there are many strong amplitude anomalies in NW direction. They are nearly perpendicular to the extended direction of Chang 8 channel sandstone geologically drawn for many years. The amplitude anomaly extension in the north west direction has a great influence on the prediction of sandstone thickness and distribution in Chang 8 formation by means of attribute and inversion. Based on the 3D seismic data of 700km2 Daijiaping and more than 60 drilling wells in this area, it can be seen from the comprehensive analysis that the NW amplitude anomaly of Chang 8 is completely consistent with the amplitude trend along the formation of Chang 7, but has nothing to do with the surface geomorphology of Loess Plateau. It is different from the extension trend of amplitude anomalies along the layers of the Cretaceous, Jurassic, Yanchang 6 and Chang9 segments. The amplitude of synthetic channel in different amplitude areas of Chang 8 section is consistent with the actual amplitude of well point on amplitude slice, and its amplitude enhancement is related to the increase of Zhangjiatan shale thickness and the decrease of wave impedance in Chang 7 member. The variation of shale thickness may be related to the erosion of Chang72 gravity channel perpendicular to the lakeshore line. The strong reflection of low speed seam in Yan'an formation has no obvious relation with the abnormal amplitude of Chang8 zonal amplitude, and the weakening of amplitude of some NW fault zone also has a certain strengthening effect on the formation of band amplitude anomaly. These amplitude changes have a great impact on the identification of 3D seismic reservoir of Chang 8 sandstone, which is one of the important problems that need to be solved in seismic exploration in this area.
【作者单位】：中国石化华北分公司;西北大学大陆动力学国家重点实验室地质学系;
【基金】：国家自然科学基金重大项目(41390451) 中石化华北分公司企业委托项目联合资助
【分类号】：P618.13;P631.4

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