鄂尔多斯盆地西缘二叠系隐伏构造特征及勘探意义

利用线束三维地震、非地震以及YT2等井的实钻资料，结合鄂尔多斯盆地西缘银洞子地区构造演化特征及其与油气成藏的关系，对该区逆冲推覆构造的构造特征、油气成藏条件和勘探前景进行了研究。研究结果表明：①鄂尔多斯盆地西缘银洞子地区构造模式为典型的前展式逆冲构造，新逆冲体发育在老逆冲体之下，自西向东发育韦州—安国断裂（韦安断裂）、青龙山—平凉断裂（青平断裂）及惠安普—沙井子断裂（惠沙断裂）。②在惠沙断裂与青平断裂下盘，受燕山期自西向东的推覆应力作用，地层发生褶皱变形，发育呈排状展布的隐伏构造。③在鄂尔多斯盆地西缘，隐伏构造对油气成藏具有明显的控制作用。隐伏构造内二叠系源储配置关系良好，发育多套砂岩储层，圈闭较多，且保存条件较好，是鄂尔多斯盆地西缘上古生界勘探领域的重要有利区带。

Characteristics of Permian concealed structures in western margin of Ordos Basin and its significance for oil and gas exploration

Based on the actual drilling data of 3D seismic,non-seismic and wellYT2,combined with the structural evolution characteristics of Yindongzi area in the western margin of Ordos Basin and its relationship with oil and gas accumulation,the structural characteristics,oil and gas accumulation conditions and exploration prospects of thrust nappe structure in this area were studied. The results show that:(1)The structural model of Yindongzi area in the western margin of Ordos Basin is a typical forward thrust structural,moreover,the new thrust bodies were developed under the old ones,with Weizhou-Anguo fault(Wei'an fault),Qinglong Mountain- Pingliang fault(Qingping fault)and Huianpu-Shajingzi fault(Huisha fault)stretching from the west to the east accordingly.(2)There were obvious folding and deformation within the strata in the footwall of Huisha fault and Qingping fault because of the effect of nappe stress from west to east in Yanshan period,additionally,there were concealed structures developed in rows.(3)The concealed structures have obvious controlling effect on hydrocarbon accumulation in the western margin of Ordos Basin. With good source-reservoir assemblages in Permian, the concealed structures promote the development of multiple sets of sandstone reservoirs,and the development traps are relatively considerable and the preservation conditions are relatively better to some extent. Therefore,it is regarded as favorable areas for the exploration within Upper Paleozoic in the western margin of Ordos Basin.