鄂尔多斯盆地红井子-罗庞塬地区长9油层组物源分析

Provenance Analysis of the 9th Member of Yanchang Formation in Hongjingzi-Luopangyuan Area,Ordos Basin

主要根据详细的岩芯观察,结合测井解释成果和铸体薄片分析,以及阴极发光实验,对红井子-罗厐塬地区长9油层组物源进行了系统研究。研究区长9油层组主要为一套灰色细砂岩、中砂岩与粉砂岩、深灰色泥岩及粉砂质泥岩互层,岩石中芦木化石较为常见,局部富集形成薄层煤。同时层理类型丰富,总体反映牵引流沉积特征,为典型的浅水三角洲沉积体系。根据岩石薄片鉴定和阴极发光分析成发现,研究区西部及东北部为变质岩岩屑高含量区,中部为火山岩岩屑高含量区,其中花岗岩岩屑主要分布在研究区东部。长9沉积期,研究区为多物源交汇带,主要受北东、北西及北部物源控制,同时受西南部物源影响,来自南西部的三角洲河道砂体与北东及北西的三角洲河道砂体在高吴仓堡-吴起地区附近交汇。

Based on core observations,well log interpretations,thin section identification and cathodoluminescence analysis,the provenance of the 9th Member of Yanchang Formation in Hongjingzi-Luopangyuan area,Ordos Basin was stndied. The results show that the 9th Member of Yanchang Formation in study area are mainly composed of inter-bedding layers of gray fine sandstone,sandstone,siltstone and dark gray mudstone and silty mudstone.Calamite fossils are common and locally enriched to form thin coal layers. Besides,various beddings are developed in the strata. These characteristics generally reflect the traction current depositions of typical shallow water delta system. According to the thin section identification and cathodoluminescence analysis,the west and northeast of study area is characterized with high metamorphic fragments,while the middle part with high volcanic fragments and the eastern region with high granite fragments. During the Chang 9 oil reservoir of Yanchang Formation deposition,provenance of Hongjingzi-Luopangyuan area as much provenance intersection are controlled by the northeastern,northwestern and northern rock sources,also influenced by the southeastern rock source,and delta channel sand-bodies from southwest,northeast and northwest are intersected near the Gaowucangbao-Wuqi area.