鄂尔多斯盆地长8油层组浅水三角洲沉积特征及其地质意义

The Features and Geological Significance of Shallow Water Delta of Chang 8 Formation in Ordos Basin

根据沉积标志、砂体结构、测井响应及盆地底形等特征,认为鄂尔多斯盆地长8油层组发育浅水三角洲沉积,具有地层厚度稳定、植物化石及动物遗迹化石发育、浅水沉积构造明显等特点;由于水体较浅,湖岸线迁移频繁且迁移范围大,在长82油层沉积期形成沿湖岸线分布的坨状砂体(滩坝砂),在长81油层沉积期分流河道砂体交汇连片,且向湖中心延伸较远;这些砂体为有利储集体,是勘探评价的主要目标。

On the basis of the features of depositional markers,architectures of sand bodies,logging response and bottom configuration of the basin,the study revealed that the Chang 8 Formation of Ordos Basin was a shallow delta deposition.It had the characteristics of stable formation thickness,plant and animal remains development and obvious shallow sedimentary structure.Because of the shallow water,frequent transmigration of lake strandline in Chang 82 period,the distributary channel sand of delta front is formed as strand-bar sand bodies.In the period of Chang 81,the distributary channel sand of delta front is the main style of Chang 81 and extends far away from the center of lake.These sand bodies are the favorable reservoirs,they are the beneficial targets for oil exploration evaluation.