鄂尔多斯盆地长7段浊积岩沉积演化模式及石油地质意义

Sedimentary evolution model and petroleum significance of Chang-7 member turbidite,Ordos Basin

鄂尔多斯盆地长7深湖区广泛分布浊积岩,在岩性、沉积构造、沉积序列及电测曲线等方面均具有明显的识别特征。在古地理演化过程中,长73期湖盆达到鼎盛,深湖区分布范围最大,碎屑物供应有限,浊积岩零星分布。从长73—长72—长71,深湖线向湖内收缩,浊积砂体逐渐发育,文章建立了该区浊积岩沉积演化模式。深湖区具备良好的石油成藏地质条件,浊积砂体可以作为深湖区好的储层,研究区西南部浊积岩发育区已发现多口工业油流井,可作为下一步的重点勘探区域。

The extensive extent turbidite can be identified by structure, sedimentary sequence and well logs of Chang-7 member evolution of Chang-7 member, lake basin and deep lake are both such apparent signatures as lithology, sedimentary deep lake, Ordos Basin. During the paleo-geographic at their maximum extent during Chang-7^3 stage, and turbidite was distributed fragmental-like in plane view, due to interplay of extensive extent deep lake and limited clastic supplying. Deep lake line was gradually moved toward lake center and turbidite sand bodies were gradually developed better from stages of Chang-7^3, Chang-7^2 and Chang-7^1. And depositional evolution model in study area is established. There is better petroleum accumulation in deep lake, and turbidite sandstone can be better reservoir in deep lake. At present, some commercial oil wells were found in Southwest Ordos Basin and the turbidite sandstones can be the main exploration targets in the near future.