鄂尔多斯盆地定边-吴起地区长6沉积相研究

通过对岩石学特征、岩石颜色、沉积构造、生物化石标志、粒度分析等特征综合研究,证明鄂尔多斯盆地定边-吴起地区长6油层组属于辫状河三角洲-湖泊沉积,发育三角洲平原、三角洲前缘及深湖-半深湖亚相。研究区长6油层组受西北和东北方向上的两个主要物源控制,平面上发育规模较大的北东-南西、北西-南东方向展布的水下分流河道,延伸至南部入湖。从长63至长61,研究区湖岸线逐渐向南推移,半深湖-深湖范围逐渐缩小,北部三角洲平原面积扩大,是一个逐渐湖退的过程。

Sedimentary facies of the Chang-6 oil reservoirs in the Dingbian-Wuqi region, Ordos Basin

The integration of the petrology, colour, sedimentary structures, organic fossils and granulometric analysis shows that the Chang-6 oil reservoirs in the Dingbian-Wuqi region, Ordos Basin are assigned to the braided delta-lacustrine deposits which may be grouped into the delta plain, delta front and abyssal to bathyal lake subfacies. The sediment sources dominantly come from the northwest and northeast of the Basin. In a plan view, there are two subaqueous distributary channels oriented NE to SW and NW to SE, respectively. From Chang-6₃ to Chang-6₁, the study area displays a depositional pattern of lake regression, including southward migration of the lake strandline, the gradual decrease of the abyssal to bathyal lake area, and the increase of the northern delta plain area.