鄂尔多斯盆地子洲地区上古生界沉积体系特征

FEATURES OF UPPER PALEOZOIC DEPOSITIONAL SYSTEM IN ZIZHOU REGION, ORDOS BASIN

为了搞清楚鄂尔多斯盆地东部子洲地区上古生界的沉积体系,进而寻找有利砂体及高产天然气聚集区,采用野外观察与室内研究相结合的方法进行了专项研究。结果认为,子洲地区上古生界主要发育辫状河三角洲、三角洲、湖泊、障壁海岸及浅海陆棚5种沉积体系;在古地理演化过程中,本溪组发育障壁岛—潟湖及浅海陆棚相,太原组在研究区东部及西南部形成浅海陆棚沉积,在中部和西北部形成潮坪沉积;山西组发育三角洲前缘亚相,盒8段发育辫状河三角洲前缘亚相;研究区上古生界的水下分流河道、砂坪及障壁岛沉积区均可作为该区的有利储层。

Upper Paleozoic depositional system in Zizhou region in the eastern Ordos Basin is determined through field observation and laboratory study to search for favorable sandbodies and prolific gas accumulations. Five sedimentary systems, including braided river delta, delta, lake, barrier shore, and shallow shelf, are mainly recognized in the Upper Paleozoic in the study area. In the process of paleogeographic evolution, barrier island-lagoon and shallow shelf facies were developed in the Benxi Formation; shallow shelf facies were developed in the Taiyuan Formation in the eastern and southwestern parts of the study area, while tidal flat facies were developed in the Taiyuan Formation in the central and northwestern parts of the study area; delta front subfacies were developed in the Shanxi Formation; braided river delta front subfacies were developed in the He-8 member. The deposits of underwater distributary channel, sand flat and barrier island facies in the Upper Paleozoic are favorable reservoirs in the study area.