南黄海盆地下三叠统层序地层格架

SEQUENCE STRATIGRAPHY OF LOWER TRIASSIC IN THE SOUTH YELLOW SEA BASIN

南黄海盆地是下扬子地块向海洋的延伸,中、古生界海相地层研究程度较低,仍未开展过系统的地层格架研究,制约了研究区的油气勘探进程。结合陆域下扬子的研究成果,利用研究区以及陆上苏北盆地的地质、钻井、测井、岩心等资料建立起下三叠统的三级层序地层格架。研究结果表明:三级层序边界为岩性转换界面或者不整合面;下三叠统可以划分为3个三级层序,其中每个三级层序又可以划分为海侵和高位体系域,低位体系域均不发育。以上研究为后期沉积相划分、储层预测等提供了可靠的地质依据。

The South Yellow Sea Basin is the extension of the Lower Yangtze Block to the sea where the Mesozoic-Paleozoic marine strata are poorly studied. The lack of stratigraphic framework restricts the oil and gas exploration in the study area. Upon the correlation with the research results of the Lower Yangtze area, we establish the third-order sequence stratigraphic framework of the South Yellow Sea Basin by using the geological, drilling, logging, cores and other data available in the study area and the North Jiangsu Basin. The results show that the boundaries of third-order sequences are either lithologic contacts or unconformities. The Lower Triassic can be subdivided into three third-or- der sequences. Each third-order sequence consists of transgressive and highstand system tracts and the lowstand system tracts are missing. The framework may provide a reliable geological basis for further study of sedimentary facies and reservoir prediction.