The Feature Of Sequence-based Lithofacies And Paleogeography During Paleogene Of Luda Area, Liaodongwan Basin

The Shahejie and Dongying Formations of Paleogene in Luda area from Liaodongwan Basin are discussed on this paper. Liaodongwan Basin is regarded as a downfaulted basin, since Mesozoic, it have experienced three stages that were tension crack, rift, and sag, resulting in the formation of the north to east tectonic configuration of sag and uplift, which can be divided into five sub-firstgradestructure, three is sag, the other two is uplift, the feature of structural unit is several rift segistrations and heavy partition, every sag is comparted by uplift and often formed the pattern of graben or half graben. It can constitute a standalone system of oil-forming and oil-storage, the development of stratum sandbody and oil source is controlled obviously by sedimentary structure and palaeogeomorphology.According to dozens of drilling core's sedimentary structure marks, electrofacies marks and fossil marks, it can identify several depositional systems in Luda area of Liaodongwan Basin, including braided-river delta, meandering-river delta, lacustrine and turbidite fan. the paper have analyzed in detail the sedimentary facies, parfacies and microfacies. on the basis of detailed sedimentary facies analysis. combinating with three-dimensional seismic date, the Paleogene is divided into two super long-term sequence cycles, including 6 long-term sequence cycles, 18 middle-term sequence cycles and about fifty short-term sequence cycles, which guided by the method of high-resolution sequence stratigraphy, seismic stratigraphy and geophysical logging geology theory. then a couple of chief interwell correlation cross sections of north by east and south by west are chosen and the high-resolution sequence stratigraphic framework is founded.on the basis of interfaces and structure characteristics, by selecting the rising and falling base-level phases of each long-period sequence cycle as the isochronous mapping unit, the sequence-based lithofacies and paleogeography maps have been drawn, and the regulation of the change is deduced: during the phase of the LSC2 and LSC3, the primary depositional environments are shallow lake and sublacustrine turbidite fan, and the sublacustrine turbidite fan and delta are developed during the phase of the LSC4,while during the phase of the LSC5 and LSC6, delta and shallow lake become prevalent. From bottom to top, the shallow lake, sublacustrine turbidite fan and delta depositional configuration formed.on the basis of studying on high-resolution sequence stratigraphy, lithofacies and paleogeography. utilizing connected three-dimensional seismic date, well logging date and core date of studying area. taking Lada 16-3s target area for example, two representational sand groups were choosed , which came from Dongying and Shahejie Formations, the purpose of its is to predict and evaluate for prospective reservoirs.