Analysis Of Fluvial Facies Sequence Stratigraphy Of Neogene In The North Slope Of Chengning Uplift

The north slope of Chengning uplift is one region which has huge prospect potential in Huanghua depression in Neogene. To research its sediment and strata sequence characteristic is very important toward oil and gas exploration and exploitation. For its fluvial facies strata, the author used the high-resolution sequence stratigraphy theory and means to study this region's stratigraphy characteristic and the regularities of distribution of reservoir.Based on rock cores, logging, three-dimentional seismic, the sedimentary facies of this region were analyzed in detail. The primary facies are braided fluvial facies and meandering fluvial facies, and their depositional features were discussed. The source direction, palaeocurrent and the river type evolution were analyzed systematically, the sedimentary facies models were found, and the depositional pattern and sandstones distribution regularity of different time were discussed.By applying the high-resolution sequence stratigraphy theory and means, the Neogene was divided into one superlong-term, seven long-term, and several middle-term and short-term base level cycles. And discussed the structure types, depositional array and stacking pattern of these cycles. On the basis of these studies, the author established high-resolution isochronous stratigraphy framework.The Neogene of researched region is inland river facies strata, so the formation and evolution of the sequence stratigraphy are controlled mainly by tectogenesis, climate, topographically appearance and river pattern factors. By means of frequency spectral analysis method, for the first time, the author use the Gamma-ray curves to analyze the sedimentary cycle, and discover that the ratio of sedimentary cycles are close to the ratio of Miankovitch cycles. So it is reasonable to deduce that the high frequency sedimentary cycles are controlled by palaeoclimate.The reservoir performance and regularities of distribution in isochronous stratigraphy framework of braided stream and meandering stream sandstone were contrasted and analysed. On the basis of this, the author revealed the impact of base lever on reservoir, and made the conclusion that the best reservoir develop at the lower part of the rose hemicycle of base lever.