关键词: 曲流河, 干旱气候, 氧化环境, 沉积控储作用, 边滩, 河床滞留, 东三段, 古近系, 清苑地区, 保定凹陷, 渤海湾盆地

Abstract: Based on the study of petrological characteristics of Paleogene Dong 3 Member in Qingyuan area，Baoding Sag，Bohai Bay Basin，three aspects such as lithofacies description，sedimentary facies identification and analysis of geophysical response characteristics were analyzed，in order to clarify the sedimentary distribution characteristics，sedimentary model and the control mechanisms of sedimentation on reservoir. Meanwhile，the favorable zones were predicted in this area. The results show that：（1）The mudstone color of Dong 3 Member in Qingyuan area were mainly oxidation color，the sandstones were dominated by lithic feldspathic sandstone and feldspathic lithic sandstone，the rock of Dong 3 Member have low-middle compositional maturity and textural maturity，and have obvious river traction flow characteristics. During the deposition of the Dong 3 Member，the climate was arid and semi-arid，which indicated a terrestrial freshwater and oxidizing environment.（2）Nine lithofacies types can be identified in the study area，including four kinds of sandstone lithofacies，three kinds of siltstone lithofacies，two kinds of mud stone lithofacies. The study area developed meandering river facies， which can be divided into six microfacies：river bed retention sediment，point bar，natural levees，oxbow lake， crevasse splay，flood plain，five well logging response characteristics can be identified，including middle-high amplitude box-shaped，middle-high amplitude bell-shaped，middle amplitude finger-shaped，middle-low amplitude funnel-shaped，low amplitude linear，and the reservoir have moderate-strong ampitude，high frequency，middle and bad continuity on seismic section. The sand bodies were deposited in southwest-northeast trending in the plane，the thickness and distribution of the sand body of meandering river decreases from lower to upper，single belt type and network continuous sedimentary model of meandering river were established.（3）The sedimentation determined the reservoir characteristics in study area，the reservoirs physical properties of river bed retention sediment and point bar were the best microfacies，strong and stable hydrodynamic conditions，low content of clay mineral and thick sandbody were the basis of the formation of high-quality hydrocarbon reservoirs，the Ⅰ reservoir have the best physical properties，which were mainly distributed in the Ⅱ and Ⅲ oil-bearing formations in the vertical direction，well area G77-70X and G77-30X were the favorable target areas.

Key words: meandering river, arid climate, oxidation environment, controls of sedimentation on reservoir, point bar, river bed retention, Dong 3 Member, Paleogene, Qingyuan area, Baoding Sag, Bohai Bay Basin