Abstract: Quantitative analysis of fluvial sand body is important for efficient oilfield exploration and development. In this paper, quantitative core analysis, well logging facies analysis, quantitative seismic sedimentology, and 3D seismic profile identification are used to quantitatively calculate the thickness of paleochannel sand body, width of channel (belt), depth of channel and other river parameters of Dongying formation in Wen’an slope of Baxian sag. The analyses reveal that there are three provenance entrances in Dongying formation of Wen’an slope, Suqiao in the north, Wenan in the middle, and Changfengzhen in the south. The rivers flowed on the Wen’an slope in NEE-SWW directions. The width (W) of the channel belt is 1.04-2.61 km, and the average width (wcb) is 1.71 km; the width (W) of the main channel is 15.2-179.6 m, and the average width (Wc) is 84.4 m; the depth (D) of the main channel is 1.34-5.21 m, and the average depth (Dc) is 3.29 m; the full depth (Dmax) of the main channel is 2.35-9.15 m, and the average full depth (Dmax) is 5.77 m; the thickness (H) of the main channel is 2.15-8.32 m, the average thickness (Hc) is 5.25 m, the length of river channel (L) is 18.5-28.2 km, the average length of river channel belt (Lcb) is 25.1 km, and the flow direction is 40°-65°. It is considered that Dongying formation of Wen’an slope are braided river deposits. The outer zone of the

slope is the main unloading area of sandstone, the river is dominatly vertically excavated and supplemented by lateral migration,
and the plan view of channel sandstone is “strip belt”. The inner zone of Wen’an slope is dominated by laterally migrating rivers, supplemented by erosion, and channel sandstone occurs as a sheet blanket. The channel sandstone of Dongying formation has the sedimentary conditions of “lower generation and upper reservoir”, and the development of lithologic and structural lithologic reservoirs has a promising prospect for oil and gas exploration.

Key words: fluvial facies, channel parameters, quantitative analysis, Dongying formation, gentle slope, Baxian Sag