Research On Sedimentary Facies And Sand Body Distribution Of Neopaleozoic Reservoir In Sulige Area Of The Ordos Basin

Although there is huge amount of resource in this Block in Sulige area of the Ordos Basin, the exploration rate is extremely low with even less-level exploration beyond the explored reserve block. However there still exists great exploration potential due to its favorable geological condition for gas accumulation, and so all directions of the Sulige area will be potentially advantageous exploration targets.In this article, after having analysed pictures of exposures, recordations of 20 drilling well core and logs,the author drew 30 sheets single well bar chart map,some maps have been devided sequence and sedimentary facies ,and drew well tie cross section diagrams,then established intended interval sand body maps and palaeoareal maps,thus the autor get geology conclusions.In the region of interest,Neopaleozoic strata develop Carboniferous System Benxi set(C₂b),Lower Permian Taiyuan set (P₁t) and Shanxi set ( P₁s ), mid- Permian Xiashihezi set (P₁x) and Shangshihezi set (P₂sh) , and Upper Permian Shiqianfeng set (P₁q) . In this article, The number 8 segment of Xiashihe set is named He 8, the number 1 segment of Shangxi set is named Shan 1, and the number 2 segment of Shangxi set is named Shan 2. the most intended interval in the region of interest are He 8 and Shan 1.In the sequence stratigraphy, C₂b is divided into two tertiary level ,so does P₁t and He 8, Shanxi set is divided into five tertiary level, and Shan 1 is divided into two tertiary level.In the sedimentary facies,what Ordovician system contact the bottom of C₂b is accordant unconformity.the top of C₂b t is slight coal bed ,somewhere it is sandstone. Feature of Taiyuan set is limestone. what Taiyuan set contact Shanxi set is scour surface,the marker bed of P₁s's bottom is Baidaigou sandstone.and the marker bed of it's top is Luotuobo sandstone. C₂b—P₁t develop chiefly barrier island and lagoonal facies, somewhere P₁t develop delta facies,Shan 2 develop meandering river sedimentary facies because of its diadactic composition,and figure of gamma ray is chiefly campaniform,in the partly area sedimentary facies of Shan 2 is delta facies. and Shan 1 develop braided stream sedimentary facies, and He 8 is like with shan 1. the main sediments of HE 8 and Shan 1 is conglomeratic sand or coarse sand, and the next sediments are siltstone and fine sandstone,mud rock is little,and sand selected separately is bad,its granula psephicity is also bad,and interstitial material is chiefly kaolinite and goeschwitzite.and the figure of gamma ray is microdontella box, the contact surface of the top and bottom of box is saltatory evolving.In the distribution of sand body,sediments in the region of interest stem from Yimen uplift of the Ordos Basin. Shan 1 present longitudinal through-going the sand body .and so does He 8. Shan 1 develop chiefly two rivers ,Sulige and Shizuishan river. Sulige river go through Wushenqi area ,and The thickness of sand body of Sulige river is about 8 to 12 meters,and width is about 30 kilometres.Shizuishan river go through Pingluo area , and The thickness of sand body of Shizuishan river is about 10 to 14 meters,and width is about 25 kilometres.In the particular period of He 8,the thickness of sand body is thicker more than in the particular period of Shan 1,and the area of sand body is increase.The sand body of He 8 inherit wholly the framework of Shan 1,and the thickness of sand body towards south is decrease.