Research Of Sedimentary System And Reservoir Evaluation In The Southern Steep Slope Zone Of The E₂d₁ In Gaoyou Sag

Gaoyou Sag is a typical dustpan shaped subsidence lacustrine basin with a fault as its south boundary and a slope to the north caused fault activity between the time of Yizhen Movement of Late Cretaceous and Wubao Movement of Late Palaeocene. Sand reservoir is complicated in the southern steep slope zone of Gaoyou Sag,and its distribution scope is smaller,just in Huangjue,Zhenwu,Caozhuang,Fumin and Zhouzhuang District.There are many problems needed being resolved especially the distribution laws of oil and gas because of lack of research intension and superficial degree of understanding.The thesis is on the reservoir sediment,petroleum geology, reservoir geology,sequence stratigraphy and hydrocarbon accumulation dynamics. Using geology,geochemistry,geophysics,set up the distributing mode of sedimentary system in the southern steep slope of the E₂d₁ of Gaoyou Sag,unfold the sedimentary facies research and the partition of sedimentary facies belts;set up the reservoir sedimentary mode,and do the research of the quality of reservoir.According to the detailed observation and description of core,progress the synthesized analysis by combining the well logging,data of areal geology,assured the sedimentary mode of the southern steep slope of the E₂d₁ of Gaoyou Sag,braid delta was developed in Huangjue,Zhenwu,Caozhuang,Fumin and Zhouzhuang District, gravity fluid sediment was developed in Shaobo District.In the sedimentary time of the E₂d₁²,the scope of braid delta was larger because of the southern steep slope and abundant material in this zone except Shaobo District;in the sedimentary time of E₂d₁¹,Dainan Activity made the scope of lake broaden and the depth of lake increase, resulting in the scope of braid delta smaller than that of E₂d₁².According to the research of reservoir quality,distribution of reservoir,local distribution of sedimentary system,reservoir are evaluated,the results are as below: reservoir are mainly developed by braded river and bar-front,and the sandstone qualities of braded river is higher than these of bar-front;The sandstone qualities of E₂d₁² is higher than these of E₂d₁¹.Most of reservoir in Huangjue,Zhenwu, Caozhuang,Fumin and Zhouzhuang belong toⅡ～Ⅲ,Ⅰin some zones in these districts;Ⅳin Shaobo District.