The Analysis Of The Middle And Low Part Of The Cenozoic Tectonic Sequence,Sedimentary Filling Evolution Characteristics And Factors Controlling Oil Accumulation Of Qi'nan Area

The research work area mainly includes the eastern and southern of Qikou sag,shortly named "Qi'nan Area",whose main purpose formation is from S2 to ML.The drilling is very little and not uniformly distribute around structure;At the same time,because of the structure,the change of the source system,the plane and space distribution of the reservoir,and the distribution rule of the subtle trap are not recognized clearly,which greatly influenced the exploration and development of this area.Tt is necessary to do research about tectonic sequence,sedimentary evolution and the analysis of the factors controlling hydrocarbon accumulation.The research about source,sedimentary and analysis of factors controlling oil accumulation are done through establishing the Paleogene and Neogene sequence stratigraphic framework.In this research,four developments are made about the Neogene sequence,Neogene the distribution of sedimentary system,the source and the change of some wells formation,the prediction of the subtle trap:First of all,ten 3rd sequences are divided from S2 to MLby the sedimentary cycle,regional unconformities and their correlative conformities.At the first time,two 3rd sequences are indentified in Guantao formation(SQg1,SQg2)and three 3rd sequences are indentified in ML formation(SQmL1,SQmL2,SQmL3).Based on the Qi'nan seismic interpretation,the Qibei seismic sequence interpretation question are solved by calibrated the sequence and flooding surfaces.Second of all,the formation in the well region of CFD13-1 and QK17-9 are modified combined with the results the tectonic involution and core observation.Third of all,two sources are found out which are the Shaleitian Uplift source and Chengning uplift,but the Shanan low uplift only provide sometimes source through the research of relic landform,heavy minerals and ratio of sandstone.The oil fields of QK17-1?QK17-2?QK17-3 and QK18-1 are influenced by source of the Chengning uplift which is different from the original knowledge that the oil field of QK18-1 was influenced by source of the Shaleitian Uplift.At the same time it is different that the source of the Shanan low uplift was main source in the early time.The Shaleitian Uplift only influenced the small distance and can't influence the subwater alluvial fan.Fourth of all,because of tectonic movement,large accommodation is made in SQ2 period,which provided the good condition for braided river deltas and made it different from other place in Guantao formation in the Bohai Bay Basin.The three 3rd sequences of ML formation develop Shadow water delta because there are deep water in someplace.Fiveth of all,through the analysis of the sequence,sedimentary and factor controlling oil accumulation,it is found that the favorable subtle oil zones are the subwater alluvial fan developing in the downdip block of the Haisi fault,lacustrine floor fan in the downdip block of the Haiyi fault and dam-and-beach in Shanan low uplift.Combined with the tectonic map,6 subtle traps are found.