Study On The Reservoir-forming Conditions And Good Exploration Target Of The Paleogene Shehejie Formation In Eastern Slope Of Gudao Uplift

The main exploration and development layer is Neogene in Gudao uplift.The exploration degree of the Paleogene formation is very low and has no larger breakthrough until now.The B70 and B701 well in Dongying and Shahejie formation on the east slope of Gudao uplift has reached the oil layer,and the B701 well got the deliverability of 35.8 t/d,which shows the exploration potential.Because of the weak research basis,the unclear hydrocarbon accumulation conditions and oil and gas enrichment regulation,the understanding about the exploration of new formation is not enough,which restricted the future exploration direction and the formulation and deployment of exploration targets.Based on the distribution of oil and analysis of producing well,we makes a detailed and systematic description to the oil enrichment regulation of Es2 and Es3 formation in xxx through the analysis of the the hydrocarbon source rocks,reservoir and seal condition,fluid transporting conditions.We make it clear that the distribution of oil and gas,revealing the oil accumulation conditions and regulation,and establish the hydrocarbon accumulation model of the east slope in Gudao uplift.Based on the mentioned analysis,the prediction of the potential target areas is accomplished.There is five concludes of this study:(1)the palaeogene sequence stratigraphic framework of Gudao uplift is established.The Paleogene strata has been divided into 2 second-order sequences and 3 third-order sequences.The eastern slope is overall ramp-type sequence mode,with relatively flat layers which overlapped one by one;(2)the depositional system of Es2 and Es3 formation is transgressive braided river delta deposits,and the distributary channel sandstones under water are the main reservoir,Minghuazhen formation and Guantao formation mainly developed the regional caprocks,and Es1 and Dongying formation as located caprocks;(3)the distribution of oil and gas in the east slope is heterogeneous.In horizontal,oil and gas of Es2 and Es3 mainly concentrates around the Gunan Fault(Well Bo 70 and Well Bo 42).It has the characteristics of the distribution of the hourglass in the vertical from Guantao formation to Shahejie formation;(4)The genetic mechanism of the crateriform distribution of oil and gas is discussed.Discrepant conduction of faults,distribution of cap rocks and trap property are the main factors which control the diversity of hydrocarbon accumulation and lead to Es2 and Es3's the weak indication of oil and gas in the slope zone;(5)The main exploration directions in the future are: areas around the downthrow side of Gunan Fault in Gunan sag,areas of the south zone of the slope which is near to Gunan Fault,areas near the lift in the slope and structure terminal of the slope dip direction.