Concave-uplift Combination Structure Features And Hydrocarbon Reservoir Distribution In The Jiyang Depression During The Paleogene-Neogene

The Jiyang depression is an important oil and gas depression in the eastern part of China.Predecessors have conducted extensive research on their basin structures,zone structures,trap structures,and fault structures.But it is not systematic and deep to study the characteristics of the Low-high structure especially the combination of Low-high plane,which we called Concave-uplift combination structure.This paper is based on the main tectonic seismic reflection layers T6(Es3z),T2(Esi)and Ti(Ng)in the Jiyang Depression.Analysed present and each deposition period features and evolution of Concave-uplift combination structure in the Jiyang Depression.On the basis of this,Analysed the relationsghip between single or the Combination of different Concave-uplift combination structure and reservoir formation and distribution.The main conclusion are as follows:(1)Present partition of Concave-uplift combination structure in the Jiyang DepressionBased on the painting method of the slot line(the connection between the lowest point of tectonic and its relatively lowest point),long line(the connection between the highest point of tectonic and its relatively highest point),valley line(the connection between the relatively lowest point,and it located between the slot line and long line)and ridge line(the connection between the relatively highest point,and it located between the slot line and long line).Dividing the Concave-uplift combination structure of T6?T2?T1 Rock Series.Mainly divided into two categories:The first kind is the side Concave-side Uplift,The second kind is the the side Concave-middle Uplift.With the number of low points the side Concave-side Uplift can be divided into single low point side Concave-side Uplift and Multiple low points side Concave-side Uplift.The T6 layer divides 50 Concave-uplift combination domains,The T2 layer divides 41 Concave-uplift combination domains,The T1 layer divides 31 Concave-uplift combination domains.The main types are all Multiple low points side Concave-side Uplift combination domain.There are three main types of upper and lower superposition relationships in the T6,T2,T1 Concave-uplift combination structure:T6side concave-side uplift,T2-Tiside concave-side uplift,such as Chexi2 Concave-uplift combination structure;T6side concave-side uplift,T2-T1 side Concave-middle Uplift,such as Gudao2 Concave-uplift combination structure;T6side Concave-middle Uplift,T2-Tiside concave-side uplift,such as Dongyinzhong Concave-uplift combination structure.The T6,T2,and T1 layers can be vertically communicated through faults and can be divided into cut-slope faults and along-slope faults according to the relationship between faults and contour lines.(2)Partition andComparative analysis of ancient and present Concave-uplift combination structure in the Jiyang depressionThe T6 layer present concave structure and the Shasanzhong bottom in different depositional periods(Dongying formation,Guantao formation,Minghuazhen Formation and Quaternary sedimentary period of ancient Aolong)combined structure were compared;T2 present concave structure and Es1 in different depositional periods(Dongying group,Guantao group,minhuazhen the final group,Quaternary sedimentary)ancient Aolong combination structure comparison,The Ti layer structure and the concave bottom in different sedimentary period of Guantao formation(Minghuazhen Formation and Quaternary sedimentary period of ancient Aolong)combined structure comparison.It can be seen that the regional comparison of the ancient and present Concave-uplift combination structure in the T6,T2 and T1 sedimentary periods of the Jiyang depression is generally consistent.The T6 layer in the depositional period of Concave-uplift combination structure has certain inheritance in general,slot line's general position(especially the lowest and highest point)remained,a gradual increase in the number of Concave-uplift combination domain,gradually fierce fluctuation.the T2 layer showing similar characteristics to the Ti layer in the Comparasion of present tectonic zoning and palaeo tectonic zoning.However,the number of Concave-uplift combination structure decreases with the increase of burial depth,and the extent of the area enlarges.(3)Relationship between the Concave-uplift combination structure and the discovered hydrocarbon accumulationIn the T6rock strata,it has been found that Es3 and Es4 oil and gas reservoirs are mainly distributed at the high part of the slot line,the saddle,(no distribution at the low point of the slot line no distribution at the long line),the side of the valley line near the groove line,The side of the ridge line near the groove line and the high point of the ridge line;the side of the cut-slope fault near the slot line,especially the side of the cut-slope fault intersecting the ridge line near the slot line,The side of the along-slope fault near the slot line and high position of the fault.In the T2(Ti)rocks overlying strata,it has been found that Es2 and Esi(Ed,Ng and Nm)oil and gas reservoirs are mainly distributed at the low point of the slot line,long line,valley line and ridge line.But the main distribution is related to the fault.It is generally distributed on the side of the cut-slope fault near the slot line,especially the side of the cut-slope fault intersecting the ridge line near the slot line,The side of the along-slope fault near the slot line and high position of the fault.The Concave-uplift combination structure has obvious control over the formation of oil and gas reservoirs,for the T6 layer,the oil and gas reservoirs are mainly distributed in the high part of the slot line,the ridge line and the valley line near the side of the slot line.For the T2 and T1 layers,the oil and gas reservoirs are distributed at the low point of the slot line,long line,valley line and ridge line,but are mainly distributed near the fault.Based on this,favorable area predictions were made for the T6,T2,and T1 layers.