Characteristics Of Depositional Sequence And Reservoir Of Shuangyang Formation Of Changchun Oil Field

The fault depression of Luxiang,Yitong Basin is a continental rift basin located on the Yitong Basin,which is an extended area in the north of Tan-Lu fault,and its 2nd layer of Shuangyang Formation in Paleogene is the exploration target layer of C-block of Changchun oil field.Based on the previous exploration data and achievements,this thesis relies on the theory and method of sequence stratigraphy and sedimentology,and makes a fine study on the 2nd member of Shuangyang Formation by using core and logging data.The sedimentary period and the reservoir development characteristics were analyzed under the sequence framework.1.Based on the stratigraphic division scheme of 2nd layer of Shuangyang Formation in Changchun oil field,the identification marks TQ1 of third-order sequence interface are studied,and the identification marks Tq1 of system tract in SQ1 third-order sequence interface are identifie in detail by using drilling core and logging curve data,and this paper re-establishes the high-resolution isochronal stratigraphic framework of the Shuangyang Formation,and establishes a new scheme for the stratification of the study area:The 2nd layer of Shuangyang Formation is divided into 2 third-order sequences(SQ1,SQ2)?5 Parasequences(S2?,SII,SIII,SIV,SV).The comparison of the fine stratigraphic framework and the comparison of the single sandbody are drawn to show the connectivity of the 2nd layer Shuangyagn Formation's sandbody.2.According to the identification signs of sedimentary facies such as rock type and logging curve,two kinds of sedimentary subfacies and seven kinds of sedimentary microfacies are identified.In the third-order squence,the S2?and S2?sand groups are fan-delta front facies sedimentary systems,and S2?,SIII and SIV sand groups are fan delta plain facies sedimentary systems.Sedimentary microfacies are gravel river/sandy river,underwater river,abandoned river,overflow sand,estuary dam,far sand dam and flood fan.The logging response model of the lithology-rock facies and its combination type is established,and the rock facies development law of the transverse and vertical sand group is revealed in the sequence stratigraphic framework,and connected wells' profile is drawn,Which laid the foundation for the study of reservoir area.3.Based on the study of drilling core,the diagenesis and pore type of reservoir are analyzed according to the characteristics of rock type,porosity and permeability.The effect of diagenesis on pore structure is studied,the rocks are experienced during the diagenetic stage A,the types of diagenesis are compacting,pressolution,cementation,corrosion,replacement,the types of pores are primary pore,secondary pores and associated cracks.The porosity and permeability plan of each single layer are plotted,and the development law of porosity permeability of single sand layer is indicated.Finally,the reservoirs were identified as medium-low porosity,medium-low permeability heterogeneous reservoirs.4.In this paper,the boundary between the water layer and the effective reservoir is distinguished.Through the study of the logging curve and porosity and permeability data,the reservoir and oil-water zone are identified as effective reservoirs.This paper reveals that the effective reservoirs are affected by stratification and phase control,and their distribution is consistent with the sand body skeleton system and is controlled by the river facies distribution.It is concluded that the effective reservoirs of 2nd layer of Shuangyang Formation growned in the period of Parasequence set system,concentrated development in SO1 and SQ2 which is lowst and system tract and highstand system tract period.