Fine Reservoir Description Of Lower Member Of Es2 In The First Block Of Shanghe Oilfield

The first block of Shanghe oilfield is located in north of Shanghe oilfield,and it has been in high water cut development stage.As the main production layer,the remaining oil distribution is unclear of the lower member of Es2 layer due to the complexity and low degree of awareness of the deposition and reservoir characteristics.Guided by sedimentology,subsurface geology of oil and gas fields theory,making full use of sedimentary unit fine division and correlation,analysis of interface level and structure elements,the reservoir logging interpretation,and reservoir heterogeneity quantitatively evaluation techniques and methods,the paper carries out fine reservoir description on the lower member of Es2 layer of the first block of Shanghe oilfield.By the use of core data and logging data,the lower member of Es2 layer is divided into four sand groups,which is further subdivided into 19 single sand layers by the means of “sedimentary cycles-lithology thickness” and “isobaths time quautum contrast”,thus subtle stratigraphic framework of the study area is established.Based on observing and analysis of coring wells,the hierarchical division and identifying characteristics of reservoir architecture interface is determined clearly.Through integrating analysis of lithology,sedimentary structures,logging characteristic,the sedimentary facies and reservoir structure is discussed.Delta-front facies is the major deposition system which concludes underwater distributary channel,underwater natural levee,mouth bar,sheet sand,interdistributary bay,frontal delta mud structure unit in the study area.By drawing cross-section graph and plane distribution graph,the longitudinal and plane distribution characteristics of the first block of Shanghe oilfield is analyzed systematically.Based on correlation research of the porosity,permeability with the well-logging response and other parameters,the logging interpretation model is established and has been used to accomplish the comprehensive logging interpretations.By analyzing of thin slice,scanning electron microscope,mercury intrusion data and conclusion from well-logging interpretation,this paper carries out researches on the microscopic and macroscopic characteristics of the reservoir,and confirms the reservoir space and structural characteristics of pore throat.Then do research on the macroscopic heterogeneity from the aspects of in-layer,interlayer and plane.The results shows that the reservoir heterogeneity of in-layer is medium to strong,of which the interlayer is widely developed,mainly includes the shale interlayer and calcareous interlayer with poor lateral stability.Comprehensive comparison among physical property,sand body scale,drilling rate and interlayer developing scale of every single sand layers,it is believed that the interlayer heterogeneity in the study area is of medium to strong.As for plane heterogeneity,due to geometry diverse of sand body and significant variety of plane permeability of every single sand layers,it’s concluded as strong heterogeneity.The overall studies suggest that affecting factors of the reservoir heterogeneity is mainly depositional environment and diagenesis.Finally,the reservoir has been divided into three categories by a method of classification called “weight evaluation”.Among the categories,the first grade is the most favorable reservoirs in this area.