Lower Assemblage Of Yanchang Formation Reservoir Identification Methods Research In Nanniwan Oilfield

In the study of exploration and development of low porosity and low permeability reservoirs,it has great significance to evaluate the reservoir effectively.The logging evaluation of low porosity and low permeability reservoirs is always the difficulty of reservoir evaluation.The reservoirs in the lower assemblage of Nanniwan oil field are typical of low porosity and low permeability reservoirs,It has the characteristics of poor physical property,strong heterogeneity,complex pore structure and oil-water relationship.Diagenesis and pore structure differences seriously affect the ability to accurately identify and evaluate reservoirs using logging data.In this master's thesis,lower assemblage reservoir group of Nanniwan oil field,Ordos Basin is studied as the research object.Firstly,the sedimentary facies,sand body distribution and reservoir characteristics of the study area have been described systematically.Secondly,we carry out the study of Reservoir “Four-Property” relationship,and establish the reservoir parameter interpretation model to further evaluate the reservoir.Finally,using the reservoir parameter cross-plot method,the resistivity and the acoustic travel time curve overlap method and the Archie formula method identify oil-water layer qualitatively and quantitatively to recognize the oil reservoir of lower assemblage of Yanchang Formation effectively.Based on the studies above,the following results are achieved: Chang 9,Chang 8,and Chang 7 oil layer of the study area develop delta frontal subfacies;rock type is mainly composed of arkose;the pore type is mainly intergranular;the average porosity of the reservoir is 8.95%;the average permeability is 1.27×10(-3)?m2;the reservoir physical property is poor and characterized by low porosity and low permeability.Based on the reservoir parameter interpretation model and the lower limit of reservoir physical properties,the oil and water layers are identified by three methods,and the coincidence rate of interpretation is improved.