Intergrated Reservoir Evaluation Of The Chang2 Interval Of Yanchang Formation In Zhengshiwan Area Of Jingbian Oilfield,Ordos Basin

Reservoir evaluation is an important part of reservoir description,it penetrates into the whole procedure in exploration and exploitation of oilfield,it's of guiding significance in ensuring the efficient and scientific exploitation of Oilfield.The main research contents include sedimentary microfacies,in-layer heterogeneity in macro-level,heterogeneity,physical property,percolation feature in micro-level.Zhengshiwan area is located in Jingbian oilfield of Central and Southern Shanbei slope,Ordos Basin.Currently water channeling is serious in chang2 reservior of Zhengshiwan area,leading to high water content in some oil wells,which affects the effect of water injection.Through the comprehensive evaluation of Chang2 reservoir,including sandbody distribution,macro and micro heterogeneity,delineate favorable reservoir distribution,providing the basis for the well pattern arrangement and the implementation of the water injection scheme.Using the theories of sedimentology,petroleum geology and reservoir geology,combined with well logging data analysis,core observation and test methods,the stratum of chang2 Fomation was divided and sublayers were compared;analysis of the sedimentary microfacies and sandbody distribution characteristics;analysis of diagenesis and physical property;combining the macro and micro characteristics of reservoir,made an comprehensive evaluation of the reservoir.Based on cyclic correlation and recognition of the marker beds,the Chang2 oil reservoir in the Zhengshiwan area is divided into 3 sand beds,the main oil reservoir Chang21 can be further divided into 3 small layers.Core observation and logging facies analysis show that research district developed Delta-depositional systerm,delta plain subfacies,distributary channel,inter-channel bay and debouch bar microfacies;Source supply direction from the northeast of the study area.The results of single sandbody show that the sandbody connectivity is good in the orientation parallel river channel and poor in the orientation vertical channel.The main rock types in the study area are gray,light gray medium fine grained feldspar sandstone;It has experienced a variety of diagenesis,including dissolution and metasomatism that are constructive to the reservoir physical properties,compaction,cementation that is destructive to the reservoir physical properties,analysises show that Chang2 oil reservoir is in the A stage of mid-diagenetic;A large number of core samples that have been tested show Chang2 is a low porosity and low permeability reservoir;The results of wettability and sensitivity report revealed that the chang2 reservoir are hydrophilicity,no-weak velocity sensitivity,medium-strong water sensitivity,weak salt sensitivity,weak-medium acid sensitivity,weak-strong alkali sensitivity;Analysis of reservoir heterogeneity of Chang21 sand bed,chang211 and Chang213 have strong interlayer heterogeneity,while the plane heterogeneity is poor,Chang212 has poor interlayer heterogeneity,while the plane heterogeneity is poor;Selecting parameters of the physical property of reservoir and oil-bearing characteristics,sedimentary characteristics and heterogeneity,using the methods of cluster analysis on Chang2 reservoir,carrying out comprehensive evaluation of each layer in Chang 21 sandbed,chang2 reservoir is divided into good,medium and poor reservoir,211 with medium-poor reservoirs.The reservoir evaluation and prediction results are compared with those of the existing production wells in the study area.The distribution of favorable area of Chang 21 oil reservoirs in Zhenghiwan area is mainly controlled by the distribution of sedimentary microfacies,and affected by the late diagenesis.