Reservoir Characteristics And Quantitative Evaluation Of Chang 2~1 Oil Layer In Yujiaping Middle Area Of ??Yanchang Oilfield

Zichang Oilfield is located in Zichang prefecture of Shanxi province.The tectonic location of it is located in the Shanbei Slope of the Ordos Basin.One of the main producing oil layer is the Chang2 Formation.Chang2 Formation is divided into Chang21?Chang22 and Chang23 according to main symbol layer of this region,cycle correlation and graded control.The main subject investigated of this paper is Chang21 formation of Yujiaping area in Zichang Oilfield,which is rich in oil and gas deposits.So I do research about the sedimentary characteristics and the reservoir stratum of Chang21 Formation based on observation of the outcrops and the cores?costing thin sections?scanning electron microscopy?testing the oil and the well logging analysis.This paper consider that Chang21 Formation develop braided river deposits according to the sedimentary characteristics of the region.The river channel sand zonal distributes from northeast to southwest,which is controlled by sedimentary facies.The sandstone of Chang21 reservoir in central section mainly is feldspar sandstone,a few lithic feldspar sandstone is also exist.The reservoir space of it is the residual intergranular pore and the dissolution pore,the structure of porosity is mesoporous with thin throat.So the reservoir of this area is of low porosity and low permeability.Compaction?cementation and disso?lution are the main types of diagenesis of the sandstone of Chang21 Formation.The logging interpretation model is built for reservoir arguments,and the logging data are under secondary digital processing to determine the reservoir arguments of non-coring wells quantitatively.The study area is a low permeability oilfield.This paper apply the Grey Correlation Method to evaluate the reservoir comprehensively and quantitatively.First of all,the characteristic arguments of the reservoir in the study area are selected as follows:porosity,permeability,shale content,sand thickness and the thickness ratio of sandstone and strata.Then calculate the arguments weight through the correlation analysis method of grey system theory.At last,we have to figure out the comprehensive evaluation index and the influencing factors,then the reservoir is evaluated.Chang21 reservoir is evaluated that primary is type ? and ?,secondly for ? and I.Simple as the method is,the data behind it is based on actual data.