Low Permeability Reservoir Classify Method Study Based On Microcosmic Pore Structure

In this paper,using grey correlation analysis method,five-yuan taxonomy and conventional mercury injection experiment,to classify rocks come from the southern songliao basin in jilin oilfield,xinli,xinmin,honggang,yingtai,daqingzi,and qianan six blocks which are typical low porosity and low permeability rocks.Using CT two-dimensional gray image to set up digital core model and axial model response the pore throat connected situation,obtain typical rocks sample from six blocks with the basic physical characteristics and microcosmic pore structure parameters.First analyze the microscopic pore structure properties of typical sample in the studied area,because of the permeability and oil flushing efficiency is directly related to the merits of the reservoir permeability,thus it can be used as a criterion parameter of reservoir to distinguish oil and gas recovery capacity.On the basis of analyzing the digital core model extracted the pore throat radius,pore throat connected length and pore throat ligancy frequency distribution of coordination number in different sections and the relationship between them with the permeability contribution value,and compare the six typical rock pore coordination number.On the basis of above work,in order to based on computed tomography(CT)scanning experiment to establish the classification of low permeability reservoir evaluation standard,affecting reservoir evaluation with the method of grey correlation analysis of the seven indicators(pore throat radius,pore throat connected length,pore throat coordination number,porosity,the degree of pore circuity,unit volume pore coordination number and the degree deviation of section porosity)to process weighting analysis,determine the correlation sequence of seven assessment indexes and their weighting,to establish the discriminant to divided reservoir into?,?,?class,and analyze the different types of reservoir pore throat structure.In order to complete and supplement classification standards,and through the conventional mercury injection experiment to establish the classification evaluation standard of low permeability reservoir,analyzed the different permeability core distribution characteristic of pore and throat,analyze the core capillary pressure curve,according to reservoir physical property data in combination with pore throat radius,curve shape,expulsion pressure parameters to proceed comprehensive analysis,according to the shape of capillary pressure curve is divided into?,?,?class,and gives different reservoir expulsion pressure,median pressure,median radius,the largest radius of pore throat and the interval value of mercury withdrawal efficiency.And then come up with five-yuan classification method,according the low limit of five yuan taxonomy,the reservoir is divided into?,?,?class.Finally,compared the classification results of the three classificationmethods to verify the accuracy of classification results.