Effectiveness Evaluation Of Volcanic Rock Reservoir In Dehui Fault Depression

The volcanic reservoir in Dehui fault depression of Jilin Oilfield has the characteristics of low porosity and low permeability,and complex lithology pore structure,which makes it very difficult to identify the effective reservoir.Therefore,it is of great significance for oilfield development to carry out comprehensive logging evaluation of volcanic reservoir.In this paper,yingcheng formation and Huoshiling formation of Baojia and Huajia in Dehui fault depression are taken as the research targets,and the effectiveness of the reservoir is comprehensively studied and evaluated with core experiment,conventional logging,nuclear magnetic logging,imaging logging and oil test and production test data.The main research ideas and contents of this paper are as follows:Firstly,the lithology is classified by core data and thin section analysis data,and the logging response characteristics of different lithology are summarized.Crossplot,cluster analysis and correspondence analysis are used to determine lithology.Secondly,the parameters of volcanic reservoir are determined.Calculation of reservoir permeability and bound water saturation by variable T₂ cut-off method.The cation exchange experiment corrects the rock electrical parameters and W-S model calculates the water saturation.Then based on core mercury intrusion and NMR experiments,using the method of double T₂ cut-off value,NMR spectrum is divided into three parts:completely bound,partially movable and fully movable to establish quantitative characterization method of reservoir pore structure and determine reservoir quality parameters.Finally,based on the analysis of lithology and physical properties of the reservoir,the reservoir classification standard is established based on the reservoir quality and other parameters,and the classification results are compared with the gas testing data to verify the effectiveness of the reservoir identification method.