Qingxi Depression Tight Oil Reservoir Logging Evaluation Research

Xiagou formations in Qingxi depression belong to semi-deep lake facies,have huge potential for the tight oil development.This article evaluates the geochemical parameters,lithological parameters,mineral composition,porosity & permeability parameters,and fracturing parameters,and puts forwards three aspects of evaluation techniques including reservoir quality,source rock quality and engineering quality.To evaluate the geochemical parameters,the calculation methods of TOC is proposed in this paper according to the geochemical experiment information.And then combined with core analysis information,the relation model among S1?S2 and TOC is well fitted.Vitrinite reflectance,pyrolysis maximum peak temperature and thermal maturity index are chosen as the indicators of organic maturity.And the calculation model of the three indicators are also provided respectively.Finally the type of organic matter in the research area is well divided based on the calculation model.To evaluate the lithology,this article introduced the concept of fine lacustrine sedimentary.Based on the mineral content get from the whole rock analysis,I renamed the lithology of this region,analyzed the characteristic of the lithology,and combined with the analysis of logging curves,ascertained the logging curve characteristics of different lithology.On this basis,ascertained the logging curves sensitivity of different lithology through the cross plot.Then I build discriminant equation based on the method of Bayes discriminant analysis,realized the quantitative classification of lithology.To evaluate the mineral composition,firstly I as curtained the main mineral composition is sand,dolomite and clay by analyze the data get from whole rock analyze.Referenced the definition of M and N cross plot,I introduced lithological parameter TM,TN and TP to build the mineral component model.To evaluate the physical property,this article ascertained the influence factors and characteristics of physical property of this region,then built the porosity evaluation model on the basis of lithology identification.Due to the rock is very tight,the permeability is mainly affected by the fracture.So I built the permeability evaluate model based on the fracture evaluation with the conventional logging and resistivity imaging logging.As the reservoir belongs to the self-generating and self-preserving reservoir,the saturation has a lot to do with the mineral composition.So this article built the saturation calculation model on the basis of mineral composition.In the terms of the fracturability,this paper applies acoustic logging data to obtain formation parameters,such as elasticity,intensity,formation stress,burst pressure and collapse pressure,which,therefor,lays the foundation for the formation stress analysis and fraturing treatment of tight oil reservoirs.