Study On Lower Limits And Effectiveness Evaluation Of Buried Hill Reservoir

Due to the variety of reservoir spaces,strong heterogeneity,and complex oil-bearing properties in buried hill reservoir,there are many problems in determining the lower limits of the reservoir and well logging evaluation.Therefore,accurate evaluation of the effectiveness of buried hill reservoir is important for exploration and development.This paper is aimed at the Chengbei 30 buried hill carbonate reservoir in Shengli Oilfield.Combined the geology,logging,testing,logging data and petrophysical experiments of the study area,this paper carries out the determination of the lower limits of the reservoir,the identification of the logging response,the calculation of the reservoir parameters,and the effectiveness evaluation,forming a set of effectiveness evaluation methods for buried hill reservoir.In order to study the oil-bearing properties of the matrix,the lower limits of the oil-bearing properties of the buried hill matrix were studied through microscopic visualization experiments,petrophysical experiments,and logging data in the previous production process.The lower limits of the oil-bearing pore throat radius of the reservoir were studied by laser scanning confocal experiment,and the lower limits of the porosity and permeability of the reservoir were studied by the mercury intrusion experiment.The T₂ cutoff value of the reservoir was studied by nuclear magnetic resonance experiments,which provides a reference for the distinction between bound fluid and movable fluid.The classification criteria of different types of reservoir spaces were given.The identification models of different types of reservoir spaces in carbonate reservoir by electrical imaging logging and nuclear magnetic resonance logging were summarized.According to the characteristics of conventional logging responses,a comprehensive discrimination model was established,and the reservoir space types of buried hill reservoir in the study area were divided into four types:pore type,fracture type,fracture-pore type and karst cave type.The calculation models for reservoir parameters of buried hill oil reservoir have been established.An effective porosity calculation model was established by nuclear magnetic resonance logging and three-porosity regression.The numerical simulation method of multi-scale pore network model of fractured reservoir was used to study the influence of fractures on the seepage and conductivity of the rock,and the calculation models of permeability and saturation considering the coupling effect of dual-porosity media model were established.Combined with compensated neutron,resistivity and wave impedance,the comprehensive reservoir classification index was proposed,and the reservoir classification standard was established by combining with effective porosity.The buried hill reservoir in the study area were divided into three types.