Study On Influence Of The Boundary Layer On Micro Flow In Low Permeability Reservoir

So far,the low permeability reservoir development has been one of the important methods of enhancing the oil recovery.The recovery mechanism is indicated by the macroscopic percolation theory based on Darcy flow equation,which could not accurately study the influence of boundary layer and other factors on the flow.The study of digital core technology on micro scale in low permeability sandstone reservoir has obvious advantages.Many scholars have tried varieties of methods on constructing digital core that could accurately describe the pore structure characters,in which,the model based on CT technology is the closest to the actual structure of porous rock.In this paper,firstly,the digital core is constructed by CT scanning,and then the structure is optimized by deleting the isolated pores,which can reduce the computer storage space.Based on the constructed digital core,the pore network can be extracted by the pore space medial axis.The rock structure characters can be got when analyzing the geometry-topology structure of pore network model,including pore radius,shape factor,tortuosity,coordination number and network connectivity function.The oil saturation of each step of pore and throat in the water displacing oil process can be got by flow simulation.Secondly,the calculation of oil viscosity can be studied in the different situations.Based on the constructed digital core and pore network,the influence of boundary layer on flow can be analyzed.The low permeability sandstone core model can be reconstructed by iso2 mesh software.According to the finite element numerical analysis method,the flow numerical simulation of reconstructed core can be got by COMSOL Multiphysics software,the velocity distribution,pressure distribution and fluid flowing state of pore can be studied.Thirdly,the influence of pressure gradient on boundary layer thickness can be studied,and the dimensionless boundary layer thickness and viscosity are obtained.The influence of boundary layer,boundary layer viscosity,and boundary layer thickness on micro flow in the low permeability sandstone reservoir can be analyzed.In this dissertation,one comparative integral influence of the boundary layer on micro flow study method is formed,which has important application value and academic significance to the low permeability reservoir.