The Special Low Permeability Reservoir Microscopic Oil Displacement Mechanism Research

Low permeability reservoir microscopic water displacing oil mechanism is the basis forunderstanding the low permeability reservoir and Improve low permeability reservoir waterflooding oil recovery. This articlc in view of the qinghai oilfield KB and YIN low permeablereservoir，on the basis of understanding of the analysis of geological features, reservoirsensitivity, Application of real sandstone micro model the microscopic flow characteristics ofthe single-phase water and oil to drive microscopic water flow characteristics，water lfoodingmicroscopic flow characteirstics and the residual oil characteirstics and influencing factors，made the following understanding:1.The study area Microscopic single-phase water flow characteirstics show three types，that isthe main channel lfooding，multi-channel flooding and mesh displacement. The studyobserved when the pressure is low and stable, water only in a speciifc channel flowThe study observed when the pressure is low and stable，water only in a speciifc channel lfow.The water enter more channels atfer the pressure increased, the water permeabilityaccompanied by gradually increasing phenomenon，showing the study area, the reservoirwater non-Darcy lfow phenomena of the microscopic lfow2.The microscopic study of reservoir oil driving water mainly for type uniform dirve to dirvefor the two forms of non-uniform micro-heterogeneity better the YIN reservoir oil dirvingwater main uniform dirve for the type，driving water and micro-heterogeneity KB reservoiroil mainly to non-uniform drive for type，under normal circumslanccs，oil dirve the water,even dirve for a microscopic model of oirginal oil saturation was signiifcantly higher than thenon-uniform displacement type of the original oil saturation，oil displacement efficiency by anaverage of39.76%.3.The study area water displacing oil process performance to drive uniform leading edge offlooding, mesh front three forms of flooding and the leading edge of the sadden flooding,more heterogeneity the YIN reservoir water flooding，mainly in uniform leading edge oil andmesh flooding-based，heterogeneity KB reservoir water displacing oil proccss edge suddenflooding； studies have shown that the highest uniform leading edge EOR lfooding process of oil displacement efficiency, the average up to51.15%, medium-mesh flooding waterflooding efficiency, with an average of up to41.83%, suddenly into the type of flooding onthe leading edge of the oil displacement efficiency is the lowest, with an average of up to33.69%4. The study area’s reservoir drive pressure water displacing oil efficiency, driving pressureincreased by1, the water flooding efficiency of6.4%-11.3%; flooding multiples also havesome impact the efficiency of water displacing oil, water multiples to improve1PV oildisplacement efficiency of an average of2.75%-4.4%.5. The study area’s pore structure on the distribution of residual oil; this experiment threeresidual oil types: flow around the formation of residual oil, residual oil in the card off theresidual oil, corner corner on this article of the two reservoirs, residual oil flow around thelargest number of residual oil, accounting for about70-80%of the total amount of residual oilin study block; card off the formation of study block20%of the total amount of residual oil-30%; corner corner of residual oil, accounting for less than5%of the total residual oil.