Micro Flowing Model Set-up Of Low Permeability Reservoir Fluid And Inflencing Factors

The study of micro flowing characteristics of low permeability reservoir fluid is of greatimportance for understanding the low permeability reservoir flowing law and improving lowpermeability reservoir water flooding oil recovery. This article, in view of the Qinghai oilfieldand other low permeability reservoirs, with the application of the real sandstone micro-modelsimulation experiment method, focusing on systematical experimental study of the micro-flowcharacteristics of single-phase fluid and oil and water two-phase, and influencing factors, onthis basis, in combination with the understanding of pore structure of reservoir rock, rockproperties, seting up concept flowing model of the study area mainly made the followingunderstanding:(1) The study area single-phase water flow has the characteristics of heterogeneityseepage, that is under different pressures, there is large difference between water flowingchannel and flowing speed; And the corresponding flowing curve has non-darcy flowingcharacteristics. Therefore, the inhomogeneity of micropercolation fluid is one of the mainreason of the non-darcy flowing of low permeability reservoir. The strength of heterogeneityhas great relation with pore structure of flow and flowing pressure gradient. In this paper, withevery1%increase of the flowing pressure gradient, the flowing area of water in the reservoirmicro-model increased by0.20%on average. This proves that flowing pressure gradient hasvery significant influence on the flow of water.(2) The inleting pressure gradient has close relation to permeability of reservoir. Thesmaller the permeability, the bigger corresponding inleting pressure gradient and the lower themodel permeability, the higher inlet pressure gradient, and the inleting pressure gradient withgas logging permeability model has good power relations. When the study area reservoir gaslogging permeability is less than23.25×10-3μm2, inlet pressure gradient increased dramatically,fluid flows hardly.(3) With the increase of the flow pressure gradient, the water permeability measurementfirstly has a substantial increase, and then increases slowly. When the pressure gradient in thestudy area is greater than0.006MPa/cm, the water permeability increase began to slow downwith the increase of pressure gradient. (4) Even displacement for a micro-model of original oil saturation was significantlyhigher than the non-uniform displacement type of the original oil saturation, oil displacementefficiency by an average of28.13%; Bound water is mainly in the formation of flow around;KB reservoir has the largest flow around area; Non-uniform displacement type, lowpermeability and high clay mineral content can cause the decrease of the original oilsaturation.(5) The study area micro water displacing oil process has great influence on the oildisplacement efficiency. WN reservoir has front dash displacing type and channel typedisplacement. Its average oil displacement efficiency is29.66%and38.12%respectively;77.78%of KB reservoir model are front dash displacingt type, with the average oildisplacement efficiency of27.66%, the rest are channel type displacement with the average oildisplacement efficiency of46.36%; YD reservoir is piston displacement with the average oildisplacement efficiency of58.23%; Displacement type, displacement pressure anddisplacement ratio, permeability and clay mineral content in the study area all have influenceon oil displacement of the study area, of which the displacement type and the displacementpressure is the largest.(6) The main types of residual oil in the study area is the flow around formation of flakeresidual oil, thin film shape and spotty residual oil, edge corner residual oil, tufted, briquetteand oil bead shaped of residual oil, of which flake residual oil accounted for about60~70%ofthe total amount; The thin film shape and spotty residual oil accounted for about20~25%;edge corner residual oil is less than5%of the total residual oil study area.