Oil-water Two-phase Flow Research In Low Permeability Reservoir

With the development of petroleum exploration technology,low permeability reservoir has become the main source of oil and gas production.Low permeability,small porosity and pore throat,and high initial water saturation are the significant characters of low permeability reservoir,which leads to nonlinear flow in low permeability reservoir.In this paper,based on the research actuality,several models describing non-linear flow in low permeability reservoir are introduced and their applicability is analyzed,two-parameter model is more optimized.Most of traditional experimental and theoretical methods don't consider the capillary pressure influence,nearly all of these methods don't consider the influence of nonlinear segments.At the same time,most research about water flooding dynamic characteristics analysis,also does not consider the seepage characteristics of low permeability reservoirs.Aiming to obtain proper relative permeability curve in low permeability reservoir,we establish a more accurate calculation model considering non Darcy effect based on the two-parameter model,and analyze the non-Darcy seepage influence on oil-water relative permeability and oil displacement effect.And water flooding characteristic curve model is established considering the nonlinear segments,capillary force,threshold pressure gradient of low permeability reservoir.The results show that the curve of recovery factor(R)and logarithmic water oil ratio(lgWOR)presents linear relationship,having better consistent with the b characteristic curve.Finally,water flooding model in low permeability oil reservoir was established,considering the nonlinear parameter,threshold pressure gradient,capillary force and the influence of stress sensitivity.Finite difference method is used to weaken the strong nonlinear equation,obtaining pressure and saturation changes with time,and analyzed the influence of various parameters on the pressure and saturation distribution.In this paper,the research for the future water flooding development effect dynamic prediction of low permeability reservoir has theory instruction significance.