Impact On The Recovery Of Class ? Heterogeneous Layers By Zonal Chemical Flooding

After major reservoir entering into the high water cut period these years,it is much more significant to research the potential of oil production in Daqing third type oil layers in order to insuring the yield stability in Daqing oil field.The third type layers have the features of low producing degree,thin thickness,strong heterogeneity and wide distribution.As the major way of enhancing oil recovery in Daqing oil field,chemical flooding is enough mature to be used in the third type oil layers so as to improve the producing profile and enhance oil recovery.But the detail production method still need more research.To solve the problem of improving vertical sweep efficiency,the paper makes the use of physical model experiments and mechanism analysis,for the purpose of studying the impact when using zonal injection in Daqing third type oil layers.Basing on the static analysis on chemical agents used in later experiments,heterogeneous plane models with three layers are designed and made,so as to simulate the displacement in third type layers mixed with second type layers.The whole experiment contains four different projects,including general ASP drive,water flood for middle and low permeable layers before ASP drive,surfactant water flood for middle and low permeable layers before ASP drive,and polymer drive for middle and low permeable layers before ASP drive.According to the effluent samples,pressure data and resistivity data received from these experiments,oil recovery,water cut,layer pressure,concentration in effluent samples for different components and oil saturation can be calculated and analyzed.And the experiments of heterogeneity models with tracer are made to help analyze the mechanism.The results show that the low molecular polymer provided from Daqing oil field has the good functions of increasing viscosity,injectivity and shearing resistance,and the petroleum sulphonate can reduce the interfacial tension to the degree of 10^-3mN/m when it works with Weak alkali.The final recoveries of projects which use zonal drive are always better than the project using general drive.The project that using polymer drive for middle and low permeable layers before ASP drive has the highest final oil recovery,which comes up to 65.83%.The residual oil saturation in its low permeable layer is 34.51%.the polymer injected can reduce the effect of gravity for its viscoelasticity so as to enhance the performance of oil-displacement,and polymer has the advantage of plugging in high permeable layer,which help ASP slug flood in low permeable layer.The result of research can provide good ideas and supports for Daqing oil field exploitation.