Study On The Characteristics And Lows For Variation Of Ineffective Circulation In Water-driven Sandstone Reservoirs

Starting from numerical simulation and taking geological parameters of daqing oilfield as reference,this study set various conceptual models that intersect and combine reservoir rhythm,well pattern type,coefficient of variation,oil-water viscosity ratio and well spacing,after complete the optimization of well pattern well spacing,through oilwater two phase shunt volume equation established the invalid judgment of loop formation,namely when the moisture content of 98% of the size of water saturation.Combined with the reservoir numerical simulation results,when the water saturation after reaching the above judgment according to the calculated value that reservoir ineffective seepage channel beginning to form,then for the sensitivity analysis for the influence of the simulation results,like well spacing,oil-water viscosity ratio,reservoir heterogeneity.And then introduce the concept of coefficient of fingering,fitting and found the fingering coefficient and the initial formation of ineffective seepage channel of composite water cut is good,a logarithmic relationship between fingering coefficient and ineffective seepage channel initial composite water cut eventually established.In the same way,the logarithmic relationship between the index coefficient and the final thickness of the ineffective seepage channel is established.After Solves the problem of the initial formation and the final form of the ineffective seepage channels,this study also has carried on analysis of the ineffective seepage channel thickness change law,Through qualitative analysis and fitting of the simulated production data,the power exponential relationship between the thickness of ineffective seepage channel and the water content in the same well network and the same reservoir rhythm is finally obtained.This provides a theoretical basis for improving the development effect of high water-cut oilfield.