Research On Plane Sweep Evaluation Of Water Flooding In Ultra Low Permeability Reservoir

Some ultra-low permeability reservoirs in China have been effectively developed by water injection,but the contradiction of water injection is still relatively large,and the water flooding coefficient is difficult to evaluate.Due to the existence of threshold pressure gradient,fractures and anisotropy,the calculation method of plane sweep coefficient of conventional reservoirs cannot be applied to ultra-low permeability reservoirs,and the study of evaluation method of plane sweep coefficient is urgently needed.Firstly,in this paper,considering the characteristics of anisotropy,threshold pressure gradient,and artificial fracturing in ultra-low permeability reservoirs,the flow tube model of ultra-low permeability reservoirs is established.This can quickly calculate the water flooding plane sweep of ultra-low permeability reservoir.Secondly,using the established flow tube model,the effects of well pattern,well pattern parameters,reservoir parameters,fluid properties,artificial fractures and production regimes on water flooding plane sweep coefficient are studied,and the primary contradiction faced in ultra-low permeability reservoirs development are summarized.Finally,combined with the flow tube method model of ultra-low permeability reservoir,a well pattern adaptability evaluation study is conducted.The calculation method of the limit well spacing is proposed,and the relationship between well pattern parameters and reservoir parameters is calculated.Besides,according to the main problems faced by the development of ultra-low permeability reservoirs,corresponding measures for improving the flooding effect of water flooding are proposed.An integrated process of “evaluation-improvement” of water flooding effect has been formed and applied in the actual reservoir G60 block.The research results in this paper provide a set of rapid evaluation methods for waterflood plane sweep for ultra-low permeability reservoirs,and have reference significance for the development and adjustment of similar reservoirs.