The Optimization Research About Well Pattern In Low Permeability Reservoirs

The low permeability reservoirs in our country are abundant,which are of great potential for exploitation.However,the strong interlayer and plane heterogeneity can lead to serious unbalanced displacement,forming a lot of remaining oil which can not be exploited.Therefore,based on its reservoir characteristics,the optimization research about water displacement technique in low permeability reservoir at high water cut stage is of great significance to achieve the inner layer balanced recovery and EOR.Based on the pseudo threshold pressure gradient model and oil-water two phase flow theory,the distribution of pressure gradient between injection-production well and the influence factors are studied.Considering the technical limits and economical terms,the technical limited well spacing and economical limited well spacing which suited to oil-water two phase flow theory are given.According to the geologic feature of low permeability formation and the feature of horizontal distribution of remaining oil,also the in-situ stress direction and the sediment source direction,the related well pattern adjustment mode is researched.Considering all the factors,the method of balanced displacement of a single thick layer is built.Based on the differences of physical properties and producing extent in the plane and inter-layer production reservoirs,the well spacing optimization method of multi-layer combined production reservoir is established.The optimization method about water displacement technique in low permeability reservoir at the high water cut stage is applied in block 5 of Bonan oilfield,the reasonable well spacing,the optimization about well pattern and the well spacing based on balanced flooding are given,at last,the development effect of the reservoir is improved obviously.The thesis provides great guiding significance to effectively improve the development result of low permeability reservoirs.