低渗非均质油藏数值模拟研究

Numerical simulation of low permeability and heterogeneous reservoir

为了更好地描述实际低渗非均质储层的启动压力梯度非均匀分布,建立了考虑启动压力梯度的二维二相渗流数学模型,并对比研究了低渗非均质储层启动压力梯度为常数和启动压力梯度非均匀分布时的数值模拟结果,结果表明两者的差异很大。因此,研究低渗储层渗流时,必须考虑启动压力梯度的非均匀分布对开发指标的影响。

Poor physical properties and high heterogeneities of low permeability reservoirs lead to the heterogeneous distribution of the threshold pressure gradient.In the past,the threshold pressure gradient of each simulation grid was considered to be a constant during studying the effect of the threshold pressure gradient on the percolation character in low permeability reservoirs.However,this method can not consider that reservoir properties' heterogeneity leads to the heterogeneous distribution of the threshold pressure gradient and can not simulate the percolation characteristics accurately.To describe the distribution of the threshold pressure gradient,this paper establishes a two-dimensional and two-phase percolation mathematical model with considering one the threshold pressure gradient,then studies and compares the numerical simulation results of the low permeability reservoir with considering one that the threshold pressure gradient is constant,and with considering one that the threshold pressure gradient is heterogeneous.The results are dramatically different under two different conditions.Therefore,during the studying of percolation characteristics in flow-permeability reservoir,the influence of development index which is resulted from heterogeneity of the threshold pressure gradient must be considered.