考虑变启动压力梯度低渗透油藏压力分布研究

Study on Pressure Distribution of Fractured Low Permeability Reservoirs With Dynamic Starting Pressure Gradient

针对低渗透油藏,综合考虑低渗透油藏启动压力梯度和应力敏感效应以及裂缝导流能力随时间变化的典型特征,将储集层的渗流分为三段,即生产井和注水井附近压裂段的一维线性渗流模型,且考虑压裂缝导流能力随时间的变化关系;以及中间地层的非线性渗流模型,且考虑低渗透油藏生产过程中存在的压敏效应对启动压力梯度的影响。研究发现考虑了裂缝导流能力随时间变化和动态启动压力梯度的因素更能准确描述实际低渗透储集层地层压力分布规律。

Starting pressure gradient and pressure sensitivity are typical characteristics of low permeability reservoirs. In this paper, the seepage flow of reservoir was divided into three sections, the reservoir pressure distribution model was established, including one dimensional linear percolation model of fractured sections near the production well and the water injection well, considering the change of fracture conductivity with time; the nonlinear flow model of the middle reservoir, considering the influence of the pressure sensitive effect on the starting pressure gradient in the middle of the reservoir. The research results show that the reservoir pressure distribution models considering the change of fracture conductivity with time and considering the influence of the pressure sensitive effect on the starting pressure gradient can more accurately describe the formation pressure distribution law.