基于启动压力梯度的致密油藏非线性渗流模型

Non-Linear Seepage Model of Tight Reservoir Based on Threshold Pressure Gradient

新疆吉木萨尔致密油储层具有较强的应力敏感性和启动压力梯度,目前的非线性渗流模型不能反映致密储层的渗流特征。因此,在室内岩心驱替物理模拟实验的基础上,建立了考虑启动压力梯度和应力敏感的致密油藏非线性渗流模型,并根据模型绘制出压力梯度利用率图版。结果表明,致密油藏启动压力梯度与渗透率呈对数变化关系;新模型的渗流特征曲线与油藏实际渗流特征曲线误差小于5.00%,能真实反映出油藏实际渗流特征;渗透率越高,压力梯度利用率(N)越高,压力损失越少;压力梯度增大,N呈对数形式增大。为提高致密油藏压力梯度有效利用率,应增大生产压差,同时采取酸化、压裂等措施改善储层渗透率。

Due to the strong stress sensitivity and threshold pressure gradient of the tight oil reservoir in Jimsar,Xinjiang,the current nonlinear seepage model cannot reflect the seepage characteristics of the tight reservoirs.Therefore,based on the physical simulation experiment of indoor core flooding,a new nonlinear seepage model of compact reservoir considering threshold pressure gradient and stress sensitivity is established,and the pressure gradient utilization map is drawn according to the model.The results show that the threshold pressure gradient of the tight reservoir has logarithmic relationship with permeability.The error between the seepage characteristic curve of the new model and the actual seepage characteristic curve of the reservoir is less than 5.00%,which can truly reflect the actual seepage characteristics of the reservoir.The higher the permeability,the higher the pressure gradient utilization rate(N),the less the pressure loss.With the pressure gradient increases,N increases logarithmically.Therefore,in order to improve the effective utilization of the tight reservoir pressure gradient,it is necessary to increase the production pressure difference,and take acidizing and fracturing measures to improve the reservoir permeability.