中文摘要：

由于存在启动压力梯度，低渗透油层中流体渗流不遵循达西定律，属于非线性渗流。对长庆西峰油田不同渗透率岩心进行室内驱替实验，改变岩心两端压差测量流体通过岩心的流速，求得“压差-流量”关系曲线并进行回归，二次多项式拟合相关系数较高，为此，将渗流速度表示为驱动压力梯度的二次多项式，与考虑启动压力梯度的理论渗流速度公式结合，即得到求解低渗透油藏启动压力梯度的数学模型。由该模型分析，启动压力梯度的主要影响因素是驱动压力梯度和流体的流度，启动压力梯度与前者成正比关系，与后者成反比关系。利用启动压力梯度可以计算低渗透油藏非线性渗流条件下油井产量、极限注采井距等。图5表1参12

英文摘要：

The fluid flow in low permeability reservoirs does not follow the Darcy equation and presents non-linear fluid flow through porous medium due to the existence of kickoff pressure gradient. A series of displacement experiments are carried out by using 23 different permeability cores of the Changqing Oilfield. Based on the mechanism of fluid flowing through porous media, the data are treated, and a new physical model is presented. According to the regression and analysis of the data, a new mathematical model is obtained between the kickoff pressure gradient and driving pressure gradient and fluidity of low permeability formation. According to the mathematical model, the affecting factors of the kickoff pressure gradient are driving pressure gradient and fluid mobility, the kickoff pressure gradient is in direct ratio to driving pressure gradient and in inverse ratio to fluid mobility. Theoretical plates between the kickoff pressure gradient and its affecting factors of low permeability reservoirs are attained.