论文部分内容阅读
实验分析和理论研究表明毛细管压力存在动态效应,即其与润湿相流体的饱和度变化率相关,已有的物理实验表明低渗透油藏中的毛细管压力动态效应对于油气渗流存在着较大的影响。该文首先根据23个低渗岩心渗流曲线的数值拟合分析结果,建立了各项物理意义明确的非线性渗流运动方程,然后通过构造三种不同的饱和度变化速率的润湿相流体饱和度时变曲线,利用有限元数值方法模拟了三种饱和度曲线对应下的一维水驱油过程,并在完全基于数学方法较少依赖于物理实验的基础上计算了毛细管压力曲线。数值模拟的结果表明,低渗透油藏中存在较为明显的毛细管压力动态效应,且动态系数与介质的固有渗透率负相关,与润湿相流体的黏滞系数正相关。并通过与达西线性渗流模拟结果的对比表明了低渗油藏中非线性渗流产生的毛细管压力动态效应更为明显,动态系数也更大。
Experimental and theoretical studies show that the capillary pressure has a dynamic effect, that is, it is related to the rate of change of the saturation of the wetting fluid. The existing physical experiments show that the capillary pressure dynamic effect in the low-permeability reservoir has large influences. Based on the results of numerical fitting of the seepage curves of 23 low-permeability cores, the nonlinear physical equations of motion of percolation were established. Then, by constructing three different saturation-rate variations of wetting-phase fluid saturation Time curve, the one-dimensional water flooding process corresponding to the three saturation curves was simulated by the finite element method. The capillary pressure curve was calculated based on the fact that the mathematical method was less dependent on the physical experiment. The numerical simulation results show that there is obvious capillary pressure dynamic effect in low permeability reservoirs, and the dynamic coefficient is negatively correlated with the inherent permeability of media, and positively correlated with the viscosity coefficient of wetting fluid. The comparison of the results with the Darcy linear simulation shows that the capillary pressure dynamic effect of the nonlinear seepage in the low permeability reservoir is more obvious and the dynamic coefficient is larger.