【摘要】 考虑启动压力梯度的不稳定渗流数学模型解法十分繁琐,主要原因是控制方程具有强烈的非线性,同时流体流动边界并非恒定不变。为简化计算,利用油藏压力分布近似表达式,研究了低渗透储层不稳定渗流压力分布特征;进而根据物质平衡原理,利用牛顿迭代方法计算得到动边界在不同时刻的运动规律;最后,作为比较和验证,分别利用近似解法和解析解法研究了定产生产时的储层压力分布特征和井底压力变化规律。计算结果表明,启动压力梯度阻碍了地层能量的传播和流体的运移,消耗了部分地层能量,不利于油井生产。更多还原

【Abstract】 The solution method of instability seepage flow with Threshold Pressure Gradient(TPG) consideration was extremely complex because the governing equation was non-linear and flow boundary was not constant. In order to simplify the solution calculation, pressure characteristic about instability seepage flow in low permeability reservoir was studied with the approximate equation of formation pressure. Furthermore, the movement rule of the flow boundary at different times was gotten with material balance approach and the Newton iteration calculation. Finally, the pressure characteristic of reservoir and well under the condition of invariable productivity was given with approximate solution and analytic solution separately. The study shows that the TPG resists the propagation of energy and migrate of fluid, consumes part of the formation energy, and is harmful to the well production.更多还原