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孔隙介质中的流体流动是用偏微分方程的扩散形式来描述的。在恒定压缩系数流体流动方程推导的过程中,对压力梯度作了一个重要的假设:假定压力梯度足够小,以至该项的平方可以忽略。在本研究中,试图将这种简化的影响定量化。为了确定证明这种简化的条件是正确的,对比了从数值摸拟模型产生的数据和解析解。除了极端条件(非线性系数大于0.01),在油的扩散方程中,忽略压力梯度的平方项是合理的。 气井的压降解包含天然气参数,其中的压力参数非常重要。当系统枯竭时,平均气藏压力下降。尽管在主导气藏压力下考虑天然气参数看起来是合乎逻辑的,但是,天然气粘度和压缩系数通常是在初始压力水平下估算的。对比不同类型测试条件下得到的解析解与数值解可以看出应用标准方法进行数据解释不准确的程度。基于这种观察,考虑了几种压力水平下的参数计算。在拟稳态流条件下应用解析方程的过程中,应该用原始和目前气藏压力的平均值估算天然气参数。
Fluid flow in porous media is described by the diffusion form of partial differential equations. During the derivation of the constant compressibility coefficient fluid flow equation, an important assumption is made about the pressure gradient: Suppose the pressure gradient is small enough that the square of the term can be neglected. In this study, we try to quantify this simplified impact. In order to confirm that the simplification of this proof is correct, the data and analytical solutions generated from the numerical simulation model are compared. Except for extreme conditions (nonlinear coefficient greater than 0.01), it is reasonable to ignore the squared pressure gradient in the oil diffusion equation. Pressure drop in a gas well contains natural gas parameters, of which the pressure parameters are very important. When the system is depleted, the average reservoir pressure drops. Although it seems logical to consider natural gas parameters under the dominant pressure of the reservoir, natural gas viscosity and compressibility are usually estimated at the initial pressure level. Comparing the analytical solution and the numerical solution obtained under different types of test conditions, we can see the extent to which the standard method is used to explain the inaccuracy of the data. Based on this observation, several stress levels are considered for parameter calculations. In the application of analytical equations under quasi-steady-state flow conditions, the natural gas parameters should be estimated from the mean values of the original and present gas reservoir pressures.