垂直气井内单相气体瞬变流动分析

ANALYSIS ON TRANSIENT FLOW OF SINGLE PHASE GAS IN VERTICAL GAS WELLS

气井开、关井过程中 ,井筒内气体的流动为瞬变流动 ,气体的压力、温度等流动参数是井深和时间的函数。本文对开井后单相气体瞬变流动的规律进行研究。根据气体瞬变流动过程中所遵循的质量、动量和能量守恒定律建立描述气体瞬变流动的数学模型。该模型是一组偏微分方程 ,采用有限差分法对其进行求解 ,给出了计算气体压力、温度、速度的差分方程和详细的计算步骤。最后用具体实例模拟了一口气井开井过程中压力、温度随时间变化的情况。证明了流动达到稳定后 ,本模型的计算结果和稳定模型的计算结果是一致的 。

During the open and shut in period of a gas well, the gas flow within the borehole changes into transient flow. The flow parameters including the pressure and temperature of the gas are the function of well depth and time. This paper studies the transient flow rule of single phase gas after the well is opened. It constructs a mathematic model to describe gas transient flow according to the mass, momentum and energy conservation law. This model is a group of partial differential equations. Th solution is obtained with finite difference method to give a differential equation of gas pressure, temperature and rate and its calculation step. Then it simulates a case in which the pressure and temperature change with time in a gas well when it is opened. It proves that, after the flow is stable, the calculation result of this method conforms to that of the stable model, and proves that stable model is a special case of transient model.