异常高压气藏产水水平井产能影响因素分析

Analysis of Effect on Productivity of Gas-Water Horizontal Well in Overpressured Gas Reservoir

由于气体非达西渗流特征及气井产水的影响,常规二项式产能公式对异常高压气藏水平井的产能计算不再适用。基于常规水平井产能分析理论,考虑储层应力敏感、气体高速非达西流效应和脉冲效应的影响,定义气水两相拟压力,利用保角变换方法推导了异常高压气藏气水两相水平井三项式产能新模型。实例验证表明,新公式与产能试井结果相对误差仅为6.89,准确性较好。敏感性分析表明,高速非达西效应和脉冲效应对气井产能影响较小,而储层应力敏感指数和水气体积比对气井产能影响较为明显,且随着应力敏感指数及水气体积比的逐渐增大,气井无阻流量逐渐减小。

Due to the effect of gas' non-Darcy flow characteristic and water production conventional binomial productivity equation would not fit for the productivity prediction of overpressued gas reservoir.Based on the conventional horizontal well's productivity analysis theory,the author defined the gas-water two phase pseudopressure by considering the effect of reservoir stress sensitivity,high-speed nonDarcy and impulsive effect,and deduced a trinomial productivity equation of horizontal well in overpressure gas reservoirs under gas-water two phase upon the method of conformal transforms to.Case study shows the result calculated by new model has a small relative error with that calculated by well test,which indicates a high accuracy.Sensitivity analysis shows high speed non-Darcy flow and impulsive effect have small effect on productivity,while stress sensitivity and water-gas volume ratio will have obvious effect on productivity,meanwhile as the increasing of stress sensitivity index and water-gas volume ratio,the absolute open flow will decrease.