一种新型气井产能方程的研究

STUDY ON A NEW PRODUCTIVITY EQUATION FOR GAS-WELL

针对气体在地层压力较高或低渗透率气藏中渗流时表现出显著的渗透率应力敏感性,以及气藏渗流时受到启动压力梯度和滑脱效应影响的问题,从气藏非达西渗流方程出发,建立了考虑启动压力梯度、滑脱效应和渗透率应力敏感气井产能方程,介绍了该方程系数的计算方法,并通过某气藏实例分析讨论了启动压力梯度、滑脱效应、渗透率应力敏感三因素分别对气井产能计算的影响。研究结果表明:考虑渗透率应力敏感、启动压力梯度后,气井产量表现为减小趋势,且启动压力梯度对产能的影响小于渗透率应力敏感的影响;考虑滑脱效应后,气井产量表现为增大趋势;综合考虑启动压力梯度、渗透率应力敏感和滑脱效应预测的气井绝对无阻流量值,比渗透率为常数且不存在启动压力梯度时预测的结果低。该研究对深入了解应力敏感气藏的产能及预测其开发动态具有一定的实际意义。

Based on high pressure or low permeability gas reservoir gas seepage in porous media showed obvious stress-sensitive characteristics,as well as threshold pressure gradient and slippage effect problems in the gas reservoir seepage,the gas reservoir non-Darcy flow productivity equation for stress-sensitiveness gas reservoirs considering threshold pressure gradient and slippage effect is established and the calculation method of the equation coefficients is described.The effect of threshold pressure gradient,slippage effect and permeability stress-sensitive to gas reservoir productivity is analyzed and discussed by means of example.The research shows that:the effect of threshold pressure gradient and permeability stress-sensitive to gas-well production was negative,threshold pressure gradient effect on the productivity is less than the permeability stress sensitivity;slippage effect was approximate increase in gas-well production trends.The value of the forecasted gas-well absolute open flow potential considering the threshold pressure gradient,slippage effect and permeability stress sensitivity are lower than the forecasted when permeability is a constant and threshold pressure gradient is in inexistence.The study is practically meaningful to understanding the productivity of stress-sensitive gas reservoirs and predicting the dynamic development.