低渗透气藏气井产量递减分析简便方法

A new method for decline curve analysis of gas wells in low permeability reservoirs.

在低渗透气藏中 ,因气井产量小 ,天然气在井周围地区流动时流速甚小 ,可以不考虑非达西流影响。Fraim根据这一特点 ,将物质平衡方程与忽略非达西流动的地层流动相关式相结合 ,推导并建立了适合低渗透气藏气井产量递减分析的图版拟合方法。但该方法拟合需要的时间长 ,且拟合精度受人为影响。在Fraim拟合方法基础上 ,通过回归分析 ,提出了根据生产史确定低渗气藏地层参数的计算公式 ,无需进行人为图版拟合 ,就可以确定气藏的储量与气层其它参数。该方法编制程序容易 ,确定参数快速准确 ,实际操作不需关井 ,特别适合关井压力恢复需很长时间的低渗透气藏气井产量递减分析。图 1表 1参 3 (王孝陵摘 )

Gas wells' production rate is low in low permeability reservoir and velocity of gas flow near well bore is much low, thus Non Darcy flow can be negligible. According to these characteristics, Fraim deduced and set up type curve matching method for production decline analysis of gas wells in low permeability reservoirs with a material balance equation and a flow model of gas reservoir. With his method to match gas well production history, it will take a long time and the matching accuracy can be affected by type curve matching with different people. On the basis of his work and by using regression analysis, the paper presents a set of formula which can be used to estimate the parameters of low permeability gas reservoirs. Reservoir parameters G, k g h and k g/ φ can be determined with these formula, and any type curve matching will be avoided. The presented formula are easy to be programmed and able to determine gas reservoir parameters rapidly and accurately. Because the method can determine gas reservoir parameters without shutting down gas wells, it is more suitable for low permeability reservoirs.