新场蓬莱镇异常高压气藏气体单相渗流实验特征

从气藏的常规岩心实验出发,结合气藏压敏性特征,引出了由于气藏压敏特征而产生的"滑脱"现象和"启动压力"特征。通过对四川蓬莱镇浅层异常高压致密气藏岩样单相渗流数据的分析,探讨其出现既有"滑脱"现象又有"启动压力"特征这种复杂渗流特征的原因,认为这种渗流特征主要是由于压敏特征,而很可能不是传统的滑脱机制或低速非达西机制所致。实验结果显示,新场蓬莱镇组气层压敏特征明显,拟合系数a的范围为0.3～1.9,渗透率降低幅度约为10%～80%。

Gas single-phase percolation characteristics of overpressured gas reservoir in Penglaizhen Formation, Xinchang gas field

Based on the conventional core experiments and pressure-sensitive features of gas reservoirs,it is suggested that the "slip flow of gas" and "threshold pressure" may be caused by pressure sensitivity of gas reservoir.This paper takes the overpressured tight gas reservoir in the shallow Upper Jurassic Penglaizhen Formation,Xinchang gas field,Sichuan province,as a research object,analyses the data collected from gas single-phase percolation experiments on its rock samples,and discusses the causes of the sophisticated percolation process with the coexistence of "slip flow of gas" phenomena and "threshold pressure" features.It proposes that the percolation process be induced by pressure sensitivity rather than by traditional Klinkenberg effect or low rate non-Darcy mechanism.The experiments also indicate that the Penglaizhen gas reservoirs in Xinchang gas field shows strong pressure sensitivity,and its fitting factor ranging between 0.3 to 1.9 and permeability reduction magnitude varying from 10% to 80%.