低渗气藏中气体非线性渗流的特征分析

Analysis of gas non-linear characteristics on low-permeability gas reservoirs

为了对低渗气藏中气体渗流特征有一个清楚和较为准确的认识,采用实验研究的方法,分析了低渗透储层中气体渗流特征。结果表明:在低渗透储层中,气体渗流表现出明显的非线性渗流特征,并且受多种因素影响;有效应力的增加,会导致岩石渗透率降低,气体在地层中渗流越困难;启动压力梯度增大,气体非线性渗流愈明显;滑脱作用越强,越有利于气体的渗流,提高气藏的产能;相同的压力梯度下含水率越高,渗流速度就越低,储层岩石的初始气测渗透率越低。该成果对天然气开采工程具有一定的参考价值和指导意义。

In order to better understand the characteristics of gas permeability in a low permeability reservoir,an experimental study on gas flow and gas percolation characteristics was conducted in this study.The results show that in a low permeability reservoir,the gas flow has an obvious nonlinear percolation characteristic and is influenced by many factors.For instance,the increase of effective stress leads to the decrease of rock permeability,and the difficulty of gas flow in reservoir.With the increase of start-up pressure gradient,the gas nonlinear permeability becomes more obvious.The stronger slippage effect is more beneficial to the gas seepage and the productivity increase in gas reservoir.In addition,under the same pressure gradient,the higher water content will result in a lower seepage velocity and low initial permeability in reservoir rock.The study results provide a very useful reference for gas reservoir exploitation.