摘要
大量现场实践和室内实验表明,煤层气藏为典型的应力敏感性气藏,随着煤层气的开采,储层孔隙压力降低,渗透率大幅度降低,引起产量下降。为了研究煤层应力敏感性与渗透率的关系,进行了应力敏感性实验,结果表明：煤层渗透率对于应力变化非常敏感,当有效围压从1MPa增加到12MPa时,其渗透率最大值只有初始的10%,即使围压恢复至1MPa,岩心渗透率损失率在54.98%~79.09%。由于煤层这种应力敏感性,其渗透率不再是常数,而是压力的函数,利用实验得到的动态渗透率与有效围压的关系,建立了考虑渗透率变化、带人工裂缝的预测煤层气产量的二维气、水两相数值模型,现场应用表明预测的产量与和实际产量吻合。
A mass of oilfield practices and laboratory experiments have shown that coal-bed methane reservoir is typical stress sensitive gas reservoir.Along with coal-bed methane exploitation progress,the pore pressure of coal-bed declines.It causes the decrease of coal-bed permeability,which leads to the decline of production.Stress sensitivity experiments were carried out by the authors to study the relationship between stress sensitivity and permeability.The results indicate that coal-bed permeability is very sensitive to the change of stress.When effective confining pressure increases from 1MPa to 12MPa,the max permeability is just ten percent of the initial value.Even if confining pressure turns back to 1MPa,the lost of permeability is between 54.98 ～79.09%.Because of stress sensitivity,permeability is a function of pressure and ceases to be constant.Based on experiments,we got a formula can set forth the relation between dynamic permeability and effective confining pressure and established a 2D gas and water two phases numerical model considering permeability changes and artificial fracture to predict CBM production.It is demonstrated in practices that predicted production is very close to the actual production.
出处
《中国煤炭地质》
2010年第4期28-30,64,共4页
Coal Geology of China
关键词
煤层气
应力敏感
渗透率
数值模拟
产量预测
coal-bed methane
stress sensitive
permeability
numerical simulation
production prediction
