考虑真实气体的低渗气藏动态预测模型

针对气藏的生产特征,基于稳定渗流理论,以气体高速非达西渗流为基础,考虑真实气体PVT参数动态变化,结合气藏物质平衡方程,推导建立同时考虑滑脱效应、启动压力梯度、应力敏感等因素共同影响的低渗气藏动态预测模型,分析各因素对气井产量变化的影响.结果表明:在考虑高速非达西流的基础上,考虑滑脱效应将导致渗流阻力降低而引起气井稳产年限增加和地层压力下降变快,考虑启动压力梯度和应力敏感效应时将导致渗流阻力增加而引起气井稳产年限降低和地层压力下降变慢;启动压力梯度和渗透率变形系数越大,气井稳产年限下降幅度越大,地层压力下降越慢,而滑脱因子越大,气井稳产年限增加幅度越大,地层压力下降越快.

Dynamic prediction model for the low-permeability gas reservoir taking the real gas into account

In view of the production characteristics of the gas reservoirs,based on the steady seepage theory and the high speed non-Darcy,considering the real gas PVT parameters with pressure changes combining the material balance equation,creating a new pseudoressure form,with the influence of the start-up pressure gradient,slippage effect and stress sensitivity taken into account,a dynamic prediction model was established for the low-permeability gas reservoirs,and the productivity characteristic was discussed by analyzing and calculating examples.The result indicates that based on the high speed non-Darcy,the lower flow resistance caused by the slippage effect will load to the increasing of the stable production period and the decreasing rapidly of the formation pressure,while the higher flow resistance caused by the start-up pressure gradient and stress sensitivity load to the decreasing of the stable production period and the decreasing slowly of the formation pressure.The bigger the start-up pressure gradient and deformation coefficient of permeability are,the more decreasing extent of the stable production period,and the slower the reduction of the formation pressure would be,while the more slippage effect,the more decreasing extent of the stable production period and the faster reduction of the formation pressure would be.