致密低渗气藏启动压力梯度实验研究

Experimental study on threshold pressure gradient of tight and low permeability gas reservoirs

致密低渗气藏具有低孔、低渗等特征,导致渗流过程中存在启动压力梯度,无法进行常规开发。通过室内物理模拟实验,研究其启动压力梯度及影响因素。实验研究表明,在致密低渗岩心中,当气体流量小于一定值时,气体在岩心中为非达西流动。气体的启动压力梯度随岩心围压的增加而增大,但其增加幅度逐渐减小。温度对气体的启动压力梯度有明显影响,气体分子质量的大小也是影响气体启动压力梯度的重要因素。

Tight and low permeability gas reservoirs can not be developed conventionally due to the presence of threshold pressure gradient caused by low porosity,low permeability and other properties.Threshold pressure gradient and its influencing factors are studied through physical simulation experiment.The experiment indicates that gas flow behaves like non-Darcy flow in tight and low permeability core when the flow rate is less than a certain value.The threshold pressure gradient of gas increases with the increasing of confining pressure,but the increasing magnitude slows down gradually.Temperature has a significant effect on the threshold pressure gradient of gas,so does gas molecular weight.