Non-linear seepage generally exists in the development of low permeability gas reservoirs. It is meaningful to study the effect of non-linear seepage on recovery factors for reasonably exploiting these low permeability gas reservoirs. Cores from the Tarim gas field are adopted and non-linear seepage experiments are conducted under different permeabilities and different water saturations. The experiment results show that low permeability gas reservoirs exhibit a start-up pressure gradient and strong stress sensitivity. The lower the permeability and the higher the water saturation, the larger the start-up pressure gradient, the stronger the stress sensitivity, and the more obvious the non-linear seepage behavior. Non-linear seepage impacts the recovery factor of low permeability gas reservoirs strongly. With the increase of start-up pressure gradient and stress sensitivity, the abandonment pressure of the gas field rises, and the recovery factor declines. During the development and deployment of low permeability gas reservoirs, the area with high permeability and low water saturation should be exploited firstly. Furthermore, well pattern infilling, reservoir stimulation and reducing water saturation are the effective methods to improve the recovery factor of low permeability reservoirs.

non-linear flow  /  low permeability  /  recovery factor  /  stress sensitivity  /  start-up pressure gradient