含硫天然气相态及渗流

近年来，四川东北部地区发现了大量硫化氢含量很高的天然气藏。天然气中元素硫的含量受地层压力、温度以及天然气组分的控制，在开采过程中，由于近井区域压力低、气体流速高，将使天然气的状态发生变化，析出的固相硫沉积在储集层的孔隙喉道中堵塞天然气渗流通道，井筒中会沉积更多的元素硫，影响气井产能。采用热力学理论解释了硫随温度和压力变化的沉积规律，建立了在达西流和非达西流条件下渗流过程中的硫沉积方程。图1参20

Phase behavior and flow of sour gas under reservoir conditions

Much sour gas reservoirs with high H2 S content have been discovered in East Sichuan Basin recently. The existence of elemental sulfur is controlled by the formation pressure, temperature and gas composition. During the development process, the relative lower near well-bore pressure and high gas flow will directly change gas flow state, thus further induce sulfur precipitation. The precipitation in the porous flow will block the gas flow and more deposition occurs in the well-bore. These changes will have a negative effect on the well productivity. A thefmodynamic model is developed for describing sulfur deposition law with the change of pressure and temperature. The sulfur deposition model is established under both Darcy and non-Darcy flow conditions.