高含硫气藏气体渗流规律研究

STUDY ON GAS PERCOLATION BEHAVIOR FOR GAS RESERVOIRS WITH HIGH SULFUR CONTENT

在高含硫气藏开发过程中,随着高含硫气体从地层中采出,地层压力不断下降,使元素硫从含硫饱和态气相中析出,并沉积到地层孔隙或喉道中,造成地层渗流通道的严重堵塞,增大气体渗流阻力。文章从物质平衡原理出发,推导了由于受元素硫沉积影响的地层物性参数随生产时间等的变化关系,并建立了高含硫气藏气体渗流模型。通过实例模拟分析了该类气藏气体渗流过程中孔隙度和渗透率的变化规律以及地层压力等的变化特征。研究结果表明,元素硫在地层中的沉积对储层的伤害沿径向呈不均匀变化;气体的渗流阻力增加,地层能量更多地消耗在近井地带,且气体渗流表现为强烈的流固耦合特征。该认识为高含硫气田的合理高效开发提供了参考依据。

During the exploitation process of gas reservoirs with high sulfur content, as the gas with high sulfur content is recovered from the reservoir and the reservoir pressure decreases continuously, the elemental sulfur separates out from the gas saturated by sulfur and deposits in the pores or throats, which leads the percolation channels to be plugged and the gas flowing resistance to be increased. According to the material balance principle, the relationship between the reservoir characteristic parameters influenced by elemental sulfur deposition and the production time is derived and the gas percolation model is established for gas reservoirs with high sulfur content. With real cases, the changing law of porosity and permeability and the changing features of reservoir pressure are simulated and analyzed in the process of gas percolation for this kind of gas reservoirs. The study results show the reservoir damage caused by elemental sulfur depositing in the reservoir is various along the radius to the boundary, Gas percolation resistance increases. More reservoir energy is consumed at the zone near the borehole. And the gas percolation appears in the characteristics of fluid/solid coupling strongly. The conclusions provide the reference for reasonable and efficient development of gas fields with high sulfur content.