考虑硫沉积的气井流入动态曲线特征

Characteristics of Gas Well Inflow Performance with Sulfur Deposition

含硫气井在生产过程中,硫元素的沉积将降低储层孔隙度和渗透率,极大地破坏气井产能,此时常规气井产能计算模型已经不再适用。考虑硫元素在近井地带沉积引起的储层渗透率变化,将储层分为沉积区和非沉积区。基于渗流力学理论,建立了含硫气藏直井、直井压裂井在平面径向非达西稳定渗流条件下的二次三项式产能方程。通过分析硫沉积、启动压力梯度、裂缝长度、裂缝宽度对气井流入动态的影响,认为气井产能随硫沉积饱和度的增大而减小,但增长速度逐渐减小。气井无阻流量与启动压力梯度呈负相关关系。压裂措施能增大含硫气井产能,当气井产能受硫沉积影响较大时,可采取压裂的办法增产,必要时可用酸化压裂工艺,并对裂缝长度设计进行优选。

During the course of production in sour gas wells,deposition of elemental sulfur will reduce the porosity and permeability,and greatly depress the productivity of gas wells.The conventional deliverability calculation model is no longer applicable.Considering the change of reservoir permeability in the near wellbore zone caused by elemental sulfur deposition,the reservoir was divided into deposition region and non deposition region.Based on the theory of fluid mechanics,vertical and fracturing wells quadratic-trinomial productivity equations were established under the condition of radial steady non-Darcy seepage in sour gas reservoir.According to the analyses of the influence of sulfur deposition,the starting pressure gradient,fracture length,fracture width on gas well inflow performance,the result shows that the gas well productivity decreases with the increase of sulfur saturation,but the growth rate gradually decreases.Gas well open flow capacity is negatively correlated with the starting pressure gradient.Fracturing measures can increase the sulfurous gas well production capacity.Taking the way of hydraulic fracturing,when the gas well productivity is greatly influenced by the sulfur deposition,acid fracturing process can be carried out when it is necessary,and the design of crack length should be optimized.