高含硫裂缝性气藏储层伤害数学模型

在高含硫裂缝性气藏气体开采过程中，地层压力不断降低，导致硫微粒在气相中的溶解度逐渐减小，在达到临界饱和态后从气相中析出，并在储层孔隙及喉道中运移、沉积，导致地层孔隙度和渗透率降低。地层压力的降低导致裂缝逐渐闭合，也会导致地层孔隙度和渗透率的降低，从而影响气井的产能和经济效益，严重时可导致气井停产。针对高含硫裂缝性气藏复杂渗流特征，基于空气动力学气固理论描述硫微粒在多孔介质中的运移和沉积，建立了一个全新的、能够综合描述多孔介质中硫微粒的析出、运移、沉积、堵塞以及应力敏感的高含硫裂缝性气藏储层伤害数学模型，并以L7井为例进行了实例分析。研究结果表明：在定产量生产条件下，硫沉积对气井生产动态的影响主要表现为气井的稳产时间缩短及气井产量在递减期内的递减速度加快。

Mathematical model for formation damage of fractured gas reservoir with high-content H2S

During the development of fractured gas reservoir with high-content H₂S, continual drop of formation pressure could lead to the declined solubility of sulfur particles in gas phase. The sulfur particles would be precipitated from gas phase after running up to saturation state and deposited at pore space and throat, which sequentially results in reduction of formation porosity and permeability. The decrease of formation pressure would result in fractures closed continually, which also results in descending of porosity and permeability of formation. The production and economic effects of gas well may be affected when sulfur deposition and fracture close become severe. According to the characteristics of complex flow through porous media in the fractured gas reservoir with high-content H₂S, based on the aerodynamics theory used to build a mathematical model for describing the transportation and precipitation of sulfur particles in the fractured gas reservoir with high-content H₂S, a new model was proposed to comprehensively describe formation damage in the fractured gas reservoir with high-content H₂S and to account for deposition, precipitation, migration and blockage of sulfur particles and stress sensitivity. The Well L7 was taken as a case of application. The results showed that the effects of sulfur deposition on production performance included the decrease of stable production period resulted from sulfur deposition and faster descending of production rate in the descending stage of production rate of gas well.