高含硫气藏非均质试井解释模型研究

Study on anisotropic analytical model of well testing of high sulfur gas reservoir

高含硫气藏在开采过程中,随地层压力不断下降,元素硫将以单体形式析出,从而堵塞天然气的渗流通道,降低地层有效孔隙空间及渗透率,影响气井的产能。针对高含硫气藏的特征,推导了地层中任一点的相对渗透率与距气井中心的径向距离之间的函数关系,并建立了高含硫气藏的非均质试井解释数学模型。然后,将模型在拉普拉斯空间的解经过解析反演后,与均质模型实空间的解进行对比分析。最后,利用Stehfest数值反演算法绘图验证了分析结果,并研究了试井分析理论曲线影响因素。研究结果表明,高含硫非均质试井解释模型能准确反映地层的渗流规律和解释地层的非均质性。元素硫在地层中的沉积具有"叠加效应",并且随地层系数的减小,越易在地层中沉积。

During the exploitation of high sulfur gas reservoir, with the formation pressure declining, sulfur element will precipitate in the form of monomer, thus blocking flow matrix for natural gas, which cause severe reduction in the effective drainage porosity and permeability, affecting gas well productivity at last. For high sulfur gas reservoir characteristics, the func- tional relationship between relative formation permeability and radial distance of the well spacing has been derived. Further more, it has established a high sulfur gas reservoir anisotropy well testing analysis model. Then, comparative analysis the model solution in Laplace after space inversion parsed and solution in the real space model with homogeneous solution. Finally, drawings made by Stehfest numerical inversion algorithm method validated the analytical results, and further research on influence factors of the well test the theoretical curve. The results showed that the anisotropic analysis model of well testing can accurately reflect the formation percolation theory and interpret the extent of formation anisotropy. In the formation of elemental deposition has a ＂duplicate effect＂, and with the decrease of formation capacity, the more deposited in the formation.