低渗凝析气井反凝析、反渗吸伤害及解除方法

凝析气藏衰竭开采过程中，受相态变化影响，在近井带地层将形成反凝析液堆栈和井筒积液。井筒积液在井筒回压、岩石润湿性及微孔隙毛管压力作用下将产生反渗吸水锁效应，造成地层渗流通道的堵塞，从而引起气井产能下降，特别是对低渗凝析气井影响更大。在分析了反凝析、反渗吸地层伤害机理和国内外现有降低和解除反凝析、反渗吸堵塞技术方法的基础上，针对低渗凝析气藏，建议采用一种有效的解除凝析气藏近井地层反凝析、反渗吸堵塞．提高气井产能的技术方法：即在注气吞吐之前注入一个甲醇(乙醇、表面活性剂)溶液前置段塞来有效地解除反凝析特别是反渗吸水锁效应所产生的地层伤害和堵塞。

Low Permeability Condensate Gas Well, Retrograde Condensate, Reverse Imbibition Damage and Removing Methods

During the depletion recovery process of gas condensate reservoirs, stacks of retrograde condensed liquids in the near bore formation by the effect of phase behavior, and reverse imbibitions water blockage effect that was caused by the well bore liquid accumulation under the action of wellbore backpressure, rock wettability and micro pore capillary pressure will lead to blockage of the permeable passages. So condensate gas wells productivities will decrease, especially in low permeability condensate gas wells. On the basis of analyzing the pollution mechanism of condensate gas wells by retrograde condensate and reverse imbibitions and internal and external technical methods that reduce or remove the pollutions, a more effective method of removing these pollutions to enhance gas well productivities was put forward directing at low permissibility gas condensate reservoir. By this method, a slug of methanol (ethanol, surfactants) solution was injected before huff and puff to more effectively remove the formation damages and blockages caused by retrograde condensate, especially reverse imbibitions water blockage effect.