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解除生产压力接近毛管吸入压力的低渗透气藏的水锁要花费相当长的时间。气井水锁效应的解除发生在两个区域: 通过流动气体蒸发, 将流体从地层中驱替出; 地层流体随压力下降变成欠饱和流体。在盐水饱和的岩心上进行了气体驱替实验。随着室温下长时间的气体注入(高达100000PV),气体相对渗透率增加。在注入50 ~100PV的气体后加入甲醇, 可提高温度及孔隙渗透率从而加快水锁的解除。岩石润湿性的改变从水湿到油湿同样促使气体相对渗透率的快速恢复。通过实验发现, 以下措施可改进水锁解除的进行: ①影响盐水驱替, 如改变润湿性; ②加快蒸发速度, 加入类似甲醇之类的挥发性溶剂。已经发现改变岩石润湿性同样会影响盐水及甲醇的蒸发速率。该项研究对影响气体相对渗透率的诸多因素进行了量化, 如岩石渗透率、润湿性、表面张力、温度。该项研究结果有助于选择一种合理的方案解除在钻井、酸化、压裂过程中造成的水锁效应, 并且推荐了向地层注入表面活性剂或溶剂来解除水锁的几种方法。
It takes quite a long time to release the water lock of the low-permeability gas reservoir near the capillary suction pressure. The release of the water-lock effect of gas wells occurs in two regions: the fluid is displaced from the formation by the evaporation of the flowing gas; and the formation fluid becomes less saturated with the pressure drop. Gas flooding experiments were conducted on brine saturated cores. With prolonged gas injection at room temperature (up to 100,000 PV), the relative gas permeability increases. After the injection of 50 ~ 100PV gas methanol, can increase the temperature and pore permeability to speed up the release of water lock. Rock wettability changes from wet to wet oil also contribute to the rapid recovery of gas relative permeability. The experiment found that the following measures can improve the water lock release: ① affect the salt water flooding, such as changing the wettability; ② speed up the evaporation rate, adding similar to the volatile solvents such as methanol. It has been found that changing rock wettability also affects the evaporation rate of brine and methanol. The study quantified many factors affecting the relative gas permeability, such as rock permeability, wettability, surface tension, and temperature. The results of this study will help to select a reasonable solution to the water lock-in effect during drilling, acidification and fracturing, and suggest several ways to release water locks by injecting surfactants or solvents into the formation.