气田地层结盐机理实验研究

The experimental study of salt deposit mechanism in formation of gas field

在开发后期,含高矿化度地层水气田随地层压力下降,井筒和地层中结盐加剧,严重影响气井产能。通过实验研究地层结盐条件,应用天然岩心与人造岩心模拟不同驱替压力条件下的地层结盐过程,确定地层结盐压力上限及结盐对岩心渗透率伤害程度。结果发现,地层结盐随压力变化分为3个阶段:结盐初始期、平衡期和加剧期,而且越到开发后期,结盐越严重,对产能影响越大。研究结论与现场气井的动态变化符合,对气田结盐预测和阶段防治具有指导意义。

In the late development period of gas field with high salinity, salt deposition becomes seriously both in formation and wellbore with the decrease of formation pressure, and it influences gas production greatly. Salt deposition conditions in the formation have been studied based on experiments, and natural cores and artificial cores are used for the modeling of salt deposition procedure under different displacement pressure to determine the upper pressure limit for salt deposition in formation and the damage to cores permeability. It is found there are three stages during salt depositing： initial stage, balancing stage, and aggravating stage, and the later the development period is, the more vigorously the salt deposition occurs, and the more serious influence to gas production exists. The test results are COlxesponded with gas well performance and the research can be an important guide to salt deposition prediction and prevention.