气田地层结盐机理试验研究及影响因素分析

含高矿化度地层水气田在开发中后期由于地层压力下降。井筒和地层结盐加剧．严重影响此类气田开发。为研究此类气田地层盐垢的形成条件与机理，室内采用天然岩心与人造岩心模拟了不同压力条件下地层结盐过程。研究发现，随压力变化，地层结盐可分为初始期、平衡期以及加剧期，且越到开发后期。结盐越严重。对产能影响越大；低渗透率地层结盐上限压力低，但结盐对岩心伤害程度大。孔喉尺寸越小，结盐对岩心伤害越大。研究结论与现场动态变化符合。对气井结盐预测和防治具有指导意义。

On the Mechanism of Salt Precipitation in Formation of Gas Well and Factors Analysis

In the middle and late development period of gas field with high salinity, salt precipitation became seriously both in formation and wellbore with the decrease of formation pressure, and affected the development of those gas fields seriously. In order to research the mechanism of salt precipitation in formation of gas wells, natural core and artificial core were used for simulating salt deposition procedures under different displacement pressures. The results show that the precipitation procedure can be divided into initial stage, balance stage, and aggravating stage with the pressure reduced, and in the later development period , the more seriously the salt precipitates, the more serious influence on gas production exists. The upper pressure limit for salt deposition in low permeability gas reservoirs is low. But the degree of formation damage is serious. The smaller size of the pore throat is, the greater damage of salt precipitation to formation is. The results are consistent with gas well performance, and important guide is provided for predicting and preventing the salt deposition.