Abstract: At present, the high water saturation of the reservoir is the main reason for the low permeability of the tight gas reservoir. It has been pointed out that the desiccant which can react with the formation water to reduce the water saturation has been injected into the pores of the tight reservoir. However, the way of reducing water saturation by injecting desiccant may encounter the solid salting out produced by the reaction, resulting in pore blockage, so it is particularly important to reduce the formation of salting out on the basis of the previous study of desiccant. It is particularly important to improve the formula of desiccant. A metal carbonization complex LC containing lithium ion was used as a synergistic agent to participate in the drying reaction of the compound drying agent formula, which mainly improved the salt resistance effect of the drying agent formula, greatly reduced the formation of solid phase salting-out after the drying reaction, and analyzed the reaction heat of various chemical substances in the reaction. Combined with the experiment, the thermal effect and drying effect of the improved composite drying agent and the original drying agent were compared. Based on the results of XRD phase analysis of the salting out, EDTA and DTPA, which can complex with metal cations, were selected as salt resistance auxiliaries, and the salt resistance effects were studied under the experimental conditions of normal temperature, normal pressure and simulated formation high temperature and high pressure. the experimental results show that the desiccant system can achieve ideal salt resistance effect by adding synergist LC and salt resistance auxiliaries. That is to say, when the water consumption is the most, the solid salting out is the least, which makes the drying agent system more perfect.

Key words: tight gas reservoir, water lock, drying agent, salt resistance improvement, synergist