In the process of well completion with mechanical screen to control sand, once the water content of the reservoir increased, the montmorillonite in clay minerals would swell which combined with formation sand has an obvious effect on the plugging of screen pipe in production string. According to the prediction of water production of reservoir, shale expansion instrument was used to establish the relationship between the different water content and swelling properties of montmorillonites and combined with the clogging test of screen under different water content to evaluate the blocking effect of montmorillonite under different water content on the clogging of screen in the process of sand control. It can be found in the experiment that: (1) If the reservoir products water, the expansion height of two kinds of montmorillonites is similar when the water content of oil is less than 10% or more than 20%, the expansion height of montmorillonites is large of which expansion rate can reach to 188% when the water content is between 10 and 20%. (2) Through the simulation experiment of sand control, when the water content is 10 and 30%, the screen blocking is the fastest, and the productivity index per meter is the lowest, the blockage rate is increased by nearly three times when the water content of oil is 0. (3) The influence of concentration ratio of oil and water on the productivity index per meter of metal mesh screen is larger than the swelling of montmorillonites which is mainly reflected in the water content is close to 20-30%. The degree and speed of screen blocking can be reduced by reducing the water content of produced fluid.

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