It happens. The new screened well is pumping too much sand, and you have the hopeless feeling that the screen slot size selected was just a little too wide to hold back the sand from the formation.
Besides abandoning the well, there are two choices to remedy the problem. First, you could continue to develop the well aggressively by surging and pumping and hope that the majority of the small grains will pass through the screen and leave behind enough larger grains to seal off the flow of the sand from the formation. The key is to aggressively purge the well by forcing water in and out of the screen in order to “shuffle” the smaller grains toward the screen and into the well for removal during its development. Development could take hours, or days in some cases, to remove the fines near the well screen.