Pre-packed screen is comprised of six parts (from outer to inner) – outer screen, outer support rod, pre-packed gravel,
inner screen, inner support rods and base pipe. This is a typical model of dual-screen prepack which features double
wire wrapped screens.
The perforated base pipe is covered by inner wire wrapped jacket, whose diameter is smaller than the outer jacket.
Between the two layers of jackets, an annular void is packed with silica sand with the appropriate size.
while the size of the sand is determined by the formulation particle size distribution.