buoyant particles 106 each have a density slightly greater than fluid 115 such that they tend to fall within fluid 115 prior to expansion of expandable screen 104 and some of the near neutrally buoyant particles 106 each have a density slightly less than fluid 115 such that they will tend to rise within fluid 115 prior to expansion of expandable screen 104 this may improve the placement of particles 106 in annular space 108 around screen 104 in another embodiment near neutrally buoyant particles 106 each have a density equal to fluid 115 such that particles 106 substantially remain in place around expandable screen 104 prior to expansion thereof with no tendency to rise or fall within fluid 115 other methods for moving and or locating particles 106 within fluid 115 are contemplated by the present invention it should be noted that larger near neutrally buoyant particles 106 may tend to sink or float faster than smaller particles thus as near neutrally buoyant particles 106 get larger the difference in density between near neutrally buoyant particles 106 and fluid 115 may be smaller in order to suspend them in fluid 115 system 100 may also include a first barrier 118 coupled near a top of expandable screen 104 and a second barrier 120 coupled near a.