Abstract: A gravel packed water-flood fluid injection mandrel is provided for a water-flood well which includes a side pocket having flow control device therein for injection of pumped water-flood fluid from the mandrel into a subsurface formation of interest. A gravel pack screen system is supported by the mandrel and is positioned so that injected water-flood fluid being discharged by the flow control device will flow through a perforate tubular member having a surrounding particulate exclusion screen. The gravel pack screen system is also arranged so that backflowing fluid flowing from the formation after termination of water-flood operations will be screened to exclude harmful particulate matter that might be entrained in the backflowing fluid. Thus, the flow control device of the mandrel will be protected against erosion or other damage by the gravel pack screen system which excludes predetermined particulate matter from the backflowing fluid.