A method and system for completing a wellbore in a subsurface formation including first and second sand screens and intermediate tubular joint for gravel transport and/or gravel packing. The assembly provides transport conduits for carrying gravel slurry and packing conduits for gravel slurry placement. The method also includes running the sand screens and intermediately connected joint assembly into the wellbore, and gravel packing not only in the wellbore annulus behind the sand screens, but also behind the intermediate joint assembly to provide a reserve of packing sand behind the intermediate joint assembly to supplement or repack any annular packing sand in the annulus behind the sand screens that may be lost due to sand screen breach, partial collapse of tubular, or other shifting of the gravel pack sand. A wellbore completion apparatus and system is also provided that allows for placement of such gravel reserve.