Gravel pack installations for wells

摘要

A gravel pack screen assembly includes a bit or sub having a flow passage which may accept a wash pipe. The wash pipe may be inserted past a flapper-type closure member which moves to a closed position upon withdrawal of the wash pipe after completion of the installation of the gravel pack assembly. The closure member can be formed of a porous material to permit the flow of liquid through the bit or sub flow passage into the interior of the gravel pack screen but to prevent flow of gravel packing or produced sand into the interior of the screen. The closure member may serve as a backup to a conventional one-way valve and permit additional gravel pack material to be placed in the flow passage upon completion of the gravel pack installation and in the event of early or late failure of the one-way valve.