Apparatus and method for placing and for backwashing well filtration devices in uncased well bores

摘要

An earth well completion apparatus and method wherein a work string equipped for jet washing downhole filtration devices, such as well screens and for back washing said downhole filtration devices and containing multiple ball catcher subs which utilize the same drop ball to prevent the inadvertent operation of hydraulically powered tools as well as to permanently valve closed a portion of said work string is concentrically disposed in a production string and run in said well simultaneously. Said ball catcher sub which prevents the inadvertent actuation of said hydraulically operated tools is contained within the main fluid bore of said work string and has an expellable inner collar with an outwardly biased catcher ring which, when expelled, shears hollow shearable means thereby actuating said tool. Expansion of said catcher ring frees said drop ball to fall into a catcher sub which has a retention groove milled into its inner circumference into which said drop ball extrudes thereby preventing its expulsion due to back pressure.