FACILITY FOR PROBLEM ZONE CLOSING DURING WELL DRILLING Russian patent published in 2006 - IPC E21B29/10 

FIELD: oil production industry, particularly reconditioning of well casings.

SUBSTANCE: facility comprises closing device made of profiled and cylindrical pipes, shoe with releasing member adapted for shoe detaching from the closing device, expanding means, connection unit to attach thereof with drilling string and ball check valve. Lower expanding means is connected with upper end of closing means and has means to connect thereof with shoe releasing member. Check valve seat is arranged over the closing means and has crossing channels. Some crossing channels communicate drilling string interior with hole annuity, another ones communicate thereof with closing device interior. Shoe releasing member is made as two-step extension having longitudinal slits on lower step and annular grooves on upper step thereof. Lower expanding means member is made as cap in which bush with end extensions and cuts is threaded. The bush extension and cuts correspond to lower shoe extension step slits. The bush comprises annular grooves with stop members built in the grooves. The stop members are split spring rings cooperating with annular grooves on upper step of shoe extension when the shoe is detached from the closing device.

EFFECT: extended manufacturability and increased working ability.

4 dwg