CALIBRATING DEVICE OF EXTENSION-TYPE WELL SHAFT Russian patent published in 2011 - IPC E21B7/28 E21B10/32 

FIELD: oil and gas industry.

SUBSTANCE: calibrating device of extension-type well shaft includes housing with inclined slots and spring-loaded stock arranged in it, piston rigidly connected from below to the stock, which is annular and arranged in the chamber formed with outer stock wall and inner wall of the housing, legs with teeth on working surface, which are fixed in inclined slots of the housing and connected by means of rods to piston. Lower reducer with inner converging channel is connected from below to housing and equipped below annular narrowing with annular extension and restrictor. Bushing with seat for tripping ball is inserted inside annular constriction and fixed with shear member, and tightly cuts out the interaction of inner cavity of the stock with chamber and has the possibility of interaction with restrictor when it is moved downwards. At that, height of bushing is less than height of annular extension of lower reducer to restrictor. Working surface of legs is made in the form of protruding screw blades on which calibrating teeth are arranged in rows and overlap each other, and installed flush with screw surface of the appropriate blades.

EFFECT: improving reliability and service life time of construction, which provides calibrated well shaft strictly of required diametre throughout the length of expanded interval, creates no additional load on drill pipes; and enlarging life time of equipment of expanding tool.

2 cl, 1 dwg