HYDRO-MECHANICAL CENTRALISER Russian patent published in 2011 - IPC E21B17/10 

FIELD: oil and gas production.

SUBSTANCE: centraliser consists of case with through radial channel, of centring elements end of which are connected with case, of unit for transfer of centring elements located on external surface of case and hydraulically connected with cavity of case by means of radial channel, of holder of initial position in form of shear pin and of unit of arresting centring elements in working position. The centring elements are made in form of straps of flexible deformed material; they are connected with the case by fixation of their ends in bushes set on the case; the centring elements rotate and travel lengthwise. The unit of transfer is made in form of a movable differential bushing with two borings interacting with grooves on an upper sub and the case. Hydraulic connection of the transfer unit with radial channel of the case is facilitated with a cavity between borings of the differential bushing. The unit arresting centring elements in working position is made in form of a split ring made of flexible deformed material and set in a groove made in the cavity of the differential bush. Circular grooves interacting with response circular lugs on external cylinder surface of the case are made on internal cylinder surface of the split ring along generatrix. Shape of grooves and lugs allows reverse travel of the split ring along the case at a value not exceeding a step of circular rings and lugs setting at travel of the centring elements into a working position. Value of a radial gap between internal surface of the groove made in the cavity of the differential bushing and external surface of the split ring in an initial position exceeds height of the circular lugs.

EFFECT: raised reliability of centraliser operation and expansion of its operational functionality.

2 dwg