DEVICE FOR TROUBLESOME ZONE OVERLAPPING DURING WELL DRILLING Russian patent published in 2012 - IPC E21B29/10 

FIELD: mining.

SUBSTANCE: device includes overlapping mechanism with cylindrical parts at ends consisting of shaped tubes rigidly connected to each other, the lowest of which is provided with a shoe from easily drilled out material with check valve, expander consisting of upper roller expander located above shaped tube and lower expanding head with cutting elements located in upper cylindrical part with internal chamfer, roller expander and expanding head being connected to connection point by adapter. Shaped tubes are designed with outside perimeter equal to perimetre of well in expanded interval and are designed shaped lengthwise with calibrated ends except for upper and lower cylindrical parts of overlapping mechanism. Joints of shaped tubes with each other are designed as welded joints of shaped ends with subsequent annealing. Roller expander is designed with constant protrusion of rollers. Adapter connection is provided with right screw thread with a special profile reciprocal to thread of upper cylindrical end of overlapping mechanism. Length of adapter is more than length of cylindrical ends of overlapping mechanism. Shoe is connected to lower cylindrical part by means of tapered thread.

EFFECT: simplifying the design, improving reliability, reducing expenses.

2 cl, 1 dwg