DEVICE FOR BOREHOLE CALIBRATION Russian patent published in 2008 - IPC E21B37/00 

FIELD: building.

SUBSTANCE: invention refers to building, in particular to means of directed drilling with expansion of drilled boreholes. The device contains a column of drawing tubes with sludge-catching device asymmetrically fixed on it and executed in the form of a scraper tool. The device is supplied with a sludge collector asymmetrically fixed on a column of drawing tubes, a pipeline located in the collector and having a hydraulic exit in a hollowness of the sludge collecting section, and hydraulically connected with the column of drawing tubes, a directing crutch, mounted on the scraper tool in an opposite direction and asymmetric against the scraper tool.

EFFECT: gathering and removing larger fragments of drillable material which is not transported by a stream of flushing fluid, but remains on a sole of a borehole space because of its considerable size and mass in the course of expansion of a horizontal-directed borehole.

3 cl, 5 dwg