Patent ID: 6176324
Filing Date: 2001-01-23
Classification: E21B

Abstract:
A drilling device, comprising: a drilling unit including a tool rotatably driven by a hydraulic motor associated with an advancing device enabling a bearing force of the drilling unit on the ground to be created;an impact device of the tool, the advancing device and the hydraulic motor being driven by at least one hydraulic pump via a set of hydraulic distributors and a set of tubes, two feed tubes of the advancing device of the drilling unit being equipped with a switch for reversing the direction of circulation of the fluid in the advancing device;a measurement device mounted on one of the tubes of a feed circuit of the hydraulic motor constantly supplying information to a compensation device for subtracting a calculated loss of head between two points in the feed circuit, situated on either side of the motor, from the pressure difference measured between those same two points, and actuating the switch for reversing the direction of circulation of the fluid in the advancing device if the value exceeds given value.