Method and means for controlling the course of a bore hole

Claim 2

Means for controlling the course of a bore hole that is being drilled in an underground formation, which means includes a down-hole motor provided with a housing and an output shaft, a first stabilizer and a second stabilizer, both stabilizers being mounted on the housing such that the first stabilizer is located nearer to the output shaft than the second stabilizer, characterized in that the central axes of the stabilizers are parallel to each other and at least the central axis of the second stabilizer is parallel to the central axis of the output shaft.

Claim 3

Means according to claim 1, characterized in that the central axis of the first stabilizer coincides with the central axis of the output shaft.

Claim 4

Means according to claim 1, characterized in that the central axes of both stabilizers are parallel to the central axis of the output shaft, wherein the eccentricity of the second stabilizer is greater than the eccentricity of the first stabilizer.

Claim 5

Means according to any one of claims 1-3, characterized in that a third stabilizer, having a central axis coinciding with the central axis of the output shaft, is positioned near the end of the housing opposite to the end of the housing from which the output shaft protrudes, and wherein the second stabilizer is arranged between the first and the third stabilizer.

Claim 6

Means according to any one of claims 1-3, characterized in that the second stabilizer is positioned near the end of the housing that is opposite to the end of the housing from which the output shaft protrudes.

Claim 7

Method for controlling the course of a bore hole that is being drilled in underground formations by means of a drill bit driven by a down-hole motor provided with a housing and an output shaft, which output shaft is in the operative position thereof during drilling of the bore hole tilted with respect to the bore hole, which method comprises the steps of: (a) lowering in the bore hole a drill string with the down-hole motor connected to the lower end thereof and having a drill bit connected to the output shaft, (b) actuating the down-hole motor to rotate the drill bit and applying a predetermined weight on bit, and (c) simultaneously with step (b) rotating the drill string over periods that are preceded and followed by selected periods during which the down-hole motor is activated but the drill string is not rotated.

Claim 8

Method for controlling the course of a bore hole that is being drilled in underground formations by means of a drill bit driven by a down-hole motor provided with a housing and an output shaft, which output shaft is in the operative position thereof during drilling of the bore hole tilted with respect to the bore hole, which method comprises the steps of: (a) lowering in the bore hole a drill string with the down-hole motor connected to the lower end thereof and having a drill bit connected to the output shaft, (b) actuating the down-hole motor to rotate the drill bit and applying a predetermined weight on bit, and (c) simultaneously with step (b) rotating the drill string over periods that are preceded and followed by selected periods during which the down-hole motor is activated but the drill string is not rotated.