Apparatus for measuring the attitude of a borehole

Claim 1

Measuring apparatus for locating position, especially the inclination with respect to the vertical and the azimuth with respect to a horizontal reference direction, of a geological drilling line, said apparatus comprising, a. a rotary kinematic series constituted principally by: a pivoting part held coaxially with the axis XX of the drilling line by bearings and capable of pivoting freely in said bearings, a yoke defining an axis ZZ perpendicular to the axis XX, to which yoke said pivoting part is rigidly fixed, a pendulum device comprising a weight borne by a vertical rod fixed perpendicularly to a horizontal rod rotatable coaxially with the axis ZZ in bearings borne by the yoke, and a motor rotating a drive-shaft of which one end terminates at the level of the yoke and bears a drive pinion in mesh with an intermediate pinion mounted freely on the horizontal rod, the fixed portion of said motor being borne by the pivoting part, and b. detector means constituted principally by: first detector means comprising a rotary sensing element rotatably supported through pinions by the motor shaft and arranged so that a first electrical pulse is delivered to a receiver when this rotary sensing element passes to the vertical from its axis of rotation, second detector means comprising a rotary sensing element rotatably supported through arms by the motor shaft and passing before a fixed sensing element situated in a direction connected to the direction of the axis XX of the drilling line, said rotary sensing elements and fixed sensing elements being arranged so that a second electrical pulse is delivered to said receiver when the rotary sensing element passes before the fixed sensing element, third detector means comprising a rotary device sensitive to the terrestrial magnetic field so as to deliver a third electrical pulse when its sensing axis YY coincides with the axis of the terrestrial magnetic field, said rotary device being mounted through bearings coaxially with a vertical rod and rotated by the driving motor through a receiver pinion itself driven by the intermediate pinion, and fourth detector means comprising a rotary sensing element rotatably supported through arms by the rotary device and passing before a fixed sensing element situated in a direction connected with the extension, in a horizontal plane, of the axis XX of the drilling line, said rotary and fixed sensing elements being arranged so that a fourth electrical pulse is delivered to said receiver when the rotary sensing element passes before the fixed sensing element, the angular amplitude of the movement of the motor shaft between the first and the second electrical pulses being representative of the inclination of the axis XX of the drilling line with respect to the vertical, while the angular amplitude of the movement of the drive shaft between the third and fourth electrical pulses is representative of the azimuth of the axis XX of the drilling line with respect to the horizontal direction of magnetic north.