Measuring speed of rotation of a downhole motor

摘要

The invention relates to downhole motors for rotating drill bits. The downhole motors may comprise stators, turbines or the like. The drilling motor may comprise a drilling apparatus comprising a drill bit connected to a rotor rotatably housed within a stator (or a turbine rotor in a housing), the rotor comprising at least one magnetic field source or magnetic field detector, and the stator comprising at least one magnetic field source if the rotor comprises a magnetic field detector or comprising at least one magnetic field detector if the rotor comprises a magnetic field source, thereby allowing the rotation speed of the rotor relative to the stator to be measured.

主权项

1. A drilling apparatus for drilling a borehole through an earth formation, comprising:
a drill bit connected to a downhole motor comprising a rotor and a stator at the bottom end of a drillstring in the borehole, with the rotor rotatably housed within the stator and the drill bit connected to the rotor, wherein:
the rotor is configured in use to be driven into motion by drilling fluid pumped down the borehole;the rotor comprises at least a first magnetic field source or at least a first magnetic field detector;the stator comprises at least a first magnetic field source if the rotor comprises a first magnetic field detector or comprises at least a first magnetic field detector if the rotor comprises a first magnetic field source; and further wherein either:
(i) the rotor or stator comprises both the first magnetic field source and a second magnetic field source, distinctive from the first, arranged never to be collinear with the centre of the rotor at any point during a full revolution of the rotor within the stator; or(ii) the rotor or stator comprises both the first magnetic field detector and a second magnetic field detector; and a processor configured to process signals generated by the at least one magnetic field detector, wherein the processor is configured to process a rotation speed and a direction of rotation of the rotor from the signals from the at least one magnetic field detector.