DETERMINING THE DEPTH AND ORIENTATION OF A FEATURE IN A WELLBORE
The invention relates to a device for determining the depth and orientation of a feature in a wellbore, and to a corresponding method. It also relates to a downhole apparatus for performing an operation in a well comprising a device for determining the depth and orientation of a feature in a wellbore and a device for performing the operation. In an embodiment, a downhole device (42) for determining the depth and orientation of a feature (24, 26, 28) in a wellbore (12) containing a ferrous tubing (14) is disclosed, the device comprising: at least one magnetic field sensor (44) for monitoring the inherent magnetic field of the ferrous tubing so that the presence of the feature can be detected; and at least one orientation sensor (48) for determining the orientation of the device within the wellbore. An output from the at least one magnetic field sensor is correlated with an output from the at least one orientation sensor so that the orientation of the feature detected by the at least one magnetic field sensor within the wellbore can be determined.